Species At Risk Act (SARA)

Large Whale Recovery Strategy

TABLE OF CONTENTS

DISCLAIMER

This draft Recovery Strategy for blue (Balaenoptera musculus), fin (B. physalus), and sei (B. borealis) whales in Pacific Canadian waters has been prepared by Fisheries and Oceans Canada. It defines the recovery goals, objectives and science-based strategies that are deemed necessary to protect and recover the species. It does not necessarily represent the views of all individuals whose expertise has been contributed to its development, or the official positions of the organizations with which they are associated. The goals, objectives and recovery approaches identified in the Recovery Strategy are based on the best existing knowledge and are subject to modifications resulting from new findings and revised objectives. Implementation of the recommended strategies is subject to appropriations, priorities and budgetary constraints of the participating jurisdictions and organizations. Further details on the implementation of the Recovery Strategy will be provided in an associated Recovery Action Plan two years following the approval of the Recovery Strategy.

RECOMMENDED CITATION

Edward Gregr, John Calambokidis, Laurie Convey, John Ford, Ian Perry, Lisa Spaven, Mark Zacharias. 2005. Draft Recovery Strategy for Blue Whales (Balaenoptera musculus), Fin Whales (B. physalus) and Sei Whales (B. borealis) in Pacific Canadian waters. Nanaimo: Fisheries and Oceans Canada. XX pp

EXECUTIVE SUMMARY

Blue (Balaenoptera musculus), fin (B. physalus), and sei (B. borealis) whales (order Cetacea, family Balaenopteridae) are collectively referred to herein as balaenopterid whales. While the degree of information on the individual species is variable, recovery is believed to be feasible for all three whale species considered in this recovery strategy. Critical habitat for these species has not been identified, and represents one of the most significant knowledge gaps, along with information of the size and distribution of the populations. The three species are considered collectively because the similar geographic distribution and shared threats warrant the development of an integrated, multi-species recovery strategy.

As the first target of the modern (i.e., steamship) whaling industry, blue whales populations were severely reduced in all the world's oceans during the early 1900s. Protected in the North Pacific in 1966, the Eastern North Pacific stock of blue whales currently numbers about 2000 animals and is one of the few populations known to be stable or recovering. In summer, the known range of this population extends from California to British Columbia and Alaska.

Fin whales were hunted concurrently with blue whales in the North Pacific. The largest catches were in the 1950s and 1960s, and resulted in significant population declines. The California/Washington/Oregon stock is believed to contain over 3000 animals, and is distinct from the Alaska stock. Fin whales are regularly seen off British Columbia in the summer months, however it is not known to which stock they belong.

Sei whales were hunted by modern whalers primarily after the preferred larger (or more easily taken) baleen whale species had been seriously depleted. Most stocks of sei whales were reduced by whaling in the 1950s through the early 1970s. North Pacific sei whales were not protected from whaling until 1976. The sei whale is the least studied of the large whales, and the current status of most stocks is poorly known. The existence of an Eastern North Pacific stock is assumed, but its range is unknown.

Whaling remains the greatest potential threat to large whales. While commercial whaling is unlikely to resume in the near future, the escalation of scientific whaling could eventually become cause for concern. More imminent threats to all three species include noise from industrial and military activities, collisions with vessels, entanglement in fishing gear, and habitat alteration due to both human and climatic effects. The possible effects of pollution on baleen whales are poorly understood. However, studies suggest that the body burdens of most contaminants (e.g., organochlorines and heavy metals) are lower in baleen whales than in toothed whales.

Trends in abundance of forage fish populations, whether driven by commercial fisheries, human-induced environmental variation, or natural processes, may affect the size and distribution of sei whale populations. However the diversity of prey known to be consumed by this species should provide some resilience to changing trophic conditions. Fin whales also appear capable of prey switching. Blue whales are most likely to be directly affected by reduced zooplankton concentrations potentially associated with global warming. With their more coastal distribution, fin whales appear to be more vulnerable to ship strikes and fishing gear interactions than either sei or blue whales.

The goal of this Recovery Strategy is to attain long-term viable populations of blue, fin, and sei whales that use Pacific Canadian waters. The objectives outlined to meet this goal are: to determine the population identities for the animals that occur in Pacific Canadian waters; to maintain or increase the portion of these populations using these waters; and to ensure that anthropogenic influences do not significantly reduce the potential habitat. The broad strategies outlined to address threats and effect recovery are: Critical Habitat Identification, Species Abundance and Distribution, and Threat Mitigation. However, significant gaps in knowledge remain, for which research activities have been identified. A multi-species Recovery Action Plan detailing specific recovery activities, timelines and estimated costs will be developed within two years of approval of this Recovery Strategy.

1. BLUE WHALE BACKGROUND

1.1 Current status

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1.2 Species description

Blue whales are the largest animals on the planet and are found in most oceans of the world. Blue whales range from the pack ice of both hemispheres to temperate and tropical waters, with distinct populations found in the North Atlantic, North Pacific, Southern Hemisphere, and the northern Indian Ocean (Mizroch et al. 1984, Rice 1998). These populations are further separated into six stocks by the International Whaling Commission (IWC) despite a poorly understood stock structure (Donovan 1991).

The longest recorded blue whale was 29.9 m (98 ft.) (Rice 1978). Body weights range from 80-150 tons (73,000-136,000 kg) with one report of a 190 ton female killed off South Georgia in 1947 (Tomilin 1967). Females are generally larger and longer than males and animals are larger on average in the southern hemisphere than in the northern hemisphere.

Blue whales have a light to slate-grey appearance above water with a characteristic mottled pigmentation. The pigmentation can range from a sparse mottling pattern to highly mottled individuals with splotches along the flanks, back and ventral surface. Chevrons often curve down and back on both sides of the rostrum behind the blowholes. This highly variable pigmentation and mottling patterns are distinctive and stable throughout life allowing individuals to be tracked using photo-identification (Sears and Calambokidis 2002).

The blue whale has a large, broad U-shaped head that comprises nearly 25% of its body length. The top of the head has a prominent rostral ridge that runs from the upper jaw and mandibles to the splash-guard in front of two blowholes. The dorsal fin is relatively small compared to other balaenopterids and is highly variable in shape. The flippers are approximately 4m in length (15% of body length) with blunt tips. The flukes are broad and triangular with a straight or slightly curved trailing edge, grey in colour, possibly with variable white patches on the underside.

Females give birth every 2-3 years in winter following a 10-12 month long gestation period. The calf weighs 2-3 tonnes and measures 6-7 m at birth. Blue whales nurse until 6-7 months of age and are likely weaned during the summer when on feeding grounds. Blue whales are thought to reach sexual maturity between 5-15 years for both sexes, and live 70-80 years (Sears and Calambokidis 2002).

Blue whales undertake extensive, seasonal north-south migrations each year from wintering grounds in the low latitudes to summer feeding grounds in productive mid to high latitude waters. Their distribution is better understood on their feeding grounds than on their winter grounds due to the extensive whaling that took place in the higher latitudes.

Global population estimates range from 5000-12,000, though these are not considered reliable (Carretta et al. 2003). Southern Ocean populations were the largest historically, with an estimated 300,000 animals pre-exploitation. Recent estimates of 710-1265 have been calculated for summer feeding grounds in Antarctic waters (IWC 1990, Butterworth et al. 1993, IWC 1996). However the wide range and dispersion of blue whales coupled with historically low sampling effort makes reliable population estimation difficult.

Historically, blue whales ranged throughout the coastal and pelagic waters of the North Pacific. Data on stock structure come primarily from historic whaling records, sightings, and acoustic recordings of vocalizations. Gambell (1979) suggested that there were three blue whale stocks in the North Pacific, while Reeves et al. (1998) concluded that as many as five sub-populations, including ones in the eastern Gulf of Alaska and California/Mexico, inhabited the North Pacific with an uncertain level of mixing between them. Analysis of blue whale calls has revealed two distinct call types; one prevalent in the western and central North Pacific and the other in the eastern North Pacific (Stafford et al. 2001), suggesting at least two populations of blue whales in the North Pacific.

The IWC manages the population as a single management unit (Donovan 1991), while the U.S. manages blue whales as two stocks, an Eastern North Pacific stock and a Hawaiian stock. The lack of recent sighting data in much of the species' former range suggests that some sub-populations may have been extirpated by commercial whaling.

The eastern North Pacific population ranges as far south as Mexico and Costa Rica during winter and is regularly sighted feeding off California during the summer. Migration begins by April and May north from the Gulf of California, Mexico, and the offshore waters of Central America and moves along the west coast of North America to concentrations in Californian waters, peaking in September.

The northern range of this population is unclear. Blue whale calls have been detected off Vancouver Island and further north in the Gulf of Alaska; however sightings at higher latitudes remain rare. The call intensity (defined as dB above ambient) off Vancouver Island from September to February (Burtenshaw et al. 2004) suggests that the animals off California may disperse northward and possibly offshore after September. A blue whale identified in the Gulf of Alaska south of Prince William Sound in 2004 had been identified frequently off California in previous years (Barlow and Calambokidis, unpublished data).

The size of the eastern North Pacific stock has been estimated using both line transect and mark-recapture (photo-identification) techniques. The population has been increasing since the moratorium on commercial whaling (Barlow 1994)and is currently reliably estimated at 2000 animals (Calambokidis and Barlow 2004). However the rate of increase is too great to be attributed to population growth alone (Barlow 1994) and may reflect a shift in distribution. Sparse sighting data throughout the northern Gulf of Alaska from Canada to the Aleutian Islands indicates that this increase does not apply to all regions of the eastern North Pacific (Sears and Calambokidis 2002). The relative contributions of population growth, distributional shifts, and habitat contraction to the increasing trends observed off California is unclear.

1.3.1 Canadian Pacific

Japanese scouting surveys (1965 - 1978) throughout the North Pacific include blue whale sightings in Pacific Canadian waters. While these data are difficult to translate into densities or abundances, they do show a relatively higher sighting rate for waters off British Columbia compared to most other areas surveyed (Sears and Calambokidis 2002).

"Discovery" tags used to examine the movements of commercially hunted whales showed a blue whale tagged on 4 May 1963 off Vancouver Island later killed on 21 June 1964 south of Kodiak Island (Ivashin and Rovnin 1967). This represents the longest distance recorded from this tagging program and provides some evidence for a proposed Central stock (as defined by Gambell 1979) that feeds in Alaskan waters. The winter range of this stock is not well understood, but may include the Hawaiian Islands (Sears and Calambokidis 2002). Historic records show an on-shelf to deep water distribution off British Columbia (Figure 1a), and a seasonal peak in abundance in July to September (Figure 2).

More recently, two blue whales photo-identified off the Queen Charlotte Islands in northern British Columbia both matched to animals seen off California (Calambokidis et al. 2004a). A whale identified on 12 June 1997 was re-sighted in the Santa Barbara Channel on 10 July 1997. It had therefore travelled at least 2500 km in 28 days representing a minimum swimming speed of 3.7 km/h (Sears and Calambokidis 2002). This individual represents the first confirmed movement between Californian waters and higher latitude feeding areas. Two blue whales were sighted near the shelf-edge off Queen Charlotte Sound in the spring of 2002, during the first of two bi-annual cruises now conducted annually by the Cetacean Research Program - Fisheries and Oceans Canada (CRP-DFO). A blue whale photo-identified south of Cape St James on a joint DFO/Cascadia Research cruise in August 2003 also matched to the California catalogue. A blue whale seen in 2004 in the Gulf of Alaska matched to the California catalogue, though in a different year (J. Barlow and J. Calambokidis, pers. comm.). In summer 2004, a blue whale tagged off California travelled as far north as Estevan Point, west coast Vancouver Island (Bruce Mate, pers. comm.). The B.C. Cetacean Sightings Network (BCCSN) database contains sightings from 1972 - 2004, with the majority collected since 1999 and virtually all of them provided by recreational boaters (Figure 3). Such opportunistically collected data do provide an indication of the distribution and relative abundance of species, however they are not corrected for effort, and consequently cannot be used to estimate population abundance or growth trends.

While visual sightings have been rare in recent years off British Columbia, Washington, and southeast Alaska, calls presumed to be from the Eastern North Pacific stock of blue whales have been consistently detected by bottom-mounted hydrophones from California to British Columbia and Alaska (Sears and Calambokidis 2002). Burtenshaw et al. (2004) showed a significant, almost constant intensity of blue whale calls off British Columbia from October to February.

Based on the available population estimates, the Eastern North Pacific stock represents anywhere from 12% to as much as 50% of the known blue whales in the world. Pacific Canadian waters appear to represent an important, secondary feeding ground for a large portion of the world's blue whales. The putative Central North Pacific stock may also, at least historically, have occasionally used Pacific Canadian waters.

Blue whales are low trophic level foragers requiring several tonnes of prey per day per individual (Sears and Calambokidis 2002). Thus, the viability and recovery of the blue whale population could be constrained by factors that limit availability of food. Given the large quantities of zooplankton required to maintain a blue whale population, their presence in, or absence from, an ecosystem is likely significant.

The massive reduction in biomass due to large-scale commercial whaling in the Antarctic is thought to have released as much as 150 million tonnes of krill annually, resulting in an increase in smaller predators such as seals, small cetaceans, and seabirds. The foraging habits of baleen whales are also thought to have major influences on the community structure in the Bering Sea, where the reduction of krill consumers due to commercial whaling may have influenced the dominant fish species observed in the Bering Sea during the 1970s and 1980s (Sears and Calambokidis 2002).

The change in the dominant fisheries in the Bering Sea is also related to large scale physical changes, or regime shifts, throughout the North Pacific. By modifying the distribution or abundance of regions of high primary and secondary production, these climatic events could affect both the total available prey for, and the foraging effectiveness of, blue whales.

Significant declines in zooplankton abundance have taken place off California since the 1970s and have been linked to increases in sea surface temperature (Roemmich and McGowan 1995). This has the potential to alter the carrying capacity of the North Pacific (Venrick et al. 1987). Broad scale changes in prey abundance have been attributed to gradual ocean warming and regime shifts (Francis and Hare 1994). Lower trophic foraging specialists such as the blue whale may be more immediately affected by these large-scale oceanographic shifts than other species with more diverse diets (Benson and Trites 2002).

Scars associated with killer whale (Orcinus orca) attacks are present on 25% of the blue whales sighted in the Sea of Cortez, however these marks are rare on blue whales in the St. Lawrence (Sears and Calambokidis 2002). One report describes an attack by a group of killer whales on a blue whale off Baja California (Tarpy 1979). While the rate of predation by killer whales on large baleen whales is unknown, increasing whale populations could lead to increased predation by killer whales. Killer whale predation may be more prevalent off California and Mexico than elsewhere based on the scarring rate of humpback whales (G. Steiger, pers. comm.).

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Blue whales feed along productive shelf break upwellings in temperate to polar waters from spring to early winter. They feed primarily on euphausiids (Euphausia pacifica, Thysanoessa spinifera, T. inermis, T. longpipes, T. raschii, and Nematoscelis megalops), though calanoid copepods (Calanus spp.) and pelagic red crab (Pleuroncodes planipes) also occur in the diet. They exploit dense concentrations of these prey species by engulfing prey with their large mouths and expanding throat pleats. Higher-latitude habitat is likely best defined by its suitability as a foraging ground.

Reproductive activity occurs in the winter season in tropical and sub-tropical waters, but no specific breeding grounds have yet been identified (Sears and Calambokidis 2002).

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2. FIN WHALE BACKGROUND

2.1 Current status

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The fin whale is the second largest member of the family Balaenopteridae, after the blue whale. It has been characterized as the "greyhound of the sea" due to its fast swimming speed and streamlined body (Reeves et al. 2002). Fin whales are widely distributed in all the oceans of the world, in both coastal and offshore waters. Although considered a single stock in the North Pacific by the IWC, there is more likely at least an eastern and a western population (COSEWIC 2004).

Fin whales can reach 27 m (88 ft) in length, with adult females 5-10% longer than males. Adult fin whales in the southern hemisphere are up to 4 m longer than their northern hemisphere counterparts, and have longer, narrower flippers. The body is generally dark grey or brownish-grey dorsally, shading to white ventrally. Some individuals have a V-shaped chevron on the dorsal side, behind the head. Asymmetrical colouring of the lower jaw, dark on the left and light on the right, continues about a third of the distance through the baleen plates, the remainder of which are a dark blue-grey. This colouration pattern is diagnostic for the species. The ventral surfaces of the flippers and flukes are also white. Some adults show scarring indicative of lamprey or remora attachment or nicks and scars on the fins or body that may stem from interactions with fishing gear or other animals. Individual animals can be identified by means of scarring, pigmentation patterns, dorsal fin shapes and nicks (COSEWIC 2004).

The head of the fin whale is narrow, measuring about 20-25% of total body length, with the rostrum particularly pointed, prominent splash guards around the double nares (i.e., nostrils) and a single median head ridge. The eyes lie just above the corners of the mouth. The lower jaw is laterally convex and juts 10-20 cm beyond the tip of the rostrum when the mouth is shut. The dorsal fin is set about three quarters of the way back along the dorsal surface, is falcate or pointed, and can be 60 cm high. Behind the dorsal fin, the caudal peduncle has a sharp, prominent ridge (COSEWIC 2004).

Fin whales can be confused with blue, sei (B. borealis) and Bryde's (B. brydei) whales, and with the recently described B. omurai. However based on the distribution of these species, confusion in Pacific Canadian waters is likely limited to blue and sei whales. The fin whale head is more pointed then that of the blue whale, with a larger dorsal fin, which is set further back and has a shallower rise than that of the sei whale. On surfacing, a fin whale's blowholes are seen first followed by the dorsal fin. In sei whales, the blowholes and dorsal fin usually appear almost simultaneously. The blue whale is the only member of the genus Balaenoptera to regularly "fluke up" (i.e., lift its flukes above the surface when starting a deep dive) (COSEWIC 2004).

Reproduction is similar to blue whales, with females calving every 2-3 years following and 11-12 month gestation period. Calves are born at about 6 m in length, and are weaned at an average length of about 11.5 m, at 6-7 months of age. Age at sexual maturity is estimated at 5 to 15 years for both sexes, at an average length in the northern hemisphere of 17.2 m (COSEWIC 2004). Similar to blue whales, the life span of fin whales is assumed to be around 80 years.

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Fin whales have a cosmopolitan distribution, though they are more abundant in temperate and polar latitudes. In the North Pacific, the known summer range extends northward to 50şN in the Sea of Okhotsk, 60şN in the Bering Sea and 58şN in the Gulf of Alaska, and southward to 40şN in the Sea of Japan and 32şN off the coast of California. The known winter range extends from Korea to Taiwan, the Hawaiian Islands and to the Baja California peninsula, although the distribution is believed to be primarily offshore (Leatherwood et al. 1988).

Fin whales summer at various locations along the eastern North Pacific coast, and are known to occupy some regions (at least the Gulf of California and south/central California) on a year-round basis. Summer aggregations have been documented in Oregon, and summer-fall groups have been observed in the Shelikof Strait/Gulf of Alaska region (Carretta et al. 2003). Acoustic detection occurs year-round of northern California, Oregon and Washington, with a concentration of activity between September and February (Moore et al. 1998).

The U.S. National Marine Fisheries Service (NMFS) recognizes three stocks in U.S. waters of the North Pacific: the Northeast Pacific stock, the Hawaiian stock, and the California/Oregon/Washington stock (Carretta et al. 2003). Fujino (1960) concluded that the North Pacific contains an eastern and a western population based on histological and marking data. The marking data further suggest that the fin whales off British Columbia may have been isolated to some degree.

Ohsumi and Wada (1974) estimated pre-exploitation abundance in the North Pacific at 40,000 - 45,000. Whaling reduced the numbers to an estimated 13,000 - 19,000 by 1973, of which 8500-11,000 were assumed to be from the eastern North Pacific (Oshumi and Wada 1974). The most recent estimate of the size of the California/Oregon/Washington stock based on ship surveys is 3279 (Coefficient of Variation (CV) = 0.31) (Barlow and Taylor 2001 cited in Carretta et al. 2003). Vessel surveys in July-August 1999 produced an estimate of 4951 (CV=0.29) fin whales in the Bering Sea (Angliss and Lodge 2003). To date, the available data are not sufficient for estimating population trends.

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2.3.1 Canadian Pacific

Pike and MacAskie (1969) regarded the fin whale as the most abundant baleen whale in Pacific Canadian waters, and suggested that the waters off Vancouver Island contained a summer feeding aggregation. Historically, fin whales were frequently observed in exposed coastal seas (Hecate Strait and Queen Charlotte Sound) and occasionally in the more protected waters of Queen Charlotte Strait and the Strait of Georgia (Pike and MacAskie 1969). Only 17% of the catch for which positions were recorded by British Columbia coastal whalers was on the continental shelf (Figure 1 and Gregr 2004).

Based on a comparison of whaling records from coastal stations around the Gulf of Alaska, Gregr et al.(2000) concluded that the species did not appear restricted latitudinally. An analysis of whaling records from British Columbia whaling stations identified fin whale habitat along the continental shelf, in the exposed inland waters of Dixon Entrance and Hecate Strait, and in a region offshore of northern Vancouver Island (Figure 1, from Gregr and Trites 2001).

Contemporary sightings of fin whales in Pacific Canadian waters are predominantly from the west coast of Vancouver Island, and the inland waters of Hecate Strait and Queen Charlotte Sound, and occur in both summer and winter. Recent annual spring and summer research cruises (2001 - 2005) have regularly recorded fin whales in off-shelf waters, near the shelf edge boundary of Queen Charlotte Sound, in Hecate Strait, and in Dixon Entrance. Summer sightings are also reported off southern Vancouver Island and in Queen Charlotte Sound and Hecate Strait (COSEWIC 2004). Winter sightings have recently been made in February, off the north end of Vancouver Island and in Hecate Strait (J. Ford, pers. comm.). The BCCSN database contains almost 100 opportunistic fin whale sightings (Figure 3).

NMFS conducted 2-week summer surveys in the northern offshore waters of Washington State each year from 1995 to 2002 and did not sight a single fin whale (Calambokidis et al. 2004b). Similarly, aerial surveys off the west coast of Washington and southwest coast of Vancouver Island in the early 1990s also did not spot any fin whales (Green et al. 1992 cited in Calambokidis et al. 2004b).

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Fin whales forage on a variety of species. Generally in the northern hemisphere they eat small invertebrates, schooling fishes and squids. Consequently, it has been suggested that that fin whale diet is as much a function of availability as preference (Gambell 1985b).

In the North Pacific, the diet is dominated by euphausiids (70%) followed by copepods (25%) with some fish and squid (Kawamura 1980). Flinn et al. (2002) examined records of stomach contents for fin whales taken in British Columbia and found similar results.

Due to the global overlap in range and diet with other baleen whales, inter-specific competition is likely (Aguilar and Lockyer 1987). Mixed groups of fin and blue whales are common and hybrids occur with surprising frequency (Bérubé and Aguilar 1998).

To some extent large baleen whales, consequent to their depletion by whaling, may have been 'replaced' in the ecosystem by ecologically-equivalent finfish stocks (Payne et al. 1990). Trites et al. (1999) suggested that in the Bering Sea some species of fish are significant competitors of whales.

Some predation of fin whales is possible by killer whales and sharks, though the degree of predation is unknown. Increased population size could lead to increased predation.

The ability to include small schooling fish in their diet shows that fin whales have some flexibility in their feeding strategy. This may allow the species to better adapt to reductions in particular prey items (e.g., euphausiids) than the more stenophagic blue whale, but perhaps not as well as the more generalist sei whale.

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The summer habitat of fin whales tends to consist of areas with dense prey concentrations (Kawamura 1980, Gaskin 1982). Woodley (1996) found that in the Bay of Fundy, fin whales occurred primarily in shallow areas with high topographic relief, and their occurrence was correlated with herring and euphausiid concentrations.

Fin whale distribution is associated with low surface temperatures off the northeastern U.S. and in the Bay of Fundy during summer months (Woodley and Gaskin 1996). Hain et al. (1992) documented an association with oceanic fronts, areas known for high biological productivity (Herman et al. 1981).

Conception and calving are believed to occur in low latitudes during winter, but no specific breeding grounds have yet been identified (e.g., Mizroch et al. 1984). Payne (2004) suggested that the long-distance communication abilities of the species may allow mating to occur without the need for breeding grounds or aggregations.

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3. SEI WHALE BACKGROUND

3.1 Current status

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The sei whale is the third largest member of the Balaenopteridae, after the blue and fin whales. Sei whales are cosmopolitan in their distribution, though they appear somewhat restricted to temperate waters, occurring within a more restricted range of latitudes than all other rorquals except Bryde's whales (COSEWIC 2003). There is evidence for three stocks of sei whales (western, central and eastern) in the Pacific (Masaki 1977).

An average adult sei whale is 15 m long and weighs 19 tonnes (Horwood 1987). Females are larger than males. Animals in the northern hemisphere appear to be smaller than those in the southern hemisphere (Tomilin 1967). The maximum reported lengths for a female were 18.6 m in the northern hemisphere and 20 m in the south (Gambell 1985a).

Sei whales are dark to bluish grey dorsally and white to cream coloured ventrally. The ventral grooves commonly have a white or light-coloured area extending from the chin to the umbilicus, although colouration is extremely variable. Oval-shaped scars from cookie-cutter shark bites and lampreys, and infestations of ectoparasitic copepods often occur on the lateral and ventral sides. The curved, slender dorsal fin is prominent measuring 0.25-0.75 m, and is set further forward on the body compared to blue and fin whales. The pectoral flippers are relatively short measuring only 9-10 per cent of the body length, dark grey ventrally, and pointed at the tips. The dark grey flukes are rarely raised to "fluke-up" before dives (COSEWIC 2003).

In the eastern North Pacific, fin and sei whales overlap morphologically in body size, colouration, and dorsal fin shape making the two easily confused. However, sei whales lack the asymmetric white colouration of the right jaw and ventral side that is diagnostic for fin whales. Confusion with fin whales, and to a lesser degree with Bryde's and minke whales, implies that sei whale population size and range could easily be underestimated (COSEWIC 2003).

Sei whales migrate from low-latitude wintering areas to high-latitude, summer feeding grounds. Catch records indicate that migrations are segregated according to length (i.e., age), sex, and reproductive status, with pregnant females leading the migration to the feeding grounds. The youngest animals arrive last and leave first, and travel to lower latitudes than adults. The wintering grounds of sei whales are largely unknown, though they are thought to occur far offshore (COSEWIC 2003).

Males and females reach sexual maturity between 5 and 15 years of age and live to approximately 60 years of age. In both hemispheres, the age of sexual maturity declined from 10-11 years to 8 years between the 1930s and the 1960s, likely in response to exploitation. Mating and calving occur in winter, followed by a gestation period of 10.5 to 12 months. Calves nurse for about 6 months and are weaned on the feeding grounds. The calving interval is 2-3 years (COSEWIC 2003).

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Historically the most abundant of the baleen whales, sei whales are now considered rare in U.S. and Pacific Canadian waters. They were once described as abundant off the west coast of Vancouver Island, British Columbia in June through August (Pike and MacAskie 1969). The pre-whaling North Pacific population, estimated at between 58,000 and 62,000 individuals, was reduced to between 7,260 and 12,620 animals by 1974 (COSEWIC 2003).

The IWC recognizes a single stock of sei whales in the North Pacific (Donovan 1991) however evidence does exist for multiple populations, at least historically. A review of marking studies, catch distributions, sighting and baleen morphology revealed three North Pacific stocks separated by 175°W and 155°W longitude (Masaki 1977). Fujino (1964) suggested a difference between sei whales caught in the inner Gulf of Alaska and off Vancouver Island based an examination of blood type. Different forms of parasites observed at opposite sides of the Pacific imply the existence of at least an eastern and western stock (Rice 1974).

NMFS recognizes an eastern and a western stock in the North Pacific, divided by 180°W (Carretta et al. 2002). The stock boundary is arbitrary due to a lack of information on population structure. An abundance estimate of 56 animals (CV = 0.61) was recently calculated by Barlow (2003 cited in Carretta et al. 2003) for the Eastern North Pacific stock, to a distance of 300 nm from shore. No population trend data are available.

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3.3.1 Canadian Pacific

Historic records clearly demonstrate that Pacific Canadian waters were once extensively used by sei whales (Figure 1), with a sharp peak in seasonal abundance during July (Figure 2). In recent years, cetacean surveys off the British Columbia coast and shelf break region have not resulted in a single confirmed sei whale sighting (Cetacean Research Program-DFO, unpublished data). Two confirmed sei whale sightings and 5 possible sightings (recorded as sei or Bryde's whales) were made in California, Oregon, and Washington waters during ship and aerial surveys between 1991 and 2001 (Carretta et al. 2003). These few sightings are the basis for the recent abundance estimate in that region.

Based on sighting data, the number of sei whales currently occurring in Pacific Canadian waters appears quite small and has shown no measurable signs of recovery since the species received protection from commercial whaling in 1976. No reliable information is available to estimate population trends. However, given the limited survey effort in portions of the range, and the difficulty in distinguishing this species from fin whales, sei whales likely continue to use Canadian waters.

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Sei whales are low trophic level foragers that feed primarily on calanoid copepods. However their diet also contains euphausiids, amphipods, and schooling fish and squid, particularly in the North Pacific (Nemoto and Kawamura 1977, Flinn et al. 2002). Stomach content analyses have revealed substantial regional differences in diet. In the Antarctic, euphausiids represented 54% of the sei whale diet whereas calanoid copepods represented 83% of the diet in the North Pacific (Nemoto and Kawamura 1977, Kawamura 1982).

Sei whales may forage more opportunistically in coastal waters, taking advantage of a more diverse prey base than is available in pelagic waters (Kawamura 1982). Stomach contents from British Columbia whaling stations reveal that copepods were the most common in 3 of 5 years, whereas fish and euphausiids each dominated in one of the other years (Flinn et al. 2002).

Differences in stomach contents between the North Pacific and the Antarctic may be due to the different trophic structures and prey availability in the two regions. In the Antarctic, the majority of biomass is in the form of zooplankton. In the North Pacific on the other hand, there is a greater abundance of zooplankton consumers, increasing the prey abundance at higher trophic levels (Nemoto and Kawamura 1977). Seasonal trends in stomach contents may also indicate a seasonal shift from a spring diet dominated by fish to one dominated by euphausiids or copepods later in the summer (Rice 1977, Flinn et al. 2002).

The ecological role of sei whales therefore seems to be that of a generalist, low-trophic level feeder. Whether this ability to generalize diet is a characteristic of all individuals, or if different individuals tend to specialize on different prey types, is unknown.

Sei whales are reported to carry both endo- and ectoparasites, and appear to be more susceptible to heavy infestations of parasitic helminthes (i.e., flatworms) than other baleen species. Although these parasites are typically not pathogenic, a sufficiently large infestation of the liver or kidneys can be fatal. The degree to which parasitic infections currently affect sei whales is unknown. Seven percent of sei whales killed in California between 1959 and 1970 were infected with a disease that caused the shedding of baleen plates. Apart from the missing baleen, these whales had fish in their stomachs and were in good condition (COSEWIC 2003).

Some predation of sei whales is possible by killer whales and sharks, though the degree of predation is unknown. Increased population size could lead to increased predation.

The sei whale's flexible foraging strategy of both skimming and gulping enables them to adapt to fluctuations in prey quality and abundance. Combined with their apparent ability to alter their distribution according to localized, periodic changes in habitat quality, this should make the species relatively resistant to shifts in biomass among lower trophic levels.

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Sei whales use both "skimming" and "engulfing" (or gulping) feeding strategies (Nemoto and Kawamura 1977) and feed primarily on calanoid copepods. They are typically found in relatively deep waters, primarily associated with offshore, pelagic habitats. In the northwest Atlantic, sei whales are associated with the continental shelf edge (Hain et al. 1985). In British Columbia, less than 0.5% of the historical coastal whaling catch for which positions were recorded were on the continental shelf (Gregr 2002).

Examinations of baleen whale distributions in relation to oceanographic conditions suggest a close association with oceanic fronts. Sei whales are reportedly observed along major mixing zones and eddies that had broken away from fronts and the animals may follow these fronts seasonally (Nasu 1966). These fronts can be somewhat permanent, near predictable oceanic features such as major upwelling areas, or they can be associated with more dynamic features such as eddies or jets formed near topographical features shearing off major currents (COSEWIC 2003).

Sei whales are often observed on the same foraging ground for many years and then disappear for prolonged periods of time. Whalers spoke of "sei whale years" in the Antarctic (Gambell 1985a), and in the North Atlantic, these dramatic influxes of sei whales were called "invasion years" (Jonsgĺrd and Darling 1977). Unpredictable arrivals of sei whales to the North Pacific feeding grounds are also reported in the British Columbia whaling records (Gregr 2002).

Nemoto and Kawamura (1977) implied that sei whales expanded their range to higher latitudes following the exploitation of blue and fin whales. If this is the case, then "pre-exploitation" distribution and population estimates may be based on data biased by the previous exploitation of these other species.

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4. THREATS

Blue, fin, and sei whales share both historic and current threats. These species are currently threatened by a variety of anthropogenic sources, including acute and chronic noise, ship strikes, fishing gear interactions, and possibly chemical bioaccumulation. The influence of some or all of these threats may result in reduced use of available habitat and/or reduced reproduction. Habitat may also be altered by medium and long term climatic shifts.

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Commercial whaling devastated the stocks of blue, fin, and sei whales in every ocean of the world in less than 80 years. Whaling continues in a variety of forms including subsistence hunts and scientific research (Clapham et al. 1999), but is typically directed at more abundant species, and is not presently considered a threat to blue, fin or sei whales in the eastern North Pacific.

Blue whales were the first target of modern commercial whaling and their populations were severely depleted in all oceans of the world. The species was protected worldwide in 1966 by the IWC. An estimated 325,000-360,000 blue whales were killed in the Antarctic during the first half of the 20th century, nearly extirpating the Southern Hemisphere population. In the North Pacific, blue whales were hunted by both coastal, shore-based whalers and pelagic whaling fleets, taking an estimated 9500 animals. Almost half of these were killed off the west coast of North America (Sears and Calambokidis 2002).

There is clear evidence that whaling depleted the populations of blue whales off British Columbia. Shore-based stations operating in British Columbia from the early 1900's through 1967 killed at least 650 blue whales, though the annual catch declined rapidly as the population was depleted (Figure 2). From 1948 to 1965 mean lengths of blue whales killed from British Columbia shore stations declined significantly along with pregnancy rates (Gregr et al. 2000).

Fin whale populations off the coast of British Columbia were reduced by whaling in parallel with blue whales, following the introduction of modern whaling. Local populations suffered further loss when the coastal fleet was upgraded in the 1950s (Figure 2). At least 7605 fin whales were taken by British Columbia coastal stations between 1908 and 1967 (Gregr et al. 2000). Fin whales were most heavily exploited through the 1950s and 1960s, when the annual catch from the North Pacific ranged from 1000 to 1500 animals. Until 1955, most whaling off the west coast of North America was off British Columbia, after which catches began to increase off California. Fin whales in the North Pacific were protected by the IWC in 1976 (Mizroch et al. 1984).

Although not a primary target for whalers until blue and fin whale populations were severely depleted, sei whales were heavily exploited during the last decades of commercial whaling. Following the depletion of blue and fin whales, over 110,000 sei whales were killed in the Antarctic between 1960 and 1970. In the North Pacific, catches peaked at over 25,000 animals per year in the late 1960s. The last year of sanctioned whaling for this species in the North Pacific was 1975. On the Pacific coast, at least 4002 sei whales were taken by coastal stations in British Columbia between 1908 and 1967, with the majority taken after 1955 (Gregr et al. 2000). The total sei whale catch from the North Pacific was almost twice the fin whale catch, and close to 20 times the blue whale catch between 1925 and 1985 (IWC unpubl. data).

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Ship strikes, chronic noise from commercial shipping, and acute noise from low frequency active sonar are potentially the greatest current threats to balaenopterid whales. Seismic surveys, oil and gas extraction, and shipping lanes have the potential to reduce potential habitat for these species by making areas uninhabitable due to increased ambient noise levels, at least for short periods of time. Entanglement in fishing gear and marine debris may also pose threats to individuals. As populations increase, fin whales in particular may become more at risk to interactions with human activities because of their more coastal distribution. Synergistic effects of seemingly unrelated stressors have recently been identified in other mammal species and cannot be ruled out for cetaceans (Sih et al. 2004 cited in Payne 2004).

While threats are difficult to prioritize given the lack of information, ship strikes should currently be considered the most important threat to individual fin whales in Pacific Canadian waters because of their more coastal distribution. Prioritizing threats for blue and sei whales is more difficult. However the possibility that habitat degradation (or loss of use) through increased ambient noise levels may limit the recovery of these species near shipping lanes and other areas of high noise production should be considered a leading threat.

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Blue and fin whales often occupy shelf edge locations that frequently coincide with shipping lanes, which concentrate large vessel traffic. Since balaenopterids sink after being struck and killed, strandings are rare and ship strikes may go unreported. While there is little evidence directly linking ship strikes with large whale mortality in the eastern North Pacific, 16% of blue whales observed in the St. Lawrence have marks associated with large propellers or hulls (Sears and Calambokidis 2002). Between 1980 and 1993, at least four blue whales were struck and killed off California. An additional four injuries and two mortalities of large whales were attributed to ship strikes during 1997-2001 in North Pacific waters (Carretta et al. 2003). Additionally, at least six fin whales were reported struck and killed in or near Pacific Canadian waters between 1999 and 2004 (COSEWIC 2004), and a single dead sei whale came into the Strait of Juan de Fuca on the bow of a ship in 2003. It appears that large vessels travelling more than 14 knots (26 km/h), particularly high-speed container ships, present the greatest risk of ship strike mortality to whales (Laist et al. 2001).

Increased data on the distribution of blue, fin, and sei whales and the identification of how their critical habitat overlaps with shipping lanes will help determine the degree to which ship strikes threaten large whales.

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Baleen whales rely on sound primarily for social communication, such as that associated with reproduction. The degree to which these animals may use sound for navigation is not known. Underwater noise has the potential to disrupt natural behaviours such as migration, foraging, and finding mates. Potential effects depend on the nature of the noise. Chronic noise may result in population level changes in both short and long term behaviour, while acute sounds may result in permanent hearing loss and mortality. Noise is therefore a potential threat to individuals, the population, and the habitat of these species (COSEWIC 2003).

While few data are available to assess physiological responses of marine mammals to anthropogenic noise, observed effects include both temporary and permanent hearing threshold shifts, the production of stress hormones, and tissue damage, likely due to air bubble formation or as a result of resonance phenomena (see studies cited in RKWRT 2005).

The 'loudness' of a sound is described in terms of pressure. How quickly a sound attenuates depends on the physical and oceanographic features of the local marine environment, and on its frequency - higher frequencies attenuate more quickly than lower frequencies. Some sounds are continuous, whereas others are pulses of sound that are generated at specific intervals. Frequency ranges are also variable, ranging from broadband sounds such as seismic surveys, to narrowband sounds such as military sonar. Thus, the length of exposure, loudness, frequency, and the nature of the sound combine to determine the impact on marine mammals (RKWRT 2005).

There has been a rapidly growing awareness that noise may be a significant threat to animals that degrades habitat and adversely affects marine life. It is estimated that ambient (background) underwater noise levels have increased an average of 15 dB in the past 50 years throughout the world's oceans (NRC 2003). One result is that in certain parts of Northern Hemisphere oceans, the area over which a fin whale can hear a con-specific has decreased by four orders of magnitude (Payne 2004).

Functional models indicate that hearing in larger marine mammals extends to 20 Hz, and may extend to frequencies as low as 10-15 Hz in several species, including blue, fin and bowhead whales. The upper range of mysticetes is predicted to extend to 20-30 kHz (Ketten 2004). Thus, anthropogenic noises produced primarily in these frequencies are of concern for balaenopterids. These include air guns and drilling used for oil and gas exploration and extraction, active sonar and explosives used for military operations, and commercial shipping traffic.

Commercial shipping has increased dramatically in recent years, and is largely responsible for the increased ambient noise levels in the marine environment over the last 100 years. In the northern hemisphere, shipping noise is the dominant source of ambient noise between 10 to 200 Hz (NRC 2003). This chronic noise likely reduces the ability of large whales to maintain contact with conspecifics, potentially reducing mating and foraging opportunities (Payne 2004). The noise from these vessels is at a frequency capable of masking blue whale calls (Richardson et al. 1995).

Active military sonars transmit pulses of tones at frequencies within the acoustic range of balanenopterid whales, and at source levels that may be heard underwater for tens to hundreds of km, depending on the frequency. There is growing evidence that these noises may pose a significant threat to cetaceans. Active military sonars have been associated with increased strandings of beaked whales and humpback whales, and with the displacement of western North Pacific grey whales from their feeding grounds (see studies cited in RKWRT 2005). Active sonar must be considered a threat to northeast Pacific balaenopterids as the U.S. and Canadian Navies conduct joint operations in Canadian waters. However information on the use of active military sonar is limited for security reasons (RKWRT 2005).

Low Frequency Active (LFA) sonars send out 'pings' to detect submarines, and operate below 1 kHz. Their range can extend tens to hundreds of km. The U.S. Navy is now forbidden from deploying these units except in one area in the western Pacific Ocean and during periods of war, but this ruling is under appeal by the U.S. government. A Canadian LFA sonar is currently being tested off the Atlantic coast (RKWRT 2005).

Mid-frequency (MF) sonars operating between 1-10 kHz are used to detect mines and submarines, and have been associated with mass stranding events in the Bahamas, Canary Islands, and Greece. MF sonars are suspended into the water by helicopters, and are hull-mounted on some classes of Canadian military vessels. It is not clear whether mitigating protocols are used when military sonars are operating in Pacific Canadian waters. However existing mitigation measures used in Atlantic waters (i.e., sonar use is discontinued if odontocetes are observed within 1 km of the ship) are likely inadequate given what is now known about the impact of high intensity low and mid frequency sounds on marine life (see studies cited in RKWRT 2005).

Commercial sonar systems are generally standard equipment on any vessel over 5 m. While units operating below 100 kHz may be of concern to balaenopterid whales, the majority of these units are operated in near-shore, shelf areas less likely to be used by blue or sei whales. Fin whale distributions tend to overlap with areas of increased commercial sonar use. However the predictable nature of this sound should provide an opportunity for avoidance, potentially mitigating any acute effects.

Seismic surveys generate high intensity sounds with most of their energy concentrated at frequencies (5-300 Hz) relevant to balaenopterids. Current survey methods involve towing airgun arrays at approximately 2.6 m/s (5 knots), and firing the guns every 10-12 seconds. Airgun arrays have been detected over 3000 km from their source (see studies cited in RKWRT 2005).

Systematic observations in the eastern North Atlantic found that cetaceans were generally seen further away from the survey vessel during periods when airgun arrays were firing (Stone 2003). Grey and bowhead whales appear to avoid seismic surveys, although in some cases male sperm whales and feeding humpback whales did not (see studies cited in RKWRT 2005). Mortality has been associated with the use of seismic surveys in the Gulf of Mexico. It could be that the degree of tolerance exhibited by cetaceans to noise is related to the behavioural state of the animals.

No experimental studies of the physical effects of seismic surveys on cetaceans have been conducted. However mammalian ears share certain structural similarities with other vertebrates (Fay and Popper 2000), and a small (20 cu in) airgun has been shown to cause permanent hearing loss in caged fish. It is reasonable to assume that airguns are capable of damaging cetacean ears if the whales cannot avoid the sound source (see RKWRT 2005 and studies therein). Since acoustics are important to large whales, the fitness costs associated with hearing damage would likely be high.

Mitigation strategies exist, to some extent, for the acute effects of military sonar and seismic surveys. In the U.S., military sonar use is to be discontinued if marine mammals are observed, while various mitigation strategies to reduce potential disturbance from seismic surveys have been used on Canada's east coast and elsewhere. DFO is currently developing standards and a mitigation policy for seismic surveys (DFO 2005). These strategies typically include 'soft starts' (the ramping up of noise levels at the start of surveys), and discontinued use if marine mammals are observed. Surveys are also scheduled to avoid seasons when the majority of animals are believed to be present. The effectiveness of these mitigation strategies has yet to be critically evaluated.

Since seismic surveys are localized to shelf regions, the acute effects are likely of limited concern for balaenopterids, except perhaps for fin whales. The chronic effects of habitat loss (actual and/or loss of use) due to ambient noise may ultimately prove to be a greater concern, again likely more for fin whales, but also for blue and sei whales given the potential for sound propagation in water. However these chronic effects remain uninvestigated.

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While gear interactions do result in some mortality of large whales on the east coast, there has been little evidence of gear-related injury or mortality for balaenopterid whales in the eastern North Pacific. The NMFS Pacific Take Reduction Plan, implemented in 1997 to reduce by-catch from fisheries, has not documented any blue or sei whale kills from 1997-2001 (Barlow and Cameron 2003). A review of stranding reports from 1990 to 1996 for Canada's west coast reported several incidents of entangled, unidentified large whales, and a fin whale was observed entangled in what appeared to be a crab-pot line during a 2004 survey (COSEWIC 2004). However as the species begin to recover the potential for gear interactions may increase, particularly for fin whales using more nearshore waters where such interactions are more likely to take place.

Whale watching tours targeting blue whales in the North Pacific are based primarily off California and in the Sea of Cortez, Mexico. Whale watching industries in British Columbia primarily target killer whales, grey, and humpback whales. However given their size, blue and fin whale watching would very likely increase should such trips become economically feasible for commercial operators. Potential impacts on blue and fin whales from whale watching would include injury from propellers and vessel strikes, and increased acoustic disturbance (see above). Sei whales are unlikely targets for any commercial whale watching operation in Pacific Canada because of their primarily offshore distribution.

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Large whales may be exposed to pollution in a number of ways, including the ingestion of contaminated prey items or through contact with oil spills. O'Shea and Brownell (1994) concluded that there was no evidence of toxic effects from metal or organochlorine contamination in baleen species (see also Sanpera et al. 1996), largely because they feed at relatively low trophic levels. However other, primarily piscivorous, marine mammals are thought to be at risk from immunotoxic chemicals (Ross 2002). Effects that have been shown for marine mammals include depression of the immune system, reproductive impairment, lesions and cancers (Aguilar et al. 2002).

Concentrations of organochlorines sufficient to warrant concern were found in fin whale samples taken in the Gulf of St. Lawrence in 1991-92 (Gauthier et al. 1997). However a retrospective analysis comparing these samples to earlier ones collected in 1971-72 off Newfoundland and Nova Scotia found that the St. Lawrence concentrations were significantly lower (Hobbs et al. 2001). Fin whales feed at a similar trophic level to sei whales, thus, the risk from chemical bioaccumulation in sei whales is likely to be similar, and possibly even lower for blue whales. Decreasing trends have been found for other marine mammals (principally pinnipeds) in eastern Canada (Hobbs et al. 2001). However Muir et al. (1999) found that organochlorine contaminants in cetaceans show both increasing and decreasing trends, depending on species and geographic location.

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Regime shifts cause major changes in ecological relationships in marine systems over large-scale oceanographic areas (Francis and Hare 1994), and are manifested sooner at lower trophic levels (Benson and Trites 2002). Increased surface water temperature could cause declines in zooplankton populations (Roemmich and McGowan 1995), thereby changing the carrying capacity of the Pacific (Venrick et al. 1987). Blue whales feed exclusively on zooplankton, primarily euphausiids. Off British Columbia, fin whales eat euphausiids and schooling fish, while sei whales have a more diverse diet that includes copepods and forage fish (which prey on zooplankton). All species require concentrations of high prey densities for successful foraging. Such concentrations depend on physical oceanographic factors such as current flows, temperature, and phytoplankton growth. Given the narrower range of prey types, the blue whale may be relatively more sensitive to climate change impacts than either the fin or sei whale.

The displacement of foraging habitat due to short- (e.g., El Nino), medium- (e.g., Pacific Decadal Oscillation) and long-term (e.g., climate change) phenomena is likely, as the timing and spatial distribution of zooplankton abundance can be directly related to physical conditions. How large whales locate suitable foraging habitats is unknown. However matrilineal fidelity to feeding grounds has been observed in other baleen species (humpback, right, and grey whales). Such fidelity implies a reduced ability to locate new feeding grounds when changing oceanographic conditions lead to a significant shift in prey distribution.

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5. Critical habitat

The Species at Risk Act (SARA) defines critical habitat as the "habitat necessary for the survival and recovery of a listed wildlife species and that is identified as the species' critical habitat in the recovery strategy or in an action plan for the species." Although the distribution of blue, fin, and sei whales is believed to be somewhat sympatric, the lack of contemporary sei and blue whale sightings in Pacific Canadian waters makes critical habitat designation difficult at this stage of the recovery planning process.

Gregr and Trites (2001) proposed that oceanographic conditions off the north end of Vancouver Island create suitable conditions for the entrainment of phytoplankton and zooplankton. These conditions include the transport of primary production from upwelled areas further south, the wash-out of zooplankton from the continental shelf, and the confluence of major currents creating entrainment features such as fronts and eddies. They proposed that the region (Figures 1, 4) represented a 'multi-species critical habitat' area for a suite of large whale species. The importance of the region has yet to be validated, and does not represent critical habitat in the SARA context. Nevertheless, critical habitat for these species may be largely ephemeral (e.g., fronts and eddies), structured by oceanographic conditions and their interactions with each other, and with permanent physical features (e.g., shelf breaks and canyons).

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Further research is needed before critical habitat in Pacific Canadian waters for balaenopterid whales can be identified. SARA allows for a schedule of studies to be developed to identify critical habitat where available information is inadequate. See Section 8.4.1 Schedule of studies to identify critical habitat for more details.

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As critical habitat for these species is believed to be ephemeral and structured largely by oceanographic conditions, it is less likely than terrestrial landscapes to be permanently destroyed by human activities. In this context, destruction of critical habitat is taken to mean its degradation to the point where it is unlikely to be occupied by balaenopterids. Once critical habitat is defined, potentially destructive activities will be more easily assessed.

Increased noise or vessel traffic could potentially degrade critical habitat, particularly for foraging. Relevant planned or anticipated activities include port expansion near Vancouver to accommodate the largest 'super' tankers (VPA 2004), and the potential for oil and gas exploration in the vicinity of Queen Charlotte Sound and Hecate Strait. In 2001, the British Columbia government lifted the provincial moratorium on oil and gas exploration and has requested that the federal government do the same. The resulting Royal Society panel (RSC 2004) recommended the lifting of the 30 year moratorium, but outlined a rigorous regulatory regime and numerous data gaps, including the collection of baseline data, and the definition of critical habitat for endangered species, that should be addressed prior to commencement of exploratory activities.

DFO receives occasional geophysical survey permit applications from industry, government (e.g., Natural Resources Canada), and universities (RKWRT 2005). These activities have the potential to degrade critical habitat, at least temporarily.

Increased use of commercial sonar concomitant with increases in shipping traffic will continue to increase ambient noise levels. The degree to which this acoustic pollution may, or already has, degraded habitat located near commercial shipping lanes has not been determined. Increased on-shelf vessel traffic could degrade habitats more commonly used by fin whales.

The role of climate change on the marine environment is a very active area of research by both oceanographers and marine biologists. The effects of decadal scale regime shifts and longer term trends in ocean climate on the habitats of marine mammals are currently poorly understood. Nevertheless the effects of such changes, whether natural or human-induced, are beyond the control of any individual jurisdiction, and will require monitoring on the scale of entire ocean basins to be completely understood.

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There are currently no marine areas designated to specifically protect the habitat of blue, fin, or sei whales. However under the Canada National Marine Conservation Areas Act, Parks Canada is responsible for the creation of National Marine Conservation Areas (NMCAs) which will be managed for sustainable use, and protected from industrial activities such as marine dumping, mining, and oil and gas exploration and development. A proposed NMCA in the southern Queen Charlotte Islands will extend 10 km offshore from Gwaii Haanas National Park Reserve. This will provide some protection to a small portion of nearshore habitat occasionally used by fin whales. Consultations on the proposed NMCA are on hold pending negotiations with the Council of the Haida Nation.

In addition to the Conservation Areas Act, the Fisheries Act has provisions to protect marine mammal habitat. Marine Protected Areas may also be established under the Oceans Act. Once critical habitat is identified (see Section 5.1), approaches for its protection under the provisions of the SARA will be more easily determined.

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6. Actions completed or underway

6.1 Legal status and protection

Blue whales have been protected from whaling by the IWC since 1966 while North Pacific fin and sei whales have been protected by the IWC since 1975. All three species are listed as "Protected", an IWC designation for stocks smaller than 40% of their maximum sustainable yield levels. The three species are also listed as "Endangered" by the IUCN (World Conservation Union) based on whaling exploitation. The Convention on the International Trade in Endangered Species of Wild Fauna and Flora (CITES) lists blue, fin and sei whales under Appendix 1 (species threatened with extinction, in which international trade is prohibited).

In the U.S., blue, fin, and sei whales were listed as "Endangered" under the Endangered Species Conservation Act of 1973 and are protected under the Endangered Species Act (ESA) and the Marine Mammal Protection Act (MMPA). NMFS and the United States Fish and Wildlife Service (FWS) share responsibility for the administration of the Act.

In Canada, the Pacific populations of blue and sei whales were legally listed and protected as "Endangered" under the SARA in January 2005. The Pacific fin whale population was designated by COSEWIC as "Threatened" in May 2005, and listing under the SARA is anticipated. The SARA prohibits harm (killing, harassing, capture or take) to listed species, includes provisions to protect critical habitat, and requires the development of a recovery strategy for each listed species.

Marine Mammal Regulations under the federal Fisheries Act prohibit the disturbance of marine mammals except for hunting or research, where a permit is required. Whale watching guidelines have been developed as a general code of conduct to avoid disturbing whales, and will soon be reflected in amendments to the Marine Mammal Regulations.

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In the U.S., NMFS finalized the recovery plan for blue whales in 1998. The recovery plan for fin and sei whales remains in draft form, awaiting legal clearance (Waring et al. 2001). NMFS researchers undertake extensive dedicated surveys of the U.S. west coast and Bering Sea for marine mammals every year. Extensive marine mammal habitat studies are underway off California for species including blue whales, and acoustic detection has been used to study their distribution in the eastern North Pacific. Since 2002, marine mammal surveys along primarily the north coast of British Columbia have resulted in two blue whale sightings in 2002, one in 2003, and none in 2004. No sighted animals have been identified as sei whales, while individual and groups (3-10) of fin whales are often sighted. Given the difficulty in positively distinguishing between fin and sei whales at sea (the right mandible must be observed for positive identification), the lack of sei whale sightings cannot be considered definitive.

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7. Knowledge gaps

Lack of information on population trends and human caused mortality are the basis of continued listing of large whale species in the U.S. (Waring et al. 2001). No current abundance estimates or population trends exist for blue, fin, or sei whales in Canadian North Pacific waters. There is an urgent need for information on the abundance and distribution of blue, fin and sei whales in Pacific Canadian waters, their habitat, and the threats they face.

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Uncertainties about stock structure, distribution and relative abundance will make mitigation of threats more difficult. A clear understanding of the populations that use Pacific Canadian waters, and how these populations are distributed in other jurisdictions within the species' range (Alaska, California/Washington/Oregon, Mexico) is needed in order to address threats to recovery.

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Critical habitat(s) have not been definitively identified for any baleen whale species in Pacific Canadian waters. This lack of delineation makes habitat protection and potential threat assessment difficult. Basic abundance and distribution data is required in order to identify critical habitat. Refer to Section 8.4.1 for a schedule of studies to identify critical habitat.

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How human activities affect the mortality, foraging, reproductive success, and critical habitat of blue, fin and sei whales requires investigation. The frequency of ship strikes and fishing gear interactions needs to be quantified to ensure that these potential sources of mortality are not responsible for the lack of recovery.

The intensity and distribution of acoustic disturbances needs to be characterized in relation to foraging areas and critical habitat. An improved understanding of the species' sensitivity and resilience to anthropogenic sounds needs to be assessed in order to determine whether noise is, or will become, a significant hindrance to recovery.

While the effect of chemical pollution on balaenopterid whales is thought to be minimal, because of their trophic position, this has not been determined definitively. The effects of oils spills, both chronic and acute, and other forms of marine pollution (i.e., plastics and other forms of floating jetsam) are also poorly understood and should be investigated to the extent possible.

Understanding how ocean climate contributes to the formation of critical habitat will facilitate the development of hypotheses describing how a changing climate may reduce or displace balaenopterid habitats.

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8. Recovery

The blue, fin, and sei whales that occur in Pacific Canadian waters are presumed to belong to populations that range over the entire eastern North Pacific. These populations move seasonally between international, Canadian, U.S., and possibly Mexican territorial waters. Thus the recovery of these populations is unlikely to be accomplished by Canadian efforts alone. The need for multi-lateral and international cooperation is therefore considered essential to the successful recovery of these species.

The recovery strategy must consider the long time scales associated with the longevity of these species and the relatively slow response of their associated life history parameters. However it must also address imminent threats and immediate conservation issues impacting the species.

It must also be recognized that marine habitats are dynamic, at both short and long time scales, and that the physical oceanographic processes that contribute to the creation of habitat are largely beyond human control. The recovery strategy should therefore focus on human actions and activities that can be directly managed.

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Recovery of the blue and fin whale populations that use Pacific Canadian waters is considered feasible. The precautionary approach requires the presumption that recovery of sei whales is also feasible, at least until proven that they no longer make use of Pacific Canadian waters.

Given their apparently low abundance and considerable longevity, none of these whale populations can be expected to recover to historic levels in the near future. For example, while the eastern North Pacific blue whale population now appears stable and may be increasing (Carretta et al. 2003), this has taken over 30 years since the cessation of commercial whaling. Expectations for recovery should therefore reflect these long time scales.

Despite being decimated by commercial whaling, blue whales continue to make use of Canadian waters, and fin whales are regularly sighted in both shelf-break and on-shelf habitats. Thus, available evidence clearly implies that these species have the opportunity to recover in Pacific Canada.

While apparently less abundant now in the eastern North Pacific than fin or blue whales, sei whales likely continue to use Canada's offshore Pacific waters. The recovery of the species in the eastern North Pacific should be facilitated by its more diverse diet.

Fin and blue whales in the eastern North Pacific are sufficiently abundant (see Sections 1.3 and 2.3 'Population size') to have the reproductive potential needed for increased population growth rates. This may also be the case for sei whales, despite recent estimates of just 56 animals for this region (Section 3.3). Sei whale populations are known to be highly mobile, preferring offshore habitats and rarely frequenting coastal areas. A longer time series of observations is therefore required before recovery feasibility is disproved.

The physical processes responsible for concentrating prey species have changed little over time. Thus, sufficient potential habitat for these species - defined as the availability of prey concentrations - is likely available in Pacific Canadian waters.

The threats identified to both individuals and populations could be mitigated through management actions, and a number of techniques have been demonstrated as effective. For example, on the east coast, shipping lanes have been moved and an early warning system has been implemented to reduce the likelihood of ship strikes on right whales; and gear modifications on both east and west coasts have been effective at reducing entanglements of humpback whales and smaller cetaceans. Mitigation strategies have also been developed in a number of jurisdictions to reduce the impact of seismic surveys and military-related sonar use.

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Blue, fin and sei whales are long-lived species with life spans between 50 and 100 years. Long term goals must span several generations, and therefore have a horizon of 150-300 years. The recovery goals for these species are:

1. To attain long-term viable populations of blue and fin whales that use Pacific Canadian waters.

2. To attain a long-term viable population of sei whales that occasionally use Pacific Canadian waters.

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Blue, fin, and sei whales that occur in Pacific Canadian waters are presumed to belong to eastern North Pacific populations. These populations move seasonally between Canadian, U.S., international, and possibly Mexican territorial waters. These objectives refer only to the portion of these populations that occur in Canadian waters.

1. By 2011, determine the identity of the population of blue and fin whales that occur in Pacific Canadian waters.

2. Maintain or increase the relative proportions of blue and fin whales in Pacific Canadian waters compared to the whole population through to 2016.
3. By 2011, confirm the presence of sei whale(s) in Pacific Canadian waters. If confirmed, maintain or increase the relative proportion of sei whales that occur in Pacific Canadian waters compared to the whole population through to 2016.
4. Ensure that anthropogenic influences do not significantly reduce the potential habitat in Pacific Canadian waters for blue, fin, and sei whales through to 2016.

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8.4.1 Schedule of studies to identify critical habitat

Threats addressed: All

Objective addressed: 2, 3, and 4

The following schedule (Table 1) outlines the activities required over the next 5 years (2006-2011) to identify, to the extent possible, critical habitat for blue, fin, and sei whales. The activities outlined in this schedule are recommendations that are subject to priorities and budgetary constraints of the participating jurisdictions and organizations.

The study of balaenopterid critical habitat has been divided into studies of potential and realized habitat. Potential habitat represents areas where suitable habitat exists, while realized habitat describes where species actually occur. In theory, realized habitat should be a small portion of the potential habitat, particularly for severely depleted species. The distinction makes it possible to distinguish between unsuitable habitat and suitable habitat that is merely unoccupied. Additionally, given the lack of baseline data on species distributions, identification of potential habitat helps prioritize scarce survey effort.

The potential habitat studies outlined in Table 1 focus on identifying oceanographic regions that could provide appropriate prey at suitable densities for blue, fin, and sei whales. The realized habitat studies focus on how balaenopterids occupy the potential habitats. Critical habitat can then potentially be defined as potential habitat areas of high use.

Table 1: Recommended studies and associated timelines for the identification of Critical Habitat for blue, fin and sei whales by 2011

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Priority: High

Threats addressed: All

Objective addressed: All

1. Estimate number of blue and fin whales using Pacific Canadian waters;

2. Establish presence of sei whales in Pacific Canadian waters;
3. Determine the extent of migrations and identify populations of blue, fin and sei whales using Pacific Canadian waters;
4. Determine relative seasonal distribution in Pacific Canadian waters of blue, fin and sei whales through surveys, photo-identification, and/or acoustic detection;
5. Establish collaborations with researchers in other jurisdictions to develop estimates of range-wide habitat use.

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Priority: Medium-High

Threats addressed: Ship strikes; noise; fisheries interactions, whale watching; and pollution.

Objectives addressed: 2, 3, and 4

1. Determine the spatial distribution of commercial shipping traffic and relate to the critical habitat of blue, fin and sei whales;

2. Investigate methods to obtain information on the frequency of ship strikes and entanglements and, if necessary, develop options to reduce their occurrence;
3. Determine likely locations and timing of seismic surveys and long-term industrial activities and relate to the critical habitat of blue, fin and sei whales;
4. Determine relative ambient noise levels and relate to location and use (or loss of use) of critical habitat;
5. Ensure whale watching regulations are in place;
6. Confirm that chemical pollution poses little threat to balaenopterid species in Pacific Canadian waters;
7. Develop response options for large, acute oil spills.

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9. Evaluation

The success of the recovery actions will be reviewed annually, while the goals, objectives and broad strategies outlined herein will be reviewed within five years of the plan's acceptance by the minister. The following performance measures will be used to assess the effectiveness of the objectives and strategies, and to determine whether recovery remains feasible. Detailed performance measures will be identified more fully during the development of the Action Plan.

Objective-based evaluation criteria include:

1. Were the population identities of blue and fin whales that occur in Pacific Canadian waters determined?

2. Was the relative proportion of blue whales in Pacific Canadian waters compared to the whole population maintained, or increased?
3. Was the presence of sei whale(s) confirmed in Pacific Canadian waters? If so, has the relative proportion of sei whales that occur in Pacific Canadian waters compared to the whole population maintained, or increased?
4. Did anthropogenic influences significantly reduce the potential habitat in Pacific Canadian waters for blue, fin, and sei whales?

Approach-based evaluation criteria include:

1. Were studies undertaken to identify critical habitat for these large whales?

2. Was research conducted and/or surveys carried out to better define the species' abundance and distribution?
3. Were threats better identified? Were threats reduced or mitigated in any way?

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10. Statement of when the Action Plan will be completed

An action plan will be developed within two years of approval of the Recovery Strategy. A single multi-species action plan for blue, fin, sei, and right whales is recommended as these large whales likely occupy similar habitat and face similar threats, and the activities required for their recovery (e.g., determine abundance and distribution) are common to all four species. The integration of what are predominantly research activities will ensure more efficient use of effort.

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11. References cited

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12. Glossary of terms

To be completed in final version.

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FIGURES

Figure 1.  Distribution of historic kills (left) and habitat model predictions (right) for blue, fin, and sei whales. Circle shows 150 nm from Coal Harbour, the only operating whaling station during the period when the majority of kill locations were recorded. Predictions are shaded from high to low probability (dark to light) (from Gregr and Trites 2001).
Figure 2.  Annual and monthly catches of sei, fin, and blue whales by British Columbia coastal stations (Gregr et al. 2000).
Figure 3.  Opportunistic sightings of blue, fin, and sei whales collected primarily by recreational boaters, 1972 - 2004 (courtesy of the B.C. Cetacean Sighting Network, N. Pinnell, pers. comm.).
Figure 4.  Generalized prediction of blue whale showing all recorded kills (coloured dots) by British Columbia whaling stations. Predictions are shaded from high (red) through yellow to low (black) (DFO-CRP, unpubl. data).

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