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Executive Summary
The panel was appointed by the Minister of Fisheries and Oceans "to provide advice on the best strategies for management of seal populations in Atlantic Canada, including a balanced and objective view of scientific information on seal populations and predator-prey relationships and how this information can contribute to development of management strategies."
The panel was asked to provide:
- an assessment of the available scientific information on dynamics of seal populations and the ecosystems of which they are part;
- if an optimum size of the seal population can be identified, advice on management strategies to attain such an optimum population size;
- advice on directions for improving scientific knowledge of dynamics of seal populations and the ecosystems of which they are part, to ensure that the scientific basis for seal management is sound;
- advice on whether and to what extent seal exclusion zones or experimental culls would provide protection to vulnerable local populations of commercial fishes;
- an assessment of all sources of harvest mortality on Atlantic seal stocks including but not restricted to harvests inside and outside Canada and mortality of animals struck and lost;
- advice on the most appropriate strategic directions for management of seal populations in the context of the above considerations and analyses and in particular for the next five years.
The panel advertised nationally in both official languages and held a number of consultations in Atlantic Canada. It commissioned re-analyses of data on hooded seal diet and harp seal pup production.
Seal abundance and mortality
The harp seal population increased substantially during the 1980s and early 1990s because of reduced harvest rates. Higher levels of harvest by Canada and Greenland in the mid-1990s appear to have stabilised the population, at least temporarily, at around 5.2 million individuals. The procedure used to estimate total population size and replacement yield (the level of harvest that will maintain the population at its current size) now takes account of the size of the Greenland harvest, and estimates of the numbers of seals killed by hunters but not landed and of the numbers bycaught in fishing gear. This has substantially improved the quality of the estimates of population size and replacement yield. The calculated replacement yield is used as the basis for the Total Allowable Catch (TAC) of harp seals in Canadian waters. Pregnancy rates have decreased since the 1980s, but the panel does not believe that the seal population is near the carrying capacity of the marine environment, as some stakeholders have suggested.
There are no reliable estimates of the current size of the hooded seal population in the northwest Atlantic. The last comprehensive surveys were in 1990/1991, and there is an urgent need for a new survey. The annual harvest of this species in Atlantic Canada has varied from less than 100 to more than 20,000 since the introduction of a ban on the sale of blueback pup skins in 1993.
Grey seal pup production has been increasing at ~13% per year on Sable Island. The rate of increase.v in the Gulf of St. Lawrence is less certain, although clearly smaller. There has been little hunting mortality since the cessation of the bounty in 1990.
Economics of the seal hunt
Although DFO sets an annual TAC for harp and hooded seals, the actual catch is determined by market forces, weather conditions, and levels of government subsidy. Harp seal catches were well below the TAC from 1983 until 1996, when they rose to ~240,000. The TAC of 275,000 was slightly exceeded in 1998, but catches declined to ~91,000 in 2000. The 2001 take was ~210,000. The TAC for hooded seals was increased to 10,000 in 1998 and was taken in full in that year, but relatively few hooded seals were taken in 1999 and 2000.
Estimates of the landed value of the seal catch in 1998 range from $5.6M to $8.75M. Traditionally, pelts have been the largest component of product value but production of oil for human consumption has grown substantially in recent years. The sealing industry believes that there is large potential for increased sales of high-grade pelts and seal oil, especially if U.S. trade barriers can be overcome.
The panel found it difficult to determine current and historical levels of direct and indirect subsidies to the industry and their effects. One study estimated that the added value of the industry in 1996 was only 0.06% of the gross domestic product of Newfoundland, after costs and subsidies had been subtracted. Meat subsidies during the 1990s contributed to high harvests, but were phased out in 1999. Subsidies provided to the Canadian sealing industry must be viewed in the context of the levels of subsidy provided to other fisheries in Canada, and to sealers in Greenland and Norway.
Prey consumption by seals and impacts on fish stocks
Estimates of the amounts of some commercial fish species (particularly northern cod, redfish, Greenland halibut and American plaice) consumed by seals in many NAFO Divisions are large in comparison to current fisheries catches. Seals also consume large quantities of capelin, which is an important prey for many of these commercial species. However, the current estimates are imprecise, and may be biased. In the case of harp and hooded seals, this is because most of the diet samples have been collected in inshore waters, whereas both species spend most of their time feeding offshore.
The impact of the calculated removals on the current size of commercial fish stocks is difficult to assess. However, the estimated consumption of Atlantic cod by seals in Divisions 4RS3Pn and 2J3KL is particularly large, and this may be contributing to the apparently high levels of mortality experienced by those stocks. In some local areas, such as river mouths, for salmon, and inlets on the east coast of Newfoundland, for cod, predation by seals may be a particularly important source of mortality.
The role of seal predation in the apparent failure of some severely depleted fish stocks is unclear. However, it should be recognized that many of these stocks will probably take a long time to recover to fully exploitable levels, even if all seal predation is removed. The situation is further complicated by the environmental changes that have occurred since the late 1980s, and the associated shifts in the distribution of important prey species such as capelin and arctic cod. The proportion of northern cod in the diet of harp seals appears to have remained relatively constant since the 1980s, despite the massive reduction in cod abundance. This has led some stakeholders to conclude that seals could be holding cod in a "predator pit", but this conclusion is based on diet samples from inshore waters around Newfoundland where recent changes in cod abundance may have been much less dramatic than those that occurred offshore.
One panel member (David Vardy) believes that the balance of evidence is sufficient to conclude that "Seal predation poses a serious threat to the recovery of northern cod and other important cod stocks in Atlantic Canada and to the rebuilding of these stocks to their historical levels." The other panel members believe that the available evidence does not justify such a strong conclusion.
The impacts of seals on the salmon farming industry in New Brunswick, and probably elsewhere, have become broadly tolerable as a result of better anti-predator nets and adequate insurance, although individual growers still suffer large losses.
"Optimum" size of the seal population and management objectives
Any change in abundance of a seal species will affect other species in the ecosystem, and these affects will have consequences for a wide range of stakeholders. For example, a reduction in harp seal numbers will certainly reduce the TAC for the sealing industry, and will probably result in an increase in cod stocks, at least in the short term. The increase in cod abundance might then result in increased TACs for cod. In the longer term, an increase in cod abundance could result in reduced TACs for the shrimp and crab industries. Furthermore, there are large uncertainties associated with the estimates of the quantities of cod, and other economically important groundfishes, consumed by seals and with any predictions about the way in which fish stocks may respond to reduced seal predation.
If what economists call "utility values" can be attached to the different outcomes that may result from a change in seal numbers, then it may be possible to identify an optimum size for a seal population. The panel's terms of reference do not provide any guidance on these values, and the panel was therefore unable to identify a single optimum size for any of the seal populations in Atlantic Canada. It could not, therefore, advise on "management strategies to attain such an optimum population size."
Scientists have been trying to find ways to cope with uncertainty in the management of fisheries for some time, and Canadian scientists have been in the forefront of this work. But seal management in Canada has not taken advantage of these developments. The most promising approach involves defining a set of control rules that are used to set the TAC and the way in which it can be taken, and a set of Reference Points that are used to monitor the effectiveness of management. In particular, the probability that the exploited population will fall below a Limit Reference Point must be kept as low as possible. The panel strongly recommends that a management approach of this kind is applied to seal populations in Atlantic Canada.
In order to illustrate how this management approach could be used and how an optimum size for the seal population might be identified, the panel evaluated the likely costs and benefits that sealers, groundfish fisheries in Divisions 2J3KL, and DFO might experience under five different management scenarios for the harp seal population. There are winners and losers under each of the scenarios, and the uncertainty associated with some of the benefits is often very much greater than that associated with some of the costs. Any decision about which stakeholder group should have the greatest chance of benefiting from seal management and which should lose out must be based on a socioeconomic analysis rather than a purely biological one.
- "Status quo". The TAC is set on the basis of replacement yield, but
may not be taken in full each year because of market forces and ice
conditions. It should never be exceeded. Because of this, there is a
greater than 50% probability that the population, and therefore overall
fish consumption, will increase. Sealers will benefit from a relatively
stable TAC in the short term, and a probable rise in the TAC in the longer
term. Seal predation on groundfishes and capelin is likely to increase.
- "Market forces". Under this scenario, a high utility value is attached
to benefits to the sealing industry. That industry is allowed to set the
TAC, but it may be reduced (possibly to zero) by DFO if the probability
that the seal population will fall below the Limit Reference Point is
judged to be too high. The size of the TAC set by the industry may be
higher or lower than that set under the "status quo" scenario, depending
on markets for seal products and how the industry discounts future
revenues. The effects of this management on capelin and groundfishes
consumption are therefore unpredictable.
- "US Marine Mammal Protection Act". The US Marine Mammal Protection Act
defines a specific Limit Reference Point for all marine mammal populations
and provides a formula to calculate a TAC that ensures there is a high
probability the population remains above this Reference Point. If this
approach is applied to the northwest Atlantic harp seal population the
Canadian TAC will be substantially lower than under the "status quo"
scenario, unless the size of the Greenland catch is also reduced. Seal
numbers would be expected to increase by around 3% per year. After 10
years of management under this scenario, annual consumption of northern
cod by seals is calculated to increase by 11,000 tonnes (of which
approximately half might be fish of commercial size) and consumption of
capelin by 155,000 tonnes. However, there are large uncertainties
associated with these calculated values
- "Stabilize fish consumption". This scenario is a modification of the
"status quo" scenario. If the TAC is not taken in full, DFO pays sealers
to kill additional seals to ensure that the entire replacement yield is
taken each year. The short-term benefits to the sealing industry are the
same as under the "status quo" scenario, but TACs are not expected to rise
in the longer term. This is because there is an equal probability that
seal numbers, and fish consumption, will increase or decrease.
- "Reduce fish consumption". Under this scenarios, potential benefits to
groundfish fisheries are given a high utility value. The objective of
management is to reduce consumption of certain fish species in Divisions
2J3KL by a specified amount. For example, the panel calculated that the
annual consumption of northern cod might be reduced by 3,000 to 4,000
tonnes after five years if the Canadian seal TAC was increased by 150,000
or if 75,000 females were killed each year in addition to the existing TAC.
A similar effect could be achieved by sterilizing 150,000 females each
year. Consumption of other groundfish species would also be reduced.
However, the panel was unable to estimate how this reduced consumption
might translate into revised TACs for groundfish stocks. Although there
may be short-term benefits to the sealing industry under this scenario if
the reduction is achieved through an increased TAC, even this will depend
on the nature of the demand for seal products. Once the desired reduction
has been achieved, the seal TAC will have to be reduced and sealers'
incomes will probably fall. If the reduction is achieved by killing or
sterilizing females, then DFO will have to bear the cost of this.
- "Seal exclusion zones." The establishment of exclusion zones to protect overwintering aggregations of cod from harp seals is probably feasible only in fjord-like environments like Smith Sound in eastern Newfoundland. The panel recommends that any attempt to establish such zones should take the form of a scientifically designed trial. Such trials are unlikely to affect seal TACs but will involve additional costs to DFO. The possibility of using acoustic devices to scare seals away from these zones should also be explored, although account should be taken of their potential effect on other wildlife such as porpoises.
Until a new estimate of pup production and more information on diet and movements is available, the costs and benefits of management scenarios for hooded seals like those described above for harp seals cannot be evaluated. The current ban on the taking of blueback seals provides much greater protection for hooded seals than the prohibition on taking whitecoated seals does for harp seals. The panel believes that, if the aim of management is to protect "baby" hooded seals (i.e. those still in their mother's care), this can be achieved without resorting to a complete ban on the hunting of bluebacks by setting an appropriate opening date for the hooded seal hunt. This would have benefits for the sealing industry.
The above management scenarios could also be applied to grey seals on the Scotian Shelf and in the Gulf. However, any calculations of expected changes in consumption of fish will involve even greater uncertainties than those applying to the calculations for harp seals. The "status quo" and "market forces" scenarios are likely to result in an increase in fish consumption because of the limited current demand for grey seal products. The two "fish consumption" scenarios could only be implemented if Sable Island was opened to a commercial pup hunt, or DFO carried out a contraception programme there. Although it has been suggested that grey seal exclusion zones could be established in Sydney Bight or St. Georges Bay, Cape Breton, the panel is skeptical about the potential benefits of this, because any seals that are killed are likely to be replaced quickly by immigrants from surrounding areas.
Recommendations for research and management
Research
- Funding for seal science in general should be increased and made less dependent on short-term, application-driven sources
- All hooded seal breeding aggregations in the northwest Atlantic should be surveyed from the air as soon as possible. All available information on age structure and reproductive status should be analysed to provide improved estimates of survival and pregnancy rates. These data should then be used to recalculate the TAC for this stock.
- Existing estimates of grey seal pup production and population size should be published as.soon as possible.
- DFO should accelerate research on all aspects of high mortalities of groundfish stocks. Funds for groundfish research could be used to improve estimates of seal consumption, because this is probably a fundamental component of these mortalities. Stock assessment programs for capelin off Newfoundland and in the Gulf should be reinstated, because the abundance and availability of this species is central to an understanding of recent and future changes in the abundance of groundfish and seals.
- Existing information on the movements of satellite-tagged harp, hooded and grey seals should be published as soon as possible. More satellite-tracking of harp and hooded seals is needed to determine if their distribution has changed since the mid-1990s, and to improve the design of seal diet studies.
- Work commissioned by the panel suggests that hooded seals may be consuming large quantities of northern cod in Divisions 2J3KL. However, these results are based on very small sample sizes, particularly in offshore areas, and more samples are urgently required.
- The results of existing work on the use of fatty acid profiles to determine the diet of grey seals should be published as soon as possible.
- Existing data on seal diet should be reanalyzed to determine the most cost-effective way of reducing the large uncertainties associated with current estimates of fish consumption.
Management
- National and provincial governments should provide consistent and accurate data on their direct and indirect financial support to the sealing industry.
- Management of seals in Atlantic Canada should have explicit objectives. DFO should commission a study to develop a generic set of control rules and Reference Points that could be applied to any of the management scenarios described above.
- Canada and Greenland should cooperate in the conduct of scientific research and in the management of seal species that are common to both jurisdictions.
- The potential benefits of seal exclusion zones should be investigated in a trial involving experienced seal collectors, with appropriate levels of replication. Stomach and blubber samples should be collected from all seals that are shot, and the abundance and distribution of cod should be monitored in experimental and control areas.
