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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.
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