The Grey
Seal Conservation Society (GSCS), a
non-profit organization based in Atlantic Canada, urges the Canadian
Department of Fisheries and Oceans (DFO) and Environment Canada to bring
an immediate end to the commercial harp seal hunt.
The
Canadian harp seal hunt is ecologically damaging on two fronts that seem
not to have been considered by DFO: (1) An unprecedented,
drastic loss of natural marine predators has already occurred. Because
major change of this nature can destabilize a marine ecosystem, no more
large fish predators, including seals, should be removed at this time. (2)
If the seal hunt is not banned outright this year, a minimum precautionary
directive from DFO and Environment Canada should immediately forbid
sealers from abandoning seal corpses to rot in the Gulf of St. Lawrence.
Sealers now routinely discard massive amounts of
rotting dead seal flesh in an ocean area with oxygen-poor bottom
water, contributing to polluting and further degrading the marine
environment.
The seal
cull approach to “cod recovery,” although strongly favoured by the fishing
industry, is naïve, and is based on outdated myths about predators in
general, and on misperceptions about the natural relationship between
seals and cod. Twenty-first century science, including DFO Science, knows
better.
MYTH 1: Cod stocks are failing to rebuild today
because there are too many cod predators in Canadian waters. MYTH 2: If seal numbers could be lowered in Atlantic
Canada, then “it stands to reason” that the numbers of cod would naturally
increase. MYTH 3: Although seals did not demolish the cod
stocks (it is generally accepted that human “overfishing” was the primary
cause of the collapse), seals have now unfortunately grown “out of
balance” with the relatively small number of cod that are left. MYTH 4: Predators inflict damage and threaten to
destroy their prey. MYTH 5: DFO Science supports seal culling as a prudent
measure to help rebuild cod stocks. MYTH 6: The seal hunt does no damage to any other
marine species, because only seals are killed. MYTH 7: Seal populations are robust and resilient and
are capable of withstanding intense commercial exploitation. They will
bounce back, because they have done so before.
MYTH 1:
Cod stocks are failing to rebuild today because there are too many cod
predators in Canadian waters.
It is
argued by the fishing industry that cod are failing to rebuild their
numbers because too many fish are being eaten by an overgrown population
of natural predators (specifically, seals).
FACT:
There are now fewer cod predators in Canadian waters than at any other
time in recorded history (1).
”…there are currently very few large fish – a
situation likely to have never been witnessed in the past.”
- DFO, 2003
Predator
pressure on cod stocks is at an historic low, despite a recent increase in
the numbers of some species of seals. The increase in seal numbers has
been massively outweighed by a huge decline in the number of other
predators capable of eating small fish (as seals do), which has occurred
with the recent disappearance of virtually all large fish (big cod, big
halibut, sharks, etc.) (1,2). DFO scientists have even
noted “insufficient predation” among the factors now having adverse
impacts on the health of fish stocks (2). Natural
predator “coverage” of the undersea world now appears to be at a
dangerously low level. This is dangerous because predator/scavengers are
vital elements that work to maintain the “cleanliness” and health of the
ocean ecosystem. Without predator/scavengers, the danger rises that “rot”
might set in and work to deaden the system.
MYTH 2:
If seal numbers could be lowered in Atlantic Canada, then “it stands to
reason” that the numbers of cod would naturally increase.
FACT:
Cod numbers in Atlantic Canadian waters are now severely constrained by
adverse environmental conditions, and removing seals will in no way lessen
these contraints.
The
environmental factors limiting cod growth include a shortage of food (3,4),
a declining availability of oxygen in some areas (4), and
a lowered resistance of cod to stressors such as cold water (1,4).
If these environmental conditions should change in their favour, the
population of Atlantic cod would predictably increase, because cod is a
naturally robust, persistent species. Under more favourable environmental
conditions, fish like cod, that mature in a few years and then produce
millions of eggs annually, can swell their ranks quite rapidly. On the
other hand, if the environment is stacked too heavily against the survival
of cod, these fish will inevitably die off. Unfortunately, at present,
adverse marine environmental changes in Canadian waters include ominous
plankton shifts, with a significant loss of the small animal plankton
(zooplankton) that ultimately feed fish. Part of the role of natural
predators, including seals, is to subtly rebuild zooplankton numbers and
to thereby work “for” and not “against” the future healthy growth of cod.
This makes the intentional elimination of seals or other fish-predators
especially risky actions today. Because natural predators crop fish
numbers down to match what their environment can currently support, while
stimulating new growth of plankton (food) and helping maintain the oxygen
content of the water, deliberate predator removal must be contraindicated
when a prey species is suffering from adverse environmental conditions,
such as is seen with Canadian cod. In today’s marine environmental
reality, with weakened plankton, lowered oxygen, and stunted, unhealthy
fish, it “stands to reason” that killing more seals will ultimately worsen
the odds of recovery for the cod stock.
DFO
scientists have recently described the cumulative impact of the massive
removal of large predatory fish from the ocean by commercial fishermen as
a factor that has contributed to the generalized starvation of cod and
other bottom fish in Atlantic Canadian waters today (3).
This is a radical new scientific insight, and one that has serious
implications for the future of the fishing industry. This also provides a
scientific rationale for ending the seal hunt.
MYTH 3:
Although seals did not demolish the cod stocks (it is generally
accepted that human “overfishing” was the primary cause of the collapse),
seals have now unfortunately grown “out of balance” with the relatively
small number of cod that are left (5).
"The trouble with
the world is not that people know so little, but that they know so
many things that ain't so."
- Mark Twain
It is
argued on this basis that seals should have their numbers reduced to
restore a more “normal” seal:fish ratio in the sea, and that, while seals
must suffer now for the mistakes of the fishing industry, it should be
remembered that people and their livelihoods are more important than the
lives of seals.
FACT:
Seals, especially if they exist in increased numbers, actually have the
potential to assist in the recovery of the cod stocks today, because all
natural predators affect environmental conditions to the benefit of fish.
For this reason, seals should now be protected.
Seals and
other natural predators positively affect ecosystem processes, including
nutrient cycling, to increase “resource availability” to their prey fish (6).
And low “resource availability” is the major problem limiting the growth
of cod today. A subtler, less immediately obvious facet of the seal-fish
relationship than the killing and eating of prey fish by seals, however
this payback scheme between seals and fish is the secret of their
long-successful healthy co-existence. In comparison to seals, the fishing
industry is young and inept, because humans have not found a way to
positively integrate their feeding and excretory habits with the lives of
fish, a feat accomplished by seals 25 million years ago.
It is a
positive sign, of residual resilience in the weakened marine animal web,
that seal numbers have made gains in recent years, even as prey fish and
large predatory fish have both declined. But it must be emphasized that
there is absolutely no reason to fear that there are now “too many seals.”
Essentially, seals are now making partial compensation for the massive
loss of the other large fish predators, and for the resulting negative
impact of that loss on the ecosystem. If the underwater domain is not
patrolled by enough large predators, who promptly eat exhausted fish as
they succumb to environmentally-induced mortality, then dangerous
microscopic organisms (rot) will multiply and will further degrade the
habitat for fish (and ultimately, for seals too.) Future ocean health must
not be sacrificed for short-term financial incentives. Therefore, the
lives of seals at this time are worth more than the economic benefit to
the commercial sealers.
Trust
the seals, fear the microbes.
MYTH 4:
Predators inflict damage and threaten to destroy their prey.
This is a
fundamental human misperception, perhaps based on a subconscious natural
fear of animals possessing teeth large enough to consume us. A
disinformation campaign has worked for many years to raise a false alarm
in the public mind about seals damaging fish stocks because they are
“predators.”
FACT:
Predators play an important positive role in maintaining ecosystem health.
Robust and
healthy marine animal life (as existed for millennia in Atlantic Canada)
is largely a promiscuous swarming web of predatory carnivores of all
sizes. Although at first glance, savage death seems to run rampant through
such a sea, the true nature and the ultimate result of this mass
unrestrained carnivorous behaviour is not destruction, but is extremely
pro-life. A paradox, perhaps, to the average human imagination, but this
is true nevertheless. The actions of ocean predators, and the number of
these predators, does not serve to damage or weaken the living animal web
in any way, but instead they work to naturally strengthen and vitalize it.
Highly evolved fish-dependent predators like seals present absolutely no
threat to the continued existence of their prey fish, in part because
their own future relies wholly on the future of fish. Seals will not
survive without fish, and these marine mammals evolved only after fish
were an established presence in the sea. The natural ecology of seals is
therefore inherently, strongly pro-fish.
In
contrast, there are other marine organisms that now increasingly
“threaten” and destroy fish, specifically dangerous primitive microbes
that existed in the sea for eons before the evolution of fish. These tiny
killers do not depend on fish for their future survival. Therefore, if the
current resurgence of bacteria in the ocean expands to the point where
fish are eliminated, and microbes dominate the sea again, then the killers
of the fish will suffer no particular setback. These species are therefore
infinitely more “dangerous” than seals. Uncontrolled growth of bacteria in
the sea, such as the microbes that cause dead flesh to “rot,” presents a
genuine “threat” to the survival of fish in today’s degraded ocean
environment. Ecologically, seals are the antithesis of bacteria.
Seals take
advantage of cod weakened or killed by adverse environmental conditions,
and this is fine. Better that fish be consumed by seals, than by microbes.
Seals and other natural predators selectively kill the weakest and least
viable fish in the cod stock. Natural predators, especially the
air-breathing seals, can patrol the periphery of a low-oxygen “dead zone,”
for example, and selectively remove the weakened and dying individual
fish. Fishermen cannot do this, yet we have long vainly assumed that we
can simply “replace” natural predators with human fisheries.
No apology
needs be offered for the fact that seals eat cod, nor for the tonnage of
cod flesh swallowed by seals, whatever that may be. Such numbers are
irrelevant to the calculation of the ultimate value of seals and other
natural predators in the ocean. When the environment is degraded and less
naturally supportive of fish, individual fish simply cannot grow to large
sizes as their kind did previously in the same area. Cod and other fish
now die off before they can reach the sizes previously attained by their
kind, and when these fish deaths occur it is very important that their
environment contains natural predators that can eat them. There is a great
life-enhancing value in the predatory/scavenger service provided by seals
versus the alternate breakdown service provided by bacteria. People who
today seek to avert what they perceive as an “explosive overgrowth” of
seals in the ocean should ask themselves if they would prefer to see an
“explosive overgrowth” of bacteria instead. Because that is exactly where
conditions in the ocean are now heading (4, 6, 7), and
blindly forging ahead with the seal cull will only serve to hasten this
end
Trust
the seals, fear the microbes.
MYTH 5:
DFO Science supports seal culling as a prudent measure to help rebuild cod
stocks.
FACT:
DFO scientists have not concluded that seal culling can help rebuild cod
stocks, in fact they have published warnings against the removal of
natural marine predators because this could trigger unpredictable negative
consequences throughout the ecosystem (8,9).
Calculating the amount of prey fish eaten by seals is not the same thing
as demonstrating a negative impact of seals upon fish stocks, although
many people (including some scientists) seem to have made this incorrect
simplistic assumption. For a while, DFO entertained the “predator pit”
hypothesis regarding seals and cod, but this idea has now given way as the
weight of evidence points toward environmental conditions being
fundamentally unsupportive of cod as they were in the past. DFO Science
knows enough today to realize that the seal cull is ecologically
irresponsible (as is the associated mass disposal of rotting harp seal
corpses in the Gulf of St. Lawrence). The seal cull in Canada is condoned
and continues in 2005 for purely political reasons – because it is what
the fishing industry demands. However, on paper, DFO is formally committed
to finer modern “ocean stewardship” ideals, to the concepts of
“ecosystem-based fisheries management” and the “precautionary approach” (9,
10). Hence, a serious conflict now exists inside DFO between the
current level of scientific enlightenment and the crude “management”
actions that are still taken, although this conflict is still largely
hidden from the public under platitudes about “sustainable harvesting of
marine resources.”
MYTH 6:
The seal hunt does no damage to any other marine species, because only
seals are killed.
FACT:
The seal cull threatens to worsen the currently degraded state of the
ecosystem in which all marine species live.
Living
seals are natural catalysts that work to enhance the general health and
survival of all larger, more active forms of sea life, including fish,
while uneaten dead seals – especially if their corpses fall into
oxygen-poor bottom waters, as exist in the Gulf of St. Lawrence – are
catalysts for death, and for the a potential runaway dominance of bacteria
and rot. Adding a catalyst, or removing one from the system, causes
significant effects that cannot necessarily be calculated based on the
weight of the catalyst alone. Ocean ecosystem
modelers, including scientists working for DFO, have not yet fully
realized this basic truth about seals, fish, bacteria, and all else in the
sea…and this important basic knowledge gap results in a great deal of the
continued “bafflement” of fisheries scientists today, and in their general
inability to offer a coherent explanation for today’s broad-scale changes
in ocean life.
Old
thought patterns – especially when tied to money – die hard.
MYTH 7:
Seal populations are robust and resilient and are capable of withstanding
intense commercial exploitation. They will bounce back, because they have
done so before.
FACT:
Not necessarily true, that is exactly what DFO and the fishing industry
wrongly assumed about the cod.
The truth
is that warning signs of stress are now appearing in Canadian seals too:
diet shifts, range shifts, lowered physical condition of seals…in short,
the same biological signals are now appearing in seals that appeared in
cod in the early 1990’s before their sudden population crash. Any honest
“precautionary approach” to “marine ecosystem management” in Canada in
2005 must include the abolishment of all commercial seal hunting.
Bundy, A. 2004. Mass
balance models of the eastern Scotian Shelf before and after the cod
collapse and other ecosystem changes. Can. Tech. Rep. Fish. Aquat. Sci.
2520.
http://www.osl.gc.ca/cdeena/pdf/esstechreport-2004.pdf
Choi, Jae S. et al, 2004.
Transition to an alternate state in a continental shelf ecosystem. Can.
J. Fish. Aquat. Sci. 61: 505-510.
Pikitch, E K et al. 2004.
Ecosystem-Based Fishery Management. Science 305: 346-347 (July 16, 2004)
Excerpts from numbered references above,
with notes:
1. DFO, 2003. State of the Eastern Scotian Shelf Ecosystem. DFO Ecosystem
Status Report 2003/004.
”…there are currently very few large fish – a situation likely to have
never been witnessed in the past.”
“Condition and growth of several groundfish species has remained low
during the past decade contrary to expectations for improvement.”
“It is not yet possible to predict how long the current situation will
persist and whether or not the system will return to its previous
groundfish-dominated state.”
“Although only a few of the several traditional groundfish species have
been routinely aged, the available information reveals striking and
unexpected reductions in growth.” (cod, haddock, Pollock, silver hake)
“…the trend of reduced size has occurred, despite current low population
levels, suggesting that a fundamental, population dynamic process
(compensatory growth) is not working among these species.”
“Concerns have been expressed repeatedly about the impact of the expanding
grey seal population on the recovery of cod. Sand lance and other
non-commercial species are the most common prey in the diet with cod
contributing a small fraction of the fish consumed. Because the cod
population is so low, it is assumed that any additional source of
mortality may be detrimental to the remaining stock.
Estimates of grey seal consumption are calculated from a population model,
which incorporates metabolic requirements of individual seals. Current
population size and diet of grey seals are not available. But if the rate
of growth has continued at past levels, then the population could have
doubled since the last survey in 1997 to near 225,000 in 2002. Based on
this extrapolation and recent evidence from fatty acids that cod may
account for only about 1% of the diet in recent years, the estimated
consumption of cod by grey seals is in the order of 3,000 t, compared to a
total cod population biomass of 8,800 t. Recent satellite tracking of
adult grey seals indicates that a fraction of the Sable Island population
forages in areas beyond the boundaries of the Eastern Scotian Shelf
ecosystem. Therefore, the consumption of cod by grey seals in this
ecosystem may be less than that currently estimated. The impact of grey
seal predation on the dynamics of cod is an active area of research and
there are continued concerns on the role of seal predation on cod
recovery.”
(DM: DFO has not yet reached the stage of considering how the massive
removal of large animal life from the sea naturally tips the balance of
power to dangerous levels of bacterial growth.)
2.
Bundy, A. 2004. Mass balance models of the eastern Scotian Shelf before
and after the cod collapse and other ecosystem changes. Can. Tech. Rep.
Fish. Aquat. Sci. 2520.
Grey seals “have become the main predator of fish” on the ESS.
(DM: This should gives an important reason to protect these seals – and
not to authorize a new grey seal cull in Nova Scotia, as DFO did in 2004.)
The size of the increase in the biomass (tons/sq. km) of grey seals on the
ESS is about 1/20th of the magnitude of the decrease in the
biomass of large fish between early 1980s and late 1990s.
(DM: The increase in seals does not come close to making up for the loss
of large fish.)
p. 106 “We know least about the part of the ecosystem that is its bedrock”
(the lower trophic levels, bacteria, plankton)
“…Note also that even with the large increase in grey seal abundance on
the eastern Scotian Shelf, there is not enough consumption of these prey
species to account for all their production.”
p. 101 “…almost all of the (recent) mortality of large cod is
inexplicable…Thus, for large cod, the total estimated mortality is twice
the production, so unless mortality is reduced, this population will
continue to decline. On top of this, we do not know what is causing the
mortality.
The question of high mortality estimates, particularly in large cod, is
problematic and is common to many Canadian East Coast cod stocks, with the
exception of NAFO Div. 4X cod. There have been DFO projects, workshops and
papers written on this problem, but there is, as yet, no resolution (e.g.
Chouinard et al. 2002, Powles 2002, Smedbol et al. 2002, Dutil et al.
2003). It remains at this stage to indicate that modelling the ecosystem
with Ecopath has not been able to shed further light on this problem.”
p. 108 “In the 1980-1985, cod was the main predator, whereas in the
1995-2000, grey seals and silver hake are the main predators. Total
consumption by grey seals, silver hake and cod is less in 1995-2000 than
it is in 1980-1985. There is thus less consumption by top predators in
1995-2000.
There are large unknown mortality estimates for several groups. The
ecosystem has greatly changed and there are few top predators in
1995-2000. Unknown mortality may be due to disease or senescence because
there is not sufficient predation.”
3. Choi, Jae S et al,
2004. Transition to an alternate state in a continental shelf ecosystem.
Can. J. Fish. Aquat. Sci. 61: 505-510.
“…coherent,
community-level reductions in body size, biomass, and physiological
condition have occurred in the resident demersal fish species…suggesting a
progressive decline in the nature and extent of the energy flow through
the benthic system…” (DM: Translation: all bottom fish are now stunted
and severely limited by a lack of food.)
(Regarding the
Scotian Shelf cod collapse) “The spectacular nature of this collapse and
the scientific and public attention that it received has obscured the much
more profound coincident ecological collapse of an entire complex of
previously abundant demersal fishes, many of which were subjected to only
modest exploitation.”
“Throughout the
1970s and 1980s, large individuals dominated the northeastern half of the
shelf. Individuals >8 kg were found in >75% of the area sampled and by the
1990s had declined to 40%. Currently large fish occur on only 10% of the
area surveyed and are restricted to the northeastern edge of the shelf.
Numerically, the magnitude of this change was profound. Relative to the
1970s, there are currently 95% fewer fish >8 kg and fish of intermediate
size (1-8 kg) are 60% lower in abundance. Conversely, small fish (<0.1 kg
and 0.1 – 1 kg) have increased by 375% and 100% respectively. These
changes in body size result from variations in species composition,
size-specific mortality, and reduced growth rates (DFO 2003).”
Between 1970s and
2000s, “a sustained reduction in physiological condition” occurred.
“Collectively, these
patterns reveal progressive erosion in the bioenergetic “well-being” of
the resident groundfish community.”
Conclusion…”…changes
seen in the groundfish community of the eastern Scotian Shelf are
indicative of a severely perturbed system with reduced functional
diversity…This makes the prediction of the conditions required for stock
recovery and their associated time scales difficult and highly uncertain.
The complexity of the interacting factors involved in the dramatic
restructuring of the Scotian Shelf ecosystem highlights the problems
inherent in attempting to manage individual species within the framework
of a complex and dynamic ecosystem.”
(DM:
These authors, DFO scientists, describe profound system-wide changes that
have unexpectedly occurred on the Scotian Shelf, and that have included a
massive loss of large fish. They certainly do not suggest that a seal cull
will help reverse the negative changes, and in fact they imply the
opposite in their suggestion that small pelagic fish (seal food) has
become overgrown to the detriment of the bottom fish, including cod.)
4. Dutil, J.D. et al. 2003. Cod stocks rebuilding and fish bioenergetics:
low productivity hypothesis. DFO CSAS Research Document 2003/060
5. Rice, J. 2002. Changes to the Large Marine Ecosystem of the
Newfoundland-Labrador Shelf. (In Sherman and Skjoldal, 2002) Jake Rice is a senior
DFO scientist.
p. 92 “…attention is turning to seal predation as a major cause of the
elevated mortality. With annual harvests well below replacement
production, the harp seal population has reached the highest abundance in
the time series (which began in 1972).
Moreover, the herd is staying in the Newfoundland Shelf large marine
ecosystem much longer than historically. Although consumption estimates
are only available for cod, and numerous uncertainties remain, seals are
estimated to be consuming at least 80% of the production of cod in 2J3KL
in recent years, and represent a source of significant mortality to cod up
to at least age 5 (DFO 1999).”
(DM: Rice, along with other DFO scientists, does not distinguish between
otherwise viable and otherwise non-viable cod that are eaten by seals. And
this represents a major flaw in this analytical approach.)
Conclusion, p. 95 “The slowness of the system to return towards an
historic “typical” configuration when stresses from both fishing and the
physical environment are largely eliminated raises new and deeply
troubling questions about managing ecosystem trajectories.”
(DM: “Deeply troubling questions” indeed…)
p. 55 “The ability to explain the dynamics of the larger marine ecosystem
of the Newfoundland shelf is severely limited by the lack of time series
data on living components of the system except for a few species of fishes
and seals.”
p. 56 “With regard to plankton dynamics…although it would be highly
desirable to incorporate dynamics of the primary producers and small
zooplankton into a grand synthesis, the data simply do not allow that step
to be taken.”
6.
N. J. Bax. 1998. The significance and prediction of predation in marine
fisheries. ICES Journal of Marine Science, 55: 997 – 1030.
(DM: This seems to be a good, comprehensive review article. Bax, however,
in common with other writers of this type of article, consistently uses
the phrase “losses to predation” when describing the direct effect of
predators’ eating their prey. Not acknowledged by this author, or by
others in my experience, is the fact that some of the flesh consumed by
“predators” was already dead or dying, and that these fish having been
eaten by a predator does not constitute a “loss” to their kind as much as
a “loss” to alternate forms of decomposition (such as bacterial) which
might occur in the absence of the predator/scavenger. )
Bax acknowledges the current inability of science to make accurate
predictions of the end results on fish stocks of culling their predators.
“Although short-term management objectives may be achieved in ignorance of
the system to which they apply, longer-term, strategic management that has
as its objective maximizing harvest under a set of constraints, requires
and understanding of the interactions of species and of fisheries within
the context of their physical environment and habitat.”
“Change is direct when a predator kills a prey, and indirect in a
multitude of ways, including predation on shared prey resources, effects
involving intermediate predators, and predation influencing prey behaviour
and resource availability.
A
typical negative assessment of the impact of the “harvesting” of fish by
marine mammals, rampant in fisheries science literature, is included here:
“…the amount of commercially important fish eaten by marine mammals is
similar to or exceeds that taken by the commercial fishery in at least
five areas (South Georgia, Kerguelen Islands, Southern Africa, North-west
Atlantic, Bering Sea).”
And another classic theme: a general resentment of fish eaten by seabirds:
“Northern gannets in Newfoundland waters, which harvest the same sizes and
species of pelagic prey as the commercial fishery in the area, often
harvest more mackerel and squid than the commercial fishery lands.”
Also described by Bax are “losses” to cannibalism – a rather awkward
concept, if cod is taken and integrated into larger cod – how is this a
“loss” to the species? “Predation by fish appears to range from 2 to 35
times the loss to commercial fisheries.”
(DM: There seems to have been a deliberate plan by fisheries managers in
the past to deliberately remove the larger fish for just this reason – it
was thought to be inefficient to have big fish consuming the smaller,
faster-growing population members that could be more profitably taken by
fisheries. So, a tendency to resent the predatory activities of fish has
been a part of classic fisheries science and management. Belatedly, we
have realized this was a serious mistake.)
The fact that predators also readily scavenge dead or injured fish is
acknowledged in the context of fishery discards, but not as a part of the
natural consumption of these types of fish by these types of predators.
“The occurrence of fish in the diets of seabirds does not necessarily
imply predation on live fish. Where commercial fisheries operate, a large
proportion of seabirds’ diet can come from fish discarded from the boats.”
(DM: Yet, the occurrence of fish in the diets of seals seems always to
imply their predation on otherwise viable fish, even when they are taking
larger individuals than they ate in the past – which is really an
indicator of the debilitated condition of larger fish today, as they are
forced down by adverse environmental conditions. )
In this article, a table shows the “annual biomass of fish lost to fish
predators and the fishery…”
(DM: Without the predators, populations of fish would naturally have a
certain lost annual biomass in fish that died. Predators selectively
consume this portion of the fish population, while fisheries are incapable
of directly targeting exhausted fish in this manner. The assumption runs
throughout this article that the ecosystem effects of “fish predators” and
the “fishery” can be compared directly, but they cannot.)
“The effects of predation are intertwined with those of food availability:
starvation leads to an increased susceptibility to predation.”
(DM: DFO should be acknowledging this fact today, along with the other
risk of starvation: death.)
8. Swain, D. P. and A. F. Sinclair. 2000. Pelagic fishes and the cod
recruitment dilemma in the Northwest Atlantic. CJFAS 57: 1321-1325.
Abstract: “…the recent suggestion that the success of large predatory
fishes may depend on “cultivation” effects in which the adults crop down
forage fishes that are predators or competitors of their young. Our result
also point to the possibility of a triangular food web involving cod,
seals, and pelagic fishes, making it difficult to predict the effect of a
proposed cull of seals on the recovery of cod.”
Discussed “implications of such an effect for management action that has
been proposed to accelerate the recovery of cod in the Northwest Atlantic,
namely a cull of seal populations in this area.”
(DM: The suggestion made here is that seals may provide an important
protective service to young cod in the absence of a strong presence of
older cod – a warning against thinking that a “seal cull” will result in
more cod survival.)
“Our results could also have implications for the recommendation that seal
herds off Atlantic Canada should be reduced to promote cod stock recovery
(FRCC 1999). It has been suggested that large increases in seal abundance
have resulted in increased predation on cod, thus delaying stock recovery.
However, pelagic fishes like herring appear to be an important component
of seal diets (e.g. Bowen et al. 1993). These results point to the
possibility of a triangular food web involving cod, seals, and pelagic
fishes. Manipulation of such food webs can lead to unexpected results (Bax
1998). Seals may have a direct negative effect on cod recruitment through
predation on prerecruit cod. They also may have an indirect positive
effect through predation on pelagic fishes, possible predators of early
life history stages of cod, so that reductions in the seal herds may not
lead to improved recruitment of cod. Bax (1998) emphasizes the danger of
concentrating only on direct predation interactions when there are
indirect interactions with the potential to reverse the direct effects.
Our results suggest that a better understanding of the interactions
between cod, seals, and pelagic fishes is needed before it will be
possible to predict the effect of a seal cull on cod abundance.”
(DM: This article was written by two DFO scientists.)
9. DFO, 2004. Habitat Status Report on Ecosystem Objectives. DFO Can. Sci.
Advis. Sec. Habitat Status Report 2004/001.
Intro: “E. To maintain trophic structure so that individual species/stages
can play their historical role in the food web.”
(DM: But we need to acknowledge the shifting roles of seals and others…for
instance, which creatures are now playing the “historical role” of the
large fish? The seals?)
H. To conserve water column properties
I. To conserve water quality
J. To conserve biota quality.
Background – “Ecosystem Objectives” are starting point for setting
“operational ecosystem objectives.”
Two types of ecosystem objectives: (1) to prevent harm (2) to achieve
desired states
“When suites of ecological and social, cultural, and economic objectives
are being set, it is essential that they be reviewed as a package, to
ensure that they are mutually inter-compatible. In particular, activities
necessary to achieve all the desired social and economic uses of marine
ecosystems may not be possible without violating ecosystem objectives set
to protect ecosystem components from harm. In such cases, it is necessary
to revise the social and economic objectives, to ensure that the
ecological conservation-based objectives are not compromised.
Suites of ecosystem objectives have to consider together, once they have
been set, to ensure that as a group they cover important parts of the
marine ecosystem adequately. They also have to be evaluated relative to
expected major threats, to ensure that the suite includes operational
objectives for ecosystem properties expected to be exposed and sensitive
to them. It is also necessary to consider in advance how the operational
objectives will be used to assist in management of cumulative impacts as
well as activity-specific impacts.”
“Generally, those setting EOs and their operational components (e.g.
reference points), should consider data and information covering as wide a
time period as possible, and encompass periods when, with current
knowledge, the ecosystem would be considered healthy.
We lack time series of data for many ecosystem properties for which EOs
may need to be set. Even where data series exist, most come from recent
decades at best, and from times when human activities had already altered
the ecosystem in important ways. Therefore our time series may limit
artificially what we perceive are the natural state or bounds of natural
variation. Given the repeated occurrence of the phrase “within bounds of
natural variability” in the conceptual objectives and components, this
limitation may have some uncomfortable implications for making the
conceptual objectives operational.
Those managing human activities in marine ecosystems have an obligation to
try to evaluate management actions intended to achieve individual
ecosystem objectives with regard to the impacts of those actions on the
other ecosystem properties addressed in these Guidelines…”
“When setting Ecosystem Objectives intended to address perceived problems,
it is important to consider root causes, and not just symptoms. Work to
improve understanding of those root causes should be a priority.”
(DM: The root cause of the failed rebuilding of the groundfish is most
definitely NOT seals.)
** “The consequences of management manipulations of trophic systems are
highly unpredictable. Therefore, only under conditions of exceptionally
good understanding would there be a scientific basis for forming Ecosystem
Objectives which might lead to planned major reductions of predators with
the intent of producing specific benefits to populations lower in the food
web.”
“Because the consequences of management manipulations of trophic systems
are highly unpredictable, Ecosystem Objectives should not knowingly guide
management to allow actions that substantially alter the ratio of
different trophic levels in the food web or size classes in the seize
composition of the web.”
(DM: So, today, when the predator “trophic level” has already been
“substantially altered” (i.e. decimated), no other organisms should now be
removed from this level – in other words, the seal cull is
contraindicated.)
“These guidelines should be applied on spatial scales large enough that
population dynamics processes are likely to dominate over extrinsic
factors such as migration. (That is, Ecosystem Objectives to maintain
particular trophic structures on very local scales are likely to be
impossible to achieve, because the presence and abundance of many of the
species may be determined by factors acting on much larger spatial
scales.)”
(DM: In other words, seal exclusion zones should not be proposed.)
“Food webs are complex and even in knowledge-rich systems ability to
predict specific consequences of management actions or environmental
factors influencing the trophic structure will be limited. However, our
knowledge of trophic relationships is very weak for most marine systems,
and better information would improve our understanding of at least general
consequences of perturbations to food webs.”
(DM: Therefore, we do not have the “exceptionally good understanding”
required for setting any objective involving “planned major reductions of
predators…”)
“Moreover, resilience of ecosystems provides another justification for
ensuring that management is aware of and responsive to the ecosystem
stresses caused by natural and anthropogenic factors. To protect ecosystem
resilience, the cumulative effects of both natural and human stresses on
ecosystems need to be recognized and accommodated in management.”
(DM: Scientists should therefore consider the oxygen consequences of the
current harp seal cull/seal corpse disposal activity, especially in the
hypoxic Gulf of St. Lawrence. Dead seals are too likely to decompose,
aggravating bottom water hypoxia…)
“…habitat is defined broadly to include the physical and chemical features
required by living organisms to carry out their life process.”
“Where biological functions of structural habitat features are known,
those should be given prominence in setting Ecosystem Objectives.”
(DM: Again, all the right phrases are in included in this article to lead
to the scientific prohibition of the dumping of seals in the
oxygen-stressed bottom waters of the Gulf of St. Lawrence.)
“Knowledge of the causes and robustness of the structural and functional
properties of communities is particularly limited, which makes it hard to
set operational Ecosystem Objectives for those properties directly.
However, there could be some role in management for Ecosystem Objectives
intended to prevent major changes in the relative abundance or
distribution of species and habitat features in the community, with the
expectation that preventing such changes at least reduce the risk of harm
to structural and functional community properties. In these cases,
however, attention should be given to ensuring that the Ecosystem
Objectives can be clearly linked to management actions with known
consequences, so the populations can be maintained with high certainty.”
(DM: All that is needed is for DFO to realize that seals are some of the
“causes” of “robust functional properties of communities”…)
** “If Ecosystem Objectives are to be set for intentionally reducing a
species’ abundance significantly, the evidence of serious and widespread
harm needs to be very strong, such as with harmful algal blooms. In such
cases there also needs to be a good understanding of the consequence of
the management actions taken to achieve the EO.”
(DM: Seals are in no way equivalent to harmful algae blooms! We can assume
that a modern large, fish-dependent, and later-evolving organism such as
the seal appeared as part of a positive, fish-sustaining ecosystem.
Harmful algal blooms and bacteria, on the other hand, can and have already
lived during eons when the sea contained no fish, or seals. They will do
so again.)
“There is very limited understanding of how ecosystem properties and
management consequences scale up and down. This area needs more study, and
management need to be cautious in making assumptions about consequences
and interactions of management actions which pursue Ecosystem Objectives
on several scales.”
“…uncertainty is amplified by a number of factors. These include…Limited
knowledge of the contributions of the various species, habitat features,
and their linkages and relationships to the higher-order ecosystem
properties like stability, diversity, resilience, etc….Limited
understanding of second order (indirect) impacts of manipulating
individual ecosystem components.”
(DM: Again, this does not compare well with the requirement for
“exceptionally good understanding” before a seal cull can be justified as
a management plan.)
“…the Guidelines reflect consensus of substantial expert knowledge, and
there is some confidence that their application will at least improve
performance relative to practice without any Guidelines.”
(DM: Fine, a great many of the right words have recently been written by
DFO’s ecosystem scientists - now let’s see some honest, gutsy translation
of this new thinking into practical resource management decisions …)
10. Pikitch, E K et al.
2004. Ecosystem-Based Fishery Management. Science 305: 346-347 (July 16,
2004)
“Ecosystem-based
fishery management (EBFM) is a new direction for fishery management,
essentially reversing the order of management priorities to start with the
ecosystem rather than the target species.
The overall objective
of EBFM is to sustain healthy marine ecosystems and the fisheries they
support. In particular, EBFM should (i) avoid degradation of ecosystems,
as measured by indicators of environmental quality and system status; (ii)
minimize the risk of irreversible change to natural assemblages of species
and ecosystems processes, (iii) obtain and maintain long-term
socio-economic benefits without compromising the ecosystem; and (iv)
generate knowledge of ecosystem processes sufficient to understand the
likely consequences of human actions. Where knowledge is insufficient,
robust and precautionary fishery management measures that favour the
ecosystem should be adopted.”
Goals of EBFM include
“protect ecosystem resilience and avoid irreversible changes.”
“The impacts of
fisheries on endangered and protected species, including ecological
processes that are essential for their recovery, should be managed through
an EBFM approach.” …EBFM also intended to “manage indirect effects” on
endangered species or processes.
“…the judicious use
of a precautionary approach. This means erring on the side of caution in
setting management targets and limits when information is sparse or
uncertain. Greater uncertainty would be associated with more stringent
management measures…Ideally, EBFM would shift the burden of proof so that
fishing would not take place unless it could be shown not to harm key
components of the ecosystem.”
“New analytical
models and management tools will be needed as well. Multispecies and eco-trophic
models must be refined and expanded to better account for system-level
uncertainties, to derive system-level reference points, and to evaluate
the ecosystem-level consequences of proposed EBFM actions.”
(DM:
This context can be interpreted for sealing too, obviously…)
“Because EBFM
emphasizes habitat and ecosystem function in the context of fluctuation,
advanced models for EBFM should incorporate spatial structure and
environmental processes.
EBFM may require
evolution from suites of single-species fishery management plans to
integrated ecosystem-based fishery management plans (EBFMP). In an EBFMP,
the impact of a management action would be assessed with respect to the
ecosystem as well as individual species. It is entirely possible that a
fishery could be considered overfished within the ecosystem plan
(ecosystem overfishing) when it is not over fished in a single-species
context.”
“Rebuilding
ecosystems from their degraded state, in turn, might inflict short-term
economic hardship on fishers. The transition to EBFM might thus involve
compensating fishers and providing incentives to other stakeholders to
support EBFM as a long-term strategy.”
“EBFM should move
forward now despite current uncertainties about ecosystems and their
responses to human actions because the potential benefits of
implementation are as large as or greater than the potential risks of
inaction.”
(DM: This eminently sensible consensus statement and visionary piece was
authored by 17 marine scientists from the United States, Europe and
Australia, and it was published in the world’s premiere science magazine.
No Canadian scientific voice chimed in on this, unfortunately.)
