Recently, a team of researchers from the National Marine
Fisheries Service, collaborating with the University of Massachusetts’ Large
Pelagics Research Center, claimed to have discovered a new spawning ground for
bluefin tuna.
On its face, the research seems fairly convincing. Five- and six-day-old bluefin tuna larvae
have been found in an area known as the “Slope Sea,” a piece of water that lies
between the Gulf Stream and the edge of the continental shelf in the Mid-Atlantic
Bight.
Prior to the announcement, the only known North American
spawning ground for Atlantic bluefin was located in the Gulf of Mexico. The NMFS research team asserts that ocean
currents could not have carried larval bluefin from the Gulf all the way to the
Slope Sea in five days, meaning that such larvae must have been spawned
somewhere else.
They also point to tagging data that shows smaller, 100- to
500-pound bluefin lingering in the Slope Sea region during certain times of the
year. A
previous study, conducted by researchers at the UMass Center, suggested that
western stock bluefin tuna mature significantly earlier than previously
believed. The two findings, taken
together, could have a meaningful impact on the fishery for western stock
bluefin.
Based on the two studies, it would not be unreasonable for
people to argue that if western-stock bluefin actually mature while relatively
young, and have more than one spawning ground, they can be sustain larger
harvests than they could if they only matured after a decade or more and only
spawned in one, vulnerable piece of the ocean.
However, a
number of scientists specializing in bluefin tuna research remain properly skeptical
of the team’s findings. “Properly”
skeptical, because the purpose of science is to discover the truth, not to make
headlines or to tell people the things that they want to hear. The NMFS team’s findings may well be correct,
but it is the duty of the scientific community to try to poke holes in their
paper and conduct further research to prove that they are wrong.
If, after the skeptics take their best shots at the data, the team's conclusions remain largely intact, then—and only then—it will be time to
announce that bluefin do, indeed, spawn in the Slope Sea.
Many fishermen, however, are already celebrating, in
anticipation of relaxed harvest regulations.
Sport Fishing Magazine, which targets
recreational anglers, addressed the study by saying
“A bombshell in the world of fisheries management fell on
March 7. That’s when a report revealed
new evidence that Atlantic bluefin tuna spawn off the northeastern United
States…
“This finding transcends pure scientific discovery, as the
study states, it possibly ‘leads to lower estimates of the vulnerability of
this species to exploitation…’
“Put more simply, there are already suggestions being heard
from various interests that bluefin that bluefin populations may be more
resilient than we had thought, that stocks may be in better shape, and that
more generous fishing quotas may be called for.”
Sport Fishing did
express one cautionary note, pointing out that some members of the scientific
community deemed the study to be preliminary, and feel that it would be
premature to change the bluefin management paradigm. However, it ended the announcement by saying
“…there is little doubt that this research will ultimately
have implications for how we manage the ocean’s most valuable apex
predator. It will be interesting to see
how this knowledge and more to come (as a search for more undocumented spawning
grounds continues) will shape those implications.”
Over all, it was an exceptionally upbeat article, expressing
none of the skepticism that should accompany news of new scientific
discoveries. In short, it was typical of
how fishermen react when they hear news that might cause quotas to rise.
We saw the same sort of thing occur a few years ago in the
Gulf of Maine cod fishery.
In
2008, NMFS produced a stock assessment that was the most optimistic in
years. Although it indicated that
overfishing was still occurring, it also showed that the stock was making a
strong recovery and was no longer overfished; estimated spawning stock biomass
was 33,877 metric tons in 2007, seemingly well on its way toward reaching the
SSB target of 58,248 mt.
When the results of the 2008 assessment were released,
fishermen had no problems in accepting its conclusions, even though it seemed
to be based on some somewhat suspect data—the
supposed strength of the 2005 year class of cod, upon which most of the rosy
analysis depended, was based on just one or two tows of the research vessel’s
net, which captured very high numbers of fish. No other tows were anywhere near as
productive.
Still, despite this obvious warning sign, the fishermen
didn’t question the data at all. It said
that the stock’s health was rapidly improving, which meant that they’d soon be
able to harvest larger numbers of fish.
That was all that they wanted to know.
However, things turned around quickly just three short years
later, after another
stock assessment, released in 2011, said that the cod stock was in some
real trouble. The new assessment
determined that the size of the spawning stock biomass was a mere 11,868 metric
tons, roughly 1/3 of the 2008 estimate.
It employed a different mathematical model than the 2008 assessment,
considered more sets of data, and was generally considered a more reliable
estimate of the stock’s true size.
“The modeling approach used in this assessment represents a
quantum leap, in terms of the ability to handle the underlying data and also
its uncertainty. There was far more
rigorous treatment of the discard information and its consequence, and also the
treatment of the landings and the survey data.”
But that’s a fishery scientist’s view. Fishermen’s views were very different.
David Goethel, a commercial
groundfisherman who sits on the New England Fishery Management
Council,complained
“…why should it be accepted that the current data and model
provide the best available science?
“…I think we need to have a thorough reexamination of
everything here. We need to examine cod,
period. We need new reference points, we
need new [Stock Assessment Review Committee] boundaries. We need all this done, and then we can
address the underlying problems, if they still exist. I’m not prepared to shut down the Gulf of
Maine, or to put out a [limit on catch levels] that would shut down the Gulf of
Maine until we address these issues.”
And that last sentence, of course, says it all.
Goethel had no problem with the 2008 cod stock assessment,
because it had the potential to increase his catch. But once the 2011 assessment came out,
declared the 2008 assessment to be inaccurate and threatened to sharply
decrease fishermen’s landings, it was time to condemn the science, call
for additional research, reset all of the existing parameters and start over
again.
For while many fishermen are willing to accept science that
leads to increased harvest as unquestionably right, they are even more inclined
to declare any science that leads to decreased landings as completely and
irreparably wrong.
It's a problem that managers have had to live with for years, and it's not likely to go away at any time soon. But it makes it very clear why, when setting annual catch limits, scientists, and not fishermen, must have the last word.
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