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Commercial Fisheries News
Volume 32 Number 12
July 2005
Scientists rethink how to assess lobsters
WASHINGTON, DC – Lobster stock assessment scientists are revolutionizing how they determine the status of the American lobster resource.
Based on advice from an independent review panel, the scientists charged with conducting the new assessment are moving away from the long-standing “egg-per-recruit” (EPR) standard and turning more to reference points and indicators that will actually mean something to people.
 
“I’m encouraged,” said Pat White, chairman of the Atlantic States Marine Fisheries Commission’s (ASMFC) American Lobster Management Board.
“They’ve been working really hard to come up with models that can do a better job of analyzing where we are and forecasting where we’re going,” he said. “We aren’t putting all our eggs into one model anymore.”
The assessment is being conducted by a subcommittee of ASMFC’s lobster technical committee, chaired by Bob Glenn of the Massachusetts Division of Marine Fisheries.
Although many had hoped the assessment would be available this summer, the subcommittee ran into data hang-ups. But the assessment is now on the homestretch, almost ready to undergo peer review in late August.
If all stays on schedule – and if the peer review panel gives the assessment a general thumbs up – the lobster board will consider the findings during ASMFC’s annual meeting this fall. The meeting will be held Oct. 31-Nov. 3 in Galloway, NJ.
Results under wraps
The assessment subcommittee is keeping the results of the assessment under close guard until the peer review is completed.
Even so, lobstermen are beginning to brace themselves for the results, knowing they’ll need to respond to the new stock status if the resource in their particular stock area is below acceptable reference points.
According to Bonnie Spinazzola, executive director of the Atlantic Offshore Lobstermen’s Association, her members understand this reality.
“We’re nervous,” she said. “We expect we’ll have to do more. I won’t say we’re happy about it, but we understand we need to do what’s best for the resource. The catch offshore is not as good as it could be.”
Most members of the Maine Lobstermen’s Association (MLA) aren’t feeling a “great cause for concern” about the pending Gulf of Maine assessment, said Patrice McCarron, the group’s executive director.
However, she added, “There’s still a feeling we’re going to be asked to do more.”
Lobstermen in Long Island Sound and Lobster Conservation Management Area 2 in Southern New England have suffered serious resource problems, and the assessment results are expected to significantly influence their future management decisions.
“A lot of people are hanging their hats on this assessment,” said Pat White.
Better way to go
Whatever the outcome, many believe the new assessment will do a better job of characterizing the status of the stock so that it more closely reflects what lobstermen themselves are seeing and experiencing.
“There’s going to be a big change,” said Carl Wilson of the Maine Department of Marine Resources, a member of the assessment subcommittee.
The idea that the assessment won’t totally hinge on the current egg-per-recruit indicator is coming as a relief to McCarron.
“It was this arbitrary reference point,” she said. “It never meant anything tangible to people.”
Spinazzola, too, thinks the shift to multiple parameters is a positive step.
“This is a more holistic approach,” she said.
At press time, the assessment subcommittee was still selecting which stock indicators would be used in the assessment, so the final list wasn’t available.
But Bob Glenn said, “I think people will be surprised at how many things we’re taking a look at.”
Models peer reviewed
The assessment got on a roll when the ASMFC Lobster Technical Committee’s Model Development Subcommittee reviewed all the available stock assessment models and picked five for consideration in the next assessment.
The finalist models were thoroughly scrutinized by a five-member independent review panel chaired by Ray Hilborn of the University of Washington. The panel also looked over something called an “individual-based lobster fishery simulator” through which most of the models were tested.
Lacking data
The peer review panel released its summary report last December. As it turned out, the panel’s most critical statements didn’t have anything to do with the models at all. They related to data.
“We found that the data available are woefully inadequate for the management needs of this fishery, and that the primary limitation on the ability to manage is limited data rather than the choice of models,” said the reviewers.
Not mincing any words, the panel concluded, “Our strongest recommendation … is that the quality of data needs to be upgraded significantly.
“The assessments need to estimate the trends in stock size, fishing mortality, and egg production in the inshore and offshore stocks and at the spatial resolution defined by stock boundaries, management regulations, and size composition. This cannot be done at present due to data limitations,” reported the panel.
Data upgrades
Wilson acknowledged that the review panel’s comments regarding data were troubling.
“Those are always my biggest concerns,” he said. “But we need an assessment, and at some point, you kind of have to hold your nose and go forward with what you’ve got.”
Spinazzola agreed.
“We have to go with it for now and make a concerted effort to get better data for the scientists to use next time. It’s up to us, too, to try and help them,” she said.
According to Glenn, the “poor resolution” of the landing data has been “extremely problematic” for the subcommittee.
“If people want to see an improvement in the assessment, we need to see an improvement in the quality of the data,” he said.
And Glenn thinks the best way to get better data is through mandatory reporting.
“That’s a really big one and it needs to be addressed,” he said. “It’s kind of the foundation to an assessment.”
Maine’s data
The state of Maine, which accounts for roughly 80% of all lobster landings, does not have a mandatory reporting program, which some members of the subcommittee view as a serious problem.
But Wilson said he is extremely encouraged that Maine’s data are getting better and better thanks to several factors.
Mandatory monthly reporting by lobster dealers and retailers alone has made a considerable difference, he said. Plus, the state has increased its sea sampling program and, while still controversial for many, the inshore trawl survey has generated large amounts of lobster information that will be critical to future assessments.
“We’ve been busting hump to try to collect more data and a wider variety of data,” said Wilson. “We’re doing as much as we can, but at the same time, it’s a huge industry.”
Panel comments
The review panel made numerous other critical comments about the models and assessment process in general.
“The panel is quite concerned that reference points are being calculated from assessments that combine management areas with different size limits or v-notching regulations,” reported the reviewers.
As for the lobster plan’s existing use of egg-per-recruit, the panel said, “We found that none of the assessment methods were demonstrated to estimate absolute EPR or the F10% with any reliability.”
The panel found, however, that “the methods and data available could provide reasonably robust estimates of trends in EPR and F (fishing mortality).” “Trends” is the key word here.
Advice taken
The ASMFC assessment subcommittee took these comments to heart and made a couple of fundamental decisions.
For one, after leaving the Gulf of Maine area as is, the subcommittee changed the other two stock assessment areas in order to break off Georges Bank proper to make it an area by itself.
Now, the Southern New England stock area encompasses the rest of the lobster producing area south of Cape Cod, including the canyons.
Though the enormity of this new area is of concern to some offshore lobstermen, Glenn said, “It makes more sense. Overall we think it’s a better fit.”
The subcommittee went through the standard egg-per-recruit model runs since the EPR indicator is still the foundation of the existing lobster plan.
But, heeding the review panel’s advice, the subcommittee is spending more time looking at resource “trends” using multiple indicators.
Pat White is convinced the new approach will benefit everyone.
“The more we look at recruitment and settlement and all these other factors, the better off we’ll be,” he said.
Yong Chen model
On an extremely positive note, the independent panel concluded that one of the models it reviewed showed great promise for the future.
It’s a size-structured stock assessment model developed by Yong Chen of the University of Maine School of Marine Sciences (SMS) with help from numerous individuals, including Wilson, post doctoral researcher Minoru Kanaiwa, and Larry Jacobson of the National Marine Fisheries Service (NMFS), who’s an adjunct professor at SMS.
“We recommend that this model be developed for the American lobster stock assessment in the long-term,” said the review panel.
The model is considered to be “data hungry,” meaning that it needs a large amount of good quality data. It is, nonetheless, “very flexible” and able to estimate abundance, fishing mortality, and catch rate “reasonably well” as long as certain variables aren’t “misspecified,” the panel reported. The panel also made several suggestions for improving the model.
“It’s a complex model but it gives you lots of options,” said Wilson, who explained that the model is fairly well developed for the Gulf of Maine but needs more work for use in the other stock areas.
Chen and the rest of the team will continue improving the model in the year ahead. Plus, Michael Errigo, a PhD student in Chen’s lab, received a three-year fellowship to conduct further testing. The $114,390 stipend and tuition grant was provided by NMFS, the National Sea Grant College Program, and the University of Maine.
Janice M. Plante
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