At the recent Scientific and Statistical Committee meeting to review Gulf of Maine cod, the Committee voted not to ratify the assessment, a significant legal step that leaves open more Council options for its meeting next week. Further, both environmental groups and the recreational fishing alliance feel the survey is flawed.
(SEAFOOD.COM NEWS) Jan 27, 2012 — At the recent Scientific and Statistical Committee meeting to review Gulf of Maine cod, the Committee voted not to ratify the assessment, a significant legal step that leaves open more Council options for its meeting next week. Further, both environmental groups and the recreational fishing alliance feel the survey is flawed.
The defenders of the study argue it is based on 'better science'. But the more they talk, the more some of the science looks like guess work.
For example, one of the arguments against the 2008 assessment was that it included large tows in 2003 and 2005 that should be discounted.
But you can't have it both ways: if you base much of your assessment on a random survey, you can't throw out the results you don't like. Increasingly treatment of survey data seems too dependent on the outcome of one or two tows.
Instead of having these results wildly push the assessment up or down, it might be more useful to reduce the reliance on the random tows during a period of transition to a new vessel with new gear. Only after a longer period can the actual random survey results be measured against other data. Side by side tows and testing are simply not good enough.
So the new survey is using re-calibrated data. The assumptions may be the best in the world, but they are still assumptions that have not stood the test of time.
Secondly, recreational catches of Gulf of Maine cod have huge importance in NOAA's understanding of the cod stock, for 2011, 33.7% of the Gulf of Maine cod was allocated to recreational and charter fishing, but now NOAA says that recreational fishermen only caught about 1/3 the amount they had expected. This also contributed to the wild swings in stock status.
The fact is that fishery science that results in wild swings in abundance is losing credibility with the public and the industry, because wild swings seem to be the results of arcane changes in the model, rather than well supported and observed changes in the actual harvest of the stock.
There is an argument that cod stocks in the Gulf of Maine are all contracting to a final refuge, that just happens to be the primary fishing ground – Stellwagen bank – for the Gloucester fleet. Therefore this theory discounts the fact that harvesters are seeing and landing a lot of fish.
The problem is that with cod, there has been not enough consensus on how the stock should be measured, at a time when the measurement systems are in transition.
This makes it a critical time to step back and look at the entire picture – i.e. the whole forest – and not make a rush to judgement.
Is the stock defined correctly? Are the recreational estimates and revisions of the prior science driving the model? How is existing catch data, length at age data, and location data as to where fish are caught integrated into the model? Throwing out things that don't fit or confuse the result is not a good enough approach by the modelers. It may be a best effort, but it has come up short.
Over the long term multi-year assessments, and multi-year catch limits are desperately needed.
But for these to work, the fishery also has to rebuild to a multi-age structure so that when catches are dominated by a single year class, there will be other ways to estimate how many years the commercial industry should live off of that year class.
Republished with permission from SeafoodNews.com