New England Fisheries

Facts from NOAA on the new Gulf of Maine cod stock assessment

Atlantic cod (Photo credit: NOAA)

As we mentioned in the news update last week, and as you may have read elsewhere,  a recent assessment of the Gulf of Maine cod stock found that the stock is at lower population levels than previously estimated. The precise way this new information will translate into changes in management measures has yet to be determined, but it is likely that catch limits on Gulf of Maine cod and other groundfish species where Gulf of Maine cod are found will be reduced. This is a hugely important issue, and TalkingFish.org feels that the government, fishermen and other stakeholders should not point fingers, but rather should continue to gather information to fully understand the situation and work to develop solutions.

To help our readers stay informed, we are sharing this document, which was produced by NOAA to explain what the assessment means and why its results are so different from the estimates that came from the most recent assessment, which was in 2008. In summary, the new assessment contains more detailed data on catch, improved biological information about growth, and does a better job of adjusting for uncertainty than the 2008 assessment did. Additionally, the 2008 assessment estimated that the class of fish born in 2005 was much larger than it actually turned out to be.

TalkingFish.org will keep providing readers with the facts about the new assessment as they develop, and this NOAA document is a great resource to help understand the issues.


Comments

One Response to Facts from NOAA on the new Gulf of Maine cod stock assessment

  • Thaddeus Bigelow says:

    “Better biological information about growth: There is more detailed information on the age and weight of fish that were caught by commercial, recreational, and scientific survey vessels. The revised weights at age showed fish in recent year classes are lighter-than-average at younger ages. This contributed to the lower spawning stock biomass relative to the 2008 assessment (since reproduction potential in these fish is primarily a function of size, not age.)”

    That is an interesting spin on it. Here is what the draft assessment document on the NEFSC web page actually says: “The largest change with respect to the GARM III results occurred from the update of the SSB/January 1
    stock weights (Run 3b). In previous assessments stock weights-at-age had been derived from only the landed catch. This approach likely overestimated the true weights at age for ages 1 through 3…Weights at age used in GARM III were estimated from only the landed fraction of the catch and likely overestimated the true stock weights-at-age.” That sounds a lot like an “oops” to me.

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