Georges Bank and surrounding areas with a long history of abundance have seen fish stock depletion and collapse of the fisheries. To speed stock recovery, parts of the area have been closed to fishing as Marine Protected Areas (MPAs) or Closed Areas (CA), shown as blue polygons. Map courtesy of NOAA Fisheries Service.
Stock Assessment
Fishery management's job of stock assessment is difficult in part because fish aren't stationary creatures, like trees, but because they also live underwater. Fishery managers have had to determine best practices to formulate stock assessments and how to develop catch quotas and limits.
Fishery management plans must specify objective and measurable criteria (reference points) to determine when a stock is overfished or subject to overfishing. A scientific analysis of the abundance and composition of a fish stock, as well as the degree of fishing intensity, is called a stock assessment. Stock assessments are subject to regional peer review as part of the process to ensure that management decisions are based on the best scientific information available. In fiscal year 2018, NOAA Fisheries conducted 198 stock assessments.
The councils and the agency use information from stock assessments to develop and recommend ACLs and other conservation and management measures. While catch limits are set annually, assessments are often done less frequently. To determine whether catch limits have successfully ended or prevented overfishing, NOAA Fisheries may use the fishing intensity metrics and reference points derived in a stock assessment or a comparison of catch to the overfishing limit (OFL). If the catch-to-OFL comparison is used, an overfishing determination is made annually. If a stock assessment is used, due to timing of the next stock assessment, several years may pass before we are able to determine if catch limits successfully ended overfishing.
Rebuilding Plans for Overfished Stock
Any stock that has previously been listed, or is currently listed, as overfished is required to have a rebuilding program until the stock has been rebuilt to levels consistent with supporting MSY on a sustainable basis. In many locations, such as Georges Bank, this rebuilding plan includes the establishment of Marine Protected Areas.
Beginning in 1994, three large areas totaling 17,000 km2 in Georges Bank were closed to fishing for groundfish. Fishing gear that might catch groundfish incidentally or damage habitats were prohibited, but other forms of fishing such as long-lining were allowed to continue. Additional fishery management measures such as groundfish fishing permit limitation, increase of trawl mesh size, and reduction of groundfish fishing time were also applied. By 1999 there was a 40% reduction in fishing by trawlers, but other forms of gear and fishing for species other than groundfish is still allowed in the areas.
2. Watch this brief video showing scientists taking a trawl assessment and performing other data gathering on the fish and habitat in a closed area on Georges Bank.
Science Bulletins: Will The Fish Return (AMNH)
Scientists did find an increase in groundfish biomass in closed areas. Haddock rebounded well and the stock was considered rebuilt in 2010. However, cod around Georges Bank, and in the whole of the Northwest Atlantic, remained overfished and overfishing continued during a number of years even with the closures in place.
3. The Gulf of Maine Research Institute issued a report in June 2013 titled The Future of Cod in the Gulf of Maine. Read Section 1. Understanding Environmental Change(Acrobat (PDF) 386kB May21 20). (Note: Section 1 begins at the bottom of the first page.)
Checking In
Check your understanding of the report.
What are some impacts the warming temperatures may have on cod over their lifetimes?
While fish stocks are growing more slowly in cooler waters, they reach larger body sizes at older ages than those fish in warmer waters. If smaller fish are a larger portion of the population of the stock, they may be producing fewer or lower quality eggs, resulting in a decline in spawning and recruitment potential, which can slow the recovery of the cod population. However, the size of the fish may also be a result of older fish not reaching top predator status due to changes in prey status, so the mature cod spend more energy foraging instead of gaining in size. This results in a lower reproductive possibility as well.
4. Visit this site to see an animation of annual SST anomalies in the US Northeast from 1982-2017. Note the outlines for the Gulf of Maine and Georges Bank areas. The animation displays temperatures as anomalies, or the degrees warmer or cooler than the long-term SST average. Note that some years are cooler, and some are warmer, and the edge of the continental shelf is clearly delineated in some years of higher SST temperature contrast.
Pseudocalanus is one of the food sources of larval cod, and in the historical data, it shows where there were higher abundances along southern New England and Georges Bank that declined in more recent decades. The sites of cod stocks in the same areas, where these phytoplankton would have been important food, have also shown similar declines in abundance.
What happened when the fishery managers didn't know to account for climate change?
Because the NE fishery managers didn't account for climate change, they set the catch quotas too high, especially during the 2012 heat wave.
Although cod and haddock are related species of groundfish, cod continues to be overfished and haddock has rebounded. Recent studies have found that while both species share many of the same needs for cold water habitat, haddock may respond better to slightly warmer temperatures than cod.
Stop and Think
6: How could knowing the influence of warming waters, such as from climate change, in the Gulf of Maine affect the ways that fisheries managers assess and protect cod stocks? Explain.
Optional Extensions
To learn more about the sustainability of Atlantic cod and important dates and events in Atlantic cod management, visit the Atlantic Cod profile at the NOAA Fishwatch website.
from NOAA Fisheries 
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