How will Fish in the Northeast Respond to Climate Change?

new study, published by the journal PLOS ONE found 82 species of marine fish and invertebrates in the northwest Atlantic (or the northeast US) to be vulnerable to climate change (A write up of the study by the New York Times can be found here). These 82 species encompass every commercially managed fishery in the region as well as a few popular recreational species and endangered species.

Not all species were predicted to experience negative effects from climate change – only about half were likely to be negatively affected. 20 percent will be positively affected by climate change and the rest will be neutral, said Jon Hare, NOAA oceanographer and lead author of the paper. However a majority of the species studied did show a high potential for a change in habitat distribution, which could create significant management challenges

“Peter Baker, director of Northeast U.S. oceans for the Pew Charitable Trusts, said the report should be a motivator for fishing managers to protect more ocean habitat and preserve marine species.”

Comment by Doug S. Butterworth, Marine Resource Assessment and Management Group, University of Cape Town

In this paper, Hare et al. report the results of the application of Vulnerability Assessment methodology to assess the extent to which abundance or productivity of species on the Northeast US Continental Shelf may alter in response to climate change. More particularly, they consider, inter alia, directional effects (whether negative, neutral or positive) and potential for changes in distribution. The determinations are based on expert opinions which lead the authors to draw firm conclusions, e.g. that climate change is expected to negatively affect about half the species they consider.

The environmental conditions associated with the habitat preferences of different species may be determined from empirical studies for which considerable data are available. Hence there is a clear basis in data and analyses to formulate the opinions that have been consolidated in this report.

What is much less clear, however, is what bases could defensibly have been used by experts to comment on directional effects for abundance and particularly productivity under projected changes in environmental variables under climate change. The productivity, and consequently to a large extent, the abundance, of a population of a fish or invertebrate species is driven by the (typically) annual recruitments to that population. The inferences drawn by these experts must consequently have been based on knowledge of how environmental variables affect such recruitment.

Yet the difficulties of reliably establishing such relationships are well known in fisheries assessment science. The classic article on this topic by Ram Myers (When do environment-recruitment correlations work?) pointed to the failure of almost all such relationships that had been proposed when tested with new data.

This then begs the questions of what bases the experts contributing inferences concerning directional effects to the Hare et al. study used for their determinations and how reliable those inferences might be. If they are reliable, why are they generally not being used in the fisheries assessments from which advice on catch limits is formulated?

I agree with Hare et al. when they argue that the expert opinions they collated “can guide future monitoring, research, and monitoring studies.” However, they go further to state that their results can be used by managers to “guide management actions” (they provide examples of species for which they suggest decreasing fishing mortality). Should they not first meet the burden of justifying the bases on which the experts who contributed to their study drew their inferences about directional effects, and also explain the associated implications for the reliability of knowledge about fishery recruitment-environmental variable relationships?

Doug S Butterworth heads the Marine Resource Assessment and Management Group in the Department of Mathematics and Applied Mathematics at the University of Cape Town
Posted in Uncategorized.

One Comment

  1. I spent 9 years working on the EPA-lead Waquoit Bay Watershed Ecological Risk Assessment which used Vulnerability to identify nutrients (N and P) as the major human stressors in this watershed on Cape Cod, Ma. We used a model developed by Drs. Ivan Valiela and Jen Bowen (Boston Univ. Marine Program) to estimate how much the nitrogen loading to the bay would have to be reduced to restore eelgrass beds to the 1971 level (20% coverage). The major sources of nitrogen from the watershed included: fertilizer usage; septic systems and atmospheric sources from the regional airshed. I participated in this project while I worked at the Northeastern Fisheries Science Center in Woods Hole, Ma. I served as the Recreational Fisheries Coordinator in the Northeast and helped the NEFMC’s Habitat Committee develop Omnibus Habitat Amendment 2

    Subsequently the Massa. Estuaries Project modeled the nitrogen loading to > 50 nitrogen impacted embayments and estimated recovery targets based on the Total Nitrogen at key monitoring stations within each impacted embayment. Ma. DEP used these TN levels as enforceable standards under the Clean Water for non-point pollution. A 2015 legal settlement between EPA Region 1 and the ConservationLaw Foundation required towns on Cape Cod to develop wastewater mitigation plans by June 26, 2016. As part of this process,Welfleet,Ma. is restoring shellfish beds and salt marshes as a way to reduce nitrogen loading from human activities within coastal watersheds,while Mashie is utilizing oyster aquaculture/sediment denitrification in Waquoit Bay to remove excess nitrogen from the water column.

    Eelgrass beds; salt marshes and shellfish beds are Essential Fish Habitat under the M-S Sustainable Fisheries Act, so that the wastewater mitigation efforts at the local level will reduce the effects of eutrophication and climate change on wild places, wild things. The projected costs for this mitigation effort is $4-6 billion over the next 20-30 years which will aid both natural fisheries and aquaculture endeavors locally. Eutrophication and Climate Change are major environmental stressors in the Northeastern US and Vulnerability Analysis and modeling engaged multiple stake holders to do something at the grassroots level to deal with this problem.

    Given this potential case study, I feel that Dr. Butterworth and other fisheries modelers/managers are short sighted in not incorporating non-traditional modeling and management approaches to address eutrophication and climate change impacts on natural mortality in fish stocks and the use of adaptive, watershed-based management approaches to deal with the effects of human activities in coastal watersheds on water quality and improving the “productive capacity” of EFH instate jurisdictional waters. Climate change impacts have stressed lobsters in Nantucket Sound which move into offshore waters in the Summer and Gulf of Maine cod stocks to the north of Cape Cod, so these human stressors extend to offshore waters as well.

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