Populations of many fish species – summer flounder, butterfish, squid, black sea bass, cod, and bluefin tuna to name a few – are clearly being impacted by changing ocean water temperatures. The challenge now is to realign fisheries stock assessment science and fisheries management protocols to acknowledge this new reality.
Climate-related changes in migration, abundance, and stock resilience are documented in several articles in this edition of CFN, including one on a report from the Gulf of Maine Research Institute about emerging fisheries in the Gulf of Maine for several species long considered denizens of Mid-Atlantic waters.
In a guest column on the new bluefin tuna stock assessment, American Bluefin Tuna Association Executive Director Rich Ruais explains how international scientists now recognize that changing environmental conditions mean it is less likely that western Atlantic bluefin can rebuild to levels last seen in the early 1970s. This more realistic view will allow the International Commission for the Conservation of Atlantic Tunas to consider adopting higher quotas when it meets in November.
And then there is our Special Report on Gulf of Maine cod. An assessment update conducted by the Northeast Fisheries Science Center and released this summer concluded that the stock is at rock bottom. The looming consequences of this finding could jeopardize much of the groundfish fishery in the Gulf of Maine.
Fisherman David Goethel of New Hampshire, a long-time participant in cooperative research, fiercely objected to the science center’s decision to conduct the update the way it did and also criticized the assessment process for failing to take into account changing environmental conditions. In a follow-up interview, Goethel explained that the stock assessment reference points for cod were based on cold-water conditions in the Gulf of Maine during the 1960s, conditions that “don’t exist anymore.”
He further noted that the situation we’re seeing today – diminished populations of cod, yellowtail flounder, and northern shrimp – are strongly reminiscent of what happened in the 1950s when water temperatures also climbed. Back then, haddock, whiting, and redfish dominated the catch, which, Goethel observed, “looks a lot like what we’re seeing now.”
National Marine Fisheries Service fishery ecologist John Manderson worked closely with the Garden State Seafood Association and fishermen to develop an ecosystem-based approach to surveying butterfish using a model that identified butterfish habitat based on temperature. The data they gathered was incorporated into the latest stock assessment, which resulted not only in a dramatic turnaround in the scientific understanding of butterfish abundance but also in significantly higher quotas (see CFNs May 2014 and September 2014).
Manderson came away from the experience convinced that integrating climate impacts, as well as fishermen’s observations and hypotheses, is necessary to produce stock assessments that more accurately reflect what is really going on with fish stocks.
It’s clear that action is needed on at least two fronts. Congress should amend the Magnuson-Stevens Fishery Conservation and Management Act to remove the requirement that all stocks be managed to achieve maximum sustainable yield at the same time, a goal that is not possible, especially given the growing impacts of climate change. And, fishery scientists and managers should move quickly to base stock assessments and management decisions on reference points that take the effects of climate change into account, rather than relying on reference points based primarily on a snapshot of stock abundance in the past.
Only then will we be able to manage fisheries as they truly are instead of what we think they
should be. /cfn/
