Climate Change to be Incorporated in Fishery Management
by Laurie Schreiber
PORTLAND – Climate change is impacting the fisheries, and should be considered as a factor in the fishery management process. That was the advice of a Northeast Fisheries Science Center (NEFSC) scientist, Dr. Jon Hare, to the New England Fisheries Management Council (NEFMC) during the latter’s June 19-21 meeting.
Hare gave a presentation on regional issues and work completed to date concerning the “state of science” as it relates to climate change and its impact on fisheries in the Northeast.
The accumulating evidence, he said, shows that the environment is changing, fish distribution and abundance is changing, and projections indicate changes will continue.
Hare is the director of the National Oceanic and Atmospheric Administration’s Narragansett Laboratory and the lead scientist for NEFSC’s Climate Research Program. He said his presentation reflected papers, projects and ideas developed with numerous colleagues.
Hare made a distinction between the terms “climate change” and “climate variability.” Climate variability refers to the natural variability within the climate system, as opposed to a wholesale change in the climate system.
In any given region, such as New England, he said there will be “winners” and “losers.”
Hare stressed that the findings to date are in the realm of research, and have not made their way into the management process. He said that, while there is variability in parameters such as temperature, ocean salinity and currents, wind patterns, and precipitation, overall conclusions can be drawn from long-term trends.
Trend lines from 1920 to the present show that there’s been a warming of ocean temperature, he said.
One example of climate change is seen in the temperature of the Northeast United States Shelf temperature, which has seen an increase of 1 to 2 degrees Celsius since 1920.
Long-term trends show that salinity on the shelf has decreased by approximately one-third of a percentage point since 1977. The decrease is linked to freshwater input from the north, he said. Freshwater inflow may be coming either from ice melt from Greenland, from melting sea ice in the Arctic Ocean, or from runoff from the Canadian Arctic.
“It’s a release of cold, fresh water, and freshening our system here,” he said.
Because the ocean water is warming, he said, the distribution of fish communities is shifting. NOAA’s trawl surveys, he said, shows, that 24 of 36 stocks have shifted northward by 1.6 kilometers per year or deeper by one-quarter of a meter per year, in search of cold water. The time series of 40 to 50 years indicates that some stocks have shifted northward by 40 to 70 kilometers, or deeper into the ocean water by 10 to 15 meters, he said. Over recent decades, the survey shows that more warm-water fauna are now found on the northeast U.S. shelf, he said.
Ocean acidification has been documented globally and can be seen in New England’s waters, he said.
There have been large-scale changes in wind patterns, primarily with the jet stream pushing north, he said. There have also be long-term changes in precipitation, in nutrients in the Gulf of Maine, and in the large-scale circulation in the North Atlantic over the last 40 years. Sea level rise is influenced by short-term variability, but there is also evidence that the rise is increasing over the long term, he said.
The trends are seen in large-scale changes in various fish and shellfish populations, Hare said. There has been a large-scale change in mackerel and surf clam distributions, due to warming ocean temperature. The effects of acidification can be seen in shellfish populations in particular, and could have impacts on recruitment, he said. Changes in phytoplankton and zooplankton have recently been documented. “We’re now at a point where we can document not only variability but also big change over all periods, over 30, 40, 50 years,” Hare said.
Hare said that, in moving forward with the information for fishery management purposes, global climate models can be coupled with population models for marine wildlife, in order to create “environmentally explicit stock recruitment models.”
For cod, for example, environmental changes are likely to be detrimental, he said. One prediction sees codfish eliminated from southern New England waters by 2080, due to increasing temperature. It is also predicted that the productivity of the stock will decrease. Although 2080 is a long time away, such predictions can help to inform fishery management benchmarks in the near term.
“Some species is will do better, some will do worse,” he said.
Atlantic croaker, in New England and mid-Atlantic waters, are predicted to do better, over a timeframe of 50 to 100 years, with changing environmental conditions, he said.
Hare said that NEFSC scientists will be integrating climate science with ecosystem-based management.
“We envision addressing climate and fisheries on three scales,” he said.
There’s the question of the sustainability of a fishery in a region on a long-term scale of 30 to 100 years. In more immediate terms, a scale of 5 to 20 years is relevant for developing rebuilding plans.
“Targets may be overly or underly optimistic,” he said. Climate scientists must develop better information for fishery management, he said.
And for the short term, of 1 to 5 years, it will be important for managers to incorporate climate information into the stock assessment process, he said.
Hare said the center’s next big push will be to work with some of the fishery rebuilding plans, from a research perspective only. The goal is to see if, had climate information been included in the planning process the management responses would have been the same.
NEFMC member Paul Howard said he was concerned about adding long-term climate predictions to the immediate management process, at a time when stock assessment science is already in question and fishermen need to know what’s going on from one year to the next. He said the NEFMC is starting to think beyond single-species management. But, with regard to the larger environmental situation, it would be best to tackle the subject on a smaller scale, he said.
Hare said the questions are currently more of a scientific exercise, to show if fishery benchmarks would be different if climate models are incorporated.
Jim Odlin wanted to know if climate information would bring into question the biomass information the NEFMC uses for rebuilding species such as codfish.
Hare said the information could not be used for fishery management at present.
“We’re definitely, as fishermen, seeing fish moving deeper and changing geographic location,” said NEFMC member David Goethel.
Goethel proposed that, as part of its examination of historical climate data, the NEFSC look into whether that data had any predictive capability that could be used in today’s fishery management projections. “Our projective capabilities at this time are to me useless,” Goethel said. “We make projections and we’re miles off.”
Hare said it wasn’t clear yet how much historical data was available, but he said he would look into the idea.
Hare said the NEFSC would conduct a “Climate Vulnerability Assessment” as a regional pilot project this summer, to cover approximately 20 species. Full regional implementation is expected in 2013, for all managed species, he said.