Some Fish Highly Vulnerable

to Climate Change

by Laurie Schreiber

“The question of flexibility, given the changes we’re seeing and the difficulty of moving quickly in a bureaucratized environment—in many cases the management regimes in place do not lend themselves to adaptability.” – Bill Karp, Northeast Science Center Chief. Fishermen’s Voice photo

MYSTIC, Conn.—Studies show that many fish and invertebrates in the Gulf of Maine are vulnerable to negative impacts from climate change.

And most of those species have a high or very high potential for redistribution.

Jon Hare, of the Northeast Fisheries Science Center (NEFSC) in Woods Hole, Mass., reported to the New England Fishery Management Council (NEFMC), at their April meeting, on the work of scientists to develop a “vulnerability matrix.” According to the matrix, Atlantic salmon is one of the species highly vulnerable, in terms of its biological sensitivity and its exposure to climate change. Winter flounder, Atlantic halibut, Atlantic sea scallop, ocean pout, thorny skate, and witch flounder are also vulnerable.

And many species are moving northward.

On the other hand, said Hare, species typically seen more to the south, such as black sea bass and summer flounder, are now coming into the Gulf of Maine.

“We’re already seeing some of this,” Hare said. “How are those species going to be managed when they’re changing jurisdictional boundaries? That’s a governance question that an assessment like this brings to light.”

Hare is one of the authors of “A Vulnerability Assessment of Fish and Invertebrates to Climate Change on the Northeast U.S. Continental Shelf,” a study published in February and funded by the National Marine Fisheries Service’s Office of Science and Technology, Office of Sustainable Fisheries, Earth System Laboratory, and Northeast Fisheries Science Center, and NOAA’s Ocean Acidification Program.

According to the study, “Climate change and decadal variability are impacting marine fish and invertebrate species worldwide and these impacts will continue for the foreseeable future.”

Change is the long-term difference in the earth, atmosphere, and ocean conditions. Decadal variability is natural variability within the climate system.

The study conducted a “climate vulnerability” assessment on 82 fish and invertebrate species in the Northeast U.S. Shelf, from Cape Hatteras, N.C., through the Gulf of Maine. Climate vulnerability is defined as the extent to which abundance or productivity of a species in the region could be impacted by climate change and decadal variability.

“We find that the overall climate vulnerability is high to very high for approximately half the species assessed; diadromous and benthic invertebrate species exhibit the greatest vulnerability,” the report says. “In addition, the majority of species included in the assessment have a high potential for a change in distribution in response to projected changes in climate. Negative effects of climate change are expected for approximately half of the species assessed, but some species are expected to be positively affected (e.g., increase in productivity or move into the region).”

The results of the assessment are expected to help marine fisheries management and conservation adapt to climate change and decadal variability.

Changes have been documented in the distribution of fishery landings and potentially the distribution and magnitude of fishing effort, the report says.

“Although fishing remains an important, and in many cases, dominant driver of population abundance, there is now substantial evidence that climate change and decadal variability affect fish and invertebrate populations,” the report says.

An increasing number of studies are linking population models to climate models and projecting the effect of future climate change on marine fish and invertebrate species, the report says. Projections from climate models are then used to project population.

“In general, these studies show that climate change will continue to impact species and the ecosystem services they provide (e.g., fisheries, forage) for the foreseeable future (decades to centuries),” the report says.

“Vulnerability assessments” that have been used to evaluate the risk of overfishing are increasingly being used to evaluate the vulnerabilities of marine species to climate change, the report says. Vulnerability assessments identify environmental variables expected to change that could impact species (also called “exposure factors”), and biological sensitivity to change.

Exposure factors “include climate variables that have the potential to affect productivity or distribution of a species (or population) in a specific region,” the report says. Temperature is one such example.

An example of species sensitivity is low growth rate, compared to species with a high population growth rate.

For fish and invertebrates in the Northeast U.S. Shelf, the study uses climate projections between 2005–2055 to evaluate climate change and decadal variability.

Hare told NEFMC that the Northeast U.S. Shelf is experiencing a combination of long-term climate change and decadal variability.

While there is much in the way of inter-annual variability—for example, 2012 was the warmest year for Gulf of Maine sea surface temperatures in a study of long-term trends, but the following summer was cooler—temperatures overall are increasing. patterns of precipitation and stream flow are changing, ocean acidification is increasing, wind patterns are changing, and sea level is rising.

“This region is a hotspot for sea level rise,” Hare said. “We’re experiencing some of the fastest rates in the nation. And there are many more changes that can be documented with data that are occurring in this region. These changes are a combination of both human forced long-term climate change and multi-decadal natural climate variability. So we’re dealing with both.”

According to the report, the 82 species were nearly equally split among the different climate vulnerability ranks: very high (~27 percent), high (~23 percent), moderate (~24 percent) and low (~26 percent). Climate exposure scores for all 82 species were high or very high. Biological sensitivity ranged from low to very high.

The results suggest that distribution of many of the species might change in response to climate change.

“More than 50 percent of the species exhibit very high or high potential for a change in species distribution,” the report says.

About half of the species were assessed to be negatively affected by climate change. “Negative impacts are estimated for many of the iconic species in the ecosystem, including Atlantic sea scallop, Atlantic cod, and Atlantic mackerel,” the report says. “In general, negative effects are anticipated for a number of benthic Invertebrate and groundfish species. However, positive effects are anticipated for 17 percent of species, including Inshore longfin squid, butterfish, and Atlantic croaker.”

Species identified as likely to increase in productivity in the region include black sea bass. Atlantic croaker is likely to move into the region.

Species likely to decrease in productivity include winter flounder, and Atlantic mackerel is likely to shift out of the region, the report says.

A relatively large magnitude of climate change is projected for the region over the next 35 years, which will result in increased vulnerability, the report says.

Ocean temperatures, shallow-water temperatures, and ocean acidification were the climate exposure factors with the largest magnitude of change expected by 2055, the report says.

“These climate-induced changes can result in changing reference points for management and changes in stock distribution, which can also influence management,” the report says. “Given the temperature changes experienced in recent decades and projected for the future in the region, temperature should be included in regional scientific advice and management.”

The effects of ocean acidification on species biology and ecology are not as well understood, the report says.

“Research is needed that tests the impacts of ocean acidification at the levels expected over the next 20–40 years,” the report says. “One example is a recent study with Atlantic sea scallop where fishery yields are projected to decrease in the coming decades owing to the effects of ocean acidification.”

Molluscs are ranked with a high or very high vulnerability to climate change. However, the reports says, “this should be interpreted cautiously, and highlights the need for more research on species specific impacts of ocean acidification.”

Hare told NEFMC that the climate models used in the assessment are state-of-the-art and used globally to think about potential impacts of climate change. Limitations to the models, however, include their low wresolution.

“They’re relatively coarse in scale,” he said.

Using those models, temperature increase by 2050 is projected to be in the range of 1.2 to 1.4 degrees. But new, higher-resolution models suggest Gulf of Maine sea surface temperature could increase by 4 degrees by 2050, he said.

“So some newer climate information becoming available now indicates that we’ve been minimizing the amount of change,” he said. “These new models suggest we might see changes at an even greater magnitude.”

Next steps, he said, include developing a climate science strategy with regional action plans that include immediate actions such as conducting climate vulnerability analyses.

“Food for thought: Many of the New England Fishery Management Council species are likely to be negatively affected by climate change,” Hare said. “Think of this as strategic advice.”

One NEFMC member asked what the management implications are. “For example, how do you maintain flexibility when the species you’ve been fishing for your whole life swims away and another one shows up? What are the implications for catch shares?” he said.

“Those are the kinds of question the council needs to be thinking about,” responded NEFSC chief Bill Karp. Getting at the specifics will be difficult, he said. “For example, the question of flexibility, given the changes we’re seeing and the difficulty of moving quickly in a bureaucratized environment—in many cases the management regimes in place do not lend themselves to adaptability.”