Southern Species Migrating North as Climate Changes

by Laurie Schreiber

Heather Deese, Island Institute, moderator. “Climate change is certainly affecting not just the way we’re fishing, but the way we’re managing the fishery.” – Steve Train ©Photo by Sam Murfitt

ROCKPORT – Fishermen are seeing evidence of climate change, as species typically found in warmer waters are migrating north.

Some are wondering, if the fish are here to stay, whether there are new marketing opportunities in store.

“Sharing Experiences from Near and Far: Climate Change and Ocean Acidification Now and in the Future” was a topic at the recent Maine Fishermen’s Forum.

According to scientists, the world’s oceans are changing at different rates due to climate change and ocean acidification. In the Gulf of Maine, the rate of warming is more rapid, although other areas of the country are seeing similar changes.

Jonathan Labaree, director of community initiatives at the Gulf of Maine Research Institute (GMRI), described the ocean “heat wave” that occurred in 2012, when the Gulf of Maine experienced markedly warmer sea surface temperatures that were in the range of five degrees Fahrenheit above the 30-year average.

“It was not an event isolated to the Gulf of Maine,” Labaree said. “It was a massive warming event that covered the entire northwest Atlantic, from the North Atlantic into the Labrador Sea and the Arctic Ocean. This was a huge event that had consequences throughout the region.”

The 18-month event, starting late 2011 and continuing into early 2013, was the largest, most intense sea surface temperature anomaly ever recorded in the North Atlantic, he said.

The temperature trend for 2013 was back down a little, but still high, he said.

“Over the last 30 or so years, one of the difficult things to figure out, when you look at these data, is there’s dramatic variability that happens year in and year out,” Labaree said. “But there are clear trends.”

According to GMRI, climate change “has made the Gulf of Maine less hospitable to many cold-water species, such as cod and northern shrimp. New species from more southerly waters, however, have begun to show up with greater frequency.” A September 2013 GMRI report, “Preparing for Emerging Fisheries: An Overview of Mid-Atlantic Stocks on the Move” by Mary Hudson and Jonathan Peros, says seven species have shown significant movement up the coast – summer flounder, scup, black sea bass, longfin and Illex squid, Atlantic mackerel, and butterfish.

Said Labaree, the Gulf of Maine is warming more quickly than 99.85 percent of the rest of the ocean.“So we’re on the leading edge of what’s happening to sea surface temperature changes globally,” he said.

In addition to the arrival of more southerly species, the changes also affect species phenology – life cycle events influenced by seasonal variations in climate and habitat. Most important for Maine, on this score, is the lobster molt. In 2012, there was an early molt due to warm temperatures, and an extra molt at the end of the year, which brought more lobsters into the fishery later in the year and may have had impact on lobsters for 2013.

The changes could impact fishery management, the GMRI report said. Most stocks trending northward are currently managed by Mid-Atlantic fisheries managers: “If they continue to move into the Northeast, major changes will be required to support and develop these emerging fisheries.”

Management, said Labaree, can no longer rely on historical indications. “These changes are happening so dramatically and so quickly that our ability to look back” and assess the effect of management strategies on populations, which are based on maintaining or rebuilding populations to some historical condition, will not necessarily inform the future, Labaree said.

Steve Train has been a fisherman on Long Island, in Casco Bay, for 38 years. “When I started fishing on my own, we would fish on a calendar,” Train said: Set the traps inshore at the start of summer, then move them to progressively deeper waters.

“About 12 years ago, we started to see a difference. You could skip where you set your gear in June and July, and start setting it where you left off in August and September….We could fish further into the season and fish further offshore.”

In addition to the shifting lobster population, he said, fishermen are seeing a much great incidence of invasive green crabs.

“We’ve always seen invasive species of some sort, primarily green crabs,” Train continued. But green crabs used to disappear, each winter, as the shore the iced up. Nowadays, he said, the shore doesn’t ice up anymore: “We don’t ever get away from the green crabs now, if you fish near the shore” and the species is also seen at greater depths.

Other invasives showing up are red hake, from southern New England and further offshore; a lot of squid; turbot; sometimes two or three bushels a day of black sea bass; and Chesapeake blue crabs. “We’re seeing less of native species – shrimp and cod,” Train said.

The arrival of southerly species will result in the emergence of new fisheries for northern fishermen, and new management considerations, Train said.

“Climate change is certainly affecting not just the way we’re fishing, but the way we’re managing the fishery,” Train said.

Rodman Sykes, from Point Judith, R.I., has been fishing 44 years.

“There’s been an awful lot of changes the past couple of years,” Sykes confirmed.

Some newly arrived species in Rhode Island include cobia, garfish, spots, croakers, mahi-mahi, tilefish, black sea bass, stingrays, and skates. Some of these used to show up occasionally, but are now occurring in quantity, he said.

“We’ve always had barn door skates, one a month,” Sykes said. “Now we see them every day, big to small….Spots are a southern fish, I never saw a spot until 2010. There must be some pretty good-size schools, a large net will get 10 or 15 per tow….We also noticed the behavior of the fish has changed. We always had blue crabs and we always saw one or two in the fall or spring. But this summer, I was catching them every day out in deep water, one or two. That was very rare, now they’re common. Black sea bass – it used to be we would see them in the spring. They would migrate in, and migrate out in the fall. Now we see them all summer – great big sea bass.”

Dewey Hemilright, from Wanchese, N.C., confirmed similar findings in his area. Bluefish, once a big fishery for North Carolina, with a quota of about 3 million pounds, now seem to be migrating north. “Last year, we probably landed less than a couple hundred thousand pounds,” Hemilright said.

“It’s changing out there,” Hemilright said. “The migratory patterns are changing. I just hope fishery management is able to adapt.”

Bill Mook, of Mook Sea Farm, a fishery hatchery in Walpole, discussed the effects of increasing ocean acidification on his shellfish product.

“We change the water at least every 48 hours, so we have a saying that goes way back, that every water change for our larvae is a bioassay. We’ve got so we really know how to grow oyster larvae and young oysters,” Mook said. “And when we see variations from that, it’s pretty likely to be a water quality issue. Large runoff events are showing up to be problematic. We see reduced feeding and growth in our larvae and, in some cases, impact on survival of the larval populations. In some cases, we see a drop in survival, but usually they slow up and it takes them another week or so to get through metamorphosis to become a bottom-dwelling little oyster.”

He continued, “We’ve seen a situation where we put fertilized eggs in the tanks, and we go back and we don’t find anything, or we find very few normal-looking larvae and a lot of deformed shells. So is it ocean acidification? We can’t say. We don’t have the tools. We think it’s a likely hypothesis.”

There are financial impacts: the loss of one spawning period is worth about $100,000 in lost seed alone, plus the loss of opportunity to grow the seed into 50-cent oysters, plus the loss to other grow-out companies that have placed orders for seed, Mook said. Mook said he is purchasing, at a cost of $20,000, a tool needed to measure partial pressure of carbon dioxide in the water, which provides precise monitoring of carbonate parameters.

In response to changing conditions, National Marine Fisheries Service (NMFS) and National Oceanic and Atmospheric Administration (NOAA) researchers have developed “the first methodology of its kind to rapidly assess the vulnerability of U.S. marine fish stocks to changing climate and ocean conditions,” according to a NMFS release. “We are using the methodology to assess the vulnerability of 79 marine fish stocks of the Northeast marine ecosystem. We expect results to be released in the summer of 2014.”

The methodology uses existing information on climate and ocean conditions, species distributions, and species life history characteristics to estimate the relative vulnerability of fish stocks to potential changes in climate.

The Fish Stock Climate Vulnerability Assessment is specifically designed to help identify which stocks may be most vulnerable with changing climate and ocean conditions; what additional information is needed to understand and address these risks; provide a basis for considering what actions might be taken to reduce fish stock vulnerability; identify where more information is needed to understand, track, and respond to fish stock vulnerability.  That information can then be used to help prioritize research, monitoring and modeling efforts.

The research includes a new web portal that displays maps of climate data, such as ocean temperature and salinity, over portions of the globe. NOAA previously had tools to show temperature and precipitation over the U.S., but the new portal is more comprehensive because it includes ocean-specific information like sea surface temperature and salinity. Users can zoom in and create plots for any region on the planet. The portal is designed for scientists, resource managers, educators and the general public. 

The portal (esrl.noaa.gov/psd/ipcc) is expected to provide fisheries scientists and managers with access to existing projections of changes in climate and ocean conditions for all U.S. marine regions and worldwide to help them assess, prepare for and respond to possible future impacts on marine ecosystems and fisheries. 

Said Mook, “The problem is, the problem is overwhelming. And if we can think of things people can do, that’s great. But we haven’t reach that point yet.”