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Go North Young Shellfish

For several years now, both the Atlantic Fisherman and its sister publication, The Navigator, have been documenting the perceived northern movement of valuable, commercial species such as lobster.

For the last decade, both Canadian and U.S. fishermen and scientists have been commenting on this water temperature-related phenomenon and another study released recently only goes to back up these earlier theories.

A new study by the U.S.-based National Oceanic and Atmospheric Administration (NOAA) projects that climate change will pose management challenges for two commercially important species ― American lobster and sea scallops ― as suitable habitats move farther north.

Findings from the study, that published recently in Diversity and Distributions, project that significant changes in the habitat of commercially important American lobster and sea scallops on the Northeast U.S. continental shelf — two of the country’s highest value fisheries.

The researchers used a suite of models to estimate how species will react as waters warm. The researchers suggested that lobster will move further offshore and scallops will shift to the north in the coming decades. 

The authors of the report say this will pose fishery management challenges as the changes can move stocks into and out of fixed management areas. Habitats within current management areas will also experience changes — some will show species increases, others will decrease and still others will show no change at all.  

“Changes in stock distribution affect where fish and shellfish can be caught and who has access to them over time,” said Vincent Saba, a fishery biologist in the Ecosystems Dynamics and Assessment Branch at the Northeast Fisheries Science Center and a co-author of the study.

“American lobster and sea scallops are two of the most economically valuable single-species fisheries in the entire United States. They are also important to the economic and cultural well-being of coastal communities in the Northeast. Any changes to their distribution and abundance will have major impacts,” he said.

The study projected that the warming waters to the south of Nova Scotia over the next 80 years showed deep areas in the Gulf of Maine becoming increasingly suitable lobster habitat.

During the spring, western Long Island Sound and the area south of Rhode Island in the Southern New England region showed habitat suitability. However, that suitability decreased in the fall. Warmer water in these southern areas has led to a significant decline in the lobster fishery in recent decades.

Sea scallop distribution showed a clear northerly trend, with declining habitat suitability in the Mid-Atlantic Bight, Southern New England and Georges Bank areas.

“This study suggests that ocean warming due to climate change will act as a likely stressor to the ecosystem’s southern lobster and sea scallop fisheries and continue to drive further contraction of sea scallop and lobster habitats into the northern areas,” Saba said.

“Our study only looked at ocean temperature and salinity, but other factors such as ocean acidification and changes in predation can also impact these species.”

“Ensemble modelling approaches like the one developed in this study can contribute to lobster and scallop assessments by improving the effectiveness of survey efforts and the precision of stock assessment models,” Saba added. “It also provides a critical step toward establishing long-term adaptive management plans for these two valuable species.”

So, as both lobster and scallops continue to vacate the traditional U.S. grounds, what will this mean for these fisheries in southwest Nova Scotia?

The substantial rise in lobster catches over the last 10 years is certainly not a coincidence. The valuable crustaceans are obviously following the cooler climates north, across into Canadian waters. Is the same thing about to happen to the local scallop fishery? Is this area in for even more of an exponential rise in catches of valuable shellfish due to climate change?

For now, the science certainly appears to be pointing in that direction. But what other changes will these warming waters bring? This is an issue that fishing industry stakeholders, on both sides of the border, will obviously be keeping a very close eye on as these warming trends show no signs of slowing any time soon.