July 21, 2022 — The following was released by the Science Center for Marine Fisheries:

Climate change is now affecting long-standing patterns for marine life, with warmer waters pushing species out of their traditional habitats and into newer areas. As these changes become increasingly common, they will create challenges for fishermen, scientists, and regulators. A team at the Science Center for Marine Fisheries (SCEMFIS) is examining the extent of the problem on two key shellfish species: surfclams and ocean quahogs.

 

Ocean quahogs, one of the longest-lived marine species on Earth, inhabit cold waters in the Mid-Atlantic; surfclams, in contrast, have traditionally inhabited warmer areas. With climate change, surfclams’ traditional habitats have become some of the fastest-warming waters in the region, forcing them to move north into the colder waters traditionally occupied by quahogs.

“The area of overlap is getting potentially larger and larger as the Middle Atlantic warms, because one species is moving in, and the other one hasn’t quite got the message and moved out yet,” said Dr. Roger Mann of the Virginia Institute of Marine Science, one of the lead scientists on the survey.

In the fall of 2021, a team from SCEMFIS partnered with an industry fishing vessel, the F/V Pursuit, to document the extent of this habitat overlap. They took samples in several areas, working through surfclam and ocean quahog habitats, as well as areas of intermingling in between. The team documented what was caught, its species, size, age, and location.

After analyzing the data, the team found significant habitat overlap and intermixing between surfclams and ocean quahogs, much more than was expected at the start of the survey.

“One of the surprises though was just how extensive the overlap is now,” said Dr. Eric Powell, of the University of Southern Mississippi, another one of the survey’s lead scientists. “This is a major community shift on the continental shelf and it’s something that the management agencies and the fishery are going to have to get their arms around and deal with.”

Intermixing of ocean quahogs and surfclams is just the latest example of how climate change is creating new problems for fishermen. Under current rules, fishermen are not allowed to harvest clams and quahogs at the same time. In an environment where these species inhabited separate parts of the ocean, these rules were easy for fishermen to comply with. But climate-influenced migration is making harvesting these species much more challenging, a problem that will only increase in importance as trends continue.

“As bad as it is, it’s going to be much worse in five years, in my opinion,” said Dr. Powell. “The challenge, both to the fishery and management, is to figure out how to revise the regulations so both of these species can be landed without causing a problem with the inherent stability of the fishery and management.”

“The information that we get is vitally important to us staying not only a sustainable fishery, but also a fishery in good stead with enforcement,” said Guy Simmons, Senior Vice President at Sea Watch International, which harvests clams and is a member of the SCEMFIS Industry Advisory Board.