9 Mar

Spike in Sea Bass Numbers Sparks Skepticism

Black sea bass. Courtesy M. Terceiro

Recreational and commercial fishermen reporting dramatic increases in the number of black sea bass (BSB) had their observations confirmed at a recent Rhode Island Natural History seminar. However, getting people to believe the numbers and forecasts is no easy task.

Dr. Gary R. Shepherd, fisheries biologist with NOAA’s Fisheries Science Center, attributes the apparent spike to increasing water temperatures in the northeast. “We’ve seen a sharp northern redistribution of BSB over the last 50 years. According to our 2016 survey, the catch has dramatically increased, with recreational catch exceeding commercial.”

NOAA has conducted twice yearly surveys since 1963 from the Bay of Fundy at the Gulf of Maine south to Cape Hatteras in North Carolina. “It’s the oldest continually monitored ecosystem in the world. We survey it every spring and fall.” Shepherd said annual water temperatures fluctuated only somewhat from the 1880’s, when less regular surveys were being done. By the 1960’s, water temperatures in Boothbay Harbor had risen to a level that allowed for breeding. Now there are BSB spawning regularly as far north as Maine.

The current population increase is likely a result of 2011-12 temperature conditions off the southern New England coast. That season produced conditions that were optimal for survival of fish. “If you go further south, there wasn’t the same level of success. That 2011 “class” is really spiking this population,” Shepherd said. Black sea bass are on the menu for a limited variety of species. “They’re eaten by sharks and tuna, but they’re primarily eaten by bluefish and other large aquatic species.” And what about striped bass? “Stripers are like the Labrador Retriever of the fish world: they’ll eat anything, and if it’s not food, they’ll spit it out later. They may try BSB, but they seem to prefer other food.” This class will be prevalent until roughly 2018 or so, as the numbers decrease through aging. Black sea bass have a life span of roughly eight or nine years.

Audience members voiced concern that the increase in sea bass population is contributing to the collapse of the lobster fisheries. Shepherd said that the evidence isn’t there to support the idea. “Recent work suggests that it’s probably not going to be a problem yet. Although they’ll occasionally eat lobster, surveys in Cape Cod indicate that they prefer crabs. Something that’s easier and that’s not going to bite back. The reduction in the lobster industry is due to activity by the lobster fishery, not from BSB.” In shallower water, BSB get most of their nutrition from crabs. When they move to deep water, their food comes from animals like squid and other invertebrates. “They’re not working for (the food). The fact that we’re seeing them spawn in the Gulf of Maine is a relatively new phenomenon. These fish are not moving from southern spawning grounds north; there is just more productivity and higher survival rates up here in the north than there used to be.”

Given the skepticism about the BSB population and impact on the lobster fishery that was evident in the auditorium, is there more work to be done in terms of spreading the scientific results? “Efforts to educate the public about the process (of assessing BSB population and behaviors) are somewhat lacking. The Gulf of Maine Marine Research Institute operates a three day program geared toward fishermen to educate them in how the assessments are done. Still, it’s fair to say that not enough direct communications have made people aware of what’s going on.” Scientists may face skepticism in part because it is their work that determines catch limits, and not everyone understands the methods they use.

“It’s difficult to persuade people that something is right when they think you’re wrong. We’ve talked a lot about this. All the numbers that come out that people hate (because it results in limits) – bass, flounder, black sea bass – that stuff comes from us. People always say, ‘You don’t survey where the fish are, so how can that information be right? I know there’s cod here, and you guys aren’t fishing here to count them all.’ ” Shepherd says that following the biggest schools would be like trying to survey the population of Rhode Island by doing a count in downtown Providence only. “You have to go to a number of places like Kingston as well, and arrive at an average number.”

No matter how much outreach they do, though, Shepherd notes that some people just won’t let go of their beliefs. “We’ve taken fishermen out on the cruises with us to survey and they say ‘Wow, this is really great…I still don’t believe you, though.’”


  • Loved the article. That is a beautiful fish. It was interesting to learn the diet of the BSB included crustaceans like crab and lobster. Maybe that explains why it is so delicious. The bigger question is what will happen to these ecosystems if the water temperature continues to rise. Well done Hugh!

    • Thanks, Sean! For better or worse, it looks like climate change is making it possible for them to breed much farther north than they used to. You’re right to be concerned about climate change’s affect on ecosystems.

  • Another interesting article, as always! Actually caught a couple using crabs off the Charlestown Breachway last summer-my father was mad I released them, he wanted lunch. Also, saw the eagle again this morning over Pachaug on my ride in!

    • Thanks, Nisa! I assume they were blue crabs; they’re the only local ones that people find tasty. And congrats on the eagle sighting! Haven’t seen any this season!

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