A recent lobster stock assessment shows the population of the state’s famous bottom-dwelling crustacean at record highs in the Gulf of Maine.
Through data collected by fishery-dependent and fishery-independent sources, the stock assessment gives fishermen and scientists a picture of the condition of the economically important stock.
According to the Atlantic States Marine Fisheries Commission, the 2015 benchmark stock assessment for lobsters shows the stock of crustaceans in the Gulf of Maine and Georges Bank is not depleted and overfishing is not occurring.
However, the situation for the stock in southern New England is far less clear, with abundance estimates appearing to decline dramatically since the late 1990s to record-low levels.
Atlantic States Marine Fisheries Commission Director of Communications Tina Berger said stock assessments for lobsters and other species are not done every year since it often takes a couple years to compile the data. The last assessment done for lobsters was released in 2009.
“Hopefully, each time we do an assessment we get a better understanding of a species,” Berger said.
She also said the study released this year was a benchmark assessment incorporating a variety of different data and models to determine the health of a region’s stock.
“It helps us to project the stock based on available data,” Berger said.
She said one of the big differences between this year’s stock assessment and assessments from other years is that this year’s assessment combines the Gulf of Maine and Georges Bank stocks into a single biological unit.
“One stock contributes to the fishery and resources in those areas,” Berger said.
She said that though the stock assessment showed a robust population in the Gulf of Maine and the 2009 stock assessment also showed record-high populations, it is hard to determine where the stock will go from here.
“There are those that feel the population is reaching a precipice; we just don’t know where that precipice is,” Berger said.
Some of the difficulty in predicting where the stock goes from here is due to the impact of environmental conditions on where lobsters feed and migrate.
“A major impact on the stock are environmental conditions, something we have little or no power to control,” Berger said.
She also said warmer water temperatures in the Atlantic Ocean impact a variety of species, not just lobster.
“Warming water temperatures are impacting fishery resources and crustaceans up and down the coast,” Berger said.
Maine Department of Marine Resources Lead Lobster Scientist Kathleen Reardon said that though scientists are unsure of the specific factors contributing to the increase in the stock, there does seem to be some correlation with water temperature, though impacts of that correlation are difficult to determine.
“One of the only things we can agree on is that the environment is changing, but it is really hard to predict the future,” Reardon said.
Reardon said lobsters have an optimal temperature range, where the species thrives and develops in a manner not seen outside of these conditions.
“Optimal temperature for lobsters is around 54 to 65 (degrees Fahrenheit). Lobsters avoid really cold water and they avoid water that is above 65 F. They actually have a stress threshold at about 68 F. At the optimal temperature they are more productive. The hatching works well, larval development works, and they develop quickly,” Reardon said.
Nonetheless, she said the scale of the stock’s increase is impressive.
“I don’t think anyone predicted the scale of the increase. We’re kind of along for the ride,” Reardon said.
She said fishermen can help promote a healthy stock by advocating and practicing sustainable fishing practices and adhering to laws governing legal and illegal catches.
“We like to think our goals will keep us sustainable,” Reardon said.
She said v-notching, a practice that dates back to the early 20th century, is one way to ensure stability in future populations.
“Egg-bearing females get marked on the base of the tail with a v-shaped notch. If the lobster is caught again without eggs, it is still released,” Reardon said.
According to the lobster scientist, returning female lobsters of legal size to the water improves prospects for the broodstock.
