The time is fast approaching when Maine lobstermen must weigh in on a proposal to respond to a changing lobster population in the Gulf of Maine. That is the underlying assumption of the Atlantic States Marine Fisheries Commission’s (ASMFC) Addendum 27 to its interstate lobster fishery management plan, nicknamed the “resiliency addendum.” In March and April, the Department of Marine Resources (DMR) met with each lobster zone council to explain the options being considered in the Addendum and to present the Department’s annual lobster science update, which indicates an overall decline in lobster abundance in Maine’s monitoring surveys.
Addendum 27 is intended to buffer the impact on the fishery of potential changes in the Gulf of Maine/Georges Bank (GOM/GBK) lobster stock. The Addendum proposes several options to standardize management measures within and across Lobster Conservation Management Areas (LCMAs), as well as changes to gauge and vent sizes to improve protection of the spawning stock.
Under the plan as it stands currently, conservation measures would not be necessary until lobster abundance dropped to 2000-2002 levels, when Maine fishermen caught around 55 million pounds. The concern is that waiting to act until this number is reached could be extremely painful to the Maine fishery given the level of current landings (greater than 100 million pounds annually in ten of the last eleven years).
DMR annual lobster surveys results
Each year DMR conducts many scientific surveys related to all life stages of the lobster and each of the surveys indicate a declining stock. “We have multiple streams of data from different areas and different depths along the coast. If the survey data showed opposing trends, then we would have more questions. But by having agreement among all the surveys we have more certainty that the direction of those trends reflects the change in total lobster abundance,” DMR lobster biologist Kathleen Reardon said.
While lobster landings remain relatively strong, sublegal lobster numbers have been declining for five years in some areas. Since approximately 2013, Maine’s Lobster Settlement Index has indicated low levels of juvenile lobster settlement along the Maine coast. In 2021, data showed once again that young-of-the-year lobster numbers remain down.
Beginning in 2018, DMR’s Ventless Trap Survey data began to indicate a decline in sublegal lobsters from previous peaks, especially in eastern areas. The most western area has remained stable over time. Catches from this survey are 90% sublegal lobsters.
The annual fall Inshore Trawl Survey has showed a decline in sublegal-size lobsters in all areas, with higher declines in eastern portions of the coast. The spring trawl survey data exhibited a decline beginning in 2019 among all sizes of lobster in all areas of the coast; the data indicate a sharp decline in 2021 (the spring 2020 survey was cancelled due to the pandemic).
Yearly commercial sea sampling data confirm that sublegal lobsters are down in number throughout the coast. In Zone C and B those numbers have dropped steeply during the past five years, though these are also areas that saw the biggest increases beginning a decade ago.
In addition, lobster landings in the state have dropped from a high in 2016 of 132 million pounds to an average annual 102 million pounds from 2019 to 2021.
“When you see such a sustained decline over a number of years, the question is whether it will level off or continue down in the future,” Reardon said. “The sublegal numbers are a good indication, however, of what we expect to see in the legal catch in the next couple of years.”
Which leads to the question ASMFC Addendum 27 is designed to address: when should action be taken to ensure the vitality of the lobster stock and fishery?
What to do and when?
Among its 2021 goals, the ASMFC Lobster Board included actions designed to keep the lobster stock at its highest biological productivity levels, creating a plan to respond proactively to a population decline by increasing protection of the spawning stock biomass. The Board’s proactive approach stands in contrast to a more passive approach taken in the early 2000s in response to the sharp drop in the southern New England lobster populations. Management actions taken then were likely too late because lobster numbers had dropped so precipitously; fewer lobsters were left to survive and successfully reproduce to sustain the population.
The ASMFC’s Lobster Technical Committee considered several options in Addendum 27: to increase the gauge size, institute trap reductions, set seasons, or set quotas. Based on the analysis, the scientists recommended an approach which would sustain the lobster population in the long term. “The Technical Committee decided that changing the gauge size in a targeted fashion would have the best biological impact on the spawning stock,” Reardon said.
Warmer water temperatures throughout the Gulf of Maine have caused female lobsters to reach sexual maturity at a smaller size than was true thirty years ago, according to a recently completed study by DMR. Yet at the current minimum legal size for lobster, less than half are able reproduce before they are caught by the fishery.
Thus, increasing the minimum size in LMCA 1 would allow a greater percentage of female lobsters to reproduce before they are caught. “Delaying harvest by increasing the minimum size by a millimeter or two can make a big difference,” Reardon noted. Because there are so many lobsters at that current minimum size in LCMA 1, making a small change to gauge size would have a proportionally greater impact on the stock. While there likely would be a small reduction in the number of lobsters caught overall, the weight of those caught would be greater in the short term, according to Reardon. In the long term, the lobster population would be able to produce more offspring, putting it in a stronger position to weather environmental changes that may have a negative effect on the habitability of the Gulf for lobster.
Increasing the minimum size in LCMA 3, on the other hand, would not be as beneficial to the spawning stock because the minimum size in that area already allows most female lobsters to reproduce before they are caught by the fishery. Decreasing the maximum size for lobsters caught in LMCA3, however, would benefit the stock by protecting the largest lobsters forever. Reardon acknowledged that there is more uncertainty about the population of larger lobsters and thus how much the lobster stock would benefit from decreases to the maximum gauge, and how this would affect offshore landings. Still, it is known that larger females carry more eggs and that larger males are necessary to mate with larger females.
A trigger to mandate management chances
One option in the Addendum is to incorporate a “trigger” that would require changes to the lobster fishery management plan if the lobster stock declines by a certain amount. That trigger mechanism would be based on numbers of sublegal lobsters from surveys in Maine, New Hampshire and Massachusetts. Management action would only be triggered based on the last three years of data; prevent management action would not be based on a single year of data.
The 2020 data on sublegal lobsters from those states’ surveys show a 16% decline compared to the 2016-2018 data. ASMFC is waiting for Massachusetts survey data to become available before completing its analysis for the 2021 surveys.
Lobstermen must now wrestle with the question of when they believe action should be taken to prevent the further decline of the lobster stock. And what management changes should be put in place then?
DMR Commissioner Keliher will be meeting with lobstermen to talk about possible answers to that question, most likely in June. The ASMFC may schedule a vote on Addendum 27 for its August meeting.