New research provides critical insights on a growing phenology mismatch between lobster larvae and their primary prey, challenging the future of American lobster populations in the Gulf of Maine. Despite the fishery doubling its landings since the early 2000s and becoming the most valuable single-species fishery in the US and Canada, benthic recruitment of young-of-year lobsters to coastal nurseries has remained persistently low for over a decade.
In a study published in 2018, Carloni and colleagues identified that the abundance of post-larval lobsters and subsequent benthic recruits had been in steady decline, despite an increase in spawners and an initial rise in larval stages. They correlated this decline with a decrease in the lipid-rich copepod Calanus finmarchicus, a critical prey species for the planktonic lobster larvae. However, other potential zooplankton prey, gelatinous predators, and environmental factors like temperature and wind advection were found to have no direct correlation with the declining lobster recruitment.
Building on this earlier research, Carloni's team investigated a widening mismatch in phenology between lobster larvae and C. finmarchicus. Over the study period, they found that the onset of lobster egg hatch and first appearance of stage 1 larvae are occurring increasingly earlier in the season due to ocean warming. Yet, the season for C. finmarchicus is ending sooner than before, frequently before the seasonal peak of stage 1 larvae. The authors of the Editor's Choice article believe that this changing timing and the declining abundance of this energy-rich prey are contributing significantly to the declining lobster recruitment seen over the past decade.
The Gulf of Maine is undergoing rapid environmental change, challenging the scientific community's ability to adapt and understand the dynamics involved. This retrospective analysis provides crucial new insights into the factors potentially affecting population dynamics and sets a foundation for further research into the mechanisms influencing the vulnerable early-life stages of American lobsters. The researchers hope this work will support new management strategies to secure the future of this valuable fishery in an era of climate change.
Read the full paper, Diverging phenology of American lobster (Homarus americanus) larvae and their zooplankton prey in a warming ocean, in ICES Journal of Marine Science.
