This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The future of Maine's lobster industry may depend on a creature the size of a sesame seed. Researchers at the University of Maine have discovered that planktonic baby lobsters, or larvae, preferentially feed on Calanus finmarchicus, a tiny, calorie-rich zooplankton species, during one of the most vulnerable stages of their lives.
Their new study upholds a theory advanced by scientists in the past decade that may be relevant to recent declines in Maine's lobster harvest. Scientists have also observed declines in both the availability of this key food source and the number of young lobsters surviving into adulthood in the Gulf of Maine. The research is published in the journal Elem Sci Anth.
For lobsters, the larval stage is a crucial developmental bottleneck that determines survival to adulthood. While many researchers have looked at egg production as the main determinant of the size of upcoming harvests, a UMaine-led team has been working to provide more insight into how diet determines whether larvae survive into adulthood. "We see evidence that larvae are eating Calanus finmarchicus at a greater rate than you would expect if they were just feeding randomly; however, we also know that the geographic range of Calanus is receding northward into cooler waters, making it less readily available," said Alex Ascher, lead research scientist at Quahog Bay Conservancy, who began this work with UMaine as part of his doctoral thesis.
Calanus finmarchicus provides lobster larvae with fatty acids that are energy-rich and beneficial for neural development during periods of rapid growth. Researchers from UMaine, Bigelow Laboratory of Ocean Sciences and the University of Southern Maine found that 30% of larval and post-larval lobsters sampled had traces of Calanus finmarchicus, whereas this species comprised only a few percent of the available zooplankton. The decline in this key food source at the southern end of its range in North Atlantic ecosystems is occurring while fewer lobster larvae in the Gulf of Maine are surviving into adolescence, which in turn affects the future number of adult lobsters available to the fishery.
Maine's lobster harvest has declined by about 40% since its peak in 2016, according to the state's Department of Marine Resources. After hatching from eggs on the ocean floor, larvae swim up to the ocean surface. They then drift with currents before settling to the seabed as small juveniles, eventually becoming adults some 6–8 years later.
Access to nutritious food during the planktonic larval stages can mean the difference between survival and starvation. These findings also further solidify Calanus finmarchicus as a keystone species, an organism that plays a crucial role in supporting a food chain that includes a diversity of fish and invertebrates, including the endangered North Atlantic right whale. With less energy-rich food available, lobster larvae have to depend on less nutritious resources, threatening their chances of survival.
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