The american lobster, homarus americanus, is the target of the most valuable single- species fishery in the united states

This Cooperative Agreement award from the National Oceanic and Atmospheric Administration (NOAA) under the Sea Grant Support program (CFDA 11.417) provides $283,407 to the Wells National Estuarine Research Reserve to conduct field-based studies on the nutritional condition and feeding behaviors of American lobsters. The research aims to better understand how factors such as diet, predation, and competition impact the energy available for lobster growth and reproduction, which is critical for stock assessments and management. Key project elements include using stable isotope analysis and biologgers to assess lobster foraging activity and nutritional status across different sites from Rhode Island to Maine. The findings will contribute to more comprehensive lobster population models and help identify environmental and ecological drivers of lobster reproductive investment.

Management actions are often geared towards increasing EGG production by ensuring sufficient biomass is left unharvested. However, these underlying analyses do not include the effects of EGG quality. In american lobsters and other crustacean species, evidence suggests that not all eggs are created equal. Larger eggs often lead to more successful larvae, both in terms of resilience to environmental stressors and successful growth and development. In our recent work, we have found that the nutritional condition of female lobsters with early-stage eggs correlates with the volume of the eggs produced, but not the overall number of eggs per clutch. Furthermore, females from different areas and years showed differences in their nutritional condition and potentially their diets. Nutritional condition is indicative of the amount of energy available for investment in growth or reproduction, yet is currently overlooked in many studies of lobster populations. We propose a series of field-based studies to better understand the causes of these differences in nutritional condition for female lobsters and consequently the energy available for investment in growth and reproduction. Our working hypotheses are: 1) female lobsters in better nutritional condition are eating higher-quality foods, foraging more often, or both; and 2) successful foraging is limited by the presence of predators and competitors. We plan a three-pronged approach to test these hypotheses across sites from rhode island to downeast maine. First, we will build on our existing sampling of diet and nutritional condition across this range to improve our understanding of the nutritional status and possible diet of lobsters, using compound-specific stable isotopic analysis with prey mixing models to more precisely determine dietary niches. This will be compared with blood protein measurements to test the relationship between diet and nutritional condition in both nearshore and offshore environments. Second, we will compare the amount of time lobsters spend active and feeding between sites using innovative biologgers which can directly measure feeding activity and movement. This will allow US to determine how often movement is associated with foraging in individual lobsters. Developing a relationship between movement and foraging will allow US to use acoustic telemetry systems capable of reporting movement alone to obtain estimates of how often lobsters may be foraging in deeper areas where dataloggers cannot be easily recovered. Finally, we will assess the composition and relative abundance of potential predators and competitors whose presence may limit the ability of lobsters to forage. We will use baited underwater camera platforms to observe what species are present in our study areas. By comparing the relative abundances of species seen on the camera footage to the amount of time lobsters spend active, determined in the previous objective, we will be able to determine whether lobster activity and foraging is constrained by other species present, and how lobster nutritional condition may vary between areas as a result. We anticipate that this project will improve our understanding of lobster nutritional condition particularly during the critical reproductive investment period as well as how this varies across environmentally-distinct regions. We believe that this proposed work also fills an important knowledge GAP in assessing the available energy for lobsters to grow and reproduce within the context of a changing suite of predator and competitor species assemblages along a latitudinal gradient. Additionally, the inclusion of diet and nutritional condition and its effects on growth and reproduction in female lobsters will contribute to more comprehensive parameterization of models used in stock assessments, especially those pertaining to EGG product