Date of Award
Master of Science in Oceanography
The Southern New England (SNE) American lobster (Homarus americanus) stock, previously one of the largest fisheries in the region, has suffered a significant decline since the early 2000s and is now severely depleted. The SNE lobster stock has struggled to recover and is currently experiencing recruitment failure, with a population bottleneck occurring between the spawner and recruit life stages. The objective of this project was to quantify the abundance and spatial distribution of larval and early benthic phase lobsters in coastal Rhode Island (RI) waters to investigate current recruitment processes. Field sampling for larval and juvenile lobsters occurred during the summers of 2021 and 2022. Neuston net tows were conducted weekly from June to August at six stations, with two replicate tows at each station to sample lobster larvae. Concurrently, passive benthic collectors were deployed at ten stations in May and retrieved in September to survey recently settled young-of-year (YoY) and older juvenile lobsters. Data were analyzed with exploratory generalized linear models (GLMs) to investigate the effects of various parameters. Additionally, active long-term monitoring data were leveraged against historical studies to view temporal trends. Larval lobsters were found in varying abundances and were caught in higher numbers at the western stations of the study area. GLMs identified day of year, sea surface temperature, wind, latitude, and longitude as significant covariates predicting larval presence and abundance. Comparisons with same-site data from the 1990s indicated that larval supply in coastal RI has decreased over the last two decades. Five YoY lobsters were observed in the benthic collectors, resulting in a cumulative density of 0.05 YoY/m2 that emphasized the continued low observed YoY densities in RI. YoY and juvenile lobsters were found in the highest densities in the lower East Passage of Narragansett Bay. GLMs found that depth, year, latitude, and longitude were significant covariates in predicting juvenile lobster presence. These results demonstrate that population declines have occurred in multiple stages of the early life history of lobsters in SNE and can inform potential management decisions to facilitate the rebuilding the SNE lobster stock.
McCormick, Declan James, "EARLY LIFE HISTORY OF AMERICAN LOBSTERS (HOMARUS AMERICANUS) IN COASTAL SOUTHERN NEW ENGLAND WATERS" (2023). Open Access Master's Theses. Paper 2368.