Dynamic changes in American lobster suitable habitat distribution on the Northeast U.S. Shelf linked to oceanographic conditions

Abstract

American lobster (Homarus americanus) supports one of the most valuable regional fisheries in the United States, with its abundance and distribution profoundly influenced by environmental conditions. To explain how lobster distribution has changed over time and assess the role of environmental variables on these changes, we used random forest classification and regression tree models to estimate occupancy and biomass in two seasonal periods. The occupancy models were fit to static and dynamic variables, which yielded model fits with AUC scores of 0.80 and 0.78 for spring and fall, respectively. Biomass models were fit with the same data and resulted in models explaining 61% and 63% of the spring and fall biomass variance, respectively. Significant variables scored in the formation of the regression trees were secondary productivity (i.e., zooplankton), bathymetry characteristics, and temperature. American lobster suitable habitat has changed regionally; habitat has increased in the Gulf of Maine and declined in Southern New England. There is also evidence of declining habitat along the inshore margin of the Gulf of Maine, which has been accompanied by a shift in occupancy probability offshore. Habitat suitability results from the random forest models provide insights on the structure and function of lobster habitat and context to understand recent population trends.

Resource Occurrence and Productivity in Existing and Proposed Wind Energy Lease Areas on the Northeast US Shelf

“…Assessing the effects of offshore wind on fisheries resources requires that we know what to measure, what survey designs to use, and how to coordinate that information with existing surveys that support regional stock assessments (Wilding, 2014;Methratta, 2020). Our traditional view of how fish habitat is defined is rapidly changing; there is expanding evidence suggesting that fish habitats can be determined by biological variables related to primary and secondary production patterns (Weber et al, 2018;Mazur et al, 2020). This highlights the need to continue, or expand, current sampling efforts related to the water column parameters such as phytoplankton and zooplankton and suspended sediment material.…”

Evaluating benthic impact of the Gulf of Maine lobster fishery using the Swept Area Seabed Impact (SASI) model

“…Ongoing changes in the distribution of fishing effort may cause varying degrees of benthic disturbance that shift over time and affect the total amount of EFH that is damaged. For example, lobster fishing effort has tracked abundance shifts northeastward (Steneck and Wilson 2001;Kleisner et al 2017), attributable to rapid warming (Pershing et al 2015;Friedland et al 2020) and increased habitat suitability (Tanaka and Chen 2016;Le Bris et al 2018;Goode et al 2019;Mazur et al 2020). Additionally, limited entry to the GoM lobster fishery has shifted the age of license holders to 50-65 years old (Stoll et al 2016;Stoll 2017), few younger potential lobster fishers are replacing those that exit the fishery (Fig.…”

“…Lobster population expansion has been attributed to relaxed top-down pressure (Jackson et al 2001;McMahan et al 2013;Wahle et al 2013), herring bait subsidization (Saila et al 2002;Grabowski et al 2010), increased algal habitat for juveniles due to reductions in urchin populations (Bologna andSteneck 1993, Steneck et al 2004), and ocean warming shifting this species' range northward (Pinsky et al 2013) and offshore (Tanaka and Chen, 2016;Mazur et al 2020) due to increased habitat thermal suitability (LeBris et al 2018;Goode et al 2019).…”

Metabolic Plasticity Improves Lobster´s Resilience to Ocean Warming but Not to Climate-driven Novel Species Interactions

“…This warming trend has led to dozens of species shifts from coastal mainland Australia to the cold-temperate waters of Tasmania 40-44 . Among them is the eastern rock lobster Sagmariasus verreauxi, the world´s largest spiny lobster reaching up to 20 kg and 70 cm total length 37,45 , that has become increasingly abundant in areas previously occupied exclusively by the resident southern rock lobster Jasus edwardsii 41 (Fig. 1).…”

“…Western Australia as well as New Zealand waters for J. edwardsii, and along the east Australian coastline between Brisbane and the North-East coast of Tasmania, including the northern waters of New Zealand for S. verreauxi (Fig.1). Both species live at depths ranging from 5-200 m at the Australian continental shelf37 . Natural temperature ranges are ~ 10.8-17.5°C for J. edwardsii (Ion Pot, Tasmania2,88 ) and ~ 12-28°C for S. verreauxi 89 .…”