American Lobster Homarus Americanus Fishery Research Articles

Bycatch in a Commercial Lobster Fishery: Effects on Two Benthic Predators, Sea Raven and Longhorn Sculpin

AbstractStudying the species‐specific responses to fishing capture is critical for effective management and conservation of bycatch species given that acute stress incurred from capture and handling may ultimately lead to mortality. While species of low commercial value are often overlooked, having accurate information on the effects of capture on all species is necessary for ecosystem‐based management. Sea Raven (SR) Hemitripterus americanus and Longhorn Sculpin (LHS) Myoxocephalus octodecemspinosus are routinely captured in the commercial American lobster Homarus americanus fishery in the Gulf of Maine, and they are discarded due to low commercial value. Despite a lack of economic value, these predatory species play important roles in shaping the benthic communities that they inhabit, highlighting the need to study their stress and mortality due to capture and handling. To help understand the effects of the lobster fishery on these species, the current study evaluated the physical, behavioral, and physiological stress responses of SR and LHS to capture in the state of Maine Zone G commercial lobster fishery. Collectively, our results suggest that although these species appeared to be resilient to capture based on an overt injury assessment, stress responses occurred based on reflex impairment and physiological perturbations, and these responses were species‐specific. Given the prevalence of behavioral and physiological stress in this study, further research into the survival outcomes of SR and LHS following release in the commercial lobster fishery is warranted.

Quasi‐Stationary Atlantic Cod Bycatch Estimation in the Maine American Lobster Homarus americanus Trap Fishery

AbstractThe Atlantic Cod Gadus morhua population in the Gulf of Maine (GOM) is currently near historically low levels of abundance. Reliable estimates of incidental Atlantic Cod bycatch from Maine's American lobster Homarus americanus fishery, which are unavailable and not included in the current stock assessment, are potentially critical for understanding complete catch dynamics and are thus essential for rebuilding the stock. Available fishery‐dependent data cannot be used directly in estimating Atlantic Cod bycatch because of nonrandom spatial and temporal sampling efforts. We developed a standardized framework for estimating Atlantic Cod bycatch in Maine's inshore lobster fishery for the years 2006–2013. We employed environmental covariates in a bootstrapped generalized additive model framework to standardize monthly zonal Atlantic Cod bycatch per unit effort (BCPUE) and lobster CPUE. Bootstrapped distributions of standardized CPUE and BCPUE were combined with landings data to estimate spatiotemporally explicit confidence intervals of Atlantic Cod discards in the Maine lobster fishery. Modeling results remained consistent throughout the study years, suggesting robustness in our approach. The estimates of Atlantic Cod discards in the lobster fishery improve the understanding of the total GOM Atlantic Cod bycatch and help to address current stock assessment deficiencies.

Lesion bacterial communities in American lobsters with diet-induced shell disease

In southern New England, USA, shell disease affects the profitability of the American lobster Homarus americanus fishery. In laboratory trials using juvenile lobsters, exclusive feeding of herring Clupea harengus induces shell disease typified initially by small melanized spots that progress into distinct lesions. Amongst a cohabitated, but segregated, cohort of 11 juvenile lobsters fed exclusively herring, bacterial communities colonizing spots and lesions were investigated by denaturing gradient gel electrophoresis of 16S rDNA amplified using 1 group-specific and 2 universal primer sets. The Bacteroidetes and Proteobacteria predominated in both spots and lesions and included members of the orders Flavobacteriales (Bacteriodetes), Rhodobacterales, Rhodospirillales and Rhizobiales (Alphaproteobacteria), Xanthomonadales (Gammaproteobacteria) and unclassified Gammaproteobacteria. Bacterial communities in spot lesions displayed more diversity than communities with larger (older) lesions, indicating that the lesion communities stabilize over time. At least 8 bacterial types persisted as lesions developed from spots. Aquimarina 'homaria', a species commonly cultured from lesions present on wild lobsters with epizootic shell disease, was found ubiquitously in spots and lesions, as was the 'Candidatus Kopriimonas aquarianus', implicating putative roles of these species in diet-induced shell disease of captive lobsters.

Short- and long-term dietary effects on disease and mortality in American lobster Homarus americanus

The American lobster Homarus americanus fishery is heavily dependent on the use of fish as bait to entice lobsters into traps. There is concern that this food supplementation is nutritionally insufficient for lobsters, but previous experiments reported conflicting results. We conducted a long-term feeding experiment in which 1 yr old American lobsters were fed one of 7 diets for a period of 352 d, a time that allowed the lobsters to molt thrice. The diets consisted of fresh frozen herring, a 'wild' diet (rock crab, mussel, and Spirulina algae), a formulated artificial diet for shrimp, paired combinations of these 3 diets or a diet formulated at the New England Aquarium (Artemia, fish and krill meal, Spirulina algae, soy lecithin, vitamins and minerals). The lobsters fed the diet of 100% fish had higher initial molting rates, but within the period of this experiment all either contracted shell disease or died. Mixed diets resulted in higher survival and a lower probability of mortality. This research demonstrated a critical time component to diet studies in lobsters. Short- and long-term impacts of diet differ. In the long term, continual high consumption rates of fish by the lobsters promote poor health in all lobsters, not just those of market size. The use of fish as bait may make lobsters more susceptible to the stress associated with environmental fluctuation, thereby leading to increased disease and mortality. This nutritional stress can be used to develop a laboratory model of shell disease in American lobsters.

Logistic Surplus-Production Model with Explicit Terms for Growth, Mortality, and Recruitment

Abstract Conventional interpretations of the logistic equation and the logistic surplus-production model appear to indicate that regulation of population size occurs as a result of competition for resources among the recruited members of a population. Compensation for fishing mortality may involve increased growth of adults and an increase in fecundity, but the major compensatory factor is increased survival of early life stages. In this study, the logistic surplus-production model is formulated in explicit terms for growth, reproduction, and mortality, and in this new formulation the capacity of a population to increase and sustain a fishery is based on a stock-recruitment relation that is a more realistic interpretation of fishery dynamics. All parameters can be estimated with catch and effort data. The models were applied to the American lobster Homarus americanus fishery in Maine and the spiny dogfish Squalus acanthias fishery. There is a considerable difference in the stock-production curves between ...