Characterizing and comparing non-target species from lobster trawls in Nova Scotian lobster fishing areas 27, 33, and 34
LE3 .A278 2022
Bachelor of Science
The unmanaged catch of non-target species in a fishery, typically referred to as by-catch, threatens the stability of fisheries and aquatic ecosystems worldwide. In Canada, >8.1% of all commercial catch by weight is by-catch. By-catch from Canada’s crab and American Lobster Homarus americanus fisheries, the latter being the most lucrative fishery nationwide, account for >2.5% of all Canadian catch by weight. Fisheries and Oceans Canada has recently introduced a by-catch monitoring program to some Lobster Fishing Areas (LFAs) to begin quantifying impacts on by-catch species, with a focus on several species of interest: Atlantic Cod Gadus morhua, Cusk Brosme brosme, Jonah Crab Cancer borealis, and Rock Crab Cancer irroratus. This study collaborated with Brazil Rock Lobster Association and Cape Breton Fish Harvester’s Association to characterize and compare by-catch from LFAs 27, 33, and 34. Metrics such as species richness and diversity, catch-per-unit-effort, and sizes for the species of interest and some others were calculated. Overall, 38 by-catch species (or taxa) were observed. Richness was highest in LFA 27, lower in LFA 33, and significantly lower in LFA 34. Diversity was similar between LFAs 27 and 33, but lower in 34. Catch-per-unit-effort was significantly lower in LFA 27 than in 33 and 34. Cunner Tautogolabrus adspersus were the most frequent by-catch species in LFA 27, while Jonah Crab were dominant in LFAs 33 and 34. Next steps with these data could include using biotic and abiotic variables to model distribution and abundance for Atlantic Cod, Cusk, Rock Crab, and Jonah Crab. Results from LFAs 33 and 34 were preliminary, so as more data are collected for these LFAs more precise inferences can be made regarding by-catch frequency and spatiotemporal distributions. Furthermore, with more data, metrics such as richness and diversity will likely estimate the true state of the fishery more accurately.
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