Spatio-Temporal Dynamics of Atlantic Cod Bycatch in the Maine Lobster Fishery and Its Impacts on Stock Assessment
Of the most iconic fish species in the world, the Atlantic cod (Gadus morhua, hereafter, cod) has been a mainstay in the North Atlantic for centuries. While many global fish stocks have received increased pressure with the advent of new, more efficient fishing technology in the mid-20th century, exc...
| Summary: | Of the most iconic fish species in the world, the Atlantic cod (Gadus morhua, hereafter, cod) has been a mainstay in the North Atlantic for centuries. While many global fish stocks have received increased pressure with the advent of new, more efficient fishing technology in the mid-20th century, exceptional pressure has been placed on this prized gadoid. Bycatch, or the unintended catch of organisms, is one of the biggest global fisheries issues. Directly resulting from the failed recovery of cod in the GoM, attention has been placed as to possible sources of unaccounted catch. Among the most prominent is that of the GoM American lobster (Homarus americanus) trap fishery. My dissertation research contributes to solving these problems by making progress in five areas: Evaluating cod discard survivability, characterizing lobster effort, estimating cod bycatch, incorporating various bycatch scenarios into the current stock assessment framework, and providing an in-depth policy analysis for management to move forward. This dissertation proceeds as follows: Chapter 1 will briefly introduce regional fishing history, and the study species. Chapter 2 a will provide a preliminary habitat analysis and field project with the object of understanding when and where cod are caught as bycatch, and their subsequent survivability post-release. Chapter 3 develops a quasi-stationary bootstrapped Generalized Additive Model method to estimate Maine’s effective lobster effort spanning 2006-2013. Chapter 4 builds on the same methodologies to estimate Atlantic cod bycatch rates on the congruent spatiotemporal scale, then incorporates uncertainties from both lobster effort and bycatch rates to estimate spatiotemporal cod bycatch. Chapter 5 uses estimates from the previous chapter alongside available federal cod data to estimate historic age-structure and magnitude of cod bycatch from 1982-2016. Then, multiple scenarios are evaluated in the current assessment framework and I report on updated assessment model diagnostics and a novel ... |
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