Improved stock estimation for Iceland scallops (Chlamys islandica) in the Svalbard area
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- Master theses 
Iceland scallops (Chlamys islandica) were commercially harvested in the Svalbard fishery protection zone (FPZ) from 1986 to 1992, when the fishery ended due to overfishing. After approximately 30 years of prohibition, a trial fishery was permitted in the scallop beds around the Bear Island (Bear Island SE, Concordia and Kveitehola) in 2021. As an extension of this trial fishery, the Norwegian fishery authorities plan to open a fishery in the Moffen and Parryflaket scallop beds north of Svalbard. We, therefore, surveyed the area in autumn 2022, taking dredge samples and video recordings. The dredge samples were used to collect biological samples, while the video recordings were used to estimate the stock density. Images were randomly selected from the video recordings, and scallops on these images were counted by six individual human counters. The density was then estimated using three different approaches; a design-based swept area estimation (approach 1) and two statistical models; a regular and a spatial generalized additive mixed model (GAMM) (approaches 2a and 2b). Data from surveys in the Bear Island region was included in the models, to compare density between the scallop beds in the Svalbard area. Our main objectives were to standardize the annotation procedure, assess shell height distribution and estimate density and biomass in the Moffen region. And then compare the results with the scallop beds in the Bear Island region. Our main findings indicate recovery in shell height distribution and density. The spatial GAMM (approach 2b) provided the most precise and conservative density estimates. These estimates are expected to serve as the foundation for quota recommendations for harvesting in the Moffen region.