Gillnet mesh selectivity of the sandbar shark (Carcharhinus plumbeus): implications of fisheries management
Journal Publication ResearchOnline@JCUAbstract
Gillnet mesh selectivity parameters for the sandbar shark (Carcharhinus plumbeus) were estimated from catches taken by an experimental net of six panels of mesh, varying in size from 10.2 to 25.4 cm. The length selectivity of each mesh size was described by five different models. According to model deviance values, the four models based on the SELECT method of estimation provided better fits to the data than the gamma model previously applied to sharks. Lengths at maximum selectivity were estimated to be between 5.3 and 7.0 x stretched mesh size. The breadth of the selectivity curves was greater than have been reported for most species of shark. Lognormal and normal curve forms yielded the lowest model deviance and were judged to provide the best fits to the data. Peak selectivity of the commercially utilized mesh sizes was generally estimated to be greater than the observed modal length class of the commercial C. plumbeus catch. This suggests that a relatively high abundance of smaller sharks in the study area offsets gear selectivity effects in determining the size composition of commercial catches. These results have important implications for the recovery of this overexploited stock and also for managing international gillnet fisheries for the species.
Journal
ICES Journal of Marine Science
Publication Name
N/A
Volume
64
ISBN/ISSN
1095-9289
Edition
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Issue
9
Pages Count
8
Location
N/A
Publisher
Oxford University Press
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Publisher Location
London, United Kingdom
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Date
N/A
EISSN
N/A
DOI
10.1093/icesjms/fsm136