Population structure and residency patterns of the blacktip reef shark Carcharhinus melanopterus in turbid coastal environments

Chin, A., Tobin, A.J., Heupel, M.R., and Simpfendorfer, C.A. (2013) Population structure and residency patterns of the blacktip reef shark Carcharhinus melanopterus in turbid coastal environments. Journal of Fish Biology, 82 (4). pp. 1192-1210.

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Abstract

This study examined the characteristics of a blacktip reef shark Carcharhinus melanopterus population in turbid coastal habitats through a multi-year fishery-independent sampling and tagrecapture programme. Results revealed a highly structured population comprised almost entirely of juveniles and adult females with individuals between 850 and 1050mm total length effectively absent. Mature males were also rarely encountered with adult sex ratio highly biased towards females (female:male=7:1). Mating scars were observed on adult females between December and April, and parturition was observed from December to March. Regression analysis showed that catch rates were significantly higher during the summer wet season between November and May. Recapture data suggested a highly resident population with a recapture rate of 21% and a mean recapture distance of 0 center dot 8km. In addition, 33% of recaptured animals were captured multiple times, indicating long-term residency. Most recaptures were, however, of adults with few juveniles recaptured. Widespread sampling at the study site and in adjacent areas suggested that the population was highly localized to a specific bay. The bimodal and sex-segregated population structure observed here differs from previous reports for this species, and in combination with reproductive observations, suggests population structuring to facilitate reproductive and recruitment success. These data also highlight the potential ecosystem functions performed by coastal habitats in sustaining C. melanopterus populations.

Item ID: 26923
Item Type: Article (Research - C1)
ISSN: 1095-8649
Keywords: catch per unit effort, dispersal, mangrove, reproduction, sex segregation, site attachment
Funders: Australian Government’s Marine and Tropical Sciences Research Facility, James Cook University, Great Barrier Reef Marine Park Authority (GBRMPA)
Projects and Grants: MTSRF 4.8.4s
Research Data: http://e-atlas.org.au/
Date Deposited: 15 May 2013 09:27
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050211 Wildlife and Habitat Management @ 50%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 50%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 30%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 70%
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