Fisheries Research Articles
Dusky sharks (Carcharhinus obscurus) undertake large-scale migrations between tropical and temperate ecosystems
Document Type
Article
Publication Date
12-7-2017
Journal Title
Canadian Journal of Fisheries and Aquatic Sciences
ISSN
Print: 0706-652X Electronic: 1205-7533
Disciplines
Aquaculture and Fisheries | Marine Biology | Terrestrial and Aquatic Ecology
Abstract
Understanding the large-scale migrations of marine predators can allow better representation of their population dynamics. The migration biology of dusky sharks (Carcharhinus obscurus), a cosmopolitan large marine predator with very low resilience to fishing, was quantified using a large-scale network of acoustic receivers deployed across Western Australia. Time-series plotting of individual shark detections and modified logistic modelling were used to determine the timing of acoustically tagged sharks’ seasonal migration, the proportion of the population migrating, and the size at which sharks start to migrate. Large (>200 cm fork length) dusky sharks migrated between areas closed (north) and open (south) to commercial shark fishing. There was limited evidence that smaller sharks occurred in the northern study area, whereas several larger individuals of both sexes undertook repeated north–south displacements, moving between disparate ecosystems within the Indian Ocean (21.7°S–35.4°S) and covering round-trip distances of 2000–3000 km per migratory event. For migrating individuals, the probability of occurring in the north was high in the austral winter–spring and low (males) to moderate (females) during the austral summer–autumn.
Recommended Citation
Braccini, M,
de Lestang, S,
and
McAuley, R.
(2017), Dusky sharks (Carcharhinus obscurus) undertake large-scale migrations between tropical and temperate ecosystems. Canadian Journal of Fisheries and Aquatic Sciences, 1 (1), 1525-1533.
https://library.dpird.wa.gov.au/fr_fja/48
