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Evidence for a broad-scale decline in giant Australian cuttlefish (Sepia apama) abundance from non-targeted survey data

Citation

Prowse, TAA and Gillanders, BM and Brook, BW and Fowler, AJ and Hall, KC and Steer, MA and Mellin, C and Clisby, N and Tanner, JE and Ward, TM and Fordham, DA, Evidence for a broad-scale decline in giant Australian cuttlefish (Sepia apama) abundance from non-targeted survey data, Marine and Freshwater Research, 66, (8) pp. 692-700. ISSN 1323-1650 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 CSIRO

DOI: doi:10.1071/MF14081

Abstract

Little is known about the population trajectory and dynamics of many marine invertebrates because of a lack of robust observational data. The giant Australian cuttlefish (Sepia apama) is IUCN-listed as Near Threatened because the largest known breeding aggregation of this species in northern Spencer Gulf, South Australia, has declined markedly since the turn of the century. We used by-catch records from long-term trawl surveys to derive abundance data for S. apama and commercial cuttlefish harvest data as a measure of exploitation. Using Bayesian hierarchical models to account for zero-inflation and spatial dependence in these abundance counts, we demonstrated a high probability of broad-scale declines in the density of S. apama, particularly surrounding the primary aggregation site, which supports the recent closure of the entire S. apama fishery in northern Spencer Gulf. Historical harvest data were positively correlated with S. apama density estimated from the trawl surveys, suggesting that the commercial cuttlefish catch tracks the species abundance. Our results also indicated the possibility that the known S. apama breeding grounds might be supplemented by individuals that were spawned elsewhere in northern Spencer Gulf.

Item Details

Item Type:Refereed Article
Keywords:range dynamics, models, conservation
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and Estuarine Ecology (incl. Marine Ichthyology)
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Marine Flora, Fauna and Biodiversity
Author:Brook, BW (Professor Barry Brook)
ID Code:107172
Year Published:2015
Deposited By:Plant Science
Deposited On:2016-03-07
Last Modified:2017-11-01
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