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The endangered Australian sea lion extensively overlaps with and regularly becomes by-catch in demersal shark gill-nets in South Australian shelf waters
Citation
Hamer, DJ and Goldsworthy, SD and Costa, DP and Fowler, SL and Page, B and Sumner, MD, The endangered Australian sea lion extensively overlaps with and regularly becomes by-catch in demersal shark gill-nets in South Australian shelf waters, Biological Conservation, 157 pp. 386-400. ISSN 0006-3207 (2013) [Refereed Article]
Copyright Statement
Crown Copyright 2012 Published by Elsevier
DOI: doi:10.1016/j.biocon.2012.07.010
Abstract
Australian sea lions (Neophoca cinerea) have typically small breeding colonies, many of which are genetically distinct populations due to female philopatry (i.e. breeding site fidelity). This situation may increase the vulnerability of the species to decline when anthropogenic influences increase levels of mortality, even by small amounts. Anecdotal reports from South Australian shelf waters suggest Australian sea lions become by-caught and drown in demersal gill-nets used to catch sharks, or escape with life threatening entanglements. This study explored the potential impact of the operational interaction by estimating the (i) extent of geographic overlap and (ii) level of by-catch. Monitoring of Australian sea lion at-sea movements and of the demersal gill-net fishery confirmed spatial overlap between the two in 68.7% of 4km2 grid cells across South Australian shelf waters and by-catch of 283-333 Australian sea lions each breeding cycle (193-227 each year). Recent changes to the management arrangements of demersal gill-netting in South Australian shelf waters are likely to have improved the situation for Australian sea lions, although it may be necessary to further refine aspects relating to (i) the effectiveness of untested electronic fishery monitoring methods, (ii) the efficacy of relatively small permanent fishery closures around breeding colonies and (iii) the efficiency in receiving, processing and responding to by-catch reports to ensure by-catch limits are not exceeded. Long-term monitoring at representative breeding colonies would be useful for determining if and where research and management should be prioritised. A recent report suggests a similar problem may exist in Western Australia, where approximately 14% of the species resides.
Item Details
Item Type: | Refereed Article |
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Keywords: | Australian sea lion, by-catch mortality, depredation, endangered, gill-net, operational interaction |
Research Division: | Environmental Sciences |
Research Group: | Environmental management |
Research Field: | Conservation and biodiversity |
Objective Division: | Environmental Management |
Objective Group: | Marine systems and management |
Objective Field: | Marine biodiversity |
UTAS Author: | Sumner, MD (Mr Michael Sumner) |
ID Code: | 89634 |
Year Published: | 2013 |
Web of Science® Times Cited: | 32 |
Deposited By: | Zoology |
Deposited On: | 2014-03-11 |
Last Modified: | 2017-10-31 |
Downloads: | 0 |
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