Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/6962
Title: Damage and partitioned mortality of teleosts discarded from two Australian penaeid fishing gears
Contributor(s): Uhlmann, Sven Sebastian (author); Broadhurst, Mathew (author)
Publication Date: 2007
DOI: 10.3354/dao076173
Handle Link: https://hdl.handle.net/1959.11/6962
Abstract: Six field experiments were performed to (1) quantify the scale loss and partitioned (immediate and short-term) mortality of key teleosts discarded from a penaeid seiner and trawler operating in 2 estuaries in southeastern Australia, and (2) assess the utility of modified operational and/or onboard handling procedures for maximising survival. For both gears, several non-target species were caught, handled and discarded according to 2 general categories of treatment ('mild' and 'extreme') representing the plausible limits of severity of commercial operations. The mild treatments involved the shortest conventional deployments of the gears followed by the immediate sorting of catches in water-filled trays, while the extreme treatments comprised the longest conventional deployments and sorting in dry trays. Discards were examined for immediate mortalities and scale loss before sorting onboard, while live individuals of key species, along with appropriate numbers of controls, were released into sea cages and monitored for mortalities up to 5 d. For both gears, there was a trend of higher percentages of immediate mortalities in the extreme treatments, and more scale loss from dead than live seined and trawled silver biddy 'Gerres subfasciatus', seined tarwhine 'Rhabdosargus sarba' and trawled yellowfin bream 'Acanthopagrus australis'. Despite considerable interspecific variabilities, few intraspecific differences were detected between treatments for the short-term mortalities of live discards; however, for all species, these deaths were greater than those incurred by the controls (most of which survived). The partitioned mortality estimates were combined to provide a range of total mortalities for seined (95.97 and 99.07%, respectively) and trawled (71.74 and 97.64%) G. subfasciatus, seined R. sarba (23.95 and 100%) and trawled southern herring 'Herklotsichthys castelnaui' (100%) and 'A. australis' (3.40 and 35.01%). Because most deaths occurred irrespective of onboard handling procedures, we conclude that simply reducing the duration of gear deployments would provide a first step toward mitigating discard mortality in these fisheries.
Publication Type: Journal Article
Source of Publication: Diseases of Aquatic Organisms, 76(3), p. 173-186
Publisher: Inter-Research
Place of Publication: Germany
ISSN: 1616-1580
0177-5103
Fields of Research (FoR) 2008: 070499 Fisheries Sciences not elsewhere classified
Socio-Economic Objective (SEO) 2008: 830204 Wild Caught Fin Fish (excl. Tuna)
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Publisher/associated links: http://www.dpi.nsw.gov.au/research/areas/systems-research/wild-fisheries/outputs/2007/824
Appears in Collections:Journal Article

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