Identifying nursery areas used by inner bay and oceanic snapper stocks in the Shark Bay region, in relation to the effect of prawn trawling on inner bay snapper stocks
Project number:
2001-061
Project Status:
Completed
Budget expenditure:
$97,634.00
Principal Investigator:
Dan Gaughan
Organisation:
Department of Primary Industries and Regional Development (DPIRD) WA
SPECIES
There is an urgent need to clarify whether the juvenile snapper taken in the Denham Sound sector of the Shark Bay Prawn Trawl Fishery recruit to the recreationally fished, depleted western gulf of inner Shark Bay stock or the sustainably (predominantly commercially) fished oceanic stock. This information is needed to ascertain whether changes to the management arrangements to the trawl fishery would significantly benefit the threatened inner bay snapper stocks. Successful resolution of this contentious issue (and management change if warranted) in the sensitive World heritage Area will refocus public debate onto the more critical issue of overall resource sustainability.
1. To establish whether trace element and isotope composition in otoliths of juvenile (0+) pink snapper is diagnostic of location on a transect from inner Shark Bay, through Denham Sound, to the oceanic waters.
2. To analyse cores of otoliths of adult snapper from the ocean and Denham Sound stocks, to establish the location of the nursery grounds for each stock
3. To evaluate Laser Abalation, Inductively Coupled Plasma Mass Spectrometry as a tool for fish stock assessment and movement studies by comparison with concurrent stable isotope ratio and previous whole otolith trace element studies on Shark Bay snapper.
Final report
ISBN:
1-887098-15-9
Author:
Dan Gaughan
Final Report
•
2004-04-07
•
2.28 MB
2001-061-DLD.pdf
This study examined two aspects of the chemical composition of snapper otoliths from Shark Bay Western Australia as an aid to determining the spatial relationship among juveniles and to better understand the spatial relationships between juveniles and adults. Otoliths were collected from juvenile snapper in Denham Sound and Freycinet Estuary in the western gulf of Shark Bay. In order to also compare otolith chemistry for juveniles from outer Shark Bay to that from the western gulf, adult snapper were collected from these locations and the portion of their otoliths corresponding to an age <1 year (i.e. young juveniles) were analysed. As well as the two western gulf sites already mentioned, the oceanic samples were obtained from Koks Island and Cape Inscription.
