Project number: 2010-003
Project Status:
Completed
Budget expenditure: $526,500.00
Principal Investigator: Rory McAuley
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 31 Dec 2010 - 29 Dec 2013
Contact:
FRDC

Need

The fishery biology (reproduction, growth, age, gear selectivity, fishing mortality, etc.) of Western Australia's four most commercially-important shark stocks are relatively well understood. However, uncertainty regarding their migratory patterns remains a significant caveat to ensuring their sustainability and for the long-term viability of their target fisheries. Dusky and sandbar shark stocks are distinctly size-segregated. Juveniles are targeted by demersal gillnet and longline fishers off the lower-west and south-west coasts, hundreds of kilometres south of adults’ primary distribution. To maintain adequate recruitment to these stocks, shark fishing has been prohibited in the north-west to protect adult sharks. However, the extent to which adults remain vulnerable to capture during their southerly natal migrations cannot be ascertained due to lack of knowledge about those migrations. Gummy and whiskery shark movements between fishery management zones have significant implications for those stocks’ continued recovery from historical periods of overfishing. In particular, the effects of gillnet fishing in the south east of the State during the seasonal closure of the fisheries west of 118 degrees longitude and an apparent westwardly emigration of gummy sharks from the south-eastern management zone are of interest to fishery managers and industry alike. A unique opportunity to evaluate these and other spatial-temporal stock dynamics currently exists in WA via acoustic telemetry infrastructure deployed around the State through various projects. Data from the proposed research will provide a better understanding of the benefits and limitations of existing fishery management arrangements and a basis for developing spatially and temporally explicit stock assessment models.

Objectives

1. Identify and describe the timing, duration and pathways of dusky and sandbar shark migrations
2. Quantify exchange rates of gummy and whiskery sharks among management zones
3. Reassess stocks’ status with greater reference to their spatial and temporal dynamics

Final report

ISBN: 978-1-877098-75-8
Author: Rory McAuley

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