Project number: 2004-067
Project Status:
Completed
Budget expenditure: $59,253.00
Principal Investigator: Keith Jones
Organisation: SARDI Food Safety and Innovation
Project start/end date: 14 Aug 2004 - 30 Jan 2007
Contact:
FRDC

Need

In recent years in South Australia there has been increased interest in the bronze whaler (Carcharinus brachyurus) and the dusky whaler (C. obscurus) shark species. The increased fishery focus has resulted in part from a redirection of effort from school and gummy sharks, whilst the development of sea cage aquaculture in inshore areas of Spencer Gulf has potentially resulted in increased mortality rates for whaler sharks.

The current understanding of the fishery and population biology of these species is too poor to know whether the populations are sustainable under these regimes of increased mortality. One problem for understanding the fishery biology is that comprehensive information on catch is not being collected. This is because both species of sharks are taken in a diversity of fisheries as either targeted or non-targeted catch, and only some information on targeted catch is being reported. Furthermore, this targeted catch and effort information is maintained in different places. Consequently, the first need for assessing the vulnerability of the populations of dusky and bronze whaler sharks in South Australia is to collate the existing catch and effort information. Once this has been achieved the data can be analysed and used in a risk analysis to assess, as far as possible, the vulnerability of dusky and bronze whaler sharks to over-exploitation.

Objectives

1. To collate the existing data for the whaler sharks in South Australian waters from numerous places where these data are maintained, as well as the information on shark mortalities associated with sea cage aquaculture
2. To analyse these data by undertaking a risk assessment, taking into account the lack of data from some sectors, as well as the poor understanding of population biology of these species in South Australia
3. To develop options for improving the collection and maintenance of catch and effort data in the future
4. To make recommendations regarding the need for biological studies on the two species in the future
5. To provide options for managing the whaler shark resource, where there is sufficient information.

Final report

ISBN: 073085350-0
Author: Keith Jones

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