2 results

Application of tracking technologies to understand space-time explicit patterns of movement, residency and habitat use of pelagic sharks in Spencer Gulf: resolving overlaps with key community activities and marine industries

Project number: 2014-020
Project Status:
Completed
Budget expenditure: $382,063.00
Principal Investigator: Paul J. Rogers
Organisation: SARDI Food Safety and Innovation
Project start/end date: 31 May 2014 - 31 Jul 2016
Contact:
FRDC

Need

Following many expressions of public concern regarding the potential for finfish/tuna aquaculture to attract sharks to coastal areas, at both regional development and individual site applications, PIRSA Fisheries and Aquaculture identified the need for an understanding of the factors that may explain associations between sharks and finfish/tuna aquaculture activities. This view was reinforced at meetings of the AAC (including a presentation from the PI on 22 Feb 2013), who are a legislated body under the Aquaculture Act 2001, advising the State Minister for Agriculture, Food and Fisheries on matters relating to aquaculture development. As a consequence, this project was listed as a priority area for investment by the SAFRAB.

A previous FRDC funded workshop (2002/040) identified a need to understand factors that may explain interactions between pelagic sharks and aquaculture activities. Some of the findings highlighted during this workshop are now considered to be outdated. For example, anecdotal accounts from finfish farmers and commercial fishers suggest that white sharks sightings have increased in the past decade in Spencer Gulf and this may have implications for the frequency of interactions with the fishing and aquaculture industry. The provision of data to further inform the public’s current perception of the aquaculture industry represents a key priority in South Australia’s Fisheries and Aquaculture R&D Strategy. During the development of this project the need for this research was discussed with key industry representatives.
This proposal addresses key objectives of the Draft White Shark Recovery Plan, 2010 (2c, 7a, 9a and 9b).

Objectives

1. Determine if activities associated with finfish aquaculture correlate with spatial and temporal residency and migration patterns of pelagic sharks.
2. Assess and compare patterns of residency of pelagic sharks in ‘natural’ foraging areas, and any overlaps with community activities.
3. Develop a Code of Practice for removal and release of pelagic sharks from finfish aquaculture cages.

Final report

ISBN: 978-1-876007-09-6
Author: Dr Paul Rogers
Final Report • 2018-09-01 • 5.12 MB
2014-020-DLD.pdf

Summary

The report focuses on the movement dynamics of two pelagic sharks, the White Shark (Carcharadon carcharias) and Bronze Whaler (Carcharinhus brachyurus), in South Australia. Specific aims were to: (1) determine if aquaculture activities correlated with patterns on fidelity and migration; and (2) assess and compare the use of natural foraging areas and areas used during human marine activities. Additional objectives included the development of: industry guidelines for removal and release of pelagic sharks from finfish aquaculture pontoons, and surveys to collect baseline information on perceptions of shark associations with aquaculture and other marine activities. 
Key outcomes of the project include provision of advice to marine policy-makers regarding overlaps between sharks, marine industries and areas used during community activities (including marine parks). This project addressed important research and management questions that existed for over a decade. 

Review of the fishery status for whaler sharks in South Australian and adjacent waters

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