PROJECT NUMBER
•
2013-021
PROJECT STATUS:
COMPLETED
ORGANISATION:
University of Melbourne
3 results
Spawning sources, movement patterns, and nursery area replenishment of spawning populations of King George whiting in south-eastern Australia - closing the life history loop
Project number:
2011-017
Project Status:
Completed
Budget expenditure:
$741,161.00
Principal Investigator:
Gregory Jenkins
Organisation:
University of Melbourne
Project start/end date:
31 Oct 2011
-
29 Nov 2014
Contact:
FRDC
SPECIES
Fisheries that have populations/stocks straddling cross-jurisdictional boundaries face particular challenges in terms of sustainable management. This is particularly the case when aspects of the species' life history are poorly understood. Fisheries managers require a clear understanding of stock-structure and life history of key species for sustainable management, particularly where the fishery is cross-jurisdictional and requires co-operation between different management agencies.
The King George whiting (KGW) fishery is an extremely important recreational and commercial fishery in southern Australia, especially in bays and inlets of Victoria and South Australia. There is some evidence that much of the Victorian fishery for KGW is dependent on spawning in South Australia and extensive larval drift through Bass Strait. There is more limited evidence that spawning may also occur in eastern Victorian waters. The degree to which adult whiting from Victorian juvenile nursery areas migrate to South Australia for spawning is unknown, with previous research suggesting a possible migration of adult fish from central Victoria to the west. The degree to which juveniles move between nursery areas is also unknown, with no previous research in Victoria. There is a need to understand the present relationship between Victorian and South Australian KGW stocks; are they strongly dependent or are they independent? The management of this species would be greatly improved if we understood the stock structure. For example, the species is presently managed independently by Victoria and South Australia but we do not understand how the populations in the two States relate to each other.
1. To determine whether King George whiting in juvenile nursery areas of Victoria and South Australia are derived from the same or different spawning sources
2. To understand the movement patterns of juvenile King George whiting between different nursery areas
3. To determine the relative importance of juvenile King George whiting from different nursery areas to the replenishment of the known spawning populations in South Australia
4. Based on a full understanding of the life history and stock structure of the species to provide information informing decision making by managers in both States relating to the need for cross-jurisdictional management
Final report
ISBN:
978 0 7340 5270 4
Author:
Gregory Jenkins
Links between seagrass habitats, piscivorous fishes and their fish prey
Project number:
1999-215
Project Status:
Completed
Budget expenditure:
$35,000.00
Principal Investigator:
Michael J. Keough
Organisation:
University of Melbourne
Project start/end date:
28 Nov 1999
-
1 Jul 2001
Contact:
FRDC
The FRDC recently commissioned a review of the importance of seagrass habitats to fisheries sustainability in which Connolly et al. (in press) identified the "gaps in our understanding and future research needs" and made "recommendations for future research" (In Press: Report No. 98/223).
Connolly et al. (in press; point seven, section 6.4. Gaps in our understanding and future research needs) suggest that the nature of the links between fish and processes such as "feeding, protection from predators and amelioration of physical disturbance" within seagrass habitats are "poorly known". "Hard data on links between seagrass and fishery species are needed urgently" (Connolly et al., in press; section 6.5. Summary of recommendations for future research). Connolly et al. (in press) identify a need for "small scale manipulative experiments", "conducted over a large enough spatial scale" so that we can increase our capacity "to predict the effects of changes in seagrass extent on commercial fish". It is important to understand the importance of "processes linking seagrass with fish" in order to be "able to predict the effects of seagrass changes on fisheries" (Connolly et al., in press; section 6.5. Summary of recommendations for future research).
Connolly et al. (in press) also suggest that "dietary and isotope studies of piscivorous fish are required " because the role of small, non-commercial species in food chains for commercial species is only known in localized areas" (section 6.4. Gaps in our understanding and future research needs, point 12, section 6.5. Summary of recommendations for future research). Isotope studies will also address the need for research which compares the ecology (e.g. extent of assimilation of food from seagrass beds) of fishery species that spend all or only part of their life associated with seagrass" (point 3, section 6.5. Summary of recommendations for future research).
Cappo et al. (1998) reiterate Connolly et al. (in press) in suggesting that information is needed about the role of predation in structuring fish assemblages within seagrass beds. "There is a surprising lack of basic life-history information for most of the major fishery species in Australia", and "consequently a paucity of information on "critical" habitat requirements and processes such as post-recruitment mortality" (section 1.3.4 Lack of knowledge of links between life-histories and habitats).
1. Quantify the contribution of fishes, which may or may not be economically valuable, within seagrass beds to the dietary composition of piscivorous fish, some of which e.g. Yank flathead (Platycephalus speculator), Rock flathead (Platycephalus laevigatus) and Australian Salmon (Arripis sp.) form commercially valuable fisheries.
2. Identify how piscivorous fish influence the abundance of juvenile fish within seagrass beds, some of which, e.g. the King George whiting, form valuable commercial and recreational fisheries.
3. Describe and quantify, using carbon and nitrogen isotope analysis, the strength of links between seagrass beds, juvenile fish inhabitants and their fish predators.
Final report
Author:
Dr Jeremy S. Hindell
Dr Michael J. Keough
Dr Gregory P. Jenkins
Final Report
•
2017-09-29
•
4.42 MB
1999-215-DLD.pdf
This project has increased our understanding of the importance of seagrass habitats to larger, commercially valuable, species of fish by combining experimental and correlative scientific principles. We found that many small fish use seagrass habitats for nutrition and to avoid predation by large predatory fish. Some of these small fish also form important parts of the diets of commercially important species, such as Australian Salmon. The importance of predatory fish varied, however, from site to site, suggesting that seagrass habitats may need to be evaluated individually. The primary outcomes of this study will be important in identifying seagrass habitats that are especially valuable as feeding and nursey sites for commercially valuable fish in Port Phillip Bay. The type of information presented in this study will help understand how and why various nearshore marine habitats may be used by various species of fish, and how best to ensure their protection and future sustainability.
