Predicting the impacts of shifting recreational fishing effort towards inshore species
Recreational exploitation of inshore, marine fishes near Perth, WA, including King George Whiting, some other whiting species and Silver Trevally, is likely to increase markedly because of effort transfer from offshore to inshore species, due to new fishing regulations to protect offshore demersal species. No reliable stock assessment information is currently available for any of these species, which may already be overexploited. Furthermore, for King George Whiting and Silver Trevally, current assessment methods are inadequate because offshore movements with increasing body size, combined with different catchabilities and fishing pressures in nearshore and offshore habitats, make it impossible to obtain a representative age composition sample for an overall stock of these species. This problem can be addressed through developing a new stock assessment approach for such species, which is also applicable to other recreational, and commercial species, e.g. Estuary Cod.
The biological information published in reports and papers on commercial and recreational fish species in south-western Australia is often inaccessible to fishers and researchers may not be aware of all available information for those species. A book explaining the basics of fisheries science and outlining key information for important temperate WA fish species would be invaluable for engaging fishers and a valuable reference for researchers and managers.
The proposed project directly addresses an urgent need of the Department of Fisheries, WA, and the recreational sector, to assess likely impacts of recreational effort transfer from offshore to important inshore species. The assessment approach and guide is also very relevant to the commercial sector.
Final report
The project outputs have led to the following outcomes:
1. A model has been developed enabling reliable estimation of mortality of fish species that undertake size-related, unidirectional, offshore movements from age and length data. This new modelling approach is likely to be applicable to stocks of a number of fish species with this life history attribute, for which current stock status information may be very limited due to the difficulty of obtaining a representative sample for an overall stock.
2. Current age and length composition data and estimates of key stock assessment parameters, including selectivity, movement and fishing mortality, are now available for Silver Trevally and King George Whiting in coastal waters near Perth in Western Australia. Managers are aware that the study results have provided preliminary evidence that Silver Trevally and King George Whiting in waters near Perth are not currently experiencing overfishing.
3. This project has provided managers with information about the relative extents to which the stocks of Silver Trevally and King George Whiting in coastal waters near Perth might be expected to be impacted if fishing pressure were to increase by specified amounts. Managers are thus aware that King George Whiting stocks are likely to be more vulnerable than Silver Trevally to increases in fishing pressure in inshore waters.
4. Detailed summaries of the biology, stock assessment and management for 30 of Western Australia’s most important and/or well-known temperate fish species are now accessible to fishery stakeholders in the form of a species guide (published separately as Fisheries Research Report No. 242 by the Department of Fisheries, Western Australia). The guide provides a comprehensive “go to” source of information for anyone who wishes to find key facts and/or literature relating to these species.
Keywords: Silver Trevally, King George Whiting, size-related movement, fishing mortality, uncertainty, model assumptions
Characterisation of the inshore fish assemblages of the Pilbara and Kimberley coasts
Effects of net fishing: addressing biodiversity and bycatch issues in Queensland inshore waters
There is a critical need for information to support management decisions about inshore fisheries resources, and to address rising industry, conservation and public concern about the impact of net fishing on sustainability and biodiversity of the ecosystem and habitats associated with the fishery. The theory of measuring changes in biodiversity have yet to be applied in net fisheries. This project will be a test case for the practical application of determining net fishing effects on biodiversity.
Information on the effect of net fishing on bycatch and biodiversity in Australia is extremely limited. While some data exist on the marketed catch, the quantity and nature of bycatch remains virtually unknown. There is little information on the total catch characteristics of net fisheries, the proportions of species caught, and the proportion of the resource harvested each year. Similarly little is known about the fate of fish discarded from nets which would help to characterise the impact of net fishing on biodiversity.
This project will address the urgent need for information on the: total catch composition from net fishing, fate of discarded fish bycatch, impact on protected species and impact on biodiversity. Baseline data collected through both fishery dependent and independent methods will provide a basis for long term monitoring of the fishery and will enhance the interpretation of existing commercial catch records. These data will help meet the requirements of the ‘National Strategy for Conservation of Australia’s Biological Biodiversity’ of a) improving the knowledge base of fisheries, b) improving fisheries management and c) assessing and minimising the impact of commercial fishery practices on non-target and bycatch species, ecosystems and genetic diversity.
Final report
Tactical Research Fund: managing inshore stocks of southern rock lobster for a sustainable fishery
There is clearly a concern in the Tasmanian lobster industry about the status of inshore component of the stock. Catch has declined in a number of areas, despite improvements in catch rates. In the Northeast, catch is at record lows, but CPUE has remained stable, which is a possible indicator of hyper-stability or false stability. The apparent stability in catch rates occurs because aggregations containing a major proportion of the population are fished down, as the fleet moves from one area of good catch rates to the next, resulting in a serial depletion of the aggregations, which is masked by the apparent stability in the fishing block. This can result in a very sudden decline in biomass once the entire block is depleted, posing a serious and immediate risk to the inshore component of the stock. There are two potential sources of this problem. Firstly, the scale of the current assessment model, of eight inshore areas (64m) and three offshore areas (>64m) is not be fine enough to detect localised changes in the CPUE or biomass. Secondly there are changes in fishing practices that have increased effort on inshore stocks, and it is unclear whether the extra effort in these practices is adequately recorded in estimates of CPUE. There has been a recent increase in potting effort, commonly referred to as double night fishing, whereby fishers set and haul their pots twice a night, compared to the standard practice of emptying pots once at dusk and/or once during the day. Currently we have no data on the composition of the catch in double night shots, and what proportion of captured lobsters are handled and released, and in fact what consequence this handling has on the overall health of the fishery.
Final report
Beyond GVP: The value of inshore commercial fisheries to fishers and consumers in regional communities on Queensland’s east coast
There are multiple threats to ongoing access/operation of commercial inshore fisheries (finfish and crab) along Queensland’s east coast. These include port developments and expansions, coastal development, public perception (which influences management) and competition between fishing sectors (which also influences management). These threats to access could adversely affect not only commercial fishers themselves, but also secondary industries as well as the availability of seafood to local communities. It is now well documented that consumers prefer local seafood products, and are willing to pay more for seafood labelled ‘local’ (Tobin et al. 2010; Calogeras et al. 2011).
It could be assumed that reducing these threats and ensuring ongoing operation of commercial fisheries and local seafood supply is desirable, for many social and economic reasons. Yet there is little information about the value inshore commercial fisheries and fishing businesses provide to communities (aside from the much used GVP, which has long been recognised as a nonsensical measure of value (e.g. Edwards 1991, McPhee & Hundloe 2004)), or the relative value of local seafood compared to non-local seafood for consumers.
Without knowing the real economic value of commercial fisheries and local seafood for regional communities, decisions regarding management of, and access to, resources are likely to be ill informed. Real value information can be used to ensure appropriate access of fishers and consumers to fisheries resources, better assess the economic impacts of other coastal activities that negatively affect fishing, or better inform reallocation processes where necessary.
Final report
Impact of gillnet fishing on inshore temperate reef fishes, with particular reference to banded morwong
Final report
Low cost management regimes for sustainable, small low-value fisheries based on coastal inshore species
Tactical Research Fund: spreading the risk: management strategies for multi-method inshore fisheries in a changing climate
The NSW Department of Primary Industries continues to work with the NSW commercial fishing industry to investigate structural changes to the management of commercial fisheries which will lead to improvements in efficiency and profitability. One issue that requires consideration in these deliberations is the highly variable inshore-offshore production that is linked with rainfall in coastal NSW. Such changes are exacerbated during periods of drought or flood and result in significant shifts in the behaviour of fishers. It is expected that such variations in rainfall will continue, and are likely to become more extreme, under projected climate change scenarios.
This project will examine the NSW commercial catch records and ascertain if there are patterns of endorsement holdings that are the basis of more robust fishing businesses during periods of drought or flood. We expect that many fishers will understand these patterns based upon extensive practical experience, but an empirical confirmation of such patterns will lend additional weight to any associated decisions by government and industry.
This project will also shed light upon an important facet of risk management in fisheries. The textbook economic argument that increased specialisation results in increased efficiency must be contrasted with potential lost opportunities for fisheries production in a highly variable environment. The adage "don't put all your eggs in one basket" is likely to be highly applicable for inshore and coastal fisheries in NSW. Increased specialisation will likely be associated with costs as well as benefits.
Final report
Aquatic Animal Health Subprogram: Metazoan parasite survey of selected macro-inshore fish of southeastern Australia, including species of commercial importance
Metazoan parasites threaten the sustainability and profitability of the Australian finfish aquaculture industry. It is critical, therefore, to identify local parasite species and determine which are potentially harmful. There have been many studies assessing metazoan parasite fauna of wild fish and fish farmed in sea-cages in the northern hemisphere, but such research is notably absent in the Australia. With current low stocking densities and dispersed farm locations in Australia, the potential for parasitic disease problems in sea-cage aquaculture may not yet be realised.
In the sea-cage environment farmed fish can acquire infections found in local populations of wild fish. The natural occurrence of wild fish near sea-cage farms provides an opportunity for transfer of parasites between wild and farmed populations. The parasite assemblage of the wild fish species and the potential risks of these parasites for sea-cage aquaculture are largely unknown. By gathering biological data about parasites, we will gain a better understanding of how to manage and control them on fish in captivity.
Parasite identification, knowledge of parasite biology, diagnostic tools and how parasites impact on their host is critical for effective parasite management. This project will use a powerful combination of morphological and molecular genetic techniques to provide a comprehensive understanding of copepod, monogenean and trematode parasites infecting selected aquaculture, recreational and commercial finfish species in southeastern Australia, plus barramundi in the northwest.
This research will enable proactive parasite management and rapid identification of pathogenic parasite species. It will also identify appropriate site selection for expansion of the industry away from infection sources. Appropriate husbandry practices and management practices can be put in place to control parasite infections thereby reducing morbidity and mortality in fish stocks.