Opportunities and impacts of range extending scalefish species: understanding population dynamics, ecosystem impacts and management needs
Species-level responses to ocean warming is a priority research area as they underpin the structure and function of marine ecosystems and the productivity of fisheries that operate within them.
There are a number of range extending species that have become increasingly abundant in Tasmanian waters, providing new fishing opportunities for recreational and, to a lesser extent, commercial fishers. Species in this group include Pink Snapper, King George Whiting and Yellowtail Kingfish. While King George Whiting are known to spawn off the north coast it is unclear as to whether the other species have or are likely to become established as self-sustaining populations in Tasmanian waters or simply persist as spill-over from populations that are centered off mainland Australia. If the former is the case, it will be especially important to consider population attributes such as growth, mortality and reproductive dynamics relevant to the Tasmanian populations when developing and refining management arrangements to maximise the opportunities these 'new' species bring.
In addition, the broader ecosystem impacts of such range extending species, including competition with resident species at similar trophic levels, are unknown but could have consequences for other recreationally and commercially important species. Understanding these relationships will have benefits for the assessment and management of the Tasmanian recreational fishery more generally.
Final report
This work set out to quantify the biology and diet of three key range-shifting species in Tasmania with both recreational and commercial fishery value. The project was heavily reliant on engagement from the recreational fishing community and multiple citizen science initiatives, as well as historical data.
The information collected was used in modelling to predict how suitable habitats for each species may shift under future climate change projections. The work also indicated the potential changes to the ecosystem (such as food web) if these species’ ranges were to move.
Assessing the population biology of Black Jewfish (Protonibea diacanthus) in Queensland
Australian salmon (Arripis trutta): Population structure, reproduction, diet and composition of commercial and recreational catches in NSW
The eastern Australian salmon stock appears to have increased substantially in recent times and is believed to be under-utilized. Despite this, management of this species in NSW has been contentious, and is restricted by a lack of knowledge on biology and population dynamics. Specifically, managers require information that will assist their decision making concerning: (i) the status of the stock; (ii) potential expansion of the commercial fishery; (iii) impacts of resource allocation, and; (iv) ecosystem effects of salmon population expansion.
There is a lack of information on the sizes and ages of salmon being harvested and little knowledge of their biology. Research on age and growth in the 1970’s was based on scales, which have since been shown to be inaccurate (Egglestone 1975). Studies on reproduction have been limited to the timing of spawning in the southern regions. Results from this project will provide the necessary information on the composition of landings, age, growth, reproduction, movements and diet to enable informed management of the salmon resource. This project aims to address issues directly related to NSW management, however the baseline information will be valuable for management across the range of the stock.
The project outcomes of improved knowledge and management of salmon will directly address the FRDC R&D program “Natural Resources Sustainability” and the strategic challenge to “Improve the sustainability of natural resources supporting wild-catch and aquaculture”. At the state level, this project will satisfy three priority areas of research listed under the key document “Planning strategic research, aquaculture and aquatic conservation in New South Wales, 2004-2009.” These are: (i) to examine the predatory impacts of Australian salmon on other commercially important fish species; (ii) information on age and growth of recreationally important species, and; (iii) development of stock assessments for target species in the ocean hauling fishery.