Life history specific habitat utilisation of tropical fisheries species
The health and longevity of fisheries depend on access critical habitats appropriate to each particular life-history stage. While many key fisheries habitats are under threat from rapidly increasing coastal development, management of those habitats is severely hampered by very poor understanding of these life history-stage habitat requirements. This not only prevents effective management of critical fisheries resources but hampers the ability to direct development to enhance, rather than degrade fisheries value. At the moment many management and offsets actions are unsatisfactory to all users because they are based on incomplete understanding of fish-habitat relationships. This means actions and offsets rarely product tangible gains in ecosystem health or biodiversity, frustrating fishers, environmentalists, developers and governments alike. Not only can carefully designed developments provide new areas of critical habitat to replace habitats damaged in the past, but the opportunity exists for directing mandatory offsets from new coastal developments towards beneficial fisheries outcomes. This would provide the basis for greatly improved management of coastal fisheries habitats and would help to direct effective offset strategies, assist in directing fisheries friendly infrastructure design, and allow the development of metrics appropriate to the definitive measurement of specific fisheries outcomes from particular offset actions. Consequently, improved understanding of stage-specific habitat requirements of fisheries species is central to both the long-term health of fish stocks and fisheries productivity, and the effective management of coastal development to enhance fisheries values.
Final report
Relative efficiency of fishing gears and investigation of resource availability in tropical demersal scalefish fisheries (NDSF)
There is an urgent need for fishery independent data to improve and calibrate abundance measures of tropical demersal finfish species derived from commercial catch data that underpins quota setting processes. More specifically, species specific catchability measures are required for the main target species in the NDSF and other similar fisheries, to determine how the landed catch of each species relates to the overall biomass of the stock in the fishery region. At present the limited understanding of the catchability relationship is leading to the management need to set conservative risk-averse effort quota levels which are allegedly constraining the development of this fishery. This project will use ‘baited remote underwater video’ (BRUVs) and research vessel trawl surveys to directly assess the size composition and abundance of relevant fish species in trap and line fishing areas to generate the necessary data on catchability for each fishing method. The trawl survey derived size composition data for target species will also be used to meet the need for unbiased population samples in the stock assessment models, and will be designed to be replicated in the future (at an appropriate temporal scale). The successful completion of this project will meet the requirement for more precision in the stock size estimates and therefore meet industry’s requirement for an optimal and possibly less constraining approach to effort quota setting in the NDSF and similar fisheries.