Understanding the combined roles of fishing effort and environmental factors in determining the distribution and abundance of target-sized sardines is essential to the sustainable, ecological and economical, development of the fishery.
In response to recent fluctuations in fish size and quality, the SASF seeks to increase the productivity and profitability of the fishery through the development and implementation of an industry-led, real-time monitoring system for optimising the size, quality and quantity of sardines harvested.
To address these needs industry must: 1) establish the skills and systems required to conduct real-time monitoring of fish harvesting, 2) obtain advice on the key oceanographic factors affecting sardine size distributions, 3) gain ongoing access to information on oceanographic conditions in near real-time and, 4) develop systems for linking spatial fishery performance with oceanographic conditions to optimize the size and quality of fish harvested.
In order to improve the commercial profitability and sustainability of the South Australian Sardine Fishery (SASF) there was a need to establish improved monitoring and harvest management practices based on an understanding of Sardine habitat preferences. In this project, the South Australian Sardine Industry Association Inc. (SASIA) was empowered with the resources to autonomously implement near real-time monitoring of fish movement in relation to changes in environmental conditions. As a part of the harvest management optimisation, an understanding of the environmental conditions which characterise the habitat preferences of juvenile, adult and spawning Sardines was investigated.
This project was developed at the request of SASIA and comprises two inter-related components with the common objectives of improving the economic value and ecological sustainability of the fishery.
Firstly, the SASIA was assisted in developing and implementing an autonomous near real-time harvest management system. The system is composed of three inter-connected components; fish measurement, data storage and spatial mapping. SASIA collected data on fish length (caudal- fork length) are efficiently measured and stored directly into a database using an electronic fish measurement board. The database has been designed to store and present information related to the location and size of the commercial catch from which sample measures of fish length are collected. Finally, GIS spatial mapping software is linked with the database to provide maps showing the spatial distribution of target and non-target sized fish. Maps detailing changes in the spatial distribution of target and non-target size are updated fortnightly and used by the SASIA to optimise the size of fish harvested.
Secondly, to augment the adopted real-time harvest management system, habitat suitability studies using generalised additive models (GAMs) were undertaken to understand the environmental conditions that explain the habitat preferences of juvenile and adult Sardines, as well as the summer-time spawning habitat. Historical datasets used in the modelling studies included 1) Sardine egg densities and coincident oceanographic measurements made during Daily Egg Production Method (DEPM) surveys conducted since 2004, and 2) fish length measurements made by independent observers aboard commercial vessels since 2004 and corresponding satellite measures of sea surface temperature and surface chlorophyll a concentrations.