The fish communities and main fish populations of the Jurien Bay Marine Park

Abstract

The Strategic Research Fund for the Marine Environment funded a range of floral and faunal research projects to determine the characteristics of the marine communities in the Jurien Bay Marine Park (JBMP), which was gazetted in 2003. This project has determined the diversity, density and species compositions of the fishes that occupy reefs, seagrass, unvegetated sand and nearshore surf zone habitats in three different types of management zones in the JBMP. The zones were (1) General use zones, where all types of fishing are allowed. (2) Scientific reference zones, where recreational and commercial rock lobster fishing and selected shore-based fishing activities are allowed. (3) Sanctuary zones, where no boat-based fishing is permitted. Future management of the marine park requires a sound understanding of the relationships among the fish faunas, both within and among the main habitat types in each of the different management zones, and of the variability that occurs at different spatial scales. The vision provided by the management plan for the JBMP was: “In the year 2025, the marine flora and fauna, habitats and water quality of the Jurien Bay Marine Park will be in the same or better condition than in the year 2005. The area will support viable and ecologically sustainable fishing, aquaculture, recreation and nature-based tourism and the marine park will be considered an important asset by the local community” (Anon., 2005). Key performance indicators, described in the management plan, were designed to ensure that this vision is met. This requires data on how estimates of abundance of fishes varied according to the type of sampling method used during this study. The baseline values for different sampling methods can then be used, in the future, to assess whether the vision for the marine park has been achieved. This study used the following complementary sampling methods to survey fishes in the different habitats in the JBMP, i.e. underwater visual census (UVC) and baited remote underwater video stations (BRUVS) over reefs, BRUVS and trawling in seagrass and over unvegetated sand and seine netting in surf zones. The combined results from the different methods demonstrated that the fish fauna of the JBMP is diverse and comprises temperate, sub-tropical and tropical species. Variability in the fish faunas was detected both within and among the main habitat types and was related to the range of physical and biological characteristics present. The compositions of species sampled by each method differed. In particular, whereas the samples obtained using UVC, trawling and seine netting contained a range of trophic groups, those collected employing BRUVS were dominated by carnivorous species. These differences in ichthyofaunal composition within and among habitat types and between sampling methods must thus be taken into account when selecting the methods used both for long-term monitoring of fish communities and for providing the types of data necessary for assessing whether the marine park is achieving its objectives