Oral Presentation Australian Society for Fish Biology Conference 2017

Fish-habitat associations on subsea pipelines on the north-west shelf, Western Australia (#37)

Dianne McLean 1 , Todd Bond 1 , Julian Partridge 1 , Tim Langlois 1
  1. The University of Western Australia, Crawley, WA, Australia

Remote Operated Vehicles (ROVs) are routinely used to undertake inspection and maintenance activities of underwater pipelines in north-west Australia. In doing so, many terabytes of geo-referenced underwater video are collected at depths, and on a scale, usually unobtainable for ecological research. We assessed fish diversity and abundance from existing ROV videos collected along Woodside Energy Ltd's ‘Echo Yodel’ pipeline on the north-west shelf at 130 m depth. The pipeline was characterised by a high abundance of commercially important snapper (Lutjanidae) and grouper (Epinephelidae) species. Fish assemblage composition varied across survey years and also from day to night with many fish species exhibiting day time peaks in abundance on the pipeline. Complex deepwater epibenthic habitat forming invertebrates were observed including deepwater corals, crinoids (featherstars), Gorgonocephalidae (basket stars), hydroids, true anemones and sponges. Historically high trawling effort is thought to have extensively removed and modified complex epibenthic habitats in the region. These habitats were considered to be important to commercial target species and the modification or loss of these habitats is thought to have negatively impacted the valuable commercial fisheries in the region. However, the current study demonstrates that modern pipelines offer hard substrate for the development of epibenthic habitats and refuges for fish, potentially comparable in physical complexity, if not in extent, to the historical habitats lost to trawling. The study builds knowledge of deep-water coastal fish ecology in north-west Australia and will help to inform discussions regarding the ecological and fisheries implications of decommissioning.