Handline surveys of deep water fish on the outer Great Barrier Reef

Three surveys were conducted off the Great Barrier Reef (GBR) in 1992. The first and third surveys (16-21 April and 26-31 December) were in the vicinity of Myrmidon Reef in the central section of the GBR. The second survey (19-29 June) was conducted at No.9 and No.10 Ribbon Reefs in the northern section of the GBR.

Hawaiian-style deep-water handlines were used to survey fish at depths ranging from 40 to 340 m. Fishing operations were conducted during the day over the outer slope of the continental shelf. The vessel drifted over bottom features such as ledges, pinnacles, and drop-offs, which were located using a depth sounder. The rate of drift was controlled by using the engines to keep the bow of the vessel at a quartering angle into the dominant wind, sea, or current.

At capture, fish were photographed next to a 30-cm rule, measured for standard length (SL) in cm and weighed. Otoliths were removed for age and growth studies and tissues were removed for genetic studies. One specimen of each species was frozen and deposited in the Western Australian Museum (WAM) for identification and cataloguing. Catch per unit effort was also calculated (number of fish/handline hour and kg/handline hour).