Fish of the Yongala shipwreck and nearby deep water shoals, central Great Barrier Reef (CRC Reef Research Centre Project)

Five fish surveys were conducted on the wreck of the Yongala between June 1996 and September 1997. In addition, surveys of fish on two nearby deep water shoals, Tink Shoal and the unnamed "Small" Shoal were carried out in May 1997.Fish were surveyed by a visual census method using Log5 abundance estimates. Two dives along the length of the shipwreck were conducted during each visit to the Yongala, with a total observation time of 45 minutes. The bottom of the shipwreck was surveyed on the first dive and during the second dive fish visible from midway down the shipwreck were surveyed. The second dive built on the estimates and species recorded during the first dive. All fish in sight on the shipwreck were counted.A single 25 minute dive was made at each of the shoals. Each dive covered approximately 200m straight line distance and Log 5 abundance of fishes was recorded in an estimated 10m band along the swimming path. Dives on the shoals began at 30m depth and finished on the reef slope at around 15m.Additional observations recorded included habitat type, visibility, currents, the presence of other vessels with divers and fish behaviour.
The objective of this project was assess the significance of the Yongala wreck as a fish refuge in the inshore region of the Great Barrier Reef. To achieve this objective the following tasks were identified:1. to compile an species list of the fish associated with the Yongala wreck2. to compare the Yongala fish community with those of nearby deep water shoals3. to assess the relative abundance of different fish species and temporal changes in abundance