Behaviour of the western rock lobster to commercial traps
Toon, N. and Loneragan, N. (2011) Behaviour of the western rock lobster to commercial traps. In: 48th Annual Conference of the Australian Marine Science Association, 3 - 7 July, Fremantle, Western Australia.
Video observations were made of the behavioural interactions of Panulirus cygnus with commercial traps in the laboratory and under commercial fishing conditions. The laboratory observations investigated the influence of temperature and moonlight intensity on the lobster behaviour. However, presented here are the results from in situ observations of the western rock lobster with a baited commercial trap. Video recordings were analysed from deployments of the trap in the shallow waters at North Island (5 nights) and Pelsaert group (7 nights) within the Houtman Abrohlos Islands between April and May 2008 and Jurien Bay in March 2009 (4 nights). Lobsters were observed to predominately interact with the traps between dusk and dawn, with fewer trap interactions occurring after midnight. Entry and feeding activity at the trap remained consistent throughout the night. Low catch rates and observations of lobsters occurred at Jurien Bay, potentially as a result of lower water temperatures and higher surge. Only a small number of P. cygnus were retained in the trap compared with the number of interactions observed on top and to the sides of the trap. Lobsters were seen entering and exiting the trap throughout the night at all locations in this study. Fewer than 15 % of the lobsters entering the traps were retained at the Houtman Abrolhos locations. Only 30 % of the lobsters that approached the side of the trap at Pelsaert group continued to further investigate the trap. The behaviour of P. cygnus at the traps varied greatly among nights, indicating that the behaviour of lobsters is highly variable. The behaviour of lobster was influenced by the presence of octopus in traps as no P. cygnus entered traps containing octopus. Octopus, however, appeared to be attracted to and entered the traps due to the bait and shelter rather than the presence of P. cygnus. The use of video in this study has developed a better understanding of gear efficiency and the interactions of P. cygnus with baited traps.
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|Murdoch Affiliation:||Centre for Fish and Fisheries Research|
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