New Zealand Journal of Marine and Freshwater Research abstracts
Impact of lunar cycle and swell on the daily catch rate of western rock lobster (Panulirus cygnus) using time series modelling
Sukanlaya Srisurichan*
Edith Cowan University
Perth
WA, Australia
Nick Caputi
Western Australian Marine Research Laboratories
P.O. Box 20, North Beach
WA 6920, Australia
email: ncaputi@fish.a.gov.au
Jim Cross
Edith Cowan University
Perth
WA, Australia
*Present address: Rajabhat Institute Nakhonsawan, Amphur Muang, Nakhonsawan, 60000, Thailand.
Abstract The western rock lobster fishery is one of the most valuable single-species fisheries in Australia, valued at au$300 million per year. The impact of environmental factors such as lunar cycle and swell on the daily catch rate of the western rock lobster (Panulirus cynus) is of particular interest in the stock assessment and management of the fishery. The variation in daily catch rates was examined for two periods (migrating period November-January, non-migrating period February-June), at different depths in three management zones for three categories of lobster (undersize, legal size, and setose). Regression and transfer function models for relationships between catch rates and environmental data were considered and compared. The lunar cycle has a significant impact on the daily catch rates with c. 30% lower catch rate during the full moon and c. 20% higher catches near the new moon. This impact occurs mainly during the non-migrating period both in deep water (40-100 m) and shallow water (<40 m). The swell on the day before fishing was also shown to be significantly related to the catch rate with an increase of c. 10-15% for an increase in swell from light to moderate or moderate to high. These environmental factors can be used to standardise catch rates to provide an improved abundance index for stock assessment. Also, management closures are being considered for 3-5 days over the low catch rate, full moon period to reduce fishing costs and lower fishing effort.
Keywords daily catch rates; western rock lobster; lunar cycle; swell; time series
M04075; Online publication date 8 June 2005
Received 31 March 2004; accepted 14 December 2004
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39: 749-764
0028-8330/05/3903-0749 © The Royal Society of New Zealand 2005
PDF file of entire paper: Print-quality (720K) | screen-quality (246K)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
