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Title Energy efficiency in trawling operations
 
Names Boopendranath, M.R.
George, V.C.
Hameed, M.S.
Date Issued 2010 (iso8601)
Abstract Diurnal variation in trawl catches and its influence on energy efficiency of trawler operations are discussed in this paper, based on data on landings of a Japanese factory which operated in the Indian waters during 1992-93. The factory vessel equipped for stern trawling had a length overall of 110 m, GT of 5460 and installed engine power of 5700 hp. Operations were conducted off the west coast of India between 31 and 278 m depth contours, using a 80.4 m high opening bottom trawl with an adjusted vertical opening of 7.60.9 m. The catch data were grouped according to the median towing hour, by the time of the day, CPUE obtained was 3713.4 kg/h for day time operations and 1536.6 kg/h for night-time operations. Mean daily catches were 31367 kg/day (SE: 2743) for day time operations and 9430 kg/day (SE: 966) for night-time operations. Fuel consumption was 0.399 and 0.982 kg fuel.kg/fish, respectively for the day and night-time operations. Total catch and catch components, such as threadfin bream, bull's eye, hair tails, trevelly, lizard fish, showed significant improvement during the day-time operations , while swarning crabs showed a significant improvement in the night-time operations. The difference in catch rates between day and night could be attributed to diurnal variation in the spatial distribution and schooling behaviour of the catch categories, their differential behaviour in the vicinity of trawl systems under varying light levels of day and night and consequent effect on the catching efficiency and size selectivity at different stages in the capture process. The results obtained in addition to its importance in the operational planning of trawling in order to realisc objectives of maximizing catch per unit effort and minimizing fuel consumption per unit volume of fish caught, has added significance in the use of bottom trawl surveys in stock abundance estimates.
Genre Article
Topic Diurnal variation
Identifier Journal of Coastal Environment 2010: 1(1), 53-70