Energy efficiency in trawling operations

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 trawler 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 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 7.60.9 m. The catch data was grouped according to the median towing hour, by the time of the day. CPUE obtained was 3713.4 kg.h-1 for day time operations and 1536.6 kg.h-1 for night-time operations. Mean daily catches were 31367 kg.day-1 (SE: 2743) for day time operations and 9430 kg.day-1 (SE: 966) for night-time operations. Fuel consumption were 0.399 and 0.982 kg fuel.kg fish-1, respectively for day and night-time operations. Total catch and catch components such as threadfin bream, bulls eye, hairtails, trevelly, lizard fish showed significant improvement during day-time operations while swarming 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 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 realise objectives of maximising catch per unit effort and minimising fuel consumption per unit volume of fish caught, has added significance in the use of bottom trawl surveys in stock abundance estimates.

Compreensão de manchetes sob a perspectiva da mesclagem e da metáfora conceptual

Nesta dissertação, investiga-se o processo de construção do significado de manchetes jornalísticas. Parte-se do pressuposto que a Metáfora Conceptual, proposta por Lakoff e Johnson (2002[1980]) e a Mesclagem, proposta por Fauconnier e Turner (2002), são as operações cognitivas complexas imbricadas no processo de compreensão e de construção de textos. A metáfora consiste em um importante recurso que estrutura o pensamento, as experiências e as ações humanas e a mesclagem, um mecanismo que permite significar eventos e experiências, aproximando realidades diversas, (des)comprimindo conhecimentos e rotinas cognitivas ativadas na conceptualização. Nesse sentido, este trabalho traz a lume a forma como o processo de construção de significado integra informações armazenadas em na mente, intercambiando domínios estáveis e ativando espaços mentais que se comungam para a culminância de estruturas emergentes. Para tanto, elucidamos as evidências de que metáforas e mesclagens podem explicar os sentidos produzidos pelas manchetes publicadas nos jornais Meia-Hora de Notícias, O Dia e O Globo. As manchetes foram coletadas no período de 18 de abril a 14 de setembro de 2011. Reunido o corpus, foi iniciado o cotejamento das manchetes à luz das referidas teorias. Realizou-se, em seguida, uma pesquisa com alunos do Ensino Médio de um colégio da rede pública estadual, a fim de confrontar as ponderações da análise com a compreensão empreendida pelos estudantes. Os resultados da análise e da mensuração das respostas dos alunos deram conta do papel da mesclagem na compreensão das manchetes analisadas, como um processo cognitivo, imaginativo e criativo, manifestado no uso da língua, de modo a promover a construção do significado. Foi possível também descrever o papel da metáfora nas mesclas postuladas para explicação do sentido das manchetes, na medida em que conceptualizações metafóricas fundamentam espaços mentais de algumas redes de integração postuladas para análise das manchetes

Effects of lunar cycle and fishing operations on longline-caught pelagic fish: fishing performance, capture time, and survival of fish

Commercial longline fishing data were analyzed and experiments were conducted with gear equipped with hook timers and timedepth recorders in the Réunion Island fishery (21°5ʹS lat., 53°28ʹE long.) to elucidate direct and indirect effects of the lunar cycle and other operational factors that affect catch rates, catch composition, fish behavior, capture time, and fish survival. Logbook data from 1998 through 2000, comprising 2009 sets, indicated that swordfish (Xiphias gladius) catch-per unit of effort (CPUE) increased during the first and last quarter of the lunar phase, whereas albacore (Thunnus alalunga) CPUE was highest during the full moon. Swordfish were caught rapidly after the longline was set and, like bigeye tuna (Thunnus obesus), they were caught during days characterized by a weak lunar illumination—mainly during low tide. We found a significant but very low influence of chemical lightsticks on CPUE and catch composition. At the time the longline was retrieved, six of the 11 species in the study had >40% survival. Hook timers indicated that only 8.4% of the swordfish were alive after 8 hours of capture, and two shark species (blue shark [Prionace glauca] and oceanic whitetip shark [Carcharhinus longimanus]) showed a greater resilience to capture: 29.3% and 23.5% were alive after 8 hours, respectively. Our results have implications for current fishing practices and we comment on the possibilities of modifying fishing strategies in order to reduce operational costs, bycatch, loss of target fish at sea, and detrimental impacts on the environment.