Blue Marlin, Makaira nigricans, Movements in the Western North Atlantic Ocean: Results of a Cooperative Game Fish Tagging Program, 1954-88

Blue marlin, Makaira nigricans, tag and recapture data are summarized for 1954-1988. During this period, 8,447 fish have been tagged and only 30 (0.35 percent) have been returned. Results of the tagging program indicate that blue marlin not only travel considerable distances (7,OOO km from the U. S. Virgin Islands to the Ivory Coast of West Africa), but have remained at large for up to 8 years. Seasonal movements, however, are difficult to determine accurately.

The Fish Funnel: A Trawl Modification to Reduce Fish Escapement

In the Gulf of Mexico there is a need to assess the potential of underutilized fish resource stocks before a commercial fishery develops. Standard sampling trawls used in the Gulf are ineffective for sampling the resource, so larger, high opening, bottom trawls have been introduced. The larger trawls are more effective, but most of the faster swimming fish species are able to escape these nets, especially during haul back. To reduce fish escapement, webbing panels, attached inside the trawls ahead of the cod ends, were tested. Initial tests were conducted with two single panel designs--a fish flap and a "floppa." Neither design reduced fish escapement. The floppa distorted the trawl webbing and actually increased fish escapement. A multi-panel conical funnel design (the fish funnel) was tested and found to increase fish retention by trapping the fish after they passed through it. When used in combination with a technique known as pulsing the trawl, the fish funnel substantially increased trawl catch rates with no indication of fish escapement.

The Effects of Fish Trap Mesh Size on Reef Fish Catch off Southeastern Florida

Catch and mesh selectivity of wire-meshed fish traps were tested for eleven different mesh sizes ranging from 13 X 13 mm (0.5 x 0.5") to 76 x 152 mm (3 X 6"). A total of 1,810 fish (757 kg) representing 85 species and 28 families were captured during 330 trap hauls off southeastern Florida from December 1986 to July 1988. Mesh size significantly affected catches. The 1.5" hexagonal mesh caught the most fish by number, weight, and value. Catches tended to decline as meshes got smaller or larger. Individual fish size increased with larger meshes. Laboratory mesh retention experiments showed relationships between mesh shape and size and individual retention for snapper (Lutjanidae), grouper (Serranidae), jack (Carangidae), porgy (Sparidae), and surgeonfish (Acanthuridae). These relationships may be used to predict the effect of mesh sizes on catch rates. Because mesh size and shape greatly influenced catchability, regulating mesh size may provide a useful basis for managing the commercial trap fishery.

The review of recent advances in fish genetics and biotechnology

Great advances have been, and are being made in our knowledge of the genetics and molecular biology (including genomics, proteomics and structural biology). Global molecular profiling technologies such as microassays using DNA or oligonucleotide chip, and protein and lipid chips are being developed. The application of such biotechnological advances are inevitable in aquaculture in the areas of improvement of aquaculture stocks where many molecular markers such as RFLPs, AFLDs and RAPD are now available for genome analysis, finger printing and genetic linkage mapping. Transgenic technology has been developed in a number of fish species and research is being pursed to produce transgenic fish carrying genes that encode antimicrobial peptides such as lysozyme thereby achieving disease resistance in fish. Also it is a short cut to achieving genetic change for fast growth and other desirable traits like early sexual maturity, temperature tolerance and feed conversion efficiency. KEYWORDS: Fish genetics, transgenesis, monoploidy, diploidy, polyploidy,gynogenesis, androgenesis, cryopreservation.

Feeding Ecology of the Franciscana (Pontoporia blainvillei) In Marine And Estuarine Waters Of Argentina

Stomach contents of 110 franciscanas (Pontoporia blainvillei), from northern Argentina were analysed in order to improve our knowledge about the feeding habits of this species and to better characterise the lactation period. The samples included calves, juveniles and adults of both sexes. Evidence of predation by franciscanas is seen at a very young age (2.5-3 months), with a transition diet composed by both milk and solid food, mainly represented by crustaceans. Weaning seems to begin by April, when franciscanas are about 6-7 months old. Franciscanas inhabiting two different habitats were analysed in this study: a brackish water estuary and an adjacent marine coastal system. The diet of Pontoporia blainvillei in northern Argentina was composed by a total of 26 prey species: 20 teleosts, 4 crustaceans and 2 cephalopods. Based on the Index of Relative Importance (IRI) the main prey species were Cynoscion guatucupa, Micropogonias furnieri, Loligo sanpaulensis and Urophycis brasiliensis. Estuarine franciscanas preyed mainly on Micropogonias furnieri (dominant species), Cynoscion guatucupa, Odonthestes argentinensis and Macrodon ancylodon, while dolphins from marine areas preyed mainly on Cynoscion guatucupa (dominant species), Loligo sanpaulensis and Urophycis brasiliensis. Our results confirm that franciscanas prey mainly on juvenile fish (< 8cm) and small loliginid squids, in close agreement with previous results obtained in southern Brazil and Uruguay. Qualitative and quantitative differences observed in the diet of dolphins from each habitat emphasise the need to discriminate between samples from different habitats and environmental parameters. SPANISH: Se analizaron 110 contenidos estomacales de franciscanas (Pontoporia blainvillei) provenientes de la costa norte de Argentina, para extender en conocimiento sobre su dieta y caracterizar la lactancia. Las muestras incluyeron cachorros, juveniles y adultos de ambos sexos. Las primeras etapas de predación se inician a muy temprana edad (2,5-3 meses), presentando una dieta de transición compuesta tanto por leche como por presas sólidas, principalmente crustáceos; el destete se iniciaría a partir de abril, a una edad estimada entre 6 y 7 meses. Las franciscanas estudiadas provienen de dos habitats diferentes: un área estuarial de baja salinidad y la region marina adyacente. La dieta de Pontoporia blainvillei de Argentina estuvo compuesta por un total de 26 especies: 20 teleósteos, 4 crustáceos y 2 cefalópodos. Basados en el Indice de Importancia Relativa (IIR), las presas más importantes fueron Cynoscion guatucupa, Micropogonias furnieri, Loligo sanpaulensis y Urophycis brasiliensis. Las franciscanas provenientes del área estuarial predaron principalmente sobre Micropogonias furnieri (especie dominante), Cynoscion guatucupa, Odonthestes argentinensis y Macrodon ancylodon, mientras que los delfines marinos predaron sobre Cynoscion guatucupa (especie dominante), Loligo sanpaulensis y Urophycis brasiliensis. Nuestros resultados confirman que la franciscana preda sobre peces juveniles (< 8cm) y pequeños calamares Loliginidae, coincidiendo con resultados previos obtenidos en el sur del Brasil y Uruguay. Las diferencias cualitativas y cuantitativas observadas en la dieta de cada uno de las áreas analizadas, nos sugieren que los futuros estudios sobre ecología trófica de la franciscana deberían discriminarse de acuerdo al origen de los ejemplares y a la tipificación del ambiente.

Fish quality and processing in Malawi: responding to challenges through institutional capacity building

Fish processing and quality control in Malawi are still poorly developed. Traditional fish processing methods are widely employed resulting in considerable post-harvest losses. One of the major challenges to steady and sustainable development in fish processing and quality management is the lack of adequately trained personel. This is directly reflected in poor institutional capacity. This project analyses the situation in fish processing and quality management in Malawi to identify gaps that require improvement. Specifically, the project assesses the role of training institutions in Malawi in capacity building for fish processing and quality management. The institution under discussion in this project is the Aquaculture and Fisheries Science Department at Bunda College of Agriculture, Malawi which is responsible for training students in aquaculture and fisheries science at the undergraduate level.Improvement in the teaching of fish processing and quality management in the Department of Aquaculture and Fisheries Science was identified as the major gap requiring action. The current teaching syllabus was thus analysed to identify weak areas. In conclusion, the project developed (as the major output) a teaching handbook for the Department of Aquaculture and Fisheries Science.

Ecologia funcional de duas comunidades de peixes de riacho: a importância da variação intraespecífica e interespecífica em diferentes atributos ecológicos

A compreensão sobre a estrutura e funcionamento das comunidades biológicas é uma das principais questões das teorias ecológicas e principalmente no contexto de diversidade funcional, já que os atributos das espécies influenciam fortemente a distribuição e o papel que os organismos desempenham nos ecossistemas. Neste trabalho, tivemos como objetivo avaliar a variabilidade intraespecífica e interespecífica dos atributos ecológicos em duas assembleias de peixes localizadas em riachos sujeitos a diferentes condições físicas. A variação na utilização dos recursos, seja entre indivíduos e/ou entre espécies pode nos ajudar a compreender as interações bióticas e a estrutura das populações e comunidades de peixes. Os atributos referentes a morfologia, dieta, uso do habitat e alguns aspectos comportamentais foram avaliados e suas variações foram testadas a partir dos valores individuais. As coletas foram realizadas em dois riachos tropicais, sendo um localizado no ambiente da Mata Atlântica e o outro, no ambiente do semiárido brasileiro. Além das análises empíricas, uma revisão bibliográfica sobre o tema e uma possível composição funcional dos grupos de peixes de riacho foram descritas no capítulo 1 da presente tese. Nos capítulos 2 e 3, foram testadas as hipóteses de que existe alta variabilidade intraespecífica em relação aos atributos ecológicos dos peixes e que esta variabilidade é influenciada pela alta disponibilidade de recursos, enquanto no capítulo 4, a variação entre os indivíduos foi testada em relação a aspectos comportamentais. Nossos resultados revelaram que, de fato, a variação intraespecífica foi alta em ambas as assembleias, porém na assembleia do semiárido, esta variabilidade foi maior. Este resultado pode estar relacionado a alta disponibilidade de recursos espaciais encontrada nesta localidade. A morfologia e a dieta apresentaram correlação significativa, porém foi fraca em ambas as assembleias, demonstrando assim a importância de mensurar esses dois aspectos da biodiversidade dos peixes. Os resultados relacionados ao uso do habitat também apresentaram alta variabilidade entre os indivíduos e entre as espécies nos dois riachos em estudo. A assembleia do semiárido apresentou maior variabilidade física com potenciais microambientes formados por bancos de macrófitas a serem explorados pelos organismos, permitindo assim, o uso diferenciado e a escolha individual por diferentes recursos espaciais. A variabilidade individual também foi encontrada no comportamento social de duas espécies desta assembleia, onde houve formação de cardumes compostos por indivíduos maiores nas extremidades com maior capacidade de fuga na relação presa-predador. Neste sentido, a alta variação intraespecífica para diversos aspectos funcionais avaliados neste trabalho evidencia ainda mais a importância de mensurar as características ecológicas dos peixes a partir de valores individuais. Adicionalmente, a partir desta ferramenta, podemos compreender melhor a complementaridade da especialização e originalidade ecológica dos indivíduos e finalmente, sugerir de que forma os atributos funcionais dos organismos influenciam a estrutura das populações e comunidades de peixes de riachos tropicais

Choosing the best model in the presence of zero trade: a fish product analysis

The purpose of the paper is to test the hypothesis that food safety (chemical) standards act as barriers to international seafood imports. We use zero-accounting gravity models to test the hypothesis that food safety (chemical) standards act as barriers to international seafood imports. The chemical standards on which we focus include chloramphenicol required performance limit, oxytetracycline maximum residue limit, fluoro-quinolones maximum residue limit, and dichlorodiphenyltrichloroethane (DDT) pesticide residue limit. The study focuses on the three most important seafood markets: the European Union’s 15 members, Japan, and North America.

Considerations about effective dissemination of improved fish strains

Aquaculture production systems in developing countries are largely based on the use of unimproved species and strains. As knowledge and experience are accumulated in relation to the management, feeding and animal health issues of such production systems, the availability of genetically more productive stock becomes imperative in order to more effectively use resources. For instance, there is little point in providing ideal water conditions and optimum feed quality to fish that do not have the potential to grow faster and to be harvested on time, providing a product of the desired quality. Refinements in the production system and improvement of the stock used must progress hand in hand. In this paper we deal separately with genetic and non-genetic issues pertaining to the multiplication and dissemination of improved strains. The separation is somewhat arbitrary, and as will be evident from our discussion, there is frequent interaction between the two.