Materials and methods for tagging purse seine and baitboat caught tunas

ENGLISH: The percentages of return of purse seine-tagged yellowfin and baitboat- tagged yellowfin and skipjack subjected to various combinations of treatments were tested statistically to determine the effects of the treatments. For yellowfin the precentages of return differed among sets or dates of release, and were higher for double-tagged fish, larger fish, and fish released soonest during each set. For skipjack the percentages of return differed among dates of release, and were higher for single-tagged fish and fish tagged in plastic-covered cradles. SPANISH: Los porcentajes de retorno de aleta amarilla marcado en barcos cerqueros y los de aleta amarilla y barrilete marcados en los de carnada sometidos a varias combinaciones de tratamientos fueron probados estadísticamente para determinar los efectos de los tratamientos. Con respecto al aleta amarilla los porcentajes de retorno fueron diferentes entre los lances o fechas de liberación, y fueron más altos para los peces con doble marca, peces de más talla y peces liberados lo más pronto durante cada lance. Los porcentajes de retorno del barrilete fueron diferentes entre las fechas de liberación, y fueron más altos para peces con una sola marca y peces marcados en cunas cubiertas con plástico. (PDF contains 41 pages.)

The BACOMA cod-end. History and recent developments in BACOMA cod-end regulations and a proposal for abetter specification of the BACOMA cod-end for Baltic Sea cod fishery

To improve the cod stocks in the Baltic Sea, a number of regulations have recently been established by the International Baltic Sea Fisheries Commission (IBSFC) and the European Commission. According to these, fishermen are obliged to use nets with escape windows (BACOMA nets) with a mesh size of the escape window of 120 mm until end of September 2003. These nets however, retain only fish much larger than the legal minimum landing size would al-low. Due to the present stock structure only few of such large fish are however existent. As a consequence fishermen use a legal alternative net. This is a conventional trawl with a cod-end of 130 mm diamond-shaped meshes (IBSFC-rules of 1st April 2002), to be increased to 140 mm on 1st September 2003, according to the mentioned IBSFC-rule. Due legal alterations of the net by the fishermen (e.g. use of extra stiff net material) these nets have acquired extremely low selective properties, i. e. they catch very small fish and produce great amounts of discards. Due to the increase of the minimum landing size from 35 to 38 cm for cod in the Baltic, the amount of discards has even increased since the beginning of 2003. Experiments have now been carried out with the BACOMAnet on German and Swedish commercial and research vessels since arguments were brought forward that the BACOMA net was not yet sufficiently tested on commercial vessels. The results of all experiments conducted so far, are compiled and evaluated here. As a result of the Swedish, Danish and German initiative and research the European Commission reacted upon this in June 2003 and rejected the increase of the diamond-meshed non-BACOMA net from 130 mm to 140mm in September 2003. To protect the cod stocks in the Baltic Sea more effectively the use of traditional diamond meshed cod-ends with-out escape window are prohibited in community waters without derogation, becoming effective 1st of September 2003. To enable more effective and simplified control of the bottom trawl fishery in the Baltic Sea the principle of a ”One-Net-Rule“ is enforced. This is going to be the BACOMA net, with the meshes of the escape window being 110 mm for the time being. The description of the BACOMA net as given in the IBSFC-rules no.10 (revision of the 28th session, Berlin 2002) concentrates on the cod-end and the escape window but only to a less extent on the design and mesh-composition of the remaining parts of the net, such as belly and funnel and many details. Thus, the present description is not complete and leaves, according to fishermen, ample opportunity for manipulation. An initiative has been started in Germany with joint effort from scientists and the fishery to better describe the entire net and to produce a proposal for a more comprehensive description, leaving less space for manipulation. A proposal in this direction is given here and shall be seen as a starting point for a discussion and development towards an internationally uniform net, which is agreed amongst the fishery, scientists and politicians. The Baltic Sea fishery is invited to comment on this proposal, and recommendations for further improvement and specifications are welcomed. Once the design is agreed by the Baltic Fishermen Association, it shall be proposed to the IBSFC and European Commission via the Baltic Fishermen Association.

A 30-Year History of Tide and Current Measurements in Elkhorn Slough, California

Elkhorn Slough was first exposed to direct tidal forcing from the waters of Monterey Bay with the construction of Moss Landing Harbor in 1946. Elkhorn Slough is located mid-way between Santa Cruz and Monterey close to the head of Monterey Submarine Canyon. It follows a 10 km circuitous path inland from its entrance at Moss Landing Harbor. Today, Elkhorn Slough is a habitat and sanctuary for a wide variety of marine mammals, fish, and seabirds. The Slough also serves as a sink and pathway for various nutrients and pollutants. These attributes are directly or indirectly affected by its circulation and physical properties. Currents, tides and physical properties of Elkhorn Slough have been observed on an irregular basis since 1970. Based on these observations, the physical characteristics of Elkhorn Slough are examined and summarized. Elkhorn Slough is an ebb-dominated estuary and, as a result, the rise and fall of the tides is asymmetric. The fact that lower low water always follows higher high water and the tidal asymmetry produces ebb currents that are stronger than flooding currents. The presence of extensive mud flats and Salicornia marsh contribute to tidal distortion. Tidal distortion also produces several shallow water constituents including the M3, M4, and M6 overtides and the 2MK3 and MK3 compound tides. Tidal elevations and currents are approximately in quadrature; thus, the tides in Elkhorn Slough have some of the characters of a standing wave system. The temperature and salinity of lower Elkhorn Slough waters reflect, to a large extent, the influence of Monterey Bay waters, whereas the temperature and salinity of the waters of the upper Slough (>5 km from the mouth) are more sensitive to local processes. During the summer, temperature and salinity are higher in the upper slough due to local heating and evaporation. Maximum tidal currents in Elkhorn Slough have increased from approximately 75 to 120 cm/s over the past 30 years. This increase in current speed is primarily due to the change in tidal prism which has increased from approximately 2.5 to 6.2 x 106 m3 between 1956 and 1993. The increase in tidal prism is the result of both 3 rapid man-made changes to the Slough, and the continuing process of tidal erosion. Because of the increase in the tidal prism, the currents in Elkhorn Slough exhibit positive feedback, a process with uncertain consequences. [PDF contains 55 pages]

A review of the Japanese longline fishery for tunas and billfishes in the Eastern Pacific Ocean, 1967-1970

ENGLISH: This report deals with the Japanese longline fishery for tunas and billfishes from 1967 through 1970, extending the studies made by Kume and Joseph (1969a, 1969b). The distribution of effort and catch is discussed and evaluated, and the changes in apparent abundance are examined. An analysis is made of the sexual maturity and size composition of the fish, and a brief comparison of the size composition of the catches from the longline and the surface fisheries is included. SPANISH: Este informe analiza la pesca palangrera japonesa de atunes y peces espada desde 1967 a 1970, ampliando los estudios hechos por Kume y Joseph (1969a, 1969b). Se discute y avalúa la distribución del esfuerzo y la captura, y los cambios en la abundancia aparente. Se hace un análisis de la madurez sexual y de la composición de talla de los peces y una breve comparación entre la composición de talla de los peces capturados en la pesca palangrera y la epípelágíca. (PDF contains 166 pages.)

Strategies for increasing freshwater fish production in the Green Revolution Programme

Sources of fish and fishery products in Nigeria were reviewed. The problems of various agencies involved in freshwater fish production in Nigeria were also analysed, such problems included shortage of manpower, inadequate training for personnel, shortage of funds, lack of infrastructures, among others

Improved utilization and increased availability of fishery products as an effective control of aggravated animal protein deficiency - induced malnutrition in Nigeria

The estimated potential of Nigerian fish resources is 1,830,994 tonnes(t) whereas the demand based on per capita consumption of 12.0kg and a population of 88.5 million is 1.085 million tonnes. Supply is presently less than 500,000 tons. The gap between demand and supply have to be met through improved utilization and increased availability of fish and fishery products. The role of fish in nutrition is recognized, since it supplies a good balance of protein, vitamins and minerals and a relatively low caloric content. This paper appraises the consumption and utilisation pattern of fish in Nigeria, the spoilage of fish and prevention of losses as a means of increasing the availability of fish for human consumption and consequent control of aggravated animal protein deficiency - induced malnutrition. The paper further highlights the point that without increased landings, increased supply of fish can be achieved through reduction of postharvest loss of what is presently caught. The use of newly designed smoke - drying equipment to achieve such goal is highlighted. The paper also emphasises the need to put into human food chain those non-conventional fishery resources and by-catch of shrimp and demersal trawl fishes by conversion into high value protein products like fish cakes, fish pies and salted dried cakes

Utilization of freshwater fish species in Nigeria

The paper examines the pattern of utilization of freshwater fish species in Nigeria. It was observed that although fishermen have a preference for fresh fish sales only 30% of fresh fish captured actually get to the consumers. The rest are preserved by smoke curing (60-65%), salting and sundrying (less than 5%), deep frying and fermentation (about 1%). Constraints to fish utilization were identified which include poor infrastructure, losses of fish and fish products as a result of traditional post harvest technology and socio economic factors. The need for the development of appropriate research to solve the problems of traditional post harvest technology was emphasised

Growth responses and yield of heterotis (Heterotis niloticus) on artificial diet

The growth responses and yield of Heterotis niloticus on artificial diets of varying protein levels were studied in a bid to assess the implication of feeding Heterotis in intensive fish production venture for a rearing period of 84 days. One hundred and twenty juvenile H.niloticus were fed for 12 weeks on 28%, 31%, 34% and 37% dietary crude protein levels. The fish were reared in 4 concrete tanks stocked at the rate of 10 fish per M super(2) 100,00/hectare). Consequently, the weight gain, food conversion ratio, serum protein and albumin-globulin ratio were determined to assess the growth and state of health of the fish. The yield was appraised through economic considerations of cost of production of fish and diets (feed). The varying crude protein levels significantly influenced mean weight gain, percentage weight gain and food conversion ratio however, the 37% crude protein in diet produced the best growth. The serum protein was highest in fish raised on 31% crude protein diet while the highest value was recorded for albumin-globulin ratio on diet containing 34% crude protein. The yield from treatments 1, 2, 3, and 4 were 114.38 of/84 days 571.9kg/g hect);146.79g/84 days 733.95kg/hect), respectively. However, treatment 3 recorded the highest value for profit index

TUNPOP: A simulation of the dynamics and structure of the yellowfin tuna stock and surface fishery of the Eastern Pacific Ocean

ENGLISH: Three distinct versions of TUNP0P, an age-structured computer simulation model of the eastern Pacific yellowfin tuna, Thunnus albacores, stock and surface tuna fishery, are used to reveal mechanisms which appear to have a significant effect on the fishery dynamics. Real data on this fishery are used to make deductions on the distribution of the fish and to show how that distribution might influence events in the fishery. The most important result of the paper is that the concept of the eastern Pacific yellowfin tuna stock as a homogeneous unit is inadequate to represent the recent history of the fishery. Inferences are made on the size and distribution of the underlying stock as well as its potential yield to the surface fishery as a result of alterations in the level and distribution of the effort. SPANISH: Se han empleado tres versiones diferentes de TUNP0P, un modelo de simulación de la computadora (basado en la estructura de la edad) de la población y la pesca epipelágica del atún aleta amarilla, Tbunnus albacares, del Pacífico oriental, para revelar los mecanismos que parecen tener un efecto importante en la dinámica pesquera. Se emplean los datos verdaderos de esta pesca para hacer deducciones sobre la distribución de los peces y para mostrar cómo puede influir esta distribución en los eventos de pesca. La conclusión más importante de este estudio es que el concepto de que la población del aleta amarilla del Pacífico oriental es una unidad homogénea, es inadecuado para representar la historia reciente de pesca. Se teoriza sobre la talla y distribución de la población subyacente como también sobre su producción potencial en la pesca epipelágica al cambiar el nivel y distribución del esfuerzo.

Demand for fish in Calabar, Cross River State, Nigeria

It is generally recognized from the food balance sheet prepared by experts that Nigeria is a protein deficient country. Not only is the daily intake of protein low but the contribution from animal sources is extremely low. Fish has been found to be the cheapest source of protein in Nigeria hence the consumption of fish will supply the needed protein at a relatively low cost. The study, conducted in Calabar in 1981, was analysed using stepwise ordinary least square multiple regression technique as well as Pearson correlation analysis. The regression result was used to generate some demand curves for different levels of per capital income, as well as own price elasticity of demand. The results show that both own price elasticity of demand for fresh and frozen fish decreased as the level of per capital income increased while income elasticity of demand increased as per capital income increased. The calculated per capital consumption was found to be 5.18 kilograms and 4.31 kg per annum for fresh fish and frozen fish respectively. This is considered rather small since Calabar is a sea port where fish should be more readily available. The values of own price and income elasticities indicate that more fish will be consumed at every increase in income if both production and marketing are improved

Herbicidan control of water hyacinth at Ere, Ogun State: implications for fish production

A brief account is given of a pilot demonstration of the chemical control of water hyacinth (Eichhornia crassipes) at Ere (a channel) in Nigeria using the herbicide glyphosphate. Results suggest that there was an increase in the nutrient content of the channel after herbicide application. This implied an upsurge of available food for fish and other aquatic organisms within the channel after the herbicide application. The decaying water hyacinth mass which sinks into the medium is likely to boost nutrient content, promoting the growth of fish and other aquatic animals. It is concluded that herbicidal control of water hyacinth is possible, especially under specialists' management with the conservation of fish and other non-target aquatic organisms alongside improved fish production

Northwest Fish Culture Conference, Eugene, Oregon, December 2-4, 1986 [proceedings of the 37th conference]

(PDF contains 226 pages)

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic): Alewife/Blueback Herring

This profile covers life history and environmental requirements of both alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis), since their distribution is overlapping and their morphology, ecological role, and environmental requirements are similar. The alewife is an anadromous species found in riverine, estuarine, and Atlantic coastal habitats, depending on life cycle stage, from Newfoundland (Winters et al. 1973) to Soutn Carolina (Berry 1964). Landlocked populations are i n the Great Lakes, Finger Lakes, and many other freshwater lakes (Bigelow and Sch roeder 1953; Scott and Crossman 1973). The blueback herring is an anadromous species found in riverine, estuarine, and Atlantic coastal habitats, depending on life stage cycle, from Nova Scotia to the St. Johns River, Florida (Hildebrand 1963)