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DocumentSummary report on cruise of the R/V Shoyo Maru in the north Arabian Sea, 2 October 1976 - 13 January 1977 1977
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No results found.At the Fifth session of the IOFC Executive Committee held in Rome in April 1976, the Indian Ocean Programme reported its success in bringing the R/V Shoyo Maru to the Arabian Sea and adjacent waters off India and Pakistan in November and December 1976. The present paper gives a brief description of the survey and its results, summarized from the original report in Japanese which will be published by the Fishery Agency of Japan in 1977. The activities covered oceanographic observation, convention al biological survey (sighting of pelagic shoals and collection of fishes) and acoustic survey. In spite of special attention, the squid Sympleototeuthis oualaniensis did not appear abundantly during the present cruise. The equatorial undercurrent did not exist in the equatorial waters during the transitional period, from the southwest monsoon to the northeast monsoon. Although the upwelling was recognized in the western part of the Second Area in the 1975 cruise, this was not encountered in the 1976 cruise. This might be attributed to the difference in the survey period; the first cruise in 1975 covered the late southwest monsoon season while the present cruise the early northeast monsoon season. The coastal upwelling on the continental slope was evidently less remarkable during the present cruise than during the previous one. The pelagic shoals again appeared rather scarce in the offshore waters throughout the survey period as was the previous cruise. There was a considerable number of important commercial fishes, almost the same species of the previous survey, on the Pakistani continental shelf, but none of them appeared to be large enough to attract a large-scale operation. In the present survey, the squids were not caught as often as in the previous survey. The index of echo abundance in the Second Area in 1976 was half of that in 1975. Since the duration of our cruise was very limited, it was difficult to find any reasoning for such year-to-year variation. However, it might be suggested that the squids moved toward the west coast of India or the southern Arabian Peninsula, or a deeper layer during the northeast monsoon season. -
DocumentStock assessment 1971
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No results found.Information on the Indian Ocean fishery resources is not yet extensive enough to permit estimates of maximum sustained yields for most species. Data are especially lacking for the coastal fisheries of scattered nature. 20 Among oceanic species, those heavily exploited are the large-sized tunas. The maximum sustained yields for the longline fishery are estimated to be 107,000 to 128,000 tons. The billfish catch is now reportedly around 10,000 tons by longline (Table 2). Untouched oceanic species are the small tunas and sharks at the fourth trophic level, and saury, squids, and other small shoaling pelagic forms of the third trophic level. The skipjack is the most promising species for future exploitation, estimated to provide a catch of 200,000 to 400,000 tons. Further surveys inclusive of larva collection and acoustic and experimental fishing will present more reliable estimates of the pelagic potentials. It is also possible to develop demersal fisheries on offshore banks, supposed to sustain three million tons of catch, after intensive exploratory operation. Present coastal fisheries are not intensive, except those for prawns and other valuable Crustacea (Table 17). This makes it difficult to determine levels of the maximum sustained yields or of the potential yields. Estimated potential yields, three to eight million tons in the western Indian Ocean and three to five million tons in the eastern Indian Ocean, a.re far larger than the present catches, which are about one mil lion tons in each of the two parts of the ocean (Table 18). What is needed in order to obtain more appropriate measures of the maximum sustained yields and potential yields are the collection of catch statistics and information on distribution, etc., by exploratory fishing outside the traditional fishing grounds. Prawns, especially Penaeus followed by Metapenaeus, are exploited by mechanized trawlers together with traditional gear. Heavy exploitation has already been known, at least, in the Gulf between Iran and the Arabian Peninsula, in the waters around Karachi, West Pakistan; off Kerala State in India, and in Shark Bay, Australia (Table 19). Shrimp fisheries are developing in other parts of the Indian Ocean, such as Tanzania, Madagascar, Indonesia, and Western Australia. It is urgent to collect and analyse the catch statistics and other biological information. In addition, the limited distribution of prawns in inshore waters often causes overcrowding of commercial boats therein, res ulting in intensive fishing of other fish stocks in these areas, some of which are discarded at sea, thus resulting in the waste of living resources. It is essential to prepare catch statistics and other scientific information so as to assist the industry. -
ProjectAcoustic biomass estimates of pelagic forage species in the offshore waters of the Lesser Antilles
Scientific Basis for Ecosystem-Based Management in the Lesser Antilles Including Interactions with Marine Mammals and Other Top Predators (LAPE)
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No results found.A recently completed survey of the Lesser Antilles pelagic ecosystem used a combination of multi-frequency acoustics and pelagic trawling to locate and estimate the biomass of forage species. Stratified zig-zag transects were used to investigate an area of 610 000 km2 in the waters east and west of the Lesser Antilles from Antigua to Trinidad. Distinct pelagic layers and aggregations observed acoustically were sampled using a multiple (3) codend pelagic trawl. Pelagic organisms were identified to the lowest taxon possible and categorized by the presence or absence of a swim bladder. The acoustic data were grouped into nine broad categories based on the multi-frequency returns considering backscattering strength, aggregation appearance, depth and time of day. The resulting acoustic density was converted to indicative biomass density (kg/m2) by application of target strength estimates from published sources. Relative abundance and composition of the nine acousti c categories for the 18 and 38 kHz frequencies are presented. The spatial distribution of these broad categories displayed several distinct patterns. There was an inshore-offshore segregation of some groups throughout the survey area, but there was little sign of latitudinal gradients in distribution of these broad groupings. In the open pelagic waters, diel vertical migrations were observed by several identifiable acoustic categories, particularly mesopelagic fish (largely Myctoph ormes and Stomiiformes), and squids. Dusk and dawn vertical excursions were observed daily between depths from 500 m to less than 100 m.
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