Aspects of the Distribution and Ecology of the Myctophidae from the Western and Northern Arabian Sea

Jakob Gjøsæter

Aspects of the Distribution and Ecology of the Myctophidae from the Western and Northern Arabian Sea

Pelagic Fish Assessment Survey North Arabian Sea

Year of publication 1977

Place of publication Rome, Italy ;

Author Jakob Gjøsæter

Publisher Institute of Marine Research, Bergen ;

Product type Project

Edition 1

Full item page

Synopsis (short abstract) The mesopelagic fauna of the western and northern Arabian Sea between Mogadisco and the Indo-Pakistanean border was studied with R/V “Dr. Fridtjof Nansen” during 1975-1976. A DSL laying in depths between about 250 and 350 m was found in the whole area. In the north-western part of the area and sometimes in the Gulf of Aden, an additional layer was found between about 100 and 200 m. Benthosema pterotum and B. fibulatum were the most abundant species in the area but Diaphus spp. were also nume rous. The Benthosema species seem to have a life cycle of one year or less. The biomass was estimated using a 38 kHz echo sounder and electronic integration technique. The area was covered five times and the estimated abundance of mesopelagic fish was 102 million tons (range 56-148 million tons). Estimates from the spring were higher than those from summer and autumn. With a 1360 mesh pelagic trawl catch rates as high as 20 tonnes/hour of trawling were reached.

Language English

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Preliminary estimates of some stock assessment parameters for the mesopelagic species Benthosoma pterotum inhabiting the Western and Northern Arabian Sea 1982

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This report provides preliminary estimates of the stock assessment parameters for Benthosoma pterotum from data collected onboard the acoustic survey vessel Dr. Nansen. The von Bertalanaffy growth estimates are K=2.0, L=5.2 cm (total length) and t =-0.09, the latter being related to assumed birthday dates of 30 April and 31 December. The constants in the power curve relationship (w = aLᵇ) of total weight (g) to total length (cm) are shown as a = 0.02, and b = 2.79. Four alternative estimates for the natural mortality coefficient M provide values of 3.6, 5, 4.8 and 4.3 for the 1975 and 1976 years. The mean numbers recruiting into the stock each half year is estimated to be 123x10¹². Recruitment is indicated as being confined to the summer to autumn and winter to spring periods, which suggests an explanation for the observed differences between biomass estimates from previous acoustic surveys; the stock numbers peak in spring and autumn from the effect of 'net' recruitment and decline to wards summer and winter from the effect of natural mortality. With the assistance of Yield per Recruit Tables, annual yields for a range of levels of exploitation and lengths at first capture are described. For example, using trawls providing a length at first capture of about 2 cm, the annual yield is maximized at about 17.5x10⁶ tones, at a fishing mortality F of almost double M. It is suggested that the most appropriate levels of future exploitation are likely to be considerably lower than in the example with the identification of the best levels requiring additional knowledge, such as concerning commercial operating costs, availability of markets etc.
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WECAFC - Nineteenth Session - Bridgetown, Barbados, 6-8 September 2023 - Review of biological data, spatial distribution of the stocks and ecological connectivity between areas beyond national jurisdiction and exclusive economic zones in the Western Central Atlantic Fishery Commission Region
WECAFC/XIX/2023/Inf.6
2023

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Review of biological data, spatial distribution of the stocks and ecological connectivity between areas beyond national jurisdiction and the exclusive economic zones in the Western Central Atlantic Fishery Commission region 2024

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This review was developed as a project in response to the needs of the Intersessional Working Group of WECAFC in its task of identifying key options and priorities. The review describes a group of selected species that are considered to be important to Member States of the WECAFC. It classifies them into transboundary and straddling/highly migratory stocks and their fisheries and provides information on the state of exploitation of the selected species. The review also considers the ecological connectivity between the high seas and the EEZs of coastal nations. Lastly, it highlights issues that need to be addressed to generate a sound scientific knowledge base in support of the strategic reorientation of the Commission.

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