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| Timohina, O.I.; Romanov, E.V.. |
| Based on histological analysis of gonads taken from 616 specimens of skipjack tuna (Katsuwonus pelamis) in the western part of the equatorial Indian Ocean, a thorough description of all stages of maturity and cells is given at different stages of ovogenesis. Different phases of cell development were defined for each stage, and size of cells is given. A comparison of visual and histological determinations of maturity stages is made. Fish sizes and ages at which mass maturation is observed, sex ratio and its variation for different size groups in the area studied are suggested. Mass onset of maturity (50%) is observed when females reach 43 cm and males 40 cm in length and 1.5 years of age. Assessment of portioned fecundity is given. The spawning period of... |
| Tipo: Proceedings Paper |
Palavras-chave: Sexual reproduction Oogenesis Sexual maturity ISW; West Indian Ocean Euthynnus pelamis Spawning Developmental stages. |
| Ano: 1996 |
URL: http://hdl.handle.net/1834/19 |
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| Romanov, E.V.. |
| The yield of associated and dependent species taken as bycatch by the purse seine tuna fishery from the Indian Ocean pelagic ecosystem is estimated from data collected by scientific observers aboard Soviet purse seiners in the Western Indian Ocean (WIO), 1986-1992. A total of 494 sets on free swimming schools, whale shark associated schools, whale associated schools, and log associated schools were analyzed. More than 40 fish species and other marine animals were registered. Among them only two species, yellowfin and skipjack tunas, are target species. Average levels of non-tuna bycatch equal 0.518 t per set, 27.2 t for 1,000 t of target species. By the author’s estimates, the annual catch of yellowfin and skipjack tunas in 1990-1995 of the total... |
| Tipo: Proceedings Paper |
Palavras-chave: Tuna fisheries By-catch Purse seining ISW; Indian Ocean. |
| Ano: 1998 |
URL: http://hdl.handle.net/1834/45 |
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