Nassir Niamaimandi; Javad Shabani; Abdolrasol Esmaily; Ali Mobarrezi; Gholam Moradi
Abstract
Growth parameters of cuttlefish (Sepia pharaonis) was estimated from northern Persian Gulf, (27˚ 50´ 06˝ and 30˚ 06´ 07˝N to 52˚ 02´ 56˝and 50˚ 05´ 14˝E) from October 2017 to May 2018. 100 to 150 specimens were randomly separated each time from total catch and mantel length ...
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Growth parameters of cuttlefish (Sepia pharaonis) was estimated from northern Persian Gulf, (27˚ 50´ 06˝ and 30˚ 06´ 07˝N to 52˚ 02´ 56˝and 50˚ 05´ 14˝E) from October 2017 to May 2018. 100 to 150 specimens were randomly separated each time from total catch and mantel length and body weight were measured by sexes. Based on the Von-Bertalanffy growth formula in males, growth parameters were estimated with K=0.3 year-1 and L∞=37 cm. In females, growth coefficient, K and asymptotic length, L∞ were estimated 0.5 year−1 and 30 cm respectively. Maximum of fishing effort was observed in November 1.08±0.71 kg per trap and minimum was 0.06±0.02 kg per trap in May. Maximum catch per trap was 0.65±0.56 kg in 21-30 m depths and minimum was 0.10±0.05 kg in 41-50 m depths. Low growth coefficients in males and females show that this species reached to maximum growth during presence in the study area. Also, its aggregation in the depths of 30-21 m indicates the accumulation of mature spawning specimens in the area, which needs serious protection.
Nassir Niamaimandi; Tooraj Valinassab; Reza Dehghani; Reza Daryanabard
Abstract
Abstract Biodiversity indices and abundance of demersal resources in Hormozgan waters (53 00E to 57 00E) was studied by bottom trawl survey during winter season, 2013. Sampling was done by R/V Ferdos 1. In this study, 89 stations within the 10-20 m, 20-30 m and 30-50 m depth layers were sampled and abundance ...
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Abstract Biodiversity indices and abundance of demersal resources in Hormozgan waters (53 00E to 57 00E) was studied by bottom trawl survey during winter season, 2013. Sampling was done by R/V Ferdos 1. In this study, 89 stations within the 10-20 m, 20-30 m and 30-50 m depth layers were sampled and abundance and species diversity of demersal fish communities at different depths were evaluated using various indices. In this study 99 taxa communities were identified including 88 fish species and 13 species or species groups that belonged to the other marine organisms such as crabs, sea cucumbers, sea snakes, jelly fish and corals. The value for the Shannon (H́) index for the entire investigated area (10-50 m depths) were 3.21, Simpson (D), 0.06, Pielou (J), 0.69, Margalef (R), 7.55 and Menhinick (IMen), were 0.16. The value indices in different depths of 10-20 m, 20-30 m and 30-50 m were identical. Based on the results of Shannon and Simpson indices, this area has a fair quality of population in number of species, however species richness indices indicated low species richness and due to high water temperature and salinity degree, this area is under stress.
Nassir Niamaimandi; Azizollah Mahdevi
Volume 7, Issue 1 , September 2018, , Pages 45-53
Abstract
Abstract In the Persian Gulf waters, the sciaenid species, Otolithes ruber, plays an important role in the commercial fishery and to this reason, the resources are under catch pressure. Stock assessment and population dynamics parameters of this species were studied in Bushehr and Khozestan waters from ...
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Abstract In the Persian Gulf waters, the sciaenid species, Otolithes ruber, plays an important role in the commercial fishery and to this reason, the resources are under catch pressure. Stock assessment and population dynamics parameters of this species were studied in Bushehr and Khozestan waters from April 2012 to March 2013. In the present study, 4203 of specimens obtained from gillnet landing places and length frequency data (fork length) were recorded. Length frequency ranging from 11 to 50 cm. The parameters of the von Bertalanffy growth equation (males and females combined) for asymptotic length (L∞) was 52.5 cm and instantaneous growth coefficient (K) was 1.1 year−1. The instantaneous rates of total mortality (Z), fishing mortality (F) and natural mortality (M) were 3.42, 1.85 and 1.57 per year, respectively. Estimated parameters of precautionary target (Fopt) and limit (Flimit) biological reference points were 0.79 and 1.04 respectively. The values of two parameters Fopt and Flimit were lower than fishing mortality (F) that showed this species is over exploited in the Bushehr and Khozestan waters by gillnet fishery.
