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Growth and mortality parameters for Kawakawa (Euthynnusaffinis Cantor, 1849)were studied using the length frequency composition and biometry of 13716 individuals in Hormozgan province waters in 2013. Length range and mean length range of this species were obtained as 22-85 cm and 59.36 cm, respectively. ELEFFAN I method in FISAT program were used for data analyses.Growth parameters were estimated aslength infinity (L_∞) =88.2 cm, growth rate (K) =0.51 year^-1 and the age at the length 0 (t₀) =-0.23. Overall,eight cohorts were distinguished for kawakawa and maximum recruitment pattern was obtained as 14.48%in August.Total mortalityestimation was found to be Z= 1.87 year-1using catch curve.Natural and mortality coefficients were estimated using the Pauly's formula which resulted in M= 0.64 year^-1and F=1.23 year^-1, respectively.Exploitation rate (E) was calculated as 0.65 indicating that kawakawa was fully exploited in Hormozgan provincewaters.

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The objective of the present study was to determine the effects of fish aggregation device (FAD) deployment on biodiversity, catch composition and length frequency distribution in the Qeshm Island handline fishery. Two FADs were deployed in the Qeshm Island. Four biodiversity indices including Margalef, Shannon-Weaver, Simpson and Pielou and also catch composition and length frequency distribution were calculated and compared between FAD and non-FAD area among spring and fall seasons. Comparing catch composition between FAD and non-FAD area by simper analysis showed that Scomberoides commersonnianus, Acanthopagrus latus, Scomberomorus commerson, Argyrops spinifer, Nemipterus japonicas and Caranx sexfasciatus were responsible for 78.03 dissimilarity. However, Comparing catch composition between spring and fall seasons indicate that A. spinifer, C. sexfasciatus, Netuma thalassina, S. commerson N, japonicas and Pomadasys kaakan were responsible for 82.77 dissimilarity. Length frequency distribution of all species (except P. kaakan) was differed significantly between FAD and non-FAD area (P<0.05). All of the biodiversity indices were lower significantly around the FAD area (P<0.05). But no significant difference was found in biodiversity indices between spring and fall seasons (P>0.05). In other mean, limited species comprise the catch dominantly. Quantifying biodiversity on the basis of diversity indices is essential both for sustainable development policies and for addressing ecological issues, such as the relationship between biodiversity and ecosystem functions.
 

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The purpose of this research was to investigate the catch composition and length frequency of S. putnamae using Four meshe sizes of 64, 83, 95 and 110 mm in gillnet in the February (winter) and June (Summer) 2022, in the coastal waters of Sistan and Baluchistan province. In the Sampling period, 22 species were caught, in the summer season, the highest catch rate was 33.04% for the S. putnamae and P. pelagicus was the least caught with 0.37% , and in the winter season, S. putnamae was the most caught with 35.68% and T. croaker the lowest catch rate of 0.31%. Also, The rate of by-catch was 17.10%, A. thalassinus the highest percentage of by-catch. The highest length frequency with 52.8% for 83 mm mesh size in the summer and the highest length with 57.2% for 95 mm mesh size obtained in winter. the comparison of the length frequency of S. putnamae caught by different mesh sizes in summer and winter season and the average length of S. putnamae in the different mesh sizes showed that there is a significant difference between them. Also, the comparison between the mesh sizes showed that the 83 mm mesh size in summer and the 95 mm mesh size in winter had a significant difference with the size of other and similar mesh size in other seasons. The results showed that more fish were Snagged in smaller mesh size and more fish were Gilled in larger mesh size.