Growth parameters, Mortality and exploitation ratio of Euthynnus affinis (Cantor, 1849) in Hormozgan Province Waters

Euthynnus affinis is one of the most commericial tuna species in Northern of the Persian Gulf and Oman Sea. In order to come up with the responsible fishing pattern, there was a need to identify some of characteristics and population dynamic parameters. Data were collected randomly from three major artisanal fish-landing sites Bandar Jask, Bandar Abbas and Bandar Lengeh in Hormozgan Province, from April 2015 to March 2015. The average of fork length estimated 60.1 cm. The "a" and "b" parameters in Length- Weight relationship were estimated 2.84 and 0.0000212 respectively and showed that E.affinis has allometric growth. The growth parameters of L∞, K and t0 were computed 90.9 (cm), 0.78 (1/year) and -0.15 year respectively. The fork length attained at the end of 1, 2 and 3 year to be 53.8, 73.9 and 83.1 cm respectively. Growth performance index caculated 8.77 which was in agreement with the finding of the other studies. Total mortality, natural mortality and fishing mortality were estimated 2.49, 0.85 and 1.64 (1/year) respectively. The Fopt and Flimit as biological reference point were calculated 0.43 and 0.56 (1/year) respectively. The exploitation ratio was estimated 0.66. The results showed overfishing on E.affinis stocks in Hormozgan Province and it is necessary to reduce activity for fishing management.