Studies on Population Characteristics of Frigate tuna, Auxis thazard (Lacepede,1800) Occurring in the North West Coast of India

This study is an attempt to understand the population characteristics such as Length-weight relationships, age, growth, mortality, length at age and exploitation rate of Frigate tuna, Auxis thazard occurring in the North west coast of India. The data collected from various fish landing centers from 2008 to 2012 were considered for this study. The mean fork length and weight 32.35 cm and 1.040 kg were observed respectively. The length-weight relationship W=2.4321x10 FL 2.27658, and r 0.9576 was obtained. The value of ‘b’ found to be less than 3 and hence this species was shown negative allometric growth. The growth parameters on von Bertalanffy for L∞ estimated as 47.03, K was 1.30 and to was -0.23. The Phi-prime value (⏀) of 3.33 was derived. The length at age observed at the end of 1 to 4 years was 27.0, 42.0, 50.0 and 55.0 cm year respectively. The natural mortality (M) 1.00 year, total mortality (Z) of 4.43 year and fishing mortality (F) 3.43 year were derived with the mean temperature of 27°C. The exploitation ratio (E) and exploitation rate (U) was 0.77. The results derived in the present study with regard to population characteristics of frigate tuna in the coastal waters of North west coast of India indicate catching of this species in the area to be minimized Key-wordsExploitation ratio, Exploitation rate, Length-weight relationships, Length at age, Mortality INTRODUCTION Among the neritic tunas occurring in the Indian waters, under the genus Auxis, two species viz., Auxis thazard and Auxis rochei are contributing to the marine fish landings to the tune of 13,418 tonnes during 2016 . An increase of 64% of these species landings has been observed when compared to 2015 (8,176 t). Determinations of population characteristics are vital for understanding changing trends in the marine fish production and also to evaluate the level of exploitation. The effective fisheries management depends on the fish catch data, biological information and population characteristics etc. As per the literature, the developed countries in the world observed to conduct regular stock assessments for the major commercial fisheries, thereby, the resources are better managed. Commendable works on this species have been attempted by various researchers from the Philippines waters, Indonesia, Taiwan, Sri Lanka, and Thailand. Access this article online Quick Response Code Website: