Study of some biological characteristics of golden grey mullet (Liza aurata) in Iranian Coastal waters of the Caspian Sea

During last 65 years the catch of mullets had increasing trends with some fluctuations in the Iranian coastal water of the Caspian Sea .In this period about 138 thousand tons of mullets have been caught. Mullet’s account for 35% of total catch annually .In recent years species composition of mullets has chanched in the Iranian coastal water of the Caspian Sea and catch composition of golden grey mullet increased from 76% in 1995 to 98% in 2006. In this survey some biological characteristics of golden grey mullet have been studied in Iranian coastal water of the Caspian Sea .Fish samples have been gathered from commercial catch of beach seine cooperatives monthly in Iranian coastal water of the Caspian Sea over 2006 and 2007. In the laboratory fishes have been measured biometrically and biological parameters have been calculated .Also catch statistics of mullets during 2006-2007 have been obtained and discussed. Results showed that the catch of mullets in beach seine cooperatives during 2006 and 2007 was 4181 and 3685 tons respectively that golden grey mullet contribute 99% and 98% of the catch composition of mullets respectively. Length range of golden grey mullet caught by beach seine cooperatives was 19-50.2 cm with mean length of 32.7 ± 6.4 (± SD) and weight range was 67-1475 gr with mean weight of 411 ± 255 gr. The age structure of this species was comprised 2-10 years old fish with mean age of 4.42 years old. In this survey totally the sex ratio of male:female of golden grey mullet was 356: 434 that was significant variation from equal sex ratio. Pick of the spawning in Guilan province was in October and in Mazandaran and Golestan provinces was in November. In October the proportion of spawning females declined from western area (Guilan province) towards eastern parts (Golestan province).The highest proportion of spawning females was in December in Golestan province. The highest GSI index value was observed in September and October and it was decreased in November and December and it was consistent during January till April. The mean absolute fecundity was 700881 ± 429987 eggs with minimum and maximum fecundity of 200112 and 2282862 eggs respectively. The Lm 50% for female golden grey mullet was calculated as 33.6 cm.

Iranian Fisheries Science Research Institute

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