Abstract
This study was conducted in Mousa bay area. Mousa bay is a large estuary was located in north of Persian Gulf (West south of Iran). Sampling was monthly from September 2009 to August 2010. Fish were catch by using gill net (Mesh size 20 mm). Total Weight, gonad weight and total length were measured. Gonads stages were determined. Gonadosomatic index and lm50 were calculated. On the results of this study lowest GSI were recorded in October 2009 and August and September 2010. The minimum size of fish was 16.4 cm and the mean size at first sexual maturity (Lm50 %) was 16.6 Cm.
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Keywords- Female maturity, Liza macrolepis, Lm50, Mousa bay, Persian Gulf.
Introduction
The grey mullet Liza macrolepis (Smith) is one of the important food fishes of India and contributes substantially to the mullet fishery in certain areas. Individual fish seems to spawn only once in a season, the spawning period extending from June to February with a peak during July and August (Luther, 1963). Liza macrolepis (Smith) forms a significant component of moderate economic importance in the Mousa bay area. The grey mullets have been described as plankton feeders, herbivores, omnivores, slime feeders, foul feeders, bottom feeders, etc. Despite the extensive records on the subject, in this group of fishes, there are very few accounts based on studies for an extended period of time in respect of different size-groups from different environs (Khodadadir, 1998).
The aims of this study was to determine some reproductive characteristics such as egg number, sex ratio, gonadal development; gonad somatic index (GSI), total weight (Wt) - fecundity (F), and total length (Lt) - fecundity (F), and the microscopic study of gonads of Liza macrolepis in Musa bay in south west of Iran. In this article we present some parts of that study.
Materials and Methods
Mousa bay is a large estuary (134 km2) in west north of Persian Gulf (in Iran south)(fig:1). Mousa bay occurred between 49, 00 to 49, 20 east longitudes and 30, 15 to 30, 32 north latitudes (Khodadadi, 1998).
Sampling was monthly from November 2009 to October 2010. Fish were catch by using gill net (Mesh size 20 mm) (samples were unavilable in May). Lengths were taken using a measuring board and recorded to the nearest 1 cm total length (TL) with monthly target sample size of 100 fish. Whole wet weight was taken with an electronic balance and recorded to the nearest 0.01 grams. Gonad stage determined according 6 stages procedure (Biswass, 1993).
The Gonadosomatic index of each individual of L. macrolepis was calculated from (Biswass, 1993).
Minimum and maximum of average water temperature were 15.3±0.5 ◦C at December and November and 31.3±0.96 ◦C at July. Annually average of water temperature was 23.7±0.72 ◦C. The mean GSI from examined females showed seasonal differences during the study period (α=0.05) Fig.3). The lowest GSI were recorded in October 2009 and August and September 2010 (not significant deference); these values then increased in November, peaked in March 2010 and then dropped sharply in July 2010. The minimum size of fish was 16.4 cm and the mean size at first sexual maturity (Lm50 %) was 16.6 Cm. More than 50 percent of all class lengnt of fish were mature. Actualy we wasn't need to calculte pridect of L50. Frequncies of maturity in different months. According the results of present study in October maturity of females gonads began and cotinued to April. Fishes spowoned in may and July.
Discution
Gonads of females in July periods were in the relaxing position. The present research showed a long reproductive time period for L. macrolepis of approx. 7 months (November -May) with a clear peak in April, based on GSI, macroscopic observation. The L. macrolepis gonads began to develop in September, when the water temperature began to decrease (25.1 ◦C), and the GSI increased rapidly to .76 ±.13 in December (water temp. ◦15.3), and was maximal at 7.8±1.05 in April when water temperature became 27.1 ◦C. Gsi peak of L. macrolepis in April same the results of reference (Erdinc et al., 2011) in reproductive study of Liza abu in Attaturk dam. The peak value of GSI for female Mugil cephalus was attained in mid-August and continued to early October, and then decreased gradually from November until August (Samira et al., 2008). All reference Zaki et al., 2008, Millan., 1999, Hotos., 2000 showed ours founds isn't same to results of them on Oblada melanura; on Engraulis encrasicolus; on Liza aurata respectively. Reference (Ergene, 2000) on Liza ramada; and reference (Mcdonough, 2000) and reference (El-Gharabawy et al., 2006) on Mugil cephalus reference (Abdallah et al., 2005) on Liza klunzingeri. Of course this results is against present results. It is maybe relate to differences of ecosystem condition factors of or species differences. Whoever in present study more than of 50 percent of all the class groups of fish were mature first sexual maturity is reached at size >26 cm (TL) for all Liza aurata specimens. The smallest reproducing individuals were observed at 19.6 cm (TL) for males and 20.8 cm (TL) for females aged 3+. The mean first maturation (L50) of the golden grey mullet occurs at age 5+, 23.84 cm and 23.73 cm (TL) for males and females respectively (Ezzat , 1965). Reference (Fehri-Bedoui et al., 2005) shows that the species was mature at size 27 (age 3+) and 34 cm (age 4+) respectively for males and females in the gulf of Marseille.
References
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