بررسي تكثيرماهي هامورمعمولي(Epinephelus coioides) به روش نيمه مصنوعي دراستان خوزستان

Investigation on semi-artificial propagation of orange-spotted grouper (Epinepheluscoioides) in Khuzestan Province

ارزش اقتصادي ماهي هاموردرصنعت آبزي‏پروري وتهديدات زيست‏محيطي زيستگاه‏هاياينماهيسب بافزايش اهميت تكثيردراسارت اينگونه شده است. دراين مطالعه سعي شدهاست تابه بررسي كاراي يتكثيرنيمه‏مصنوعي ماهيهامورمعمولي دراستان خوزستان پرداخته شود. دراينخصوص، 8 مولد (4 مولدمادهو 4 مولدنر) به مركزتكثيرماهي اندري اييمنتقلشدهوپسازبيهوشي،خصوصيات مرفولوژي كنظيرطولكل،طول استانداردووز نكلبدنآن‏هااندازه‏گيري شد. بطورهمزمان،تخمك‏هاي مولدينجهتبررسيكيفيتموردبررسيقرارگرفتند. پسازذخيره‏سازيمولدينبهنسبت 1:1،تخم‏ريزيبصورتطبيعي (بدونتزريقهورمون) درشبصورتگرفت. درهرمرحلهتخم‏ريزي، 30 عددتخمنمونه‏برداريشده،سپسقطرودرصدلقاحتعيينگرديد. سايرفاكتور‏هايمرتبطباكاراييتكثيرنظيردرصدهچ،طوللاروودرصدبقالارودرزمانموردنظراندازه‏گيريشدند. نتايجبهدستآمدهنشانمي‏دهدكهمولدينيباوزنوطولبيشتردارايتخمك‏ها،تخم‏هايلقاحيافتهولارو‏هاييبااندازهبزرگترهستند (05/0 > P). دراينمطالعهدرصدلقاحودرصدهچبهترتيببهميزانحداكثر 98 و 88 درصدمحاسبهشدهاست. درصدبقالارو‏هانيزتامرحلهجذبكيسهزردهدرتماميمولديناز 20 درصدتجاوزننمود. آناليزرگرسيوننيزروابطمعني‏داربينطولكلووزنبدنباقطرتخموتخمكرانشاندادهاست. طوللارو،طولوعرضكيسهزردهوقطرگلبولچربينيزدراينمقالهموردبحثوبررسيقرارگرفتهاست

The economic value of grouper in aquaculture industry as well as existing of threatening environmental factors in their natural habitats of this fish has led to an increase in importance of captive breeding of this species. In this study, the efficacy of semi-artificial propagation of orange-spotted grouper in Khuzestan province has been investigated. In this respect, eight breeders, including four males and four females, were transferred to the Center of Marine Fish Propagation. After anesthetizing, the morphometric parameters, including total length, standard length and body weight have been recorded. Simultaneously, ova were checked for their quality. All fish were hold in ratio of 1:1 (male to female) and breeding was performed at midnight without hormonal injection. At each spawning time randomly thirty eggs were collected and egg diameters and fertilization rate have been determined. Other related parameters to breeding efficacy, including hatching rate, larvae length and larvae survival rate were measured in an appropriate time. The obtained data show that fish having higher length and weight produced more ova, eggs and larvae in size (P < 0.05). In this study, the maximum amount of fertilization and hatching rates were estimated as 98 and 88% respectively. Survival rate of larvae were also determined until yolk sac absorption time and its amount was not more than 20% in all cases. Using regression analysis, ova and egg diameters showed significant relationships between the total length and body weight. Moreover, larvae total length; total width; yolk sac length and oil globule diameter have been also measured and discussed in this manuscript.