بررسي پويايي جمعيت و ارزيابي ذخيره ماهي صبور (Tenualosa ilisha) در سواحل استان خوزستان

Population dynamics and stock assessment of Hilsa Shad, Tenalosa ilisha in Khuzestan province coast

پويايي جمعيت و ارزيابي ذخيره ماهي صبور (Tenualosa ilisha) با جمع آوري اطلاعات از منطقه تخليه صيد در سواحل استان خوزستان (آبادان) تخمين زده شد. دراين پروژه يك‌ساله (از فروردين تا اسفند سال 1386) در مجموع بيش از 9000 ماهي در ايستگاه مذبور، بيومتري شد. طول بي‌نهايت 81/42=L? (سانتي‌متر)، ضريب رشد (year-1) 9/0=K، زمان طول صفر 25/0-to=، ميزان فايم پريم مونرو 21/3= ʹ?، مرگ و مير طبيعي ( (year-137/1= M، مرگ و مير صيادي (year-1) 41/2=F، مرگ و مير كل (year-1) 78/3=Z و ضريب بهره‌برداري (year-1) 64/0 E= محاسبه شد. محاسبه‌هاي كلي نرخ بهره‌برداري 61/0U=، ميزان كل سالانه ذخيره در شروع سال برحسب تن 7615P=، ميانگين سالانه ذخيره سرپا برحسب تن 1927 B=و ميزان حداكثر محصول پايدار برحسب تن 3642MSY= براي ذخيره ماهي صبور برآورد گرديد. اين تحقيق نشان مي‌دهد كه ميزان برداشت سالانه از ذخيره ماهي صبور به بيش از حداكثر ميزان خود رسيده و جهت كاهش ميزان صيد و تلاش صيادي بايد تدابيري انديشيده شود.

The present study was carried out the population dynamics and stock assessment of Hilsa Shad in costal of the Khuzestan province (including Abadan) using the commercial catch data. Totally, more than 9000 specimen of Hilsa Shad were measured during 2007-2008. Population parameters were estimated using FiSAT software program. The growth parameters of von Bertalanffy equation were estimated as: L?: 42.81 and K: 0.9 and t0: -0.25. Mortality coefficients such as total mortality (i.e. Z: 3.78) and natural mortality (i.e. M: 1.37) and fishing mortality (i.e.F:2.41) were estimated. Exploitation ratio, E, was estimated to be 0.64 and these high values of E showed that the Hilsa Shad stock in the region is overexploited. Exploitation rate was estimated 0.61 and Annual total stock at the beginning of the year and the annual average standing stock and MSY were estimated 7615 ton, 1927 ton, 3642 ton respectively. The result of the study showed exploitation ratio of the Hilsa Shad stock (is reaching to the max and in order to decrease it, a serious tact should be thought.