شناسه هاي افزوده :
درويشي، صمد ، همكار طرح , حدادي مقدم، كورش ، همكار طرح , فرزانه بازقلعه، اسمعيل ، همكار طرح , پوردهقاني پيشكناري، محمد ، همكار طرح , چوبيان، فروزان ، همكار طرح , منصف شكري، مريم ، همكار طرح , نعمتي، هانيه ، همكار طرح , فلاحي كپورچالي، مريم ، همكار طرح , صيادفر، جواد ، همكار طرح , صفري، محمدرضا ، همكار طرح , يونس حقيقي، بهاره ، همكار طرح , آبيار ، مجتبي ، همكار طرح
چكيده فارسي :
ماهيان خاوياري در گذشته بطور گسترده جهت تخم ريزي به رودخانه سفيدرود مهاجرت مي¬¬كردند، هم اكنون به دلايل صيد قاچاق و نيز كاهش دبي آب رودخانه سفيدرود كمتر وارد آن مي¬شوند. امروزه رهاسازي ميليونها بچه ماهي خاوياري حاصل از تكثير و پرورش در استخرهاي خاكي به رودخانه سفيدرود، با بحراني اساسي روبرو شده است. لذا ضرورت يافتن مكاني امن كه بتوانند همانند رودخانه سفيدرود جهت رهاسازي بچه ماهيان خاوياري و حفظ ذخاير انها نقش داشته باشد، بسيار ضروري است. در اين راستا پروژه تحقيقات حاضر بر اساس بند 2-2-1 سياست¬هاي استراتژيك مصوبات كمسيون عالي مديريت بهره¬برداري ذخاير آبزيان درياي خزر (ماهيان خاوياري) پيشنهاد شد و امكان رهاسازي بچه ماهيان خاوياري در مسير آبراهه اسكله كياشهر واقع در پارك ملي بوجاق، مورد بررسي قرار گرفت.
عمليات بررسي در سه مرحله قبل از رهاسازي، در زمان رهاسازي و بعد از رهاسازي و نمونه¬برداري از آب و رسوب در 3 ايستگاه در منطقه مورد بررسي اسكله كياشهر و آبراهه مشرف به دريا انجام شد. اولين نمونه¬ها در ساعت 4 صبح و 4 عصر همان روز با هدف اندازه¬گيري حداقل ميزان اكسيژن محلول در بستر برداشته شدند.
پس از اطمينان از عدم ايجاد شرايط بحراني اكسيژن محلول، رهاكرد بچه ماهيان شروع شد و نمونه¬برداري دوم در زمان رهاكرد صورت گرفت. فاكتورهاي فيزيكي آب شامل دماي آب، اسيديته، شفافيت و همچنين فاكتورهاي شيميايي از قبيل اكسيژن محلول (DO)، ارتو فسفات، نيترات، نيتريت، آمونيوم، BODو COD آب اندازهگيري شدند. نوع دانه¬بندي بستر تعيين شده و نمونه¬هاي موجودات كفزي هم شناسايي شدند.
pH آب قليايي بود و اختلافي در دماي آب با رودخانه سفيد¬رود مشاهده نشد. حداقل ميزان اكسيژن محلول در بررسي¬هاي انجام شده در شبانه¬روز بيشتر از mg/L3 در ليتر در ساعت 4 صبح در كف بستر داخل اسكله و حداكثر mg/L 10در بخش مياني آبراهه در ساعت 9 صبح ثبت شد. حداكثر BOD در آبراهه اسكله كياشهر و سفيد¬رود كمتر از mg/L5 بود. ميانگين ميزان نيترات در حد مجاز و ميانگين ميزان آمونياك و نيتريت در آبراهه كياشهر كمتر از مكان رهاكرد در سفيد¬رود بود. مقادير ارتوفسفات در آبراهه اسكله كياشهر بيشتر از سفيدرود بود. ماسه با بيش از 75 درصد، دانه¬بندي غالب بستر در آبراهه بود. بررسي فراواني موجودات بنتيك حاكي از فراواني مواد مغذي در بستر آبراهه براي بچه ماهيان است و در مقايسه با بستر سفيدرود كه موجودات بنتيك در آن مشاهده نشدند، از شرايط مناسبي براي تغذيه بچه ماهيان خاوياري تا مرحله ورود به دريا برخوردار مي¬باشد. در سال 1398 تعداد 5000 بچه ماهي از طريق قفس¬هاي شناور و هدايت قفس در طول مسير آبراهه به دريا، رهاسازي شدند. در اين بررسي ضريب رشد 8/4، درصد شاخص افزايش وزن 150٪ ، سرعت رشد 9/0 و بازماندگي 73 ٪ مشاهده شد. در بررسي ديگري كه بر روي 1000 بچه ماهي خاوياري بدون استفاده از قفس با استفاده از سبدهاي شناور سازگاري انجام شد، بازماندگي 100 درصد با شناي فعال مشاهده شد. در سال 1399 عمليات رهاسازي مجموعاً حدود 192 هزار بچه ماهي خاوياري در طي12 تكرار در مقياس واقعي ساليانه و متداول كارگاه تكثير و پروش شهيد بهشتي با استفاده از پن با موفقيت 10 درصدي انجام شد و بچه ماهيان در نهايت با شناي فعال وارد دريا شدند. نتايج بدست آمده از نمونه برداري با استفاده از تور پرتابي يا ماشك در مسير در دهانه رودخانه و محل ورود بچه ماهيان به دريا نيز مؤيد ورود بچه¬ماهيان به دريا بود. نتايج بافت شناسي آبشش بچه ماهيان آسيب¬هايي را نشان داد كه ميزان آنها در زمان رها كرد از استخرهاي پروشي در آبراهه نسبت به زمان ورود بچه ماهيان به دريا بسيار بيشتر بود. به اين معني كه بچه ماهيان در اين شرايط وضعيت بهتري را تجربه مي¬كنند و با عوارض كمتري وارد دريا شدند. نتايج بافت-شناسي كليه و كبد نيز اين نتيجه¬گيري را تأييد كرد.
چكيده انگليسي :
In the past, sturgeons migrated extensively to the Sefidrud River to spawn. But at present, due to illegal fishing and construction of dams on the migratory route of these fishes and also the reduction of water flow in this river, they rarely enter the river. In order that, now the release of millions of sturgeon fry from breeding in earthen ponds into the Sefidrud River is facing a major crisis. Therefore, it is necessary to study the rivers that can play the role of Sefidrud River in releasing sturgeon fry and preserving their reserves. This project is proposed based on clause 2-2-1 of the strategic policies approved by the High Commission for the Management of Caspian Sea Aquatic Reserves (Sturgeon).
In this regard, the possibility of release in the Kiashahr waterway located in Bojagh, which is located in the protected area of Bojagh Wetland, was investigated.
The investigation was performed in three stages before releasing, at releasing time and after releasing. Water and sediment sampling was performed at 3 stations in the study area. The first sampling was performed at 4 am and 4 pm of the same day aimed to measuring the minimum amount of dissolved oxygen in the bed. After ensuring that no critical conditions for dissolved oxygen were created, the juveniles were released and a second sampling was performed at the time of release. Physical factors of water including water temperature, acidity, transparency as well as chemical factors of dissolved oxygen DO, orthophosphate, nitrate, nitrite, ammonium, BOD and COD of water were measured.
About 192,000 sturgeon juveniles were released during 2019 and 2020 in the waterway of Kiashahr pier. The catching operations of the released juveniles were performed using a throw- net with a 0.7 cm mesh size and the condition of the fish and their abundance were compared with Sefidrud River.
In this study, Kiashahr pier waterway was selected as an alternative place in cases of necessity to release sturgeon juveniles. In the first stage, the survival of juveniles and their safe arrival at sea were examined. After releasing, the survival of juveniles was recorded 100% in 12 repetitions until reaching the shore and entering the Caspian Sea. One of the reasons for choosing this waterway for releasing juveniles in emergencies was its location in the no-hunting and protected area of Bojagh Wetland. Bojagh Wetland is National Land - Marine Park and one of the areas under the management of the Environmental Protection Organization, which is the closest water passage to the Sefidrud River, and of course there is no climate difference between them.
The water was alkaline and there was no difference in water temperature with Sefidrud River. The minimum amount of dissolved oxygen in the studies performed during the day and night was more than 3 mg /L per liter at 4 o'clock in the morning on the bed inside the pier and the maximum was 10.0 mg/L in the middle part of the waterway at 9 o'clock in the morning. The maximum BOD obtained in the waterway of Kiashahr and Sefidrud was less than 5 mg/L. The average amount of nitrate was within the allowable level and the average amount of ammonia and nitrite in Kiashahr waterway was less than the releasing place in Sefidrud River. The amount of orthophosphate in the waterway of Kiashahr was higher than Sefidrud due to the presence of aquatic plants. More than 75% of sand, was the predominant granulation of the substrate. Also, the study of the abundance of benthic organisms showed the abundance of nutrients in the waterway bed for juveniles and in comparison with Sefidrud bed where benthic organisms were not observed, it has suitable conditions for feeding sturgeon juveniles up to the stage of entering the sea. In 2019, 5,000 juveniles were released through floating cages and transferred to cages along the waterway. In this study, a growth coefficient of 4.8, weight gain percentage of 150%, growth rate of 0.9 and survival rate of 73% were observed. In another study of 1000 sturgeon juveniles without cage using floating adaptation baskets, 100% survival was observed with active swimming in the coastal part of the Caspian Sea. In another study of 1000 sturgeon juveniles without cage using floating adaptation baskets, 100% survival was observed with active swimming in the coastal part of the Caspian Sea.
In 2020, the operation of releasing sturgeon fry with more than 12 repetitions in the real annual scale of Shahid Beheshti propagation and rearing complex was performed using a pen, which caused the proper management of the movement of fish in an enclosed path and no deaths or mortality of juveniles were observed along the way and when entering the sea. The fry eventually entered the sea and were spotted actively swimming in the sea. The results obtained from sampling using a throwing net (throw net) on the route at the mouth of the river and the entry of juveniles into the sea also confirmed the entry of juveniles into the sea.
Histological results of juvenile gills showed damage that was much higher in the time of release from rearing ponds in the waterway than when the fish entered the sea. This means that the juveniles experience a better situation in these conditions or the juveniles entered the sea with less complication. Histological results of kidney and liver also confirm this conclusion.
كليدواژه :
رهاسازي , رهاسازي , بچه ماهيان خاوياري , تالاب بوجاق , اسكله كياشهر
