Sillaoru hüdroelektrijaama mõju lõhe noorjärkude laskuvale rändele Purtse jões
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Kuupäev
2018
Kättesaadavus
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Eesti jõgedel on üle 50 hüdroelektrijaamaga (HEJ) paisu ning kõigi nende juures on oluliseks probleemiks kaladele ohutute allarände tingimuste tagamine. 2015. a Purtse jõel Sillaoru HEJ juures läbi viidud lõhesmoltide laskuva rände uuring oli Eestis esimene sellelaadne. Eesmärgiks oli uurida smoltide laskuva rände ajalist ja ruumilist kulgu ning erinevate rändeteede ohutust töötava HEJ, kalapääsu ja liigveelaskmega paisu juures. Uuringus kasutati RMK Põlula kalakasvatuskeskuses ettekasvatatud lõhesmolte, kes enne asustamist märgistati rasvauime lõikamisega, 40 isendit ka individuaalsete akustiliste märgistega. Kalade laskuva rände kulgu jälgiti mõrrapüükide ja akustilise telemeetria meetodit kasutades. Selgus, et vaatamata suhteliselt väikesele vooluhulgale valis enamik smolte (71–74%) paisu juures laskumiseks kalapääsu. Oluline osa laskujatest (23–26%) valis rändeteeks põhivoolul oleva HEJ derivatsioonikanali ning vaid üksikud isendid (3%) eelistasid allarändeteena paisu liigveelasku, mille vooluhulk oli lähedane kalapääsu vooluhulgale. Rände ajaline analüüs näitas, et asustatud kalad alustasid koheselt allarännet. Esimesel päeval läbis paisu 69%, teisel 20%, kolmandal 6% ja neljandal 3% laskujatest. Laskumise intensiivsus oli kõrgem perioodil õhtul kella 18-st hommikul kella 6-ni, maksimum vahetult enne südaööd. Laskumisel läbi HEJ oli smoltide kohene suremus vähemalt 33% ning järelsuremus 7%. Laskumisel üle liigveelaskme ja läbi kalapääsu suremus puudus. Uuringust järeldub, et senini seadusega nõutud 25 mm võre HEJ turbiinide sissevoolul pole piisava tihedusega tõkestamaks lõhesmoltide sattumist turbiinidesse.
There are more than 50 dams with hydroelectric power stations (HPS) on Estonian rivers and providing safe conditions for the downstream migration of fish is an important issue with all of them. The study of the downstream migration of salmon smolts, conducted in 2015 at the Sillaoru HPS on Purtse river, was the first of its kind in Estonia. The goal was to analyze the spatial and temporal progress of the downstream migration of smolts and the safety of passage in the HPS channel, fish pass and water spillway. The salmon smolts used in the study originated from RMK Põlula fish rearing centre. All of them were marked by removing the adipose fin and 40 of the smolts were fitted with individual acoustic trackers. The downstream migration was monitored using trapping and acoustic telemetry. Most smolts (71–74%) preferred the fish pass for downstream migration despite the relatively low water flow. A significant part of the smolts (23–26%) chose the HPS channel and only a few (3%) migrated over the water spillway. The fish started their downstream migration right after being introduced to the river. 69% of the smolts descended through the dam complex on the first day, followed by 20% on the second, 6% on the third and 3% on the fourth day. The descent intensity was highest from 18 PM to 6 AM, reaching the maximum just before midnight. The immediate mortality while descending through the HPS was at least 33%, with an after-mortality of 7%. The mortality while descending through the fish pass or water spillway was 0. The study shows that a grate with 25 mm (legally required minimum) gaps is not sufficient to stop smolts from reaching the HPS channel.
There are more than 50 dams with hydroelectric power stations (HPS) on Estonian rivers and providing safe conditions for the downstream migration of fish is an important issue with all of them. The study of the downstream migration of salmon smolts, conducted in 2015 at the Sillaoru HPS on Purtse river, was the first of its kind in Estonia. The goal was to analyze the spatial and temporal progress of the downstream migration of smolts and the safety of passage in the HPS channel, fish pass and water spillway. The salmon smolts used in the study originated from RMK Põlula fish rearing centre. All of them were marked by removing the adipose fin and 40 of the smolts were fitted with individual acoustic trackers. The downstream migration was monitored using trapping and acoustic telemetry. Most smolts (71–74%) preferred the fish pass for downstream migration despite the relatively low water flow. A significant part of the smolts (23–26%) chose the HPS channel and only a few (3%) migrated over the water spillway. The fish started their downstream migration right after being introduced to the river. 69% of the smolts descended through the dam complex on the first day, followed by 20% on the second, 6% on the third and 3% on the fourth day. The descent intensity was highest from 18 PM to 6 AM, reaching the maximum just before midnight. The immediate mortality while descending through the HPS was at least 33%, with an after-mortality of 7%. The mortality while descending through the fish pass or water spillway was 0. The study shows that a grate with 25 mm (legally required minimum) gaps is not sufficient to stop smolts from reaching the HPS channel.
Kirjeldus
Bakalaureusetöö
Vee ja maismaa ökosüsteemide rakendusbioloogia õppekaval
Märksõnad
bakalaureusetööd, lõhelised, ränne (biol.), hüdroelektrijaamad