探討降低黑鯛魚苗運輸緊迫及增加放流存活率之研究

Abstract

由於台灣沿近海漁業資源量大幅減少，行政單位在沿海縣市進行養殖魚苗放流，然而在這些放流作業措施中，運輸所造成魚苗的緊迫會影響魚體行為、生理狀態，將影響放流成效。因此，調控運輸時環境鹽度及運輸後的靜置時間顯得相當重要。本研究分為三實驗進行，(1)推估回復時間，以震盪儀震盪黑鯛魚苗來模擬運輸。震盪後測量2小時內鰓蓋拍動頻率，以及魚苗呈現快速游動、停在水底、慢速游動與停在水體中四種行為活力來探討振盪所造成的緊迫反應，並利用非線性迴歸方法尋找魚苗行為回復時間；另以汽車運輸數尾黑鯛魚苗後，測量經運輸緊迫後魚體單位皮質醇含量的變化來探討生理回復時間。(2)模擬放流，採巢式設計，從台灣大學用汽車運輸3組養殖黑鯛魚苗至卯澳種苗繁殖場，鹽度分別為7.5‰、14.9‰與29.8‰，各組在運輸後皆於靜置0、1、2小時後分別取10尾魚放至中間育成池以模擬放流。以探討經不同鹽度及靜置時間之運輸緊迫及放流活存率差異。(3)抵抗天敵，分為3鹽度震盪黑鯛魚苗，分別為7.5‰、14.9‰與29.8‰，各組在震盪後皆於靜置0、1、2小時後面臨石斑，以比較各組魚苗於石斑出現前後群游行為、游至底部以及游離天敵等抵抗天敵行為反應。 在推估回復時間中，以鰓蓋拍動頻率得知約為60分，而行為活力約於75至90分後呈現穩定。在魚體單位皮質醇中，回復時間約為1天。在模擬放流實驗中，運輸、放流、綜合存活率中皆以鹽度29.8‰組最低(p<0.05)，而靜置時間無顯著性差異(p>0.05)。在天敵實驗中，由於鹽度29.8‰組大量死亡，故不進行實驗。抵抗天敵行為中，均顯示靜置0小時較差(p<0.05)，鹽度14.9‰與7.5‰無顯著性差異(p>0.05)。本研究發現黑鯛魚苗經運輸緊迫後，需60至90分可達成行為回復，需一天可達成生理回復，而以高鹽度運輸黑鯛魚苗有較低的運輸、放流、綜合存活率，另外，運輸後若無經靜置回復其抵抗天敵行為反應能力較差，建議將來黑鯛魚苗運輸時，應保持養殖場中較低的鹽度環境，運輸後應藉由短暫的靜置60至90分，使魚苗達成行為回復再行放流，以增加放流成效。

Due to the fisheries resources decreasing in recent years, several coastal counties released hatchery-reared fry to enhance stocks in Taiwan. However, the fry physical state after transportation in releasing procedure will influence the release efficiency. Therefore, it is important to handle the salinities during transportation and calm times after transportation. This study included three experiments. Firstly, estimate the recovery time after handling stress by measuring opercular beat frequencies and behavior activity of black porgy (Acanthopagrus schlegeli), and estimate the recovery time after transportation stress by measuring cortisol. Secondly, three groups of fish were transported by car from National Taiwan University in Taipei to Mao Aw hatchery in Northeastern Taiwan. The treatments of salinities were 7.5‰, 14.9‰ and 29.8‰, and calm times were 0h, 1h and 2h, respectively. Then, each was moved to the tank and encountered the Malabar grouper (Epinephelus malabaricus) after ten minute. The aim of this experiment is to compare the antipredator responses including schooling, swimming to the bottom of the tank, and swimming after the Malabar grouper. iii&nbsp; The results are as follows: (1) time to recovery estimated by measuring opercular beat frequencies was 60 minute, and by behavior activity was 75 to 90 minute, and by cortisol was one day; (2) the survival rate of 29.8‰ group was lower than that of 15‰ and 7.5‰ after transportation, 1 week releasing (p<0.05); (3) the antipredator responses of 0h calm time group was lower than that of 1h and 2h(p<0.05). In this study, we found the time to recovery after transportation was 60 to 90 minute based on behavior, and one day based on physical, there were lower transportation and releasing survival rates of the black porgy fry after transportation with high salinity, and there were weaker antipredator responses without time to calm. It was suggested that low salinity during transportation and 60 to 90 minute calm time after transportation were necessary for the releasing program.