農業部水產試驗所全球資訊網

海鱺是台灣積極開發的箱網養殖魚種之一，但目前受限於幼魚易疾病感染，常造成大量死亡，且繁殖數代近親化的海鱺，有日愈早熟及成長遲緩的問題，使產業規模一直無法擴大，故有必要透過選種育種的程序，改善種苗的品質。本計劃以野外捕獲之海鱺種魚，經與人工育成之種魚雜交(雜交組)，來選育優良魚苗，並進行魚苗抗病力研究，期望能解決產業問題，提升競爭力。本年度共有6次產卵，野生親魚繁殖之卵受精率在14.7~26.5%間，近親組為11.7~21.9%。另外在飼料轉換率(Feed conversion ratio, FCR)的表現，經餵養8週後，野生親魚子代FCR為1.034，表現明顯優於近親化子代(1.312)。另外，以60克左右的幼魚進行發光菌攻毒試驗，結果野生親魚子代較具有抗病能力，在感染病菌第四天之後，其存活率明顯高於近親化子代。在子代選育保種方面，保存二批去年野生親魚所繁殖之子代，共76尾，體重約3~8公斤，在此次莫拉克風災後，分送45尾予民間繁殖業者，進行育種試驗。由上述各項試驗結果顯示，經野生親魚繁殖交配之子代明顯優於近親繁殖之子代，未來需要進行親源分析及箱網田間試驗，以驗證海鱺種魚培育與育種之可行性及成效。

研究報告摘要(英) Cobia, Rachycentron canadium, is one of the most potential sea-cage farmed fish species in Taiwan. Recently, we find that the disease resistance of cobia juvenile is low, resulting in low survival rate. The possible reason is probably due to the inbreeding depression. We want to use selected breeding method to improve the growth performance and disease resistance of cobia juvenile. The purpose of this study is aimed to compare the growth performance, feed conversion ratio and disease resistance between the progeny of wild-catched cross artificial reared broodstock (Hybrid) and in-bred artificial reared broodstock(Inbred). Spawning behavior were observed 6 number of times during all year. Fertilization rates of Hybrid eggs are the range of 14.7% to 26.5%, and Inbred eggs are the range of 11.7 to 21.9%. In the growth performance and feed conversion ratio (FCR) of fingerlings, the better(lower, 1.034) FCR was observed in Hybrid progeny than Inbred’s (1.312) after 8 weeks feeding with commercial diet. Mortality of hybrid cobia progeny is lower than inbred after4 days challenged with immersion of Photobacterium damselae subsp. piscicida solution. In conclusion,the study showed that hybrid cobia progeny is better than inbred and improved the quality of the seed.