Isolation and characterization of bacteria causing mortality in early stage larvae of captive-bred Japanese eels (Anguilla japonica Temminck & Schlegel)

摘要

Bacteria with lethal effect on eel larvae were isolated from moribund captive-bred eel larvae and their 16S rRNA gene sequences were analysed. Nucleotide sequence of 10 isolates showed highest similarity with Lacinutrix algicola, Crocinitomix catalasitica and Pseudoalteromonas rubra. Age-dependent changes in the susceptibility of eel larvae were observed in response to challenge by a highly lethal isolate. Compared with 10 and 11days after hatching (DAH), larval susceptibility to the highly lethal isolate was lower at 18 DAH. We found that the bacterial isolates have lethal effect on the captive-bred eel larvae, especially at the early developmental stage. These results will be useful to establish appropriate culture practices for eel larvae that will improve the success of mass production of glass eels for aquaculture.