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Hen egg yolk and skinned krill as possible foods for rearing leptocephalus larvae of A nguilla japonica T emminck & S chlegel
Author(s) -
Okamura Akihiro,
Yamada Yoshiaki,
Horie Noriyuki,
Mikawa Naomi,
Tanaka Satoru,
Kobayashi Hideki,
Tsukamoto Katsumi
Publication year - 2013
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/j.1365-2109.2012.03160.x
Subject(s) - biology , japanese eel , yolk , japonica , larva , fishery , krill , zoology , spiny dogfish , squalus acanthias , botany , endocrinology
Usual diets for rearing leptocephalus larvae of J apanese eel A nguilla japonica include eggs of the endangered spiny dogfish S qualus acanthias ( SE ). We investigated the effects of alternative food materials, hen egg yolk ( HEY ) and exoskeleton‐free (skinned) A ntarctic krill ( SAK ), on the growth and survival of eel larvae. We found that feed comprising whole krill including exoskeleton ( WAK ) containing higher levels of fluoride (37.89 mg kg −1 ) was acutely toxic to eel larvae exposed to this alone. In contrast, extract from SAK containing lower concentrations of fluoride (4.25 mg kg −1 ) showed no apparent adverse effects. Growth of larvae fed a mixture of SE and SAK in a feed trial of 58 days [mean body weight (BW), 6.0 mg] was about twofold higher than that of larvae fed a mixture of SE and WAK (3.2 mg) ( P < 0.01). A mixture of HEY and SAK also had some dietary benefits for eel larvae, enabling them to survive for up to 58 days and to grow significantly (mean BW, 2.4 mg), compared with their initial weight (mean BW, 0.2 mg) ( P < 0.001). Although additional nutritional improvements are needed, the present results suggest that combination diet HEY and SAK may be a good alternative to SE as an effective diet for eel larvae.