ヤマメ同質・異質倍数体の成長と生残

抄録

Diploid and triploid fish produced in crosses between female masu salmon (MS) Oncor-hynchus masou and males of six species, namely, MS, rainbow trout (RT) O. mykiss, brown trout (BN) Salmo trutra, Japanese common charr (JC) Salvelinus leucomaenis pluvius, white-spotted char (WS) Salvelinus leucomaenis leucomaenis, and brook trout (BK) Salvelinus fontinalis, were subjected to efficiency tests for aquaculture. Diploids and triploids of MS×MS, MS×JC, MS×WS and MS×BK, in addition to triploids of MS×RT and MS×BN, survived beyond the swimming-up stage, and thereafter the survival rate of every allotriploid group clearly exceeded that of their diploid hybrid counterparts. The daily growth rates of immature 1-year-old diploids and triploids of MS×JC and MS×WS and triploids of MS×BN were superior under controlled feeding, but inferior at satiation level to those of diploid and triploid MS×MS. Triploids appeared to perform better than diploids at satiation level in crosses of MS×JC and MS×WS. During the 6 months of accelerated gonadal development preceding the spawning season, the survival and growth rates of hybrids remarkably surpassed those of MS×MS for both ploidy levels.