1Central Fisheries Research Institute, Hokkaido Research Organization, Yoichi, Hokkaido 046-8555, 2Kushiro Fisheries Research Institute, Hokkaido Research Organization, Kushiro, Hokkaido 085-0024, Japan
Two groups of Pacific herring Clupea pallasii juveniles, i.e., with and without intermediate culture before release, were released on the same day to clarify the damage to the juveniles during the transportation and release processes. A sudden decrease in triglyceride content, a sudden rise in acid phosphatase activity, and abnormal ring formation in the otoliths were observed in the juveniles after transportation and release. Abnormalities such as variations in swimming depth of the juveniles and abnormal feeding behavior of the juveniles were observed in the early periods after release. The damaged juveniles required approximately 5 days after transportation and more than 10 days after release to achieve recovery. Obvious differences in rates of abnormal ring formation in the otoliths in both groups suggest that the damage was more pronounced in the group without intermediate culture before release than in the group with intermediate culture before release.