编码金属标签对牙鲆(Paralichthysolivaceus)苗种标记的效果

Tagging Juvenile Japanese Flounder(Paralichthys olivaceus) with Coded Wire Tags

为了开发适宜牙鲆(Paralichthys olivaceus)苗种放流的标志技术,利用编码金属标签(CWT)对不同规格牙鲆苗种进行了标记实验,并从标记死亡率、脱标率、适宜标记鱼规格等方面评价了CWT的标记效果。结果显示,CWT标记3种规格的牙鲆苗种后,脱标均发生在标记后的4 d内,其后未再发生脱标现象。小规格苗种[全长为(5.92±0.41)cm]死亡率较高(13%),中规格苗种[全长(8.92±0.36)cm]死亡率为2%,大规格苗种[全长为(12.06±0.62)cm]死亡率为1%。小规格、中规格和大规格苗种脱标率分别为3.3%、2.4%和0.7%。建立了标记死亡率(M)与苗种全长(TL)、体厚度(BT)的关系模型:M=0.7254 TL^2–15.3220TL+79.4260(R^2=0.9601);M=1.3627 BT^2–15.5610 BT+44.4330(R^2=0.9645),为适宜苗种规格选择与标记效果评价提供了依据。今后利用CWT标签进行牙鲆苗种标志放流时,建议选择全长6 cm以上的苗种进行背部肌肉标记,标记对苗种游泳行为和生长无影响,表明CWT是一种适宜在牙鲆大规模标志放流中应用的理想标志方式。

In this study we tested the feasibility of coded wire tags （CWTs） as a novel high-efficiency tagging method for Japanese flounder （Paralichthys olivaceus）. A total of three size groups were tested. The total lengths for small, medium, and large size groups were （5.92±0.41） cm, （8.92±0.36） cm, and （12.06±0.62） cm respectively. In a short-term experiment, we marked hatchery-reared juveniles with CWTs in the dorsal muscle and examined whether the fish size affected the tag retention and tagging-induced mortality. Tag retention was above 96% in all the three size groups and appeared to be unaffected by the fish size. Tag loss was only observed within 4 days post tagging. Tagging-induced mortality for small juveniles （13%） was significantly higher than that for the medium （4%） and the large （1%） juveniles. The tag shedding rates for the small, medium, and large juveniles were 3.3%, 2.4%, and 0.7% respectively. Linear dependence models were established to describe the relationships of tagging-induced mortality, the total length, and the body thickness. Death of small marked juveniles usually occurred within 4 days post tagging. In order to reduce the post-tagging mortality and biases in stocking assessment, we recommended CWT tagging on juveniles at least 6 cm in body length. The CWT tagging may have no effects on the growth and swimming behavior of the fish, therefore could be an ideal tagging method for Japanese founder juveniles. It is potentially a good tool in large-scale tagging and evaluation of Japanese flounder in the future.