Reference |
Nagata, M., J. R. Irvine, M. Miyamoto, S. Ockubo & M. Kobayashi. 1998. Tag loss of masu salmon marked with coded wire tags in different tag placements. Sci. Rep. Hokkaido Fish Hatchery 52:37-43. |
Abstract |
Coded wire tags (CWT’s) implanted in snout have been used broadly in North America to elucidate migration routes, and to evaluate effectiveness of fish enhancement and management. Interesting cultural differences between North Americans and Japanese might necessitate novel approaches to resource assessment of young salmon in Japan. Since Japanese normally eat the heads from salmon, they catch or buy the fish as they are. So, this is not a suitable location for tag implantation. Also, the use of stainless steel tags might not be permitted when there is a possibility the consumers might accidentally eat the tag. Therefore, experiments were conducted on masu salmon examining: (1) influences of tagging location on tagging rates, tag loss, tag visibility, growth and mortality related to tagging and (2) the utility of gold (non-magnetic) CWT’s. Standard stainless steel CWT’s were introduced to the snout, adipose eye tissue, adipose fin, and dorsal fin and gold CWT’s were placed in the adipose eye tissue, adipose fin, and dorsal fin of groups of each of about 400 smolts. Smolts (~15 cm in fork length) were tagged in April 1995, each group was given a unique fin clip and fish were placed in concrete raceways. Fish were examined after 1 week, 7 months, and 13 months. There were no consistent differences in growth between fish tagged with stainless steel CWT’s and gold CWT’s. CWT retention and tagging speed were highest when fish were tagged in the snout (traditional North American tag site) and the adipose eye tissue. Tag visibility, an important consideration when it is necessary to sample fish at fish markets, was good when fish were tagged in the eye tissue as well as the adipose fin. It is concluded that when CWT’ing fish in Japan, the adipose eye tissue and the adipose fin appear to be suitable tagging sites. |
Tag |
Coded Wire Tag (CWT) |
Objective |
Evaluate tags |
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