Retention of Jet-Injected Marks on Juvenile Coho and Sockeye Salmon

Abstract

Abstract Juvenile coho salmon Oncorhynchus kisutch and sockeye salmon O. nerka were marked by jet injection to determine mark retention of three substances: Alcian Blue dye, black india ink, and acrylic paint (red, fluorescent yellow, and fluorescent orange). Fish were marked on the caudal fin and then held for 40 weeks in flow-through freshwater tanks. Coho and sockeye salmon both retained Alcian Blue and fluorescent orange marks best. The highest mark retention after 40 weeks was 73% for Alcian Blue marks on sockeye salmon. Overall mark retention was greater for orange-, yellow-, and black-marked coho salmon than for similarly marked sockeye salmon. Differences in growth rate—sockeye salmon grew about 7 mm more than coho salmon—probably contributed to the differences in mark retention between species. All colors appear suitable for short-term ( 6 weeks) marks, we recommend Alcian Blue dye or fluorescent orange or yellow acrylic paint for coho salmon and Alcian Blue dye fo...