PNNL

Abstract

Abstract.—The influence of a surgically implanted acoustic micro-transmitter and passive integrated transponder (PIT) tag on the growth and survival of hatchery-reared juvenile Chinook salmon was examined. Growth and survival were compared between treatment (implanted) and control fish within three fork length (FL) size groups (80-89, 90-99, and 100-109 mm). The acoustic micro-transmitter and PIT tag implanted in our study had a combined weight of 0.74 g. Weights of study fish ranged from 4.7 to 16.3 g for treatment fish and from 5.1 to 16.8 g for control fish. The burden for the combined acoustic and PIT tag experienced by implanted fish ranged from 8.8% to 15.7% for the 80-89 mm FL group, 6.0-10.9% for the 90-99 mm FL group, and 4.5-8.6% for the 100-109 mm FL group. Results indicated that growth and survival were size-dependent among implanted juvenile Chinook salmon. Significant differences in growth rate and survival were observed between treatment and control fish in the 80-89 mm FL group. Within this group, growth of fish smaller than 88.5 mm FL (tag burden > 10.0%) was negatively affected by the implantation or presence of an acoustic micro-transmitter and PIT tag. Survival of fish in the 90-99 mm FL group did not differ between treatment and control fish. However, survival of implanted fish within this size group that were smaller than 97.2 mm FL (tag burden > 7.4%) was negatively influenced. These results indicate that the burden of an acoustic micro-transmitter and PIT tag should be maintained at or below about 7.0% for studies that use hatchery-reared juvenile Chinook salmon.