PNNL

Abstract

Maturing female anadromous salmonids receiving surgical intraperitoneally-implanted telemetry transmitters may experience difficulty depositing eggs during natural spawning. We allocated maturing adult steelhead females to three treatments: tags surgically implanted in the body cavity (internal), tags implanted between the skin and muscle tissue (subdermal), and non-tagged, and allowed them to spawn naturally in an experimental channel. Internally tagged females retained significantly more eggs than both the subdermally tagged treatment (P = 0.005) and non-tagged controls (P = 0.001); the subdermal and non-tag controls did not differ significantly (P = 0.934). The internal, subdermal and non-tag treatments retained an average of 49%, 11% and 2% of their eggs, respectively. The onset of sexual activity did not differ significantly among treatments (P = 0.413). Post-spawning mortality was 70% for both internally and subdermally tagged females and 0% for non-tagged females (P