Capture and Brief Invasive Procedures Using Electronarcosis Does Not Appear to Affect Postrelease Habits in Male Atlantic Sturgeon During the Spawning Season

With advances in technology and demand for life history information, researchers are increasingly conducting invasive procedures on fish that require an anesthetic. This study examined the effectiveness of electronarcosis as a field anesthetic on Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus during the spawning season in the James River, Virginia. Concerns about sampling Atlantic Sturgeon during spawning runs prompted our examining whether movements after capture, narcosis, and tagging were noticeably modified. An electronarcosis system, which consisted of a power supply, fiberglass tank, and hardware cloth, were set up both on land and on a sampling boat. During the spawning season Atlantic Sturgeon were caught and implanted with Vemco V16 telemetry tags using electronarcosis as an anesthetic. Anesthesia induction, surgery, and recovery averaged 5 min. Telemetry data from the tagging year was compared with returning fish tagged in previous years. This showed movements during the spawning season and spawning exit dates were similar between the two groups, suggesting that electronarcosis was effective and time-efficient for conducting invasive procedures. Capturing and implanting transmitters in Atlantic Sturgeon during spawning runs does not appear to modify spawning movements. Managers may benefit from targeting adult Atlantic Sturgeon and other iteroparous anadromous fishes in rivers during spawning periods, which is typically very efficient due to high densities of fish during that period.