Tagging Juvenile Pacific Lamprey with Passive Integrated Transponders: Methodology, Short-Term Mortality, and Influence on Swimming Performance

Abstract

This study was conducted to determine the feasibility (i.e., efficiency and nonintrusiveness) of tagging juvenile Pacific lampreys Lampetra tridentata with passive integrated transponder (PIT) tags and to determine any associated impacts on survivorship and swimming ability. Juvenile Pacific lampreys were obtained from the John Day Dam fish collection facility and tests were conducted at the Pacific Northwest National Laboratory in 2001 and 2002. A new PIT-tagging procedure was used to inject 12-mm tags 5 mm posterior to the gill openings. Lampreys were allowed to recover for 3–4 d following surgery before postmortality and swimming tests were conducted. The PIT tagging procedure during 2001 did not include a suture, and 2.6% of the tags were shed after 40 d. During 2002 a single suture was used to close the opening after inserting a tag, and no tag shedding was observed. Overall short-term mortality rates for lampreys 120–155 mm (total length) held for 40 d at 8°C was 2.2% for tagged and 2.7% for untagged fish. Mortality increased significantly when tagged and untagged groups were held in warmer (19–23°C) river water: 50% for tagged and 60% for untagged animals. Lengths did not significantly affect survival for either the tagged or untagged group held in warm water. A fungal infection was observed to be the cause of death when water temperature increased. Swimming tests to determine any adverse effects due to tag insertion showed no significant difference (P = 0.12) between tagged and untagged lampreys for mean burst speed; however, maximum burst speeds were significantly lower for the PIT-tagged group.