Effects of surgically and gastrically implanted radio transmitters on swimming performance and predator avoidance of juvenile chinook salmon (Oncorhynchus tshawytscha)

Abstract

Radiotelemetry data are often used to make inferences about an entire study population; therefore, the transmitter attachment method should be the one that least affects the study animal. Juvenile chinook salmon (Oncorhynchus tshawytscha) <120 mm in fork length (FL) with either gastrically or surgically implanted transmitters had significantly lower critical swimming speeds than control fish 1 and 19-23 days after tagging. For fish >120 mm FL, fish with gastric implants swam as well as controls 1 day but not 19-23 days after tagging. In contrast, fish with surgical implants swam as well as controls 19-23 days but not 1 day after tagging. During predation trials, fish with gastric or surgical implants were eaten by smallmouth bass (Micropterus dolomieu) in significantly greater numbers than controls. We do not recommend implanting transmitters (representing 4.6-10.4% of the fish's body weight) in fish <120 mm FL. Furthermore, surgical implants (representing 2.2-5.6% of the fish's body weight) may be the preferred method for biotelemetry studies of juvenile chinook salmon >120 mm FL.

Movements of Marine Fish and Decapod Crustaceans: Process, Theory and Application

“…However, some transmitters (and other tags) have been found to influence mortality and behaviour (Jepson et al, 2002). For example, predation trials with tagged and untagged juvenile Chinook salmon (Oncorhynchus tshawytscha) revealed a reduced swimming speed and higher susceptibility to predation for fish with surgically implanted transmitters (Adams et al, 1998). However, individual animals are likely to respond differently to the tag itself and the tagging procedure and therefore whenever possible it is necessary that devices be experimentally evaluated in a pilot study before being deployed for tracking (Murray and Fuller, 2000).…”

Survival of seaward-migrating PIT and acoustic-tagged juvenile Chinook salmon in the Snake and Columbia Rivers: an evaluation of length-specific tagging effects

“…Among both field and lab studies, individuals implanted with tags generally represent a range of sizes similar to the range of the population from which they were sampled and may represent an age-class of fish such as yearling or subyearling Chinook salmon (for example, [6,8,21]). Analyses thus estimate tag effects for the entire group of fish but do not provide insight as to whether some of the smaller fish within a group experience greater tag effects than larger members of the group.…”

Mobility and home-range use of Atlantic salmon parr over short time scales

“…Recent studies demonstrated that implanting juvenile salmonids with transmitters representing up to 12% of body weight did not affect the swimming performance of fish (Adams et al 1998;Brown et al 1999;Robertson et al 2003;Lacroix et al 2004). However, it has been suggested that the presence of a trailing whip antenna may sometimes cause changes in social status (Connors et al 2002), predator avoidance (Adams et al 1998) and a significant decrease in swimming performance, if its length reaches 300 mm (Murchie et al 2004). In this study, in order to minimize the potential effect of the tag on parr behavior, the transmitters represented a maximum of 3.8% of the body mass and the trailing antenna measured 210 mm.…”