Effects of surgically implanted acoustic transmitters >2% of body mass on the swimming performance, survival and growth of juvenile sockeye and Chinook salmon

Abstract

The influence of surgical implantation of an acoustic transmitter on the swimming performance, growth and survival of juvenile sockeye salmon Oncorhynchus nerka and Chinook salmon Oncorhynchus tshawytscha was examined. The transmitter had a mass of 0Á7 g in air while sockeye salmon had a mass of 7Á0-16Á0 g and Chinook salmon had a mass of 6Á7-23Á1 g (a transmitter burden of 4Á5-10Á3% for sockeye salmon and 3Á1-10Á7% for Chinook salmon). Mean critical swimming speeds (U crit ) for Chinook salmon ranged from 47Á5 to 51Á2 cm s À1 [4Á34-4Á69 body lengths (fork length, L F ) s À1 ] and did not differ among tagged, untagged and sham-tagged groups. Tagged sockeye salmon, however, did have lower U crit than control or sham fish. The mean U crit for tagged sockeye salmon was 46Á1 cm s À1 (4Á1 L F s À1 ), which was c. 5% less than the mean U crit for control and sham fish (both groups were 48Á6 cm s À1 or 4Á3 L F s À1 ). A laboratory evaluation determined that there was no difference in L F or mass among treatments (control, sham or tag) either at the start or at the end of the test period, suggesting that implantation did not negatively influence the growth of either species. None of the sockeye salmon held under laboratory conditions died from the influence of surgical implantation of transmitters. In contrast, this study found that the 21 day survival differed between tagged and control groups of Chinook salmon, although this result may have been confounded by the poor health of Chinook salmon treatment groups. # 2006 Battelle Memorial Institute

Movement and Mortality of Adult Brown Trout in the Motupiko River, New Zealand: Effects of Water Temperature, Flow, and Flooding

“…The transmitters (48 3 18 mm, 220-mm antenna) weighed 19 g (in air), which represented 0.7-2.4% of the body weight of the 0.8-2.6-kg trout (mean 1.74 kg), a percentage considered to have no effect on fish swimming performance, condition, or growth (Brown et al 1999;Jepsen et al 2002;Brown et al 2006). It is possible that the trout exhibited unnatural behavior for a short period after tagging (e.g., Walker et al 2000), but this would presumably only affect results from the first tracking occasion, which occurred 12 d after the last fish was tagged.…”

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

“…Although tag burden is a commonly used guide for making inferences regarding tag size appropriateness [8,53,54], length was used as a surrogate for tag burden in this study because measurements of weight were not recorded for PIT fish. This is standard practice when using PIT-tagged fish as controls to minimize handling.…”

“…Research has been conducted to evaluate tag effects among many species, transmitter types and sizes, and geographic areas. Specifically, laboratory research has evaluated the survival, growth, tag expulsion, swimming performance, stress levels, and predation of tagged versus untagged fish [4][5][6][7][8][9][10][11]. In these studies, untagged or sham-tagged fish (that is, fish handled in a manner identical to treatment fish, including incisions, but not implanted with a transmitter) typically serve as a comparison to tagged fish.…”

“…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.…”

Juvenile Salmon Acoustic Telemetry System Transmitter Downsize Assessment

“…Some biologists have suggested that this tag burden not exceed 2% (Winter 1996). However, there have been numerous laboratory based studies that indicate that a tag burden higher than this may not influence swimming performance, growth, tag retention, or survival (Brown et al 1999(Brown et al , 2006(Brown et al , 2010Anglea et al 2004;Zale et al 2005). To this day, discussion continues about the 2% rule presented by Winter (1996).…”