Geoscience Reference
In-Depth Information
advantages of lying near a fish's center of gravity, not being lost or entangled in
the environment, and not creating drag forces. However, these advantages can
be offset by reduction in swimming performance, increased handling time,
and stress associated with surgery, as well as the higher chance of infection fol-
lowing release. Also, implanted transmitters occasionally can be passively
expelled from the body, although sometimes without causing mortality or
morbidity (Lucas 1989). Some species appear more predisposed than others to
postoperative complications and transmitter expulsion (Mellas and Haynes
1985; Marty and Summerfelt 1986), meaning that it may be necessary to tai-
lor surgical technique and specific implantation site to the target species. How-
ever, in some species, stomach implants seem to have fewer effects than either
external mounts or surgically implanted transmitters (Henderson et al. 1966).
In all telemetry studies, transmitter size is an important consideration, and
smaller transmitters are always more desirable than larger ones from the stand-
point of effects on the animal (Stasko and Pincock 1977; Marty and Summer-
felt 1986). However, the general question regarding the effects of transmitter
mass on fish still must be addressed in controlled studies (Stasko and Pincock
1977).
Reptiles and amphibians
TAGGING
The use of marking in reptile and amphibian research is fairly
new, so fewer studies have evaluated marker effects in these taxonomic groups.
Many species of reptiles and amphibians have proven difficult to mark because
of their epidermal sensitivity, small size, and potential for tissue regeneration.
Tagging of reptiles and amphibians has included various types of branding and
the use of polymers, pigments, dyes, and radioactive substances (Ferner 1979;
Ashton 1994; Donnelly et al. 1994; table 2.2). Many of these markers are of
limited utility because they were not tested adequately for marking effects
(Donnelly et al. 1994); such limitations are particularly important for am-
phibians, given the sensitivity of their skin. A field test of marking by dye
injection did not find any effects on larval amphibians (Seale and Boraas
1974), but a controlled laboratory study did identify stunting in dyed tadpoles
(Travis 1981). Although these studies used different dyes, the results call into
question previous suggestions that some dyes are largely benign (Guttman and
Creasey 1973) and suggest that laboratory studies might be more sensitive to
detection of marking effects. Other color markers, such as fluorescent paint,
often are used to monitor amphibians in the field (Taylor and Deegan 1982;
Nishikawa and Service 1988; Ireland 1991), despite the fact that such paint
