A Critical Review of the Effects of Marking
19
via a portable scanner (Nietfeld et al. 1994). Insertion of PIT tags usually is
performed using a syringe, thus eliminating the need for extensive invasive
surgery. So far, no negative effect of PIT tags has been found in fish (Prentice
et al. 1990; Jenkins and Smith 1990), suggesting that this technique can
become an important tool for marking fish and other vertebrates. However,
one drawback of PIT tagging is that at present tags can be read only when near
a scanner.
mutilation Marking by mutilation, usually by fin removal or partial
removal, is a permanent marking technique often used by fish researchers.
However, fin removal often affects fish growth and survival (table 2.2). For
example, evaluations using mark–recapture methods (Shetter 1951; Mears
and Hatch 1976) show that fin removal causes lower probability of recapture
and, by inference, lower survival. Excision of multiple fins generally appears to
be more harmful than single-fin excision, and removal of the adipose fin
usually is less harmful than removal of other fins (Nicola and Cordone 1973;
Mears and Hatch 1976). Removal of dorsal or anal fins can be particularly
damaging (Coble 1967), partly because under certain conditions such excisions may predispose some species to bacterial or fungal infections (Stott
1968) or predation (Coble 1971). However, as with tagging, not all studies
evaluating fin removal have detected significant effects, suggesting that for
certain species or age classes, or under specific conditions, this marking technique could be acceptable. Clearly, evaluation of the effects of fin clipping on
fish biology requires more attention, particularly under controlled laboratory
conditions.
radiotransmitters Radiotelemetry has become an important technique in fishery research, allowing biologists to accurately monitor long-term
movements and survival of many species that would otherwise be difficult to
study. Transmitter sizes and types available for fish are variable, and they have
been attached to animals either externally or internally (see review by Stasko
and Pincock 1977). Laboratory studies have shown that externally mounted
transmitters increase drag and reduce or prevent swimming, particularly in
high-speed currents (Mellas and Haynes 1985). It has been suggested that
fusiform, lotic fishes are more influenced by external mounts than nonfusiform, lentic, or pelagic species (McCleave and Stred 1975). Internal implantation can be achieved by force-feeding stomach transmitters, or by surgery to attach the transmitter either in the peritoneal cavity or intramuscularly.
Implants are more commonly used than external transmitters and have the
19
via a portable scanner (Nietfeld et al. 1994). Insertion of PIT tags usually is
performed using a syringe, thus eliminating the need for extensive invasive
surgery. So far, no negative effect of PIT tags has been found in fish (Prentice
et al. 1990; Jenkins and Smith 1990), suggesting that this technique can
become an important tool for marking fish and other vertebrates. However,
one drawback of PIT tagging is that at present tags can be read only when near
a scanner.
mutilation Marking by mutilation, usually by fin removal or partial
removal, is a permanent marking technique often used by fish researchers.
However, fin removal often affects fish growth and survival (table 2.2). For
example, evaluations using mark–recapture methods (Shetter 1951; Mears
and Hatch 1976) show that fin removal causes lower probability of recapture
and, by inference, lower survival. Excision of multiple fins generally appears to
be more harmful than single-fin excision, and removal of the adipose fin
usually is less harmful than removal of other fins (Nicola and Cordone 1973;
Mears and Hatch 1976). Removal of dorsal or anal fins can be particularly
damaging (Coble 1967), partly because under certain conditions such excisions may predispose some species to bacterial or fungal infections (Stott
1968) or predation (Coble 1971). However, as with tagging, not all studies
evaluating fin removal have detected significant effects, suggesting that for
certain species or age classes, or under specific conditions, this marking technique could be acceptable. Clearly, evaluation of the effects of fin clipping on
fish biology requires more attention, particularly under controlled laboratory
conditions.
radiotransmitters Radiotelemetry has become an important technique in fishery research, allowing biologists to accurately monitor long-term
movements and survival of many species that would otherwise be difficult to
study. Transmitter sizes and types available for fish are variable, and they have
been attached to animals either externally or internally (see review by Stasko
and Pincock 1977). Laboratory studies have shown that externally mounted
transmitters increase drag and reduce or prevent swimming, particularly in
high-speed currents (Mellas and Haynes 1985). It has been suggested that
fusiform, lotic fishes are more influenced by external mounts than nonfusiform, lentic, or pelagic species (McCleave and Stred 1975). Internal implantation can be achieved by force-feeding stomach transmitters, or by surgery to attach the transmitter either in the peritoneal cavity or intramuscularly.
Implants are more commonly used than external transmitters and have the