7972

• UCREFRP Catalog Number: 7972
• Author: Helm, W. T. and H. M. Tyus
• Title: Influence of Coating Type on Retention of Dummy Transmitters Implanted in Rainbow Trout
• USFW Year: 1992
• USFW - Doc Type: North American Journal of Fisheries Management
• Copyright Material: YES

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257

North American Journal oj Fisheries ManogemRnl 12:257-259, 1992

Influence of Coating Type on Retention of
Dummy Transmitters Implanted in Rainbow Trout

WILLIAM T. HELM1

Department of Fisheries and Wildlife
Utah State University
Logan. Utah 84322. USA

HAROLD M. Tvus2

u.s. Fish and Wild/(fe Service
Post Office Box 25486. Denver Federal Center
Denver. Colorado 80225. USA

Abstract. - The retention of surgically implanted dum-
my transmillers in tests with rainbow trout Oncorhyn'
chus mykiss was influenced by outside coatings. Trans-
millers with a beeswax coating were rarely expelled (3%),
whereas those with paraffin coatings were more often
expelled (13%), and those with silicone coatings were
commonly expelled (40%). Gross tissue response to the
different types of transmiller coatings varied. but bees-
wax-coated transmillers usually were encapsulated,
whereas others often were free in the body cavity. We
were unable to detect a relationship between dummy
transmiller size and expulsion rate.

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Biotelemetry is a useful tool in fishery research
and management. However, recent laboratory
studies (Summerfelt and Mosier 1984; Chisholm
and Hubert 1985; Marty and Summerfelt 1986)
have indicated that some salmonid and ictalurid
fishes expel implanted dummy transmitters that
are coated with paraffin. The transmitters were
expelled directly through ruptured incisions or in-
directly via a transintestinal route (Marty and
Summerfelt 1986). Expulsion occurred within the
useful life of most transmitters, so it could limit
radio-tracking studies. However, such expulsion
has not been noted in field studies of some other
fishes (Tyus 1988), and expulsion noted in the
laboratory may be related to the size of the im-
plant, location of the incision, holding stress, or
type of coating used on the implant.
We implanted dummy transmitters in rainbow
trout Oncorhynchus mykiss to evaluate the effects
of three coatings and sizes on expulsion rate. Two
experiments were conducted at separate locations

I Deceased.
2 To whom reprint requests should be sent.

to determine whether different coatings, sizes of
transmitters, or holding conditions influence the
rate of transmitter expulsion. We presumed that
direct expulsion would not occur if incisions re-
mained tightly sutured and the wounds were al-
lowed to heal.
For the first experiment, 24 rainbow trout were
obtained from the Utah Division of Wildlife Re-
sources hatchery at Logan, Utah, in May 1986.
The fish were placed in two O.93-m, circular, fi-
berglass tanks, held in 100C circulating well water,
and fed a standard hatchery diet of pelleted food
,( 1-2% body weight/d). On 12 December 1986, the
fish were anesthetized in a 200-mg/L solution of
tricane and weighed and measured (total length,
TL). A dummy transmitter (DTR) was then in-
serted into the body cavity via a lateral incision
through the musculature on the left side of the
fish, anterior to the pelvic girdle along the distal
ends of the ribs. Standard 3.0-mm Ethelon sutures
(4-5 individual sutures per incision) were used to
close the wound. All surgery was performed by the
senior author. After surgery the fish were placed
in fresh water for recovery and subsequently re-
turned to their holding tanks.
Three sizes of round, weighted, wooden dowels
were used as DTRs: small-I x 2.5 cm, 3 g in air;
medium-\.25 x 3 cm, 4.7 g; and large-\.6 x
5 cm, 11.7 g. Each DTR was weighted by placing
lead in a hole drilled in one end. The DTRs were
numbered with india ink and waterproofed with
three coats of varnish (VarathaneS). After the var-
nish had dried for 24 h, 12 DTRs were coated with
melted beeswax and 12 with pharmaceutical-grade
melted paraffin (ParowaxS). Two large DTRs (one
beeswax-coated and one paraffin-coated) were im-
planted in the largest fish, and the remainder were
placed in fish regardless of size. After implanta-
tion, daily inspections were made to determ ine fish
condition and the presence or absence of expelled
DTRs in fish tanks.
All fish were killed after 419 d by placing them
in a lethal concentration of anesthetic. Fish were
weighed, measured (TL), and necropsied to deter-
mine the location of DTRs and degree of tissue
encapsulation. Growth was calculated by subtract-

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