Influence of Temperature on Mortality and Retention

North American Journal of Fisheries Management

ISSN: 0275-5947 (Print) 1548-8675 (Online) Journal homepage: http://www.tandfonline.com/loi/ujfm20

Influence of Temperature on Mortality and Retention of Simulated Transmitters in Rainbow Trout David B. Bunnell & J. Jeffery Isely To cite this article: David B. Bunnell & J. Jeffery Isely (1999) Influence of Temperature on Mortality and Retention of Simulated Transmitters in Rainbow Trout, North American Journal of Fisheries Management, 19:1, 152-154, DOI: 10.1577/1548-8675(1999)0192.0.CO;2 To link to this article: http://dx.doi.org/10.1577/1548-8675(1999)0192.0.CO;2

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Date: 29 March 2016, At: 07:24

North American Journal of Fisheries Management 19:152–154, 1999 q Copyright by the American Fisheries Society 1999

Influence of Temperature on Mortality and Retention of Simulated Transmitters in Rainbow Trout DAVID B. BUNNELL1

AND

J. JEFFERY ISELY*

Downloaded by [NOAA NMFS La Jolla] at 07:24 29 March 2016

South Carolina Cooperative Fish and Wildlife Research Unit, Department of Aquaculture, Fisheries and Wildlife, Clemson University, Clemson, South Carolina 29634, USA Abstract.—Eighty rainbow trout Oncorhynchus mykiss were implanted with simulated transmitters and held at 10, 15, and 208C for 50 d. Transmitter expulsion ranged from 12% to 27% and was significantly higher at 208C than at 108C. Mortality ranged from 7% to 25% and was not related to temperature. Although researchers should anticipate sample loss due to mortality and expulsion when designing telemetry studies with this species, these results provide evidence that rainbow trout survive at temperatures up to 208C for at least 50 d after transmitter implantation surgery. Thus, radio telemetry may be a viable option for assessing movement of rainbow trout in warm water.

Salmonids often occur in habitats where they are subjected to thermal stress during summer months. Telemetry has become a valuable tool in assessing the response of salmonids to thermal stress (Matthews et al. 1994; Garrett and Bennett 1995; Bunnell et al. 1998). However, studies of salmonids have reported fish mortality of up to 67% following transmitter implantation (Lucas 1989; Clapp et al. 1990; Helm and Tyus 1992). High water temperature has been implicated as a contributing factor to mortality of salmonids (Clapp et al. 1990; Bunnell et al. 1998) and other fishes (Mulford 1984; Schramm and Black 1984; Knights and Lasee 1996) receiving transmitter implants. In some studies, transmitters from what were thought to be inactive trout were recovered from the stream-bed (Meyers et al. 1992), suggesting that either the implanted fish died or the transmitter was expelled. Suture failure (Meyers et al. 1992), incision rupture, and gut passage (Summerfelt and Mosier, 1984; Marty and Summerfelt, 1986) are some of the most commonly documented mechanisms of transmitter expulsion. Transmitter expulsion also has been documented to be directly related to water temperature (Knights and Lasee 1996). * Corresponding author: [email protected] 1 Present address: Aquatic Ecology Laboratory, Department of Zoology, The Ohio State University, Columbus, Ohio 43212, USA. Received May 6, 1998

Accepted August 20, 1998

Identification of factors that influence fish mortality and transmitter expulsion in salmonid telemetry studies is important to ensure the success and reliability of future investigations. Herein, we assess how water temperature influences mortality and transmitter expulsion in rainbow trout Oncorhynchus mykiss receiving transmitter implants. Methods Eighty rainbow trout (204–297 mm total length, 91–293 g) were obtained from the South Carolina Department of Natural Resources Walhalla Fish Hatchery (Walhalla, South Carolina). Ten rainbow trout were stocked into each of eight 375-L recirculating insulated fiberglass raceways equipped with water chillers. Before stocking, raceway water temperatures were adjusted to match the 128C water temperature at the hatchery. Fish were acclimated to the raceways for 2 weeks, then water temperatures in each raceway were adjusted to experimental temperatures of 108C (N 5 3), 158C (N 5 2), and 208C (N 5 3) at a rate of 0.58C/d. Two weeks after the final temperature was achieved, fish were removed from raceways, anesthetized with tricaine methanesulfonate (60 mg/L), implanted with a simulated transmitter, and returned to the raceway. Simulated transmitters were cylindrical and measured about 2.0 cm in length by 31.0 cm in diameter, weighed 1.5–2.0 g, and were fitted with 15 cm of monofilament line to simulate a trailing antenna. Transmitters were constructed of solid polystyrene resin with an imbedded lead weight and were designed to be similar in size and weight to a commonly used, commercially available radio transmitter. The ratio of transmitter weight to fish weight did not exceed 2.0% of body weight for any individual fish. Simulated transmitters were inserted through a 1.5 cm incision in the ventral abdominal cavity between the pectoral and pelvic fins, and the monofilament line protruded through the incision. The incision was closed with three nonabsorbable silk sutures. Fish were fed daily with a commercially avail-

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TABLE 1.—Initial (7 d postimplantation) and final (50 d postimplantation) numbers of fish tested (N), cumulative mortality, and transmitter expulsion for rainbow trout implanted with simulated transmitters and held at three different temperatures. Within a column, values without a letter in common are significantly different (a 5 0.10).


a

Finala

Initial

Temperature (8C)

N

Mortality

Expulsion

N

Mortality

Expulsion

10 15 20

30 20 30

2z 0z 0z

0z 0z 0z

24 16 30

4z 4z 2z

3z 3 zy 8y

Excludes six fish in the 108C treatment and four fish in the 158C treatment that died due to ammonia toxicity.

able trout feed at a rate of 2% of body weight per day. Uneaten feed and accumulated waste were siphoned from each raceway as needed, and water volume was maintained with the addition of up to 5.0% dechlorinated tap water per day. Water quality was maintained through aeration and biological filtration. Sodium chloride (1 g/L) was also added to each tank to reduce nitrite toxicity (Russo et al. 1981). Temperature, pH, ammonia, and nitrite were monitored at least three times per week and remained within recommended levels (,1.0 mg/L NH 3, ,0.4 mg/L NO 2-N; Hillaby and Randall 1979; Wedemeyer and Yasutake 1978) with the following exception. On separate occasions, toxic levels of nitrite (.10 mg/L NO 2-N; Russo et al. 1981) developed due to biofilter inefficiency resulting in death of six fish over a 24-h period 31 d after implantation in one of the 108C raceways and-death of four fish over a 24-h period 36 d after implantation in one of the 158C raceways. These fish were excluded from the final (50 d postimplantation) mortality analysis. Fifty days after transmitter implantation, fish were sacrificed, and a necropsy was performed to determine the location of the transmitter and the degree of tissue encapsulation. Differences in initial (7 d postimplantation) and final (50 d postimplantation) transmitter expulsion and mortality among temperature treatments were evaluated using a chi-square analysis comparing the frequency of expelled versus nonexpelled transmitters and surviving versus nonsurviving fish in each temperature treatment pooled across raceways. Because this research was exploratory in nature and sample sizes were relatively small, a liberal probability (a 5 0.10) was used to determine significance of comparisons. Results and Discussion One fish died immediately after transmitter implantation, and an additional fish died within 1 week of surgery, both in the 108C treatment (Table

1). No temperature effect on initial mortality was observed. Because 100% mortality for transmitterimplanted brown trout Salmo trutta occurred when water temperatures exceeded 188C in a previous study (Clapp et al. 1990), we expected significant initial mortality for rainbow trout at 208C. Final mortality between treatments ranged from 7% to 25% (excluding fish that died due to ammonia toxicity), and no temperature effect was observed (Table 1). These results are consistent with the findings of Chisholm and Hubert (1985), who reported 25% mortality within 22 d of implantation for rainbow trout held in the laboratory in 12–148C water. No transmitters were expelled during the first week (Table 1). Final transmitter expulsion ranged from 12% to 27%, and was significantly higher in the 208C treatment than in the 108C treatment. For fish that retained their transmitters, the incision was closed, although the area around the antenna was often (39 of 46 fish) irritated. All retained transmitters were encapsulated in tissue and adhered to the ventral abdominal wall. No transmitters adhered to the digestive tract, and potential intestinal passage of transmitters was not evident. External examination revealed that most transmitters were expelled through the incision. In two cases, suture failure may have accounted for transmitter expulsion. In all other cases, the transmitter appeared to be expelled from an extension and enlargement of the area around the site of the antenna. In fish that had expelled transmitters, incisions were often (10 of 14 fish) open to the tissue capsule formed in the body cavity but were not necrotic. Reported long-term (.30-d) transmitter expulsion rates for rainbow trout are variable, ranging from 3% to 59% (Chisholm and Hubert 1985; Lucas 1989; Helm and Tyus 1992). Further, Helm and Tyus (1992) found that transmitter expulsion rate was related to the type of transmitter coating. Although the transmitter construction material used in our study may have affected expulsion, rates were within the published range, and


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the effect should have been similar across temperature treatments. Therefore, it may be possible to reduce transmitter expulsion by coating transmitters, but higher expulsion rates should be expected at high temperatures regardless of the material used. It has also been suggested that antenna placement may affect transmitter expulsion (Ross 1982); however, no comparative studies have been conducted. Unexpectedly, transmitter expulsion rates exceeded mortality rates among transmitter-implanted fish in our study. Although high water temperature has been implicated as the cause of mortality in studies involving brown trout (Clapp et al. 1990; Bunnell et al. 1998) and bluegill Lepomis macrochirus (Knights and Lasee 1996), we found that high water temperature alone did not cause mortality of well-acclimated rainbow trout. Although researchers should anticipate sample loss due to mortality and expulsion when designing telemetry studies with this species, these results provide evidence that rainbow trout survive at temperatures up to 208C for at least 50 d after transmitter implantation surgery. Thus, radio telemetry may be a viable option for assessing movement of rainbow trout in warm water. Acknowledgments Fish for this study were provided by the South Carolina Department of Natural Resources Walhalla Fish Hatchery. K. Burrell assisted with transmitter implantation. We also thank C. Kempton, W. Taylor, B. Jones, A. Gallman, and J. Tomasso for technical assistance. The manuscript was improved by the comments of R. A. Stein and J. Tomasso. Cooperating Agencies for the South Carolina Cooperative Fish and Wildlife Research Unit are the U. S. Geological Survey, Biological Resources Division, Clemson University, the South Carolina Department of Natural Resources, and the Wildlife Management Institute. References Bunnell, D. B., J. J. Isely, K. H. Burrell, and D. H. Van Lear. 1998. Diel movement of brown trout in a southern Appalachian river. Transactions of the American Fisheries Society 127:630–636. Chisholm, I. M., and W. A. Hubert. 1985. Expulsion of dummy transmitters by rainbow trout. Transactions of the American Fisheries Society 114:766–767. Clapp, D. F., R. D. Clark, and J. S. Diana. 1990. Range, activity, and habitat of large, free-ranging brown

trout in a Michigan stream. Transactions of the American Fisheries Society 119:1022–1034. Garrett, J. W., and D. H. Bennett. 1995. Seasonal movements of adult brown trout relative to temperature in a coolwater reservoir. North American Journal of Fisheries Management 15:480–487. Helm, W. T., and H. M. Tyus. 1992. Influence of coating type on retention of dummy transmitters implanted in rainbow trout. North American Journal of Fisheries Management 12:257–259. Hillaby, B. A., and D. J. Randall. 1979. Acute ammonia toxicity and ammonia excretion in rainbow trout (Salmo gairdneri ). Journal of the Fisheries Research Board of Canada 36:621–629. Knights, B. C., and B. A. Lasee. 1996. Effects of implanted transmitters on adult bluegill at two temperatures. Transactions of the American Fisheries Society 125:440–449. Lucas, M. C. 1989. Effects of implanted dummy transmitters on mortality, growth, and tissue reaction in rainbow trout, Salmo gairdneri Richardson. Journal of Fish Biology 35:577–587. Marty, G. D., and R. C. Summerfelt. 1986. Pathways and mechanisms for expulsion of surgically implanted dummy transmitters from channel catfish. Transactions of the American Fisheries Society 115: 577–589. Matthews, K. R., N. H. Berg, D. L. Azuma, and T. R. Lambert. 1994. Cool water formation and trout habitat use in a deep pool in the Sierra Nevada, California. Transactions of the American Fisheries Society 123:549–564. Meyers, L. S., T. F. Thuemler, and G. W. Kornely. 1992. Seasonal movement of brown trout in northeast Wisconsin. North American Journal of Fisheries Management 12:433–441. Mulford, C. J. 1984. Use of a surgical skin stapler to quickly close incisions in striped bass. North American Journal of Fisheries Management 4:571–573. Ross, M. J. 1982. Shielded-needle technique for surgically implanting radio-frequency transmitters in fish. Progressive Fish-Culturist 44:41–43. Russo, R. C., R. V. Thurston, and K. Emerson. 1981. Acute toxicity of nitrite to rainbow trout (Salmo gairdneri ): effects of pH, nitrite species, and anion species. Canadian Journal of Fisheries and Aquatic Sciences 38:387–393. Schramm, H. L., and D. J. Black. 1984. Anesthesia and surgical procedures for implanting radio transmitters into grass carp. Progressive Fish-Culturist 46: 185–190. Summerfelt, R. C., and D. Mosier. 1984. Transmitter expulsion of surgically implanted dummy transmitters by channel catfish. Transactions of the American Fisheries Society 113:760–766. Wedemeyer, G. A., and W. T. Yasutake. 1978. Prevention and treatment of nitrite toxicity in juvenile steelhead trout (Salmo gairdneri ). Journal of the Fisheries Research Board of Canada 35:822–827.