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<br />LITERATURE CITED
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<br />Avault, J. W., Jr. ]965. Preliminary studies with grass carp for aquatic weed
<br />control. Prog. Fish-Cult. 27(4):207-209.
<br />, R. O. Smitherman, and E. W. Shell. 1968. Evaluation of
<br />eight species of fish for aquatic weed control. In: FAO Fisheries Rep.
<br />No. 44 vol. 5:VII/E-3, p. 109-122.
<br />Bogorov, V. G. 1934. Instructions for collecting and examining materials
<br />obtained in investigations of plankton-eating fishes. (Transl. from
<br />Russian) 13 p. Fish. Res. Bd. Canada, Transl. Ser. No. 254.
<br />Carlander, K. D. 1969. Handbook of freshwater fishery biology. Vol. I.
<br />Iowa State Univ. Press, Ames, Iowa.
<br />Kilgen, R. H. and R. O. Smitherman. 1971. Food habits of the white amur
<br />stocked in ponds alone and in combination with other species. Prog.
<br />Fish-Cult. 33(3): 123-127.
<br />Schmittou, H. R. 1969. Some effects of supp]emental feeding and controlled
<br />fishing in largemouth bass-bluegill populations In: Proc. 22nd Ann. Meet.
<br />Southeast. Assoc. Game and Fish Comm., p. 311-320.
<br />Stevenson, J. H. 1965. Observations on grass carp in Arkansas. Prog. Fish-
<br />Cult. 27(4):203-206.
<br />Swingle, W. E. and E. W. Shell. 1971. Tab]es for computing relative conditions
<br />of some common freshwater fishes. Auburn University Agric. Exp.
<br />Sta., A]abama, Circular 183. 55 p.
<br />
<br />SURVIVAL, GROWTH, AND FEED CONVERSION OF
<br />CHANNEL CATFISH AFTER ELECTRONARCOSIS
<br />
<br />James E. Ellis, Fisher)' Biologist
<br />Bureau of Sport Fisheries and Wildlife
<br />Fish Farming Development Center
<br />P.O. Box 711
<br />Rohwer, Arkansas 71666
<br />
<br />ABSTRACT
<br />
<br />Electrically narcotized and untreated lots oftwo-year-o]d channel catfish (/c-
<br />lalurus punctatus) were held in divided cages in a pond to determine the effects
<br />of narcosis on their survival. growth, and feed conversion. Fish were narcotized
<br />by exposure to 1.5 vot]s/cm for 60 seconds duration with either 60 hertz
<br />alternating current, continuous direct current, or pulsed direct current of 15,20,
<br />or 25 pulses/sec.
<br />There was no significant difference in survival, growth, or feed conversion
<br />between the treated and untreated lots at the 0.01 probability level.
<br />
<br />INTRODUCTION \
<br />. \
<br />
<br />The use of electricity in fisheries is a recognized research and management
<br />tool. The possibility of exposure to electrica] parameters that affect the
<br />morphology and physiology of fish is of major concern to investigators in
<br />management, harvesting, and grading studies. Maxfield, et al.( 197 I) found that
<br />pulsed direct electrical current had no effect on the survival, growth, and fee un-
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<br />dity ~f yearling an~ young-of-the-year rainbow trout (Salmo gairdneir).
<br />McGnmmon and BIdgood (1965) reported that alternating current had no
<br />significant effect on vertebrae in rainbow trout, but that fish may be adversely
<br />~ffected in other ways. Another investigator, Hauck (1947), found that alternat-
<br />Ing current fractured vertebrae, ruptured arteries and veins, and caused
<br />~emorrhaging in rainbow trout. Adams, et al. (1972) suggested that the recovery
<br />tIme of common shiners (Notropis comUlUS in a direct current electrical field
<br />was related to power density and that expos ures to current for over 120 seconds
<br />resulted in high mortality due to the narcotic effect of direct current. Spencer
<br />(1967) found that bluegill (LRpomis macrochirus), channel catfish (Ictalurus
<br />punctatus), and largemouth bass (Micropterus salmoides) had broken frac-
<br />tured, and dislocated vertebrae with hemorrhaging in that area after prol~nged
<br />exposure to alternating or continuous direct current parameters.
<br />Conc~rn over the effects of electrici.ty on catfish led to this sl udy to compare
<br />the survIval, growth, and feed conversion of channel catfish exposed to narcotic
<br />levels of electricity with those of untreated fish.
<br />
<br />MA TERIALS AND METHODS
<br />
<br />Two-year-oJd channel catfish were used in this study. Test and control fish
<br />were given a prophylactic treatment for 12 hours in 25 ppm formalin and 3 hours
<br />in 5~ ppm nitrofurazone, then held for three weeks prior to electroshocking.
<br />Fls~ were exposed to selected e!~ctrical treatments, then placed into divided
<br />cages In a 1.6-ha pond. Each cagec;,-as divided in two with a control lot of catfish
<br />on one side, and experimental fish on the other. Equal numbers of fish were
<br />placed in each half-cage. The cages were 1.8 x 0.9 x 0.9-m-deep, and constructed
<br />of 4 mm square mesh aluminum wire attached to an aluminum frame.
<br />Test fish were exposed in lots of 200 to one of five electrica] treatments: 60
<br />hertz alternating current, continuous direct current, and pulsed direct current of
<br />I-mil~isecond duration of exponential shape at 15,20, and 25 pulses/see in an
<br />electncal test cham ber. The test cham ber was a fiberglass tank 1.0 x 0.6 x O.4-m-
<br />deep containing 600 I of water at 22 C and a conductivity of 200
<br />micromohos/cm. Aluminum electrodes were suspended from wooden blocks
<br />perpendicular to the long axis of the tank. Each experimental lot was placed in
<br />the chamber and immediately exposed to a voltage amplitude of 1.5 volts/em for
<br />60-secon~s ~uration. This ex~osur~ period was longer than fish usually en-
<br />counter In fishery survey studIes WIth electrical shockers. All fish in each lot
<br />regained consciousness within two hours post-treatment. Each treatment was
<br />re~licated. Ten treated groups, and 10 untreated control groups (an average
<br />weight of. 14.0 g) were held in cages in a pond to check for delayed adverse
<br />effects. FIsh were fed equal amounts of floating nutrionally--complete trout
<br />ration 112 times during a 133 day growing period (June 7 through October 17
<br />1972). '
<br />Fish were dipped from the cages after they were killed with rotenone, and
<br />allowed to harden in 10% formalin for four days, washed in water, and stored in
<br />50% isopropyl alcohol prior to taking measurements. A subsample of 50 fish
<br />from each lot was measured to determine total length and individual weights.
<br />Total numbers and weights of the remaining fish were recorded. All
<br />measurements were completed within two weeks.
<br />
<br />RESULTS AND DISCUSSION
<br />
<br />Data on survival, growth, and feed conversion are summarized in Tab]e I. An
<br />analysis of treatment of the data comparing the variance within and among
<br />treatment and control lots demonstrated that there was no significant difference
<br />(P less than 0.01) in survival, growth, or feed conversion (Tab]e 2).
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<br />625
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