MOVEMENT OF THREE SPECIES OF FISHES 535 



thermal effluents (Coutant, 1969; Merriman, 1970; Ross, 1970; 

 Kelso, 1974; Wrenn, 1976; Leggett, 1976) we chose this approach 

 for our study. Major objections to sonic tagging include the possible 

 alteration of normal behavior, the smcill number of individuals that 

 can be studied because of overlap in signals, and the expense of the 

 transmitters. 



The objective of our study was not to describe normal 

 movement, however, but to determine whether the cooling-water 

 discharge from a coal-powered steam generating plant on the Coosa 

 River, Alabama, was an impassable barrier during warm months when 

 thermal influence was maximum. Sonic tagging was meant to 

 demonstrate only the feasibility of passage through a thermal 

 effluent and not the percentage of a species which might do so. 



MATERIALS AND METHODS 



Three species of catfish and the largemouth bass were studied. 

 All bass were collected by electrofishing within the study area. 

 Catfish came from various sources. Two channel catfish {Ictalurus 

 punctatus) were seined from ponds at the Auburn University 

 Fisheries Research Unit. Two of the three flathead catfish {Pylodictis 

 olivaris) were captured in gill nets in the study area, and one flathead 

 and two blue catfish (/. furcatus) were caught in Lay Reservoir about 

 13 km downstream from the study area. We felt justified in using 

 nonresident fishes because a description of normal movement was 

 not the objective. 



Several techniques have been used successfully to attach trans- 

 mitters to fishes. We used the surgical implantation techniques 

 described by Hart and Summerfelt (1975). The fishes were anes- 

 thetized, and a 3-cm medial incision was made along the abdomen 

 parallel to the ventral midline and anterior to the pelvic girdle. We 

 inserted the tag in a lateral position and closed the incision with 00 

 Ethicon silk suture (Johnson & Johnson), using 5 to 8 interrupted 

 surgeons' stitches. The closed incision was painted with a solution of 

 malachite green to inhibit fungal growth. The average time necessary 

 to complete the surgical procedure was 9 min. Each fish was retained 

 for a 24-hr postoperative period to monitor recovery and permit the 

 fish to become adjusted to the mass of the transmitter. 



The tracking vessel was a 5-m flathull aluminum boat with a 

 40-hp outboard motor. A Smith— Root, Inc., TA-60 receiver and 

 SR-70H hydrophone were used in tracking. The hydrophone had an 

 8° cone of reception and could be rotated through 360°. Two types 

 of transmitters were used. The Smith— Root, Inc., SR-69-A had a 



