The red drum used for testing the harness were 

 caught in the Matanzas Inlet, Fla., by hook and 

 line and maintained in captivity for approximate- 

 ly 2 mo prior to testing. 



Results and Discussion 



Observations of the suitability of the inelastic 

 harness were conducted in a 3.3-m diameter fiber 

 glass tank, in an enclosed half-acre pond (max 

 depth 2.5 m), and in the Intracoastal Waterway 

 near the Whitney Marine Laboratory. In the fiber 

 glass tank, two red drum (2.5, 3.5 kg) with har- 

 nesses and "dummy" transmitters attached swam 

 normally as soon as released and accepted food of 

 shrimp and mullet within 30 min. A third red drum 

 (ca. 3 kg) with harness and active transmitter 

 (Smith Root SR 69) attached was released in the 

 half-acre pond. During the 3-wk lifetime of the 

 batteries in the transmitter, the movements of the 

 fish were monitored almost daily with a receiver 

 and hydrophone. The red drum moved actively 

 about the pond, ate readily, and schooled with 

 other fish. Mangrove roots, pilings, and other 

 obstacles in the pond were not snagged by either 

 the harness or the transmitter. More than 2 mo 

 after the fish was initially released, the harness 

 and inactive transmitter remained in place, and 

 the fish continued to feed and behave normally. 



A fourth red drum (3.2 kg) with harness and 

 active transmitter attached was released into the 

 Intracoastal Waterway on 12 January 1976 and 

 tracked continuously for 7 h from a boat with a 

 74-kHz receiver and hydrophone. The position of 

 the fish with respect to charted channel markers 

 was recorded frequently to provide the summary 

 described below. During the first 1.5 h after 

 release, the fish moved approximately 1.6 km to 

 the south of the release point. This movement was 

 against the direction of the tidal flow. During the 

 remaining time the fish moved 1.2 km to the north, 

 again against the direction of the tidal flow. 

 During this excursion, the fish entered the mouth 

 of almost every creek encountered. At nightfall 

 the fish had moved into a deep hole approximately 

 140 m up a small creek situated 400 m from the 

 original release point. The fish was not located on 

 the second day but on the third day was located at 

 the edge of the main channel of the Intracoastal 

 Waterway approximately 2 km to the south of the 

 release point. Tracking of the fish had to be 

 discontinued due to a malfunction in the receiver. 



For the studies we are initiating on migratory 

 movements of the red drum, the method selected 

 for the attachment of the transmitter was ex- 

 tremely important, and we spent considerable 

 time trying alternative methods. These methods 

 included the hooking of saddles into either the 

 dorsal or ventral musculature, surgical attachment 

 to the pectoral girdle or to the lower jaw bone, 

 surgical implantation into the peritoneal cavity, 

 and insertion into the stomach. Utilization of the 

 inelastic harness provided the following advan- 

 tages over the other methods we tried. 



1. The attachment procedure is simple and 

 quick enough such that only a few minutes elapse 

 between the time the fish is caught, tagged, and 

 released. 



2. The procedure results in no bleeding and 

 causes minimal trauma, damage, or weakening of 

 the fish. 



3. The attachment is secure and assures that the 

 transmitter remains attached to the red drum for 

 the lifetime of the transmitters we are using 

 (Smith Root SR 69 and SR 69A, lifetimes of 20 and 

 45 days). 



Ichihara (1971) described a "saddle type" meth- 

 od for affixing a transmitter to a fish. This method 

 employed an elastic strap of neoprene rubber that 

 encircled the fish anterior to the dorsal fin. The 

 author noted that fish with elastic harnesses of the 

 saddle type died within 9 to 30 days. Regarding the 

 above observations, we have also found that rub- 

 ber elastic harnesses encircling the caudal pedun- 

 cle are unsatisfactory because they constantly 

 compress the peduncle and result in a progressive 

 deterioration of the entire tail region. However, 

 our inelastic harness causes no such deleterious 

 effects. Although we have experimented with the 

 inelastic harness on the red drum only, we are 

 certain that it can be used with any large fish 

 having a fairly rigid tail that is markedly broader 

 than the caudal peduncle. 



Acknowledgments 



We are grateful to Jack R. Smith, Department 

 of Electrical Engineering, University of Florida, 

 for providing the hydrophone and 74-kHz receiver 

 used in the current study. We also thank Marine- 

 land, Inc., for permitting us to use their saltwater 

 pond and other facilities. 



999 



