HARNESS FOR ATTACHMENT OF 



AN ULTRASONIC TRANSMITTER TO 



THE RED DRUM, SCIAENOPS OCELLATA 



The use of small ultrasonic transmitters for 

 studying the movement and behavior of fish in the 

 field is becoming very popular (Stasko 1971). As a 

 result various methods have been devised for 

 attaching transmitters to fish either externally or 

 internally. These methods involve hooking into the 

 dorsal musculature or insertion into the stomach 

 (Henderson et al. 1966), surgical implantation into 

 the peritoneal cavity (Hart and Summerfelt 1975), 

 and others (Ohsumi 1969). The suitability of a 

 procedure is dependent on the species of fish and 

 on the particular objective of the study. For 

 studies we are initiating on movements of the red 

 drum, Sciaenopii ocellafa, none of the existent 

 •procedures were found to be entirely satisfactory. 

 This note describes a simple inelastic harness we 

 have developed for the external attachment of an 

 ultrasonic transmitter to the caudal peduncle. This 

 attachment method is markedly superior to other 

 methods we have tried with the red drum. We 

 believe this procedure will be of immediate value 

 to many workers involved in tracking studies and 

 therefore we are describing it now rather than 

 awaiting the completion of our investigation of 

 migratory movements of the red drum. 



Materials and Methods 



The inelastic harness for attaching an ultrasonic 

 transmitter to the caudal peduncle is shown in 

 Figure 1. The components of the harness are as 

 follows: 



1. An inelastic plastic pull-tie (5 x 190 mm) of 

 sufficient length to encircle the caudal peduncle; 



2. Sections of soft Tygon' tubing (6-mm OD) 

 and soft rubber tubing (12-mm OD, 1.5-mm wall 

 thickness) threaded over the pull-tie to provide a 

 soft flat cushion that minimizes abrasions and 

 chafing to the fish when the pull-tie is attached 

 and tightened; 



3. Small plastic pull-ties to firmly affix the 

 transmitter to the large pull-tie and tubing de- 

 scribed above. 



When attaching the harness, the large pull-tie is 

 tightened just enough such that it fits snugly 

 around the caudal peduncle and cannot slip over 

 the tail (Figure 1 inset). Care must be taken not to 

 tighten the tie so tightly that it compresses the 

 peduncle. If the latter occurs, the tie must be cut 

 off with scissors and replaced. These ties can only 

 be tightened. The final position of the transmitter 

 itself should be on the dorsal surface of the 

 peduncle with the axis of the transmitter situated 

 at a right angle to the longitudinal axis of the fish. 

 After attachment the overlapping section of the 

 pull-tie is cut off. 



Harnesses are preconstructed prior to the time 

 of use such that in the field the only modifications 

 required are the addition or removal of small 

 sections of Tygon and rubber tubing to provide a 

 cushion of the exact size for a particular fish. A 

 preconstructed harness can be attached to a red 

 drum in less than 5 min. Plastic pull-ties of various 

 lengths and widths are available at most hardware 

 stores that stock materials used bv electricians. 



'Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Ser\Mce, NOAA. 



Figure 1. -Inelastic harness for at- 

 tachment of ultrasonic transmitter to 

 caudal peduncle of red drum. 

 Transmitter = Smith Root SR 69. 

 Total length of harness = 190 mm. 

 Inset: Red drum (3.2 kg) with harness 

 and transmitter attached. 



998 



