Figure 3. — The harness, radio transmitter and 

 timed release mechanism: (A) OAR PT-202 

 radio transmitter (B) 5 mm curved aluminum 

 dorsal plate (C) Plastic-impregnated nylon re- 

 inforcing sewn on harness of Lino i^ 241 material 

 (D) Nylon reinforcing strap sewn into harness 

 and bolted to dorsal plate (E) Rows of grommets 



(F) Knurled nuts holding harness to dorsal plate 



(G) Instrument housing (H) Polyvinyl chloride bat- 

 ten (I) Harness legs with "D" rings (J) Polyurethan 

 flotation device attached by straps to dorsal 

 plate (K) Timed-release mechanism (L) Alu- 

 minum corner posts to which "D" rings of har- 

 ness legs attach (M) Receptacles for above 

 posts — spring loaded (N) Magnesium bolt 

 passes through spring loaded hole in top plate 

 and secured with a nut. 



Dimensions: (1) Harness width 40 cm (2) 

 Harness length 112 cm from timed — release 

 mechanism to first row of grommets <3) Distance 

 between each of five rows of grommets — 5 cm 

 (4) Length of harness legs 40 cm (5) Timed 

 release mechanism 10 x is cm. 



TRACKING AND 

 HARNESS RECOVERY 



The three harnessed whales re- 

 mained within a few hundred meters 

 of their release points (see Figure 1). 

 Visual tracking in daylight was greatly 

 assisted by the bright yellow float and 

 upper harness which were visible even 

 a foot or two underwater. 



in the first release, after some time 

 in the water, the calf swam purpose- 

 full> toward the Unison, turned on 

 her side, and rubbed the harness 

 against the hull and keel of the boat — 

 breaking the float partly loose, releas- 

 ing one "D" ring, and snapping the 

 fiberglass radio antenna. Transmission 

 of radio signals immediately ceased. 

 This damage could have been prevent- 

 ed by our maintaining a greater dis- 

 tance from the harnessed animal. The 

 timed-release mechanism contained a 

 ."^-hour bolt which had not released 

 by the time darkness fell. The harness 

 was recovered 2 days later in vegeta- 

 tion along the channel edge, about 2 

 km from the release point. 



The second release, timed for some- 

 what less than 5 hours, went flawlessly, 

 including radio tracking and harness 

 release. 



The third release was planned for 

 20 hours, with tracking overnight 

 from the Loiisim. To assist after dark 

 should the radio malfunction, a water- 

 proof lifejacket light was ti.xed to the 

 float. Though both radio and light 

 functioned at release, thev failed before 



62 



