FISHERY BULLETIN: VOL. 83, NO. 4 



of the porpoise. To ensure bearing accuracy, a series 

 of readings were taken at each location, and the 

 average used in triangulation (Springer 1979). Each 

 sighting or radio location was assigned to a 1 km 

 grid square of the Universal Transverse Mercator 

 System. Derived radio locations were discarded if 

 the triangulation could not place a porpoise within 

 a 1 km square; the time elapsed between fixes and 

 bearing error (± 5°) precluded more precise estima- 

 tion. Positional data were collected at least once a 

 day, but usually on a more frequent basis. 



The radio signal was received only when the trans- 

 mitting antenna was exposed, allowing the duration 

 of both submergence and surface periods to be 

 recorded. Such ventilation data were collected on 

 an opportunistic basis throughout the tracking 

 period of each porpoise. 



A detailed analysis of the methods used in this 

 study is presented in Read and Gaskin (1983). 



RESULTS 



Movements 



Eight harbor porpoises were released carrying 

 transmitters over the course of the study (Table 1). 

 During the attachment procedure, porpoises were 

 out of the water for a mean of 6.6 min (SD + 1.4, 

 n = 8), during which time most animals remained 

 fairly still. Only two porpoises exhibited any trauma 

 while being handled; RT-5 vomited briefly, and RT-7 

 (a 110 cm calf) repeatedly lashed its flukes. The lat- 

 ter porpoise appeared momentarily disoriented 

 when returned to the water, but quickly resumed 

 swimming and surfacing normally after being join- 

 ed by a larger porpoise. The larger animal, presum- 

 ably the calf's mother, had also been trapped in the 

 weir, but escaped overnight and remained in the 

 vicinity until the calf's release. 



Duration of radio contact ranged from 0.30 (RT-5) 

 to 22.4 d (RT-2), with a mean of 5.1 d (SD ± 7.1, 

 n = 8). In some instances, loss of radio contact may 



Table 1. — Data summary for harbor porpoises radio-tagged and 

 released in the western Bay of Fundy. 



have been due to the premature release of the 

 transmitter package. The rear bolt attaching the 

 transmitter to the dorsal fin of RT-3 was missing 

 when the porpoise was photographed 5 h before 

 signal loss occurred. The radio signals of RT-3 and 

 RT-7 were being monitored when contact was lost, 

 and in both cases termination of the signal was 

 abrupt, a pattern compatible with the hypothesis of 

 transmitter loss. In our limited observations of 

 radio-tagged porpoises (see below), we did not see 

 any evidence of displacement of the transmitter 

 package (Irvine et al. 1982). 



Over the course of the study, three porpoises were 

 released from the same weir in Whale Cove, Grand 

 Manan. Attempts to relocate RT-1, the first porpoise 

 released in Whale Cove, were frustrated by fog and 

 heavy seas which persisted for the entire 3-d track- 

 ing period. In addition, the shoreline configuration 

 of northern Grand Manan prevented accurate 

 triangulation. However, the strength and direction 

 of the signal received from shore indicated that the 

 porpoise remained in the vicinity of northern Grand 

 Manan until signal loss occurred. The movements 

 of the other two porpoises released in Whale Cove 

 (RT-3 and RT-7) are illustrated in Figure 3 A and B. 



On 30 August 1982, four porpoises were reported 

 trapped in a weir in Back Bay, mainland New 

 Brunswick. A female (RT-4), accompanied by a 101 

 cm calf, and a young male (RT-5) were released on 

 31 August. The remaining porpoise, another young 

 male (RT-6), was tagged and released the following 

 day. RT-4 and RT-5 remained together for at least 

 7 h, after which contact was lost with RT-5. The 

 movements of RT-4 and RT-6 are depicted in Figure 

 3C and D. 



The longest tracking sequence recorded in this 

 study was that of RT-2, released near St. Andrews, 

 mainland New Brunswick. This porpoise spent the 

 majority of its 22-d tracking period within Passa- 

 maquoddy Bay, although occasional excursions were 

 made to the east of Deer Island (Fig. 4). The home 

 range of RT-2, calculated using the convex polygon 

 method, was about 210 km^ (excluding land 

 masses). 



RT-8, the only porpoise to be radio-tagged in 1983, 

 travelled from its release point in northern Passa- 

 maquoddy Bay to West Quoddy in about 48 h. 

 Logistical constraints prevented more precise deter- 

 mination of the movements of this animal. 



Figure 3.— Movements and positions of radio-tagged harbor por- 

 poises in the Bay of Fundy. The release point of each porpoise is 

 indicated by a star. A) Position of porpoise RT-3 at 1200 of each 

 day of tracking period; B) Movements of porpoise RT-7; C) 

 Movements of porpoise RT-4; D) Movements of porpoise RT-6. 



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