RADIO TRACKING THE MOVEMENTS AND ACTIVITIES OF 



HARBOR PORPOISES, PHOCOENA PHOCOENA (L.), IN 



THE BAY OF FUNDY, CANADA 



Andrew J. Read and David E. Gaskin^ 



ABSTRACT 



Eight harbor porpoises were radio-tagged (172-173 MHz) and released in the western Bay of Fundy between 

 August 1981 and August 1983. The duration of contact with radio-tagged animals ranged from 0.3 to 

 22.4 days. One harbor porpoise was tracked for 22.4 days and utilized a home range area of 210 km^. 

 In all observed cases, the movement of radio-tagged porpoises coincided with the direction of tidal flow 

 in the major channels and passages of the region. Analysis of 39.2 hours of ventilation sequences revealed 

 that radio-tagged porpoises were relatively inactive from midnight until 0600 and more active during 

 other periods. 



This report documents the results of a study on the 

 movements and activities of radio-tagged harbor 

 porpoises, Phocoena phocoena, in the Bay of Fundy, 

 Canada. The primary objective of this research was 

 to determine the home ranges of individual harbor 

 porpoises during the summer months. The study 

 also provided insights into the behavior and ac- 

 tivities of radio-tagged animals. 



Studies of cetacean home ranges often rely on 

 resightings of tagged or naturally marked animals 

 (Irvine et al. 1981; Bigg 1982; Dorsey 1983). These 

 methods are of limited value if individual animals 

 travel outside the area under observation and may 

 result in underestimation of the utilized range. A 

 more effective means of estimating home range area 

 is to monitor the movements of radio-tagged in- 

 dividuals (McDonald et al. 1979). Several recent 

 studies have successfully employed radio-tracking 

 techniques in field studies of cetacean species (see 

 review by Leatherwood and Evans 1979). Notable 

 among these are investigations of Delphinus delphis 

 by Evans (1971), of Tursiops truncatus by Irvine 

 et al. (1981), and of Lagenorhynchus obscurus by 

 Wursig (1982). 



In a preliminary study of harbor porpoise move- 

 ments (Gaskin et al. 1975), we demonstrated that 

 radio-tracking techniques could be successfully ap- 

 plied to this species. Although this initial research 

 was promising, we felt that the transmitters 

 available at that time were too large to be carried 

 by these small porpoises (see Watson and Gaskin 

 1983). The recent development of smaller transmit- 



'Department of Zoology, University of Guelph, Guelph, Ontario 

 NIG 2W1 Canada. 



ters and the continuing availability of live porpoises 

 from herring weirs (Smith et al. 1983) have enabled 

 us to undertake the present study. 



METHODS 



The study area encompases Passamaquoddy Bay, 

 the channels and passages around Deer Island, and 

 waters further offshore to Grand Manan Island (Fig. 

 1). During the summer, mean monthly water tem- 

 peratures for the upper 25 m of the water column 

 range from 6.4° in June to 11.0°C in September 

 (Bailey et al. 1954). The oceanography of the region 

 is dominated by large semidiurnal tides, which have 

 a mean amplitude of 5.5 m at North Head, Grand 

 Manan (Anonymous 1982). The large tides generate 

 strong currents, with velocities reaching a maximum 

 of 2.4 m/s in Letite Passage (Forrester 1960). Fur- 

 ther information regarding the oceanography of the 

 region may be found in Smith et al. (1984). 



Harbor porpoises were seined from herring v/eirs 

 (Smith et al. 1983), placed on a sheet of open cell 

 foam, sexed, and measured. The porpoises were 

 liberally sprinkled with seawater throughout the 

 tagging procedure to prevent overheating. Two 0.64 

 cm diameter holes were bored through the dorsal 

 fin with a laboratory cork borer, cleansed in alcohol 

 prior to use. The holes were immediately cold- 

 cauterized with a histological freezing spray. 



Transmitters were attached to the dorsal fin with 

 two 0.64 cm diameter stainless steel bolts, each 

 covered with a thin sleeve of teflon (see Figure 2). 

 A thin, neoprene-lined plastic plate was placed 

 between the transmitter and dorsal fin and an iden- 

 tical plate was positioned on the opposite side of the 



Manuscript accepted November 1984. 

 FISHERY BULLETIN: VOL. 83, No. 4, 1985. 



543 



