GASKIN and WATSON: HARBOR PORPOISE 



METHODS 



Most observations were made from a 5 m two- 

 seater kayak (weather permitting), which appeared 

 to exercise a negligible effect on the behavior of 

 animals even at short distances (Watson 1976). A 

 small fishing boat was used above Beaufort wind 

 force 2, but this craft lacked the silent 

 maneuverability of the kayak. Few publishable 

 photographs were obtained because this species is an 

 exceedingly difficult photographic subject. The 

 method of making and maintaining contact was con- 

 sistent throughout the study period (1 June 1970-10 

 September 1978). A central route from the head of 

 Lords Cove was followed (Fig. 1); unless weather 

 was too poor for optimal sighting in Simpson's 

 Passage, or there was specific intent to track a group 

 within Fish Harbour, the boat continued on track to 

 watch-station 2 (Fig. 1). If no animals were present 

 in Fish Harbour and conditions were less than Beau- 

 fort wind force 2, the boat would remain in the vicin- 

 ity, but if the animals were already within Fish Har- 

 bour, the boat usually returned to watch-station 1 in 

 outer Fish Harbour, from which point most of the 

 study area normally used by porpoises could be kept 

 under eye or binocular surveillance. As weather per- 

 mitted, or presence and movements of animals dic- 

 tated, this search pattern was usually repeated dur- 

 ing the day at invervals of several hours. When 

 porpoises were located either visually or from the 

 sound of their expirations, the position of the boat 

 and the initial positions of animals relative to the 

 vessel were recorded to within a few tens of meters 

 by taking 3-5 bearings from the many surrounding 

 landmarks. Subsequent positions were noted in those 

 cases when movements were tracked for extended 

 periods, providing the animals surfaced long enough 

 for accurate bearings to be taken and had moved to a 

 significant distance (ca. 100 m) from the previous 

 location. The time, location, size, and apparent com- 

 position of each porpoise group was recorded on and 

 later transcribed from tape. The particular problems 

 of quantifying sightings of this small cetacean have 

 been considered by Gaskin (1977), Prescott et al. 

 (footnote 2), Taylor and Dawson (1984), Kraus et al. 

 (footnote 4, 1983), and Watts and Gaskin (in press). 

 During the present study we used only data obtained 

 in Beaufort Sea state 0-1, when visibility was 

 unlimited within the study area and lighting was 

 direct or diffuse, but uniform. In these ideal condi- 

 tions some porpoises can be detected even from the 

 air (250 m) at 650 m, although this is the least satis- 

 factory method for sighting this species (Kraus et al. 

 1983). In a simultaneous comparison of effectiveness 



of stationary, mobile, and aerial observers (Kraus et 

 al. 1983) the former, whether on land or stationary 

 vessel, not only saw far more animals than the 

 observers in the aircraft, but could detect them using 

 binoculars in calm water at 1,000 -(- m. The prob- 

 bability of contact is enhanced when animals tend to 

 surface repeatedly. The present authors found that 

 porpoises working near the Nub close to the Simp- 

 sons Island (Fig. 1) could be clearly seen with binocu- 

 lars from watch-station 1, at a distance of > 1 km in 

 optima] conditions. 



Some natural constraints on distribution of por- 

 poises within the study area reduced the effective 

 survey region to only 4 km-. Virtually no animals 

 ventured farther inshore than the shallow shelf edge 

 (ca. 5 m) even during high water. Almost all ingress 

 and egress was between Bean and Fish Islands (Fig. 

 1). Very few animals left by the southern passage 

 from Lords Cove, and only two were ever noted to 

 enter this way. Only one group of animals consistent- 

 ly visited Lords Cove in any case. No movement was 

 noted through the narrow gut west of Hardwood 

 Island, and only infrequent movement (< 5%) 

 through the passage north of Fish Island. 



Harbor porpoises in the Quoddy region appeared 

 generally indifferent to boat traffic (Watts and 

 Gaskin in press), with no noticeable attraction bias as 

 noted for Phocoenoides dalli by Kasuya and Jones 

 (1984). Because of the small size of the study area, 

 the impossibility of making random transects, the 

 highly clumped distributions, and nonrandom move- 

 ments of animals (see latter), any kind of line- 

 transect approach was inappropriate. From a 

 combination of the initial strip census search and the 

 stationary observations, we concentrated on obtain- 

 ing a "best estimate" of the mean number of animals 

 present during each observation period with 

 reference to each hour of the day and each tide sub- 

 phase within that period. All are minimum estimates 

 because some animals were probably missed at the 

 seaward periphery of the study area. We tried to 

 avoid inclusion of repeat sightings in these estimates 

 which would lead to an upward bias, except where 

 we calculated simple sightings of individuals per 

 hour. The "best estimate" data were used to give 

 relative abundance with respect to various en- 

 vironmental conditions, while sightings per hour 

 were more appropriate for time-based comparisons 

 such as relative abundance from year to year. 



When sighting conditions were particularly favor- 

 able, the movements of specific groups were plotted, 

 either by observation from one or other watch- 

 stations which commanded a wide view with many 

 landmarks, or by discreetly following them in the 



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