FISHERY BULLETIN: VOL. 82, NO. 3 



the major channel, but on 83% (125 d) of 150 cam- 

 era monitoring days, seals were present on Kl. Ten 

 and 12 pups were counted in 1978 and 1979, respec- 

 tively. After the breeding season in July, seals were 

 present on 97% (111 d) of 114 camera days. By 

 contrast, seals were counted on PWI on 56% (54 d) 

 of 96 camera census days during the breeding sea- 

 son and 73% (74 d) of 102 d in the summer. After 

 October, when the population declined, the level of 

 use was still high at Kl with seals present on 81 of 

 92 camera census days. 



Daily Use 



Peak numbers of seals usually occurred in early 

 afternoon at both sites except at Kl during winter 

 when a constant number were present until late 

 afternoon (Table 1, Figs. 2, 3). All the daily trends 

 were significantly different from randomness ex- 

 cept for PWI during winter [P = 0.02 for Kl winter, 

 P = 0.008 for Kl breeding, P = 0.007 for Kl sum- 

 mer; 0.24 < P < 0.06 for PWI winter, andP < 0.001 

 for PWI breeding and summer ("runs up and down 

 test")]. The greater use of Kl during the summer 

 and breeding seasons is also reflected in the ele- 

 vated hourly means (Fig. 2). 



Correlation coefficients revealed a positive cor- 

 relation between low tides and seal numbers (Ta- 

 ble 2). The daily temporal use pattern (Table 1) 

 was affected by tide level during winter (range of 

 r = 0.54 - 0.75) and summer (range of r — 0.49 - 

 0.69) for Kl and to a lesser extent during the sum- 

 mer for PWI (range of r = 0.11 - 0.62). No tidal 

 effect was apparent at either site during the breed- 

 ing season. 



24 

 22 



20 



18 

 a: 



O 



x 16 

 on 



LU 



°- 14 



o 

 cc 10 



LU 

 HI 



5 

 => 8 



KENT ISLAND 



• = WINTER 



t - BREEDING 



• = SUMMER 



i i i i 



7 8 9 10 I I 12 13 14 15 16 17 18 19 20 

 TIME OF DAY (PST) 



FIGURE 2. — Graph of time of day and the mean number of seals 

 hauled out per time period for winter, breeding, and summer 

 seasons at Kent Island. 



Disturbance 



Camera and field observations of Kl recorded 

 539 actual and zero-seal disturbances. Of those 

 with identifiable cause, 33.1% were nonpower 

 boats, 10.0% people on foot, 7.8% powerboats, 3.4% 

 clam diggers or bait harvesters, 2.8% dogs, and 



TABLE 1. — The relationship between time of day and the number of seals hauled out per season on Kent Island (Kl) and 

 Pickleweed Island (PWI); x is the mean number of seals per hour, SD is the standard deviation, and n is the sample size. 



496 



