( Schneider and Payne 1983 ) . Prior to the winter of 

 1979-80, a record of environmental conditions at 

 the time of the count was not maintained. Since it 

 is not known to what extent weather or human 

 disturbance near the haul-out site had on zero or 

 near-zero counts previous to 1979-80, all daily 

 counts in January with less than five seals were 

 considered unreliable and excluded from the 

 analyses. There were no available data for 

 January 1973 or January 1977. 



Results and Discussion 



The average number of seals observed per daily 

 count in January (Table 1) ranged from 9.3 seals 

 (1974) to 88.25 seals (1980) with considerable var- 

 iability among years. However, the observed 

 number of seals was not randomly distributed 

 among years; the January averages increased sig- 

 nificantly (P <0.05, r = 0.63, df = 9) between 1972 

 and 1983 (Fig. 1). 



The average annual rate of increase since 1972 

 at Stage Point (based on expected values from the 

 semilogarithmic regression, Table 1) was 11. 9% /yr. 

 The expected average number of seals per daily 

 count in January at Stage Point (Table 1) doubled 

 between 1973 and 1980. 



The observed increase in the average number of 

 seals at Stage Point has followed the termination 

 in 1962 of a Massachusetts bounty on harbor seals 

 and passage in 1972 of the Marine Mammal Pro- 

 tection Act. Rapid expansion of seal populations 

 after the passage of protective legislation has been 

 observed in the past (Hewer 1974; Bonner 1975; 

 Everitt and Beach 1982) and has likely facilitated 

 the increase since 1972 of the number of seals seen 

 at Stage Point. 



TABLE 1. — January averages of seals observed 

 per daily count, 1972-83, at Stage Point, Man- 

 omet, Mass. n.d. = no data. 



An increase in seal populations (after protec- 

 tion) due to unrestricted dispersion of juvenile 

 seals has also been noted elsewhere (Bonner and 

 Witthames 1974; Reijnders 1983). Bonner and 

 Witthames (1974) suggested that the population of 

 common seals, P. v. vitulina, located at the Wash in 

 England, acted as a reservoir from which other 

 reduced populations were replenished. Existence 

 of a seal population in the Dutch Wadden Sea 

 depends on unrestricted dispersal of juvenile seals 

 from adjacent rookeries (Reijnders 1983). Since no 

 rookeries occur south of Maine, it is apparent that 

 the population increase seen at Stage Point (and 

 throughout southern New England) has occurred 

 through the southward dispersion of seals from 

 Maine rookeries, after protection was established 

 in Massachusetts. 



_l 

 < 



tr 



UJ 

 CD 



13 



y=H4898e 

 r = 0626 

 df = 9 

 p<005 



(OII263)x 



'From the linear regression: 

 r= 0.628. P< 0.05 (Fig. 1). 



1 1.4898 e< 011263 >*, 



— I 1 1 1 1 1 i 1 1 1 1 r 



72 73 74 75 76 77 78 79 80 81 82 83 



YEAR 



FIGURE 1 . — Semilogarithmic plot of the average number of seals 

 observed per daily count in January at Stage Point, Manomet, 

 Mass., 1972-83. 



441 



