| Abstract: | Pink salmon is found from 40° to 70°N; but successful reproduction occurs over a much more restricted area, from about 47° to 60°N. The time window of spawning opportunities is censored both at the southern and the northern boundaries, and reaches its widest expansion in south east Alaska extending from 54° to 58°N, more or less in the central part of the occupied area. Duration of peak spawning time for a single population seemingly does not vary with latitude, but the number of spawning populations increases from the northern and the southern limits toward the centre of distribution. Recent intensive studies of straying of pink salmon from enhanced stocks in Prince William Sound into wild stocks and vice versa have given estimates of high straying rates (J. Seeb personal communication). But movement of tagged fish into other streams than the one of origin does not automatically indicate successful spawning. The existence of more than 2000 pink salmon streams in south east Alaska, each with a characteristic time of spawning in spite of straying, indicate that there exists barriers, which prevent or reduce successful interpopulation spawning. |
