Vol. 53 - Alaska Resources Library and Information Services

maturity as males at age 3.5 years in the Bering Sea and remain breeding
males for two seasons.
After a transitional period they subsequently
develop female characteristics by 5.5 years (Ivanov 1969; Butler 1971).
Females can mature early and circumvent the male phase entirely in populations
found in southern parts of the range (Allen 1959; Butler 1964),
but this event has not been recorded in the Bering Sea (Ivanov 1969).
Rasmussen (1967) gives comparative reproductive data for Norwegian populations
and Haynes and Wigley (1969) summarize this information, adding
data on ovigery for Maine shrimp.
Sexual development is hormonally
controlled and has been studied by Carlisle (1959).
Table 6.1 compares
life history data of P. borealis and other pandalid species.
Colder water temperatures of the Bering Sea slow growth and development,
extend the ovigerous period, and greatly determine the seasons of
spawning and hatching (Butler 1971).
The normal life span for P. borealis
in the S.E. Bering Sea can be up to 6 1/2 years (Ivanov 1969) compared
to 3 1/2-4 years for populations in the warmer water (North Sea,
Allen 1959; British Columbia, Butler 1964).
Ovarian development occurs in mature females (age 5 years) in the
summer, followed by spawning from August to mid-September in the southeastern
Bering Sea.
Eggs are extruded, fertilized and carried on the
pleopods through the winter and hatch from April through mid-May (NPFMC
1978). The average ovigerous period lasts from 7.5 to 9.5 months. Females
from Kachemak Bay, Alaska carry approximately 914 eggs per clutch
(Haynes and Wigley 1969), but a range of 300-3400 eggs, has been noted
for different P. borealis populations world-wide (Allen 1959; Haynes and
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