Vol. 53 - Alaska Resources Library and Information Services

Interannual timing of the onset of hatch and seasonal occurrence of
pelagic larvae can vary by as much as 1.5 months. Japanese data (INPFC
1963, 1965) show that nearly 100 percent of gravid females sampled
during 1960 carried "eyed" eggs (fully developed zoeae, hatch imminent)
until May 10 and 50 percent carried empty egg cases by May 20-30. In
1963, eyed eggs were carried until April 20 and 50 percent had hatched
by April 30. Larvae hatched late (mid-May) in 1976, but early in 1979
when most were already stage IV (SIV) by mid-June (Armstrong, et al.
1983b).
Horizontal transport of king crab larvae by currents is thought to move
them significant distances from the origin of hatch, and implies to
some authors that recruitment of juveniles to a given area might depend
on larvae hatched elsewhere, including areas south of the Alaska
Peninsula (Haynes 1974; Hebard 1959). Hebard (1959) calculated that
larvae hatched at Amak Island could be transported over 95 km to the
northeast and metamorphose at Port Moller based on a net current speed
of 2 cm sec- 1 . He further discussed possible transport of larvae
from south of the Alaska Peninsula through Unimak and False Passes.
Haynes (1974) adds credence to this supposition by showing a northerly
dispersion of king crab larvae off the southwest tip of Unimak Island,
and a northeast shift in areas of larval abundance from Black Hills into
Bristol Bay (May-July 1969 and 1970). This pattern may in part be due
to inadequate spatial sampling. Armstrong, et al. (1983b) concluded
that larvae could be transported over 200 km along the NAS based on the
time required for development (3.5-4 months) and current speeds of about
2 cm sec-¹ (Kinder and Schumacher 1981b).
Growth. Temperature is considered one of the most crucial physical
factors affecting survival and growth of larvae. Kurata (1960, 1961)
calculated that 460 degree-days were required to progress from hatch to
metamorphosis. Lethal temperatures are those greater than 15°C or lower
than 0.5-1.8°C (Kurata 1960). He found greatest survival of zoeae
between 5-10°C and formulated an equation that relates developmental
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