Vol. 53 - Alaska Resources Library and Information Services

1983). The relative contribution of larvae of C. opilio over the St.
George Basin to fishable stocks of Tanner crabs is not currently known,
but is an important point to consider since C. opilio contribute
substantially to the crab fishery.
Data from the period 1977-1981 clearly show that larval abundance
of C. opilio can fluctuate greatly, as much as two orders of magnitude
(Incze 1983).
Somerton (1981) concluded on the basis of size frequency
analysis of benthic populations of C. opilio that recruitment occurs
irregularly.
While other factors, such as benthic predation, also
affect recruitment to juvenile and adult crab populations, success of
the larval phase of recruitment is clearly important.
The larval abundance
data from this study indicate that some years may be much more
important than others, and that relative success of larval year-classes
may be a significant determinant of adult fisheries recruitment in some
years.
Impacts on these "key" years might have a much greater effect on
adult population dynamics than if year-class strength were more equal
each year. Factors potentially contributing to the irregular success of
larvae of C. opilio are complex and are presently not well understood
(see Incze 1983 for discussion).
4.8 Summary of Principal Findings Relevant to the
Assessment of Oil-Related Impacts
1. Most of the larvae of C. opilio hatch during April; a large proportion
of the larvae appear to hatch in the first half of this month.
2. Most of the larvae of C. bairdi hatch in late April and the first
half of May.
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