Vol. 53 - Alaska Resources Library and Information Services

oth species for 80 mm specimens, but this size represents opposite
extremes of mature female size for the two species.
Eggs hatch in the spring, generally April for C. opilio and late
April-early May for C. bairdi in the southeastern Bering Sea (Incze et
al. 1982; Incze 1983).
Within a few weeks after the old eggs have
hatched, a new egg mass is extruded and attached to pleopods on the female's
abdomen. These eggs remain attached until they are fully developed
and hatch, about one year after spawning. The larvae emerge as
prezoeae, about 2.5 mm long, which are covered with an embryonic cuticle
and molt to first stage zoeae generally within an hour (Kon 1967, 1970;
Kuwatani et al. 1971; Haynes 1973). The two zoeal stages (Haynes 1973,
1981) and the megalops stage (Jewett and Haight 1977) last about one
month each (Incze et al. 1982; Incze 1983; see also Adams 1979, Table
9), and remain primarily in the upper 20 m of the water column during
this period (Incze 1983).
The megalops is the final planktonic stage in
the life history of these crabs; all subsequent stages are benthic.
4.4 Taxonomy
Chionecetes bairdi and C. opilio zoeae were identified by D.
Wencker using criteria outlined by Wencker et al. (1982; manuscript is
appended to this report).
These criteria make use of descriptions of
the species by other authors (Kurata 1963, 1969; Motoh 1973, 1976;
Haynes 1973, 1981), but also include some new diagnostic characteristics
which were necessary for distinguishing between the two species in the
southeastern Bering Sea.
The morphological descriptions by Wencker et
al. (1982) were corroborated by field studies on larval dynamics which
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