Vol. 53 - Alaska Resources Library and Information Services

APPLICATION OF FINDINGS TO
FIELD STUDIES
Certain aspects of the timing of appearance of the larvae
in the plankton and spatial patterns of distribution and
abundance provided evidence needed to corroborate the species
identifications we had made using the above characteristics
to extend Haynes' (1981) description. The larvae with the
longer RDL and shorter, straighter CLS were found in the
plankton earlier in the season than the larvae of opposite
characteristics (see Incze et al., this volume). This was
consistent with information provided to us by D. Somerton
(see D. Somerton's larval paper, this volume), namely, that
the state of maturation of egg masses of female Tanner crabs
observed during National Marine Fisheries Service surveys in
the area indicated that C. opilio hatched earlier than
C. bairdi. The larval species description was further substantiated
by specimens collected in areas where the bottom
crab fauna was clearly dominated by one species or the other.
Finally, areas of the Bering Sea which contained zoeae of
only one description during a sampling season eventually gave
rise to megalops larvae which were identified to species
according to Jewett and Haight (1977); the megalops identifications
confirmed our zoea identifications. All the above
lines of evidence were in agreement with our zoea species
identifications from four years of plankton samples.
Some Chionoecetes zoeae from the southeastern Bering Sea
could not be categorized by the criteria described above. The
RDL of these zoeae, found in water shallower than 200 m, often
was in the area of range overlap of RDL for C. opilio and
C. bairdi (Table 1); the knob character was often intermediate;
and the CLS character occasionally did not match the knobs
even when the latter were distinct. For these specimens,
which were not abundant, no species designation could be made.
It is possible that these were F1 progeny of inter-specific
matings between C. opilio and C. bairdi, but it would not be
possible to determine this with morphological evidence alone.
Since the relationship of genetic phenotype dominance among
the various characters is unknown, it is also possible that F 1
progeny were included in one or the other (or both) of the
species groups we have established above. Because the degree
of inter-specific breeding is unknown, the extent of this
error cannot be estimated.
Some plankton samples collected from regions overlying
the continental slope contained zoeae which did not conform
in appearance to any of the zoeae described above (C. bairdi,
C. opilio or the unidentified Chionoecetes zoeae found over
the shelf). These may have been the larvae of deeper dwelling
species of Chionoecetes. As in the case of the shallower
unknown zoeae, however, such specimens were not numerous.
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