Vol. 53 - Alaska Resources Library and Information Services

DISTINGUISHING BETWEEN CHIONOECETES BAIRDI AND
C. OPILIO ZOEAE COLLECTED IN THE S.E. BERING SEA
Deborah L. Wencker, Lewis S. Incze and
David A. Armstrong
School of Fisheries, WH-10, College of Ocean
and Fisheries Science, University of Washington
Seattle, WA 98195 USA
ABSTRACT
Three morphological characteristics which enable separation
of zoea larvae of Chionoecetes bairdi and C. opilio
are discussed; two are described here for the first time.
Use of all three characteristics enables species identification
of most Chionoecetes zoeae found in plankton samples
from the southeastern Bering Sea.
INTRODUCTION
Zoeae of Chionoecetes bairdi and C. opilio are morphologically
very similar, being larvae of two very closely
related species which apparently still interbreed in nature
(Johnson 1976, Pereyra et al. 1976). Several descriptions
of zoea larvae of the two species have been published:
C. bairdi and C. opilio Stage I zoeae from the S.E. Bering
Sea (Haynes 1973), C. bairdi Stage II zoeae from Cook Inlet,
Alaska waters (Haynes 1981) and C. opilio Stage I and II
zoeae from the waters of Japan (Motoh 1973, Kurata 19631,
Kuwatani et al. 1971). Haynes (1973, 1981) compared zoeae
of both species from U.S. and Japanese waters in order to
define morphological characteristics which could be used to
distinguish between zoeae of the two species in areas where
both exist.
Based on examination in our study of several thousand
zoeae of both Chionoecetes species from the southeastern
Bering Sea (C. opilio and C. bairdi) and also specimens from
the western Beaufort Sea (C. opilio) and the Gulf of Alaska
(C. bairdi), we have found that: (1) the principal criterion
employed by Haynes in papers describing the morphological
differences between zoeae of C. opilio from Japan and C. bairdi
from U.S. waters (Haynes 1981) is more useful than the criteria
he employed earlier to describe differences between Stage I
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