APPLICATION OF A NEWLY DEVELOPED STATISTICAL PROCEDURE TO MORPHOMETRIC DATA FROM AMERICAN PLAICE (HIPPOGLOSSOIDES-PLATESSOIDES) IN THE CANADIAN NORTHWEST ATLANTIC

The population structure of American plaice (Hippoglossoides platessoi des) in the Canadian Northwest Atlantic was examined by analyzing 11 m orphometric features from 18 sampling sites. The sampling sites were d etermined based on previous knowledge of distribution, spawning, migra tion, and commercial fishing patterns of American plaice. The analysis was conducted by applying a recently developed multivariate statistic al procedure. The procedure is not constrained by the requirement of h omogeneity in the residual covariance matrices as in the MANCOVA techn iques normally used. Since this requirement is generally violated by m orphometric data, this new method for analyzing these types of data is much more robust and provides statistical validity to the results. Th e analysis indicated that all samples were statistically different fro m each other, suggesting they were all from separate stocks. While it is believed that then are several self sustaining American plaice stoc ks throughout the area, the analysis presented here suggesting so many separate stocks must be rejected based on a large body of biological evidence to the contrary. It is concluded, therefore, that morphometri c data are very limited in their usefulness for stock identification o f American plaice and researchers should be cautious in their approach when using similar data for stock identification purposes. (C) 1998 E lsevier Science B.V.