Distinction between silver hake (Merluccius bilinearis) stocks in USwaters of the northwest Atlantic based on whole otolith morphometrics

摘要

A method for using whole otolith morphometrics to identify silver hake (Merluccius bilinearis) stocks in U.S. waters of the northwest Atlantic is described. Whole sagittal otolith morphometric variables of length, width, area, perimeter, circularity, and rectangularity were extracted by image processing and, in combination with age-specific discriminant analyses, were used to differentiate two stocks of silver hake: a northern stock from the Gulf of Maine to northern Georges Bank and a southern stock from southern Georges Bank to the Middle Atlantic. Further support for these groupings is supported by growth rate analyses: fish of the northern stock grew slower than those of the southern stock, resulting in typically larger otoliths for fish from the northern stock. This study demonstrates that whole otolith morphometrics, specific to fish age, are useful in identifying silver hake stocks and can be a useful tool in identifying other fish stocks.