The use of internal otolith morphometrics for identification of haddock (Melanogrammus aeglefinus) stocks on Georges Bank

Internal otolith morphometrics, coupled with image analysis procedures and multivariate statistical analyses, were examined to investigate stock struc ture of haddock (Melanogrammus aeglefinus) on Georges Bank in the northwest Atlantic. Samples were collected during spring 1995-97 from the Northeast Peak (eastern Georges Bank) and the Great South Channel (western Georges Ba nk) spawning components. The structure of transverse sagittal otolith secti ons were described for individual haddock samples from each spawning compon ent by using a combination of linear morphometrics, shape characteristics, and growth increments. Analyses were structured to account for the effects of size, sex, age, and year class. Significant differences in internal otol ith structure were found between eastern and western Georges Bank haddock, providing phenotypic evidence of stock separation between the two spawning components. Eastern Georges Bank haddock tended to have smaller internal ot olith dimensions than western Georges Bank haddock; these differences appea red to be related to growth rates. Total classification success for each sp awning component varied from 61% to 83% for the different age and year-clas s combinations. Results from this study may be helpful in forming consisten t stock definitions that can be used by both U.S. and Canadian fishery mana gement agencies far rebuilding stocks of haddock on Georges Bank.