Stock identification of haddock Melanogrammus aeglefinus on Georges bank based on otolith shape analysis

Otolith shape analysis was examined to determine its utility for stock iden tification of haddock Melanogrammus aeglefinus on Georges Bank. Otolith sam ples were collected from the Northeast Peak (eastern Georges Bank) and the Great South Channel (western Georges Bank) spawning components to examine s tock continuity across Georges Bank. Otolith shape was described using 20 F ourier harmonics, four morphometric characteristics (area, length, width, a nd perimeter), and two shape indices (circularity and rectangularity). Pote ntial confounding sources of variation (fish length, otolith position, age- group, and year-class) were examined and accounted for in the analyses befo re interpretation of spatial/stock differences. Significant age-specific di fferences in otolith shape between eastern and western Georges Bank haddock indicated stock separation across the Bank. Classification success for eac h spawning component ranged from 63 to 80% across age-groups and appeared t o depend on growth rate differences. Otolith shape analysis has potential f or stock identification of haddock on Georges Bank, but only for year-class es with differing growth rates. The results of this study indicated an unde rlying stock structure within the Georges Bank transboundary haddock resour ce that may assist in defining consistent stock definitions used by the Uni ted States and Canada.