Growth and age structure of alfonsino (Beryx splendens) from the lower east coast, North Island, New Zealand

Abstract

Commercial landings of alfonsino (Beryx splendens Lowe, 1834) from the Palliser Bank, Tuaheni High, and Paoanui Ridge were sampled to describe growth and determine the age composition of catches. The study indicated that one opaque and one hyaline zone were formed annually in sagittal otoliths, the hyaline zone being deposited in late autumn. Fish were probably about 10 months old when the otolith nucleus was fully formed. The length‐weight equations for males and females differed and both changed throughout the year in parallel with the spawning cycle. Size‐selective mortality did not occur on the Palliser Bank. Females were significantly larger at any given age than males on all grounds examined, but growth of males and females appeared consistent between grounds. Growth was slower than in Japanese waters and the Atlantic. Age structure varied between grounds, but was reasonably constant over time on the Palliser Bank. Full recruitment to the commercial fishery occurred at age 5 on the Palliser Bank. Fish recruited onto the ground from February to July.

Keywords:

• alfonsino
• Beryx splendens
• otolith
• age validation
• growth
• age‐length relationship
• age structure
• recruitment