Report of the Workshop on Age Reading of Greenland Halibut (WKARGH)

• Main Author: ICES (11907872)
• Format: Report
• Language: unknown
• Published: 2011
• Subjects: Fisheries and aquaculture; Greenland Sea (ICES Ecoregion); Icelandic Waters (ICES Ecoregion); Greenland halibut; Reinhardtius hippoglossoides; age determination; age reading; otolith; otolith reading; WKARGH; ICES CM 2011/ACOM; Greenland; Greenland Sea
• Online Access: https://doi.org/10.17895/ices.pub.19280864.v2

Several age reading methods for Greenland Halibut were described and evaluated together with available validation and corroboration results. The different methods can be classified into two groups: A) Those that produce age-length relationships that broadly compare with the traditional methods described by the joint NAFO-ICES workshop in 1996 (ICES, 1997), typically indicating age around 10-12 years for 70 cm fish; and B) Several recently developed techniques that provide much higher longevity and approximately half the growth rate from 40-50 cm onwards compared to the traditional method. These typically produce age estimates around 20 years or more for 70 cm fish. All available validation and corroboration results, both several published and a few unpublished, were in favour of group B methods. There are still validation works to be done in order to fully appreciate the full range of variability in the formation of annuli in otoliths from different stocks within different environmental regimes. There is also a need for improved precision, especially for the group B methods. Based on the review in this report, the relevant assessment working groups are advised to seriously consider how to proceed with age reading of their stocks.