Estimated production numbers for the period from 1 January through 30 June 2009 include 14 species for a total of 15,237 specimens aged, with 3,767 test ages and 170 that were determined to be unageable.
Ageing hard structures related to special research projects is also ongoing. These projects include continued efforts to establish and verify ageing criteria for rockfish, such as shortspine thornyhead, and forage species, such a capelin and eulachon; life history and growth characteristics of deepwater grenadiers and big skates; and ageing arctic cod.
In addition, research is under way to develop new age validation tools using bomb radiocarbon (C-14) and trace elemental analysis and to understand fish growth in relation to environmental variability. Several of these special research initiatives involve collaborative efforts with other AFSC staff and external institutions.
By Tom Helser
Age Determination Manual Nearing Completion
The Age & Growth Program is putting the final touches on the manuscript "Age Determination Manual of the Alaska Fisheries Science Center Age and Growth Program," which is intended for the NOAA/NMFS Professional Paper series. This nearly 500-page document represents the culmination of many years of hard work and research by dedicated AFSC age readers and scientists who have collectively contributed to our understanding of the phenomena of fish age determination.
The primary focus of the manual is to serve as a working document for age readers and age data users by describing historic and current age estimation practices. The manual also is intended as a resource for insight into descriptive statistics (bias, precision) useful to population modelers and also as a resource for understanding the A&G Program's investigations into state of the art age validation techniques and relationships between environmental factors and fish growth.
The document is intended as a living document which will evolve with the advent of new technologies and ageing criteria.
