Reference Collections
The Fishery Biology Program has implemented reference collections for selected species. These collections consist of a few hundred fish of a given species, for which the age is reliably known. This website gives access to both annotated and unannotated images from these collections. These reference collections are used as training resources and to quantify the accuracy of age data generated by the FBP. In addition, age readers may review these samples to refresh their skills for a given species.
The development of a reference collection requires the comprehensive selection of age structure samples from representative lengths, ages, sexes, seasons, stock areas, and sampling sources for each species (Campana et al., 1995). Ideally, samples should be from known-age fish, such as those provided by tag/recapture or age validation studies, but these are difficult to obtain. As that is often not feasible, reference collections may instead consist of fish which have been aged by consensus of multiple age readers, often through age-structure exchanges and/or workshops.
Currently, the Fishery Biology Program has reference collections for American shad, Atlantic cod, and haddock. Details of how each collection has been assembled are given below. This site will be updated as more samples are added to the collections, and as annotated images become available.
Haddock
These sectioned otoliths are from NEFSC survey cruises to Georges Bank. All were aged by consensus between (at least) two NEFSC readers and an age reader from the Department of Fisheries and Oceans Canada, as part of regular ageing exchanges between the two laboratories. These fish have been aged according to our standard ageing methods (unpublished; please contact our staff for more information).
American Shad
These fish were caught on the Delaware River while migrating upriver to spawn, by the Pennsylvania Fish and Boat Commission (PFBC). The fish were marked with oxytetracyline as fry (also by the PFBC); hence the ages are known exactly. Ageing methods are described in Duffy et al. (2012). We appreciate PFBC's generosity in allowing us to use their samples.
Cod
These otoliths are from NEFSC survey cruises to Georges Bank. They were baked to enhance contrast and then broken at the nucleus. All were aged by consensus between (at least) two NEFSC readers and an age reader from the Department of Fisheries and Oceans Canada, as part of regular ageing exchanges between the two laboratories. These fish have been aged using the methods described in our Ageing Manual (Penttila and Dery, 1988).
Testing
These collections are regularly used to assess ageing accuracy. In these tests, a subsample of 50-100 fish from the reference collection is re-aged, and the test ages compared with the ages given here. Tests are usually given both before and after a year's worth of production ageing; test results are available online at our Quality Assurance and Quality Control Estimates website.
Contact Information
For further information about the program, email Eric Robillard or write to:
Fishery Biology Program
NOAA Fisheries Northeast Fisheries Science Center
166 Water Street
Woods Hole, Massachusetts 02543-1097
This page maintained by S. Sutherland
References
Campana SE, Annand MC, McMillan JI. 1995. Graphical and statistical methods for determining the consistency of age determinations. Trans. Am. Fish. Soc. 124:131-138.
Duffy WJ, McBride RS, Hendricks ML, Oliveira K. 2012. Otolith age validation and growth estimation from oxytetracycline-marked and recaptured American shad. Trans. Am. Fish. Soc. 141:1664-1671.
Penttila J, Dery LM. 1988. Age determination methods for northwest Atlantic species. NOAA Tech. Rep. NMFS-72; 135 p. (Available at https://repository.library.noaa.gov/view/noaa/5868)