The effects of different otolith ageing techniques on estimates of growth and mortality for the splitnose rockfish, Sebastes diploproa, and canary rockfish, S. pinniger
Wilson, CD.; Boehlert, GW.
California Fish and Game 763: 146-160
ISSN/ISBN: 0008-1078 Accession: 021919906
Different ageing techniques affect not only the estimates of length at age but also estimates of population growth and mortality rates. This study considers these effects for the splitnose rockfish, Sebastes diploproa, and canary rockfish, S. pinniger, based on ages determined from the surfaces and sections of otoliths collected during a trawl survey off the west coast of North America in 1980. Estimates of growth based on surface rather than section ages were nearly identical for S. diploproa but were higher for S. pinniger; slightly different whole otolith ageing techniques are suspected of producing these interspecific differences. For both species, however, estimates of mortality were reduced by more than half when section rather than surface ages were used.