Somatic-otolith size correlations for 18 marine fish species and their importance to age determination

Alaska Department of Fish and Game, Regional Report Series 5J12-13, Juneau.

Somatic and otolith measurements and their relationships are documented for 18 North Pacific marine teleost species representing 9 taxonomic families: 14 groundfish species (sablefish Anoplopoma fimbria, lingcod Ophiodon elongatus, walleye pollock Theragra chalcogramma, pacific cod Gadus macrocephalus, pacific halibut Hippoglossus stenolepis, and 9 rockfish species (Sebastes spp., Sebastolobus alascanus) and 4 forage fish species (Pacific sand lance Ammodytes hexapterus, Pacific herring Clupea pallasii, shiner perch Cymatogaster aggregata, and eulachon Thaleichthys pacificus). Strong positive relationships were found between somatic lengths and otolith lengths (range r = 0.81 to 0.98; mean r = 0.90) and otolith weights, and in symmetry between left and right sagittae otoliths (mean lengths r = 0.97; mean heights r  = 0.95; and mean weights r  = 0.99) for all species. Length-length (or height) relationships were generally isometric and length-weight relationships tended to be allometric; curvilinearity became more evident when the sample included juvenile and subadult specimens (which often were lacking in samples from commercial harvests). Vateritic and or dysmorphic otoliths were generally infrequent; the incidence across these 18 species ranged from 0% up to 11% (mean incidence = 3%). The strong correlation between somatic growth and otolith accretion supports the notion that incremental otolith accretion and intrinsic growth patterns might record and display that which influences somatic growth. The uniformity observed in these objective somatic-otolith relationships across 9 taxonomic families suggests that otolith accretion reference cues, which are used to interpret otolith growth patterns for age estimation, should tend toward consistency—and not divergence—amongst teleosts.