Dynamics of growth in the early life history of shortbelly rockfish sebastes jordani
Laidig, T.E.; Ralston, S.; Bence, J.R.
Fishery Bulletin (Washington D C) 89(4): 611-622
1991
ISSN/ISBN: 0090-0656 Accession: 007232732
The relationship between length and age of larval and juvenile shortbelly rockfish Sebastes jordani, determined from otolith microstructure, is complex. Models that assume size increases smoothly with age may not accurately describe growth in young-of-the-year rockfish. A segmented(piece-wise linear) regression model relating somatic and otolith size was used to back-calculate body length-at-age. The segments of this model coincide with different growth stanzas, which are separated by distinct life-history transitions. The composite function of this model, and a Gompertz curve relating otolith size and age, yielded a good fit to the back-calculated standard length-at-age data. Comparison of back-calculated with actual growth showed no evidence of size-selective mortality. The change in body length, as the number of otolith increments increased, was equal to the observed increase in length per day of a sequentially sampled cohort, validating the daily periodicity of the increments.