Growth and otolith ring deposition in Teleost larvae

Abstract

Growth and otolith ring deposition were examined in the larvae of turbot, plaice, herring, and in salmon embryos. Larvae were reared under various light, temperature, and feeding regimes in order to measure the response of ring deposition to different sets of environmental cues. Ring deposition in herring larvae was measured under a wide range of rearing conditions to provide the basis for ageing wild larvae collected in the Clyde and the Minch. In turbot, salmon, and herring, both growth and ring deposition rates were altered under different rearing conditions. Ring deposition rates were higher under conditions which produced faster growth. Ring deposition in these species was not directly affected by the environmental conditions, instead, the differences observed were the result of the effect that the rearing conditions had on growth and activity. Neither the growth nor the ring deposition rates of plaice larvae were affected by any of the experimental conditions tested. Length was significantly more important than age in determining ring number in individual turbot and herring larvae. At the population level there was a strong positive correlation between growth rate and ring deposition rate in turbot and herring. Age was the most important facto in determining ring number in the plaice larvae examined. Otolith ageing techniques could not be used successfully to estimate growth rates for the wild herring larval populations sampled.