Diet, Abundance, and Distribution as Indices of Turbot (Psetta maximaL.) Release Habitat Suitability

Abstract

Selection of a suitable release habitat is critical for stock enhancement. As part of the Danish turbot stock enhancement program, individually tagged, artificially reared juveniles were released into three different habitats. Data from the recaptures in the following year revealed a significant effect of release habitat on turbot growth. This raised the question whether such differences in growth could have been predicted before the release by comparing easily measurable characteristics of wild turbot caught in the different habitats. Three characteristics of wild turbot were examined: the diet, natural abundance, and depth distribution within the habitats. A marked difference was found among habitats in the timing of the diet change from the suboptimal exoskeleton carrying prey items such as crustaceans to fish. The habitat where the wild turbot had the lowest occurrence of fish in their diet was also the habitat with the highest natural abundance of age-0 individuals and the deepest distribution of wild turbot. This was the habitat where released turbot grew more slowly than in the other habitats, which indicate that the diet and depth distribution of wild turbot may provide good indicators for the success of turbot enhancement and restocking.

Post‐release feeding and growth of hatchery‐reared Japanese flounder Paralichthys olivaceus: relevance to stocking effectiveness

“…The proportion of prey fishes in the diet increased and that of prey mysids decreased concomitantly with the passage of time after release or with the body size increase, indicating the higher efficiency of piscivory for energy gain. The prompt shift of their diet to fishes might be advantageous for efficient feeding and subsequent growth, as reported for turbot Psetta maxima (L. 1758) (Sparrevohn & Støttrup, 2008), but the diet shift is not thought to be critically important. The recovery in K r of HR P. olivaceus indicates sufficient prey availability even if they consume only mysids.…”

The diet of whiting Merlangius merlangus in the western Baltic Sea

“…Furthermore, they act as a food source for other juvenile fishes in the area such as G . morhua (Fjøsne & Gjøsæter, ) and turbot Scophthalmus maximus (L. 1758) (Sparrevohn & Støttrup, ; Florin & Lavados, ). Ammodytids are the main prey of juvenile M .…”

Genetic population structure in flatfishes and potential impact of aquaculture and stock enhancement on wild populations in Europe

“…Støttrup et al (2002) even reported faster growth of hatchery-reared animals during the first season after release, probably due to their better initial body condition. Variability in growth of released fishes was partially dependant on habitat suitability (Sparrevohn and Støttrup 2008). Andersen et al (2005) also reported strong effects of the quality of the release habitat (e.g.…”