Comparison of morphological characters between wild and cultured sterlet (acipenser ruthenus l.)

Abstract

Sterlet (Acipenser ruthenus L.) populations in the Danube River had experienced severe decline during the 20th century, and have become dependant on stocking measures in significant area of their distribution. Despite the current wide use of stocking, there are few studies dealing with efficiency of stocking efforts, especially with impact of rearing conditions on fitness of released individuals. This study tried to assess existence of morphological changes in reared sterlet that could impact their swimming performance and thus reduce survival of stocked fish. Wild sterlet (n=45) from the Danube River were compared with sterlet from aquaculture (n=20), originating from wild Danube spawners. Statistical comparison of 15 morphological traits revealed that samples significantly differed in 11 traits, as well as that reared sterlet had significantly shorter pectoral fins and stockier body than those from the wild. Additional investigation is needed to determine if these morphological differences could affect adaptability and survival of reared sterlet after their release into the river. Period of adaptation in lotic environment, prior to stocking, could probably alleviate the influence of aquaculture rearing on the fitness of released fish.