A life-stage population model of the European sturgeon (Acipenser sturio) in the Elbe River. Part I: general model outline and potential applications

The European sturgeon, Acipenser sturio, experienced a dramatic decline during the late 19th century in Germany. Only after its confirmed extirpation in the wild were ex-situ measures introduced as the basis of a recovery attempt. In order to achieve effective population restoration, it is important to evaluate and compare efficiency of both planned and ongoing remediation measures. For this purpose, a stochastic age-structured model of this population was developed to conduct a population viability analysis and to assess different management and restoration measures. The model revealed a high susceptibility of the species to even very low fishery and by-catch pressures of below 5%. Population recovery was shown to be a very slow process, with a minimum timeframe of 3050years. Continuous stocking represents an important initial management measure to accelerate population recovery, reducing by two to three times the time required in comparison to only initial stocking. Habitat remediation (e.g. spawning grounds) in the Elbe River seems necessary, as according to model estimations, the present carrying capacity could sustain no more than a few thousand adults. The model showed a clear correlation between spawning habitat availability and the sustained number of adults.