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

Abstract

The European sturgeon, Acipenser sturio, experienced a dramatic decline during the late 19 th 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 30-50 years. 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.U.S.

Sturgeon and paddlefish life history and management: Experts' knowledge and beliefs

“…For example, the lifespan of 118 years reported in beluga (Huso huso; Billard & Lecointre, ) was supported by 81% of experts for this species, but supported by only 44% of all other respondents. An even higher difference in opinion between the two groups was observed for the reports on lifespans of 100 years or more in European sturgeon ( Acipenser sturio ; Jarić & Gessner, ), with 75% of species experts supporting such reports compared to 33% of the other respondents. An extreme lifespan of 154 years in lake sturgeon (Haxton, Sulak, & Hildebrand, ) received the lowest support, both from experts (46%) and other respondents (15%; Figure ), although the report was based on a valid and generally reliable assessment method.…”

“…Proportion of respondents supporting reports of extreme longevities observed in different species as being realistic ( N = 249), presented both for species experts and other respondents: beluga ( Huso huso )—118 years (Billard & Lecointre, ), European sturgeon ( Acipenser sturio )—100 years or more (Jarić & Gessner, ), Atlantic sturgeon ( A. oxyrinchus )—more than 100 years (inferred based on the age at maturity in northern populations; Jarić & Gačić, ), white sturgeon ( A. transmontanus )—104 years (Rien & Beamesderfer, ), lake sturgeon ( A. fulvescens )—154 years (Haxton et al., )…”

“…Apparent absence of older individuals in contemporary populations is likely caused by historic overfishing that targeted mature fish (Pollock et al., ), whereby the observed longevity in exploited populations tended to decline significantly (Jarić & Gačić, ; Tsoukali et al., ). A population model of the European sturgeon indicated that fishing mortalities as low as 5% can reduce previously undisturbed populations to no more than 20%–30% of their historic spawning biomass, mainly at the expense of older age‐classes (Jarić & Gessner, ). Reliable longevity estimates require access to undisturbed sturgeon populations, which are rare (Haxton & Cano, ; Jarić & Gačić, ).…”

“…Proportion of respondents supporting reports of maximum body length and weight observed in different species as being realistic ( N = 244), presented both for species experts and other respondents: beluga ( Huso huso )—600 cm (Holčik, ), up to 900 cm (Rochard et al., ), 1,500 kg (Rochard et al., ), 3,000 kg (Holčik, ), kaluga ( H. dauricus )—600 cm (Krykhtin & Svirskii, ), 1,000 kg (Chen, ), European sturgeon ( Acipenser sturio )—600 cm (Jarić & Gessner, ), 1,000 kg (Schoenevelde, ), Atlantic sturgeon ( A. oxyrinchus )—500 cm (Hilton et al., ), white sturgeon ( A. transmontanus )—600 cm (Billard & Lecointre, ), 800 kg (Billard & Lecointre, )…”

Conserving migratory species under human impacts and climate change

“…Acipenser sturio (Jarić & Gessner 2013), and Allis shad Alosa alosa (Rougier et al 2014) that incorporate all aspects of their life cycle. Nevertheless, complex models for particular anadromous species are probably not well suited to most diadromous species, which are much more poorly known.…”