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

Although sturgeons and paddlefish represent a highly endangered species group, knowledge regarding their ecology, life history and management and restoration measures still reveals substantial gaps and uncertainties. As such, it was hypothesized that the information on overall experiences and perspectives of researchers working in the field would provide a good indication of the state of knowledge, and help identify areas for further investigation. To gain in-depth insight into their perspectives on a variety of topics related to sturgeon life history, management and conservation, as well as opinions on issues characterized by a lack of data, a worldwide online survey was conducted among scientists specializing in sturgeon and paddlefish research. With a total of 277 respondents, the response rate was good (40.3% of those invited). The survey results indicated a high level of uncertainty with regard to various aspects of sturgeon life history, such as spawning migrations, reproduction and senescence. Responses differed largely with the origin and the research focus of the participants. Agreement on reported extreme dimensions and lifespans of sturgeons varied among species, but the level of agreement was generally higher among those scientists working on the species in question. Responses on major threats varied regionally, with dams and habitat fragmentation recognized as the major threats by researchers from North America, whereas poaching was considered the dominant threat in Europe and Asia. Sturgeon aquaculture was generally considered as having a positive effect on sturgeon protection by reducing the pressure on natural populations. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was recognized as the most effective instrument in international sturgeon conservation. While sturgeons are generally perceived as flagship species, especially in Europe, participants questioned their potential utilization as umbrella species. Beside providing an insight into the available scientific information and the general level of consensus regarding some of the questions tackled, the results also created a basis for further discussion within the scientific community concerning the validity, relevance, and application of the published information and future research priorities.