The ‘Pritchard Trap’: A novel quantitative survey method for crayfish

Ecological Solutions and Evidence

Michael A. Chadwick¹  Daniel D. A. Chadwick²  Ian R. Patmore²  Jan C. Axmacher²  Eleri G. Pritchard²  Carl D. Sayer²  Paul Bradley³ 

[1] Department of Geography King's College London London UK;Environmental Change Research Centre, Department of Geography University College London London UK;PBA Applied Ecology Ltd Settle North Yorkshire UK;

关键词: crayfish density;    crayfish sampling;    population demographics;    signal crayfish;    triple drawdown;    white‐clawed crayfish;   

DOI  :  10.1002/2688-8319.12070

来源: DOAJ

【 摘 要 】

Abstract As crayfish invasions continue to threaten native freshwater biota, a detailed understanding of crayfish distribution and population structure becomes imperative. Nonetheless, most current survey methods provide inadequate demographic data. The quantitative ‘Triple Drawdown’ (TDD) dewatering method has highlighted the importance of such data, yet practical constraints prevent its large‐scale application. Here, we introduce the ‘Pritchard Trap’, a novel passive sampling method that reliably generates quantitative crayfish population data while requiring substantially lower sampling effort than TDDs. This quadrat‐style sampler was extensively tested in headwater streams of North Yorkshire, England, along an invasion gradient for signal crayfish (Pacifastacus leniusculus) from well‐established sites to mixed populations of signal crayfish and native white‐clawed crayfish (Austropotamobius pallipes). The Pritchard Trap was trialled over several time intervals to determine the minimum required trap deployment time. TDDs at the same sites allowed for a robust evaluation of Pritchard Trap sampling accuracy in representing crayfish densities and population structure. The Pritchard Trap successfully sampled both invasive and native crayfish (8–42 mm carapace length). A minimum passive deployment time of 4 days was required. At low crayfish densities (0.5 individuals m−2), increased trapping effort was necessary to achieve accurate population density and size class distribution estimates. The Pritchard Trap required substantially less sampling effort (working hours) and resources than the TDD, whilst also posing less risk to non‐target species. The Pritchard Trap, for the first time, affords logistically simple, truly quantitative investigations of crayfish population demographics for headwater systems. It could be integrated into crayfish research and management, for example to explore density‐dependent ecological impacts of invasive crayfish and their management responses or to monitor populations and recruitment in native crayfish conservation initiatives.

【 授权许可】

Unknown