scholarly journals MANAGEMENT STRATEGIES, YIELD AND POPULATION DEVELOPMENT OF THE NOBLE CRAYFISH ASTACUS ASTACUS IN LAKE STEINSFJORDEN

2002 ◽  
pp. 845-860 ◽  
Author(s):  
J. SKURDAL ◽  
E. GARNÅS ◽  
T. TAUGBØL
Keyword(s):  
Management Strategies ◽  
Population Development ◽  
Astacus Astacus ◽  
Noble Crayfish

scholarly journals Environmental DNA monitoring of noble crayfish Astacus astacus: Comparison and refining of methodology

2021 ◽  
Vol 4 ◽  
Author(s):  
David Strand ◽  
Stein Johnsen ◽  
Frode Fossøy ◽  
Johannes Rusch ◽  
Brett Sandercock ◽  
...  
Keyword(s):  
Dna Extraction ◽  
Brown Trout ◽  
Detection Probability ◽  
Environmental Dna ◽  
Northern Pike ◽  
Freshwater Crayfish ◽  
Astacus Astacus ◽  
European Perch ◽  
Detection Frequency ◽  
Noble Crayfish

During the past decade, environmental DNA (eDNA) methodology has become an important non-invasive tool to monitor aquatic micro- and macro-organisms, including freshwater crayfish. In Europe, noble crayfish Astacus astacus is the most widespread native freshwater crayfish. However, the species is threatened in its entire distribution range. It is therefore included on the International Union for Conservation Nature (IUCN) red list, and on several national red lists. Reliable monitoring is essential for implementation of conservation measures. For crayfish, traditional population trends have been obtained from catch per unit effort (CPUE) data. In order to successfully apply and use eDNA monitoring for noble crayfish, or any species, it is a prerequisite to know the strengths and weaknesses of the applied methods and how they perform compared to traditional methodology. Sampling strategy and analysis methodology also depends on choice of species to be monitored, and which questions to be answered. Further, refinement of the employed methods may improve the detection probability for eDNA monitoring. Here we report the results from 1) a recently published study on noble crayfish eDNA monitoring (Johnsen et al. 2020) and 2) an ongoing study comparing and optimising the methods used for monitoring noble crayfish. 1) We compared eDNA monitoring (transects with ten 5L samples) with traditional trapping (transects with 50 traps) for noble crayfish in lentic habitats, in order to evaluate detection probability and if eDNA concentration correlates with relative density of crayfish. We also compared two commonly used analytical methods [quantitative real-time PCR (qPCR) and droplet digital PCR (ddPCR)] for eDNA monitoring. We found that qPCR outperformed ddPCR in detection frequency (Fig. 1), most likely due to some inhibition in the ddPCR analysis. eDNA monitoring provided reliable presence/absence data for noble crayfish, even in lakes with very low crayfish densities. Detection frequency increased with increasing CPUE (Fig. 1). However, we did not observe any correlation between relative crayfish densities and eDNA concentrations of crayfish. eDNA concentrations were consistently very low, even in lakes with very high crayfish densities. For lakes with very low crayfish densities, we estimated that ~5 samples (5L samples) are needed for 95 % detection likelihood, while for lakes with high densities 2 samples were needed. 2) We compared two eDNA sampling strategies (sampling from bottom or the surface), commonly used for crayfish or fish in Norway to investigate how both strategies perform. The sampled filters were divided and two DNA extraction protocols were evaluated (CTAB based vs Column based). We found that the DNA yield was higher from the column based DNA extraction protocol, and that eDNA concentrations from fish (brown trout Salmon trutta, northern pike Esox lucius and European perch Perca fluviatilis) were significantly higher than for crayfish. For crayfish and brown trout, there was little difference between detection probability for bottom and surface samples, while for northern pike and European perch the detection probability was higher for the bottom samples. Currently, we are analysing eDNA samples collected with glass fibre filters and NatureMetrix filters for noble crayfish in both lentic and lotic habitats and the preliminary results will be presented. We conclude that eDNA monitoring cannot substitute CPUE monitoring for freshwater crayfish, but it offers reliable presence-absence data, provided sufficient sampling efforts. Thus, it is suitable for large scale monitoring of threatened crayfish and combined with eDNA analysis of alien crayfish and diseases such as crayfish plague, this is a cost-efficient supplement offering a more holistic approach for aquatic environments and native crayfish conservation. Furthermore, the synergy effect of using collected eDNA samples from different projects to monitor additional species is substantial.

scholarly journals High-resolution structural and elemental analyses of calcium storage structures synthesized by the noble crayfish Astacus astacus

2016 ◽  
Vol 196 (2) ◽  
pp. 206-222 ◽  
Author(s):  
Gilles Luquet ◽  
Murielle Salomé ◽  
Andreas Ziegler ◽  
Céline Paris ◽  
Aline Percot ◽  
...  
Keyword(s):  
High Resolution ◽  
Astacus Astacus ◽  
Calcium Storage ◽  
Elemental Analyses ◽  
Noble Crayfish ◽  
Storage Structures

Fluctuations in harvest of native and introduced crayfish are driven by temperature and population density in previous years

2010 ◽  
Vol 67 (1) ◽  
pp. 157-164 ◽  
Author(s):  
Karin Olsson ◽  
Wilhelm Granéli ◽  
Jörgen Ripa ◽  
Per Nyström
Keyword(s):  
Time Lag ◽  
Mating Season ◽  
Astacus Astacus ◽  
Growth Season ◽  
Signal Crayfish ◽  
Noble Crayfish ◽  
Crayfish Population ◽  
Effects Of Temperature ◽  
Parsimonious Model ◽  
Large Adult

The effects of temperature and density on annual fluctuations in catches of large adult crayfish are evaluated using time series analysis. We tested if temperature during different stages of the crayfish life cycle influenced observed catches from 1946 to 2007 in Lake Bunn (Sweden). From 1946 to 1974, native noble crayfish ( Astacus astacus ) inhabited the lake, but then, crayfish plague wiped out the whole population. In 1985, the exotic signal crayfish ( Pacifastacus leniusculus ) was introduced and is still present. This made it possible to model the two species separately and compare how temperature and density influence the abundance of large adult crayfish. The best models indicate that both climatic- and density-dependent factors influence the observed fluctuations and there was a time lag for most factors included in the best models. Winter temperature had the strongest influence on fluctuations of both species. Also, density dependence was included in the best model for both species. Growth season for noble crayfish and temperature during the mating season for signal crayfish were also present in the most parsimonious model. Based on our findings, it is difficult to predict how further climate warming will affect crayfish population dynamics in freshwaters.

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