First records of the non-indigenous signal crayfish (Pacifastacus leniusculus) and its threat to noble crayfish (Astacus astacus) populations in Estonia

Abstract The spreading of the alien signal crayfish (Pacifastacus leniusculus) is posing an ongoing threat to native European crayfish species in Fennoscandia, like the native noble crayfish (Astacus astacus). The signal crayfish is commonly a chronic carrier of the crayfish plague (Aphanomyces astaci), thus, in addition to being more competitive than noble crayfish, it also has a competitive advantage in this disease over the noble crayfish. The challenges rising from the introduction of the alien signal crayfish to Sweden, Finland and finally also Norway, are similar in nature. The licensed and unlicensed spreading of this species also has a similar history in these countries. In this paper we describe some of the patters of the spread of alien signal crayfish and highlight the detrimental nature of an alien crayfish, accompanied by a highly virulent disease, to native Fennoscandian crayfish and also to native Fennoscandian ecosystems. A halt to the further spreading of alien signal crayfish in Fennoscandia is the only means to ensure successful conservation outcomes for the noble crayfish.

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Detection of nobel crayfish Astacus astacus v1

10.17504/protocols.io.bqtrmwm6 ◽

2020 ◽

Author(s):

Omneya Ahmed ◽

Alexander Eiler

Keyword(s):

Freshwater Ecosystems ◽

Pacifastacus Leniusculus ◽

Indigenous Species ◽

Astacus Astacus ◽

Signal Crayfish ◽

Noble Crayfish ◽

Non Indigenous Species

Crayfish play important role in freshwater ecosystems. Noble crayfish "Astacus astacus" is threatened by non-indigenous species such as signal crayfish "Pacifastacus leniusculus".

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Detection of signal crayfish Pacifastacus leniusculus v1

10.17504/protocols.io.bqypmxvn ◽

2020 ◽

Author(s):

Omneya Ahmed ◽

Alexander Eiler ◽

Mats Töpel

Keyword(s):

Freshwater Ecosystems ◽

Pacifastacus Leniusculus ◽

Indigenous Species ◽

Astacus Astacus ◽

Signal Crayfish ◽

Specific Assay ◽

Noble Crayfish ◽

Species Specific ◽

Non Indigenous Species

A species-specific assay was developed and tested by Agersnap et al. (2017) Crayfish play important role in freshwater ecosystems. Noble crayfish "Astacus astacus" is threatened to extinct by non-indigenous species such as signal crayfish "Pacifastacus leniusculus".

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f09-170 ◽

2010 ◽

Vol 67 (1) ◽

pp. 157-164 ◽

Cited By ~ 10

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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Lake Hańcza – a new site for signal crayfish (Pacifastacus leniusculus Dana) occurrence in Poland

Archives of Polish Fisheries ◽

10.2478/aopf-2018-0015 ◽

2018 ◽

Vol 26 (2) ◽

pp. 141-147

Author(s):

Dariusz Ulikowski ◽

Łucjan Chybowski

Keyword(s):

Total Body Length ◽

Pacifastacus Leniusculus ◽

Catch Per Unit Effort ◽

Large Signal ◽

Signal Crayfish ◽

Orconectes Limosus ◽

Noble Crayfish ◽

Crayfish Population ◽

Total Body ◽

Average Body

Abstract Crayfish catches were conducted using traps in Lake Hańcza, which is the deepest lake in Poland. Two crayfish populations were found to co-exist in the lake: spiny-cheek crayfish (Orconectes limosus Raf.) and signal crayfish (Pacifastacus leniusculus Dana), which is a new species for this lake. Signal crayfish dominated the samples at 98.5% of the specimens caught. The crayfish occurred at depths of 1-10 m. The mean total body length of the male and female signal crayfish (TL) was 99.5 ± 17.8 mm and 96.5 ± 11.7 mm, respectively, while the average body weight (BW) was 38.7 ± 24.9 g and 26.8 ± 9.5, respectively. Chelae were damaged in 4.5% of the individuals. Fishing efficiency (catch per unit effort – CPUE) was 0.96 crayfish trap−1 night−1. Selected characteristics of the population and of individual signal crayfish from Lake Hańcza were compared with those of the two closest neighboring populations of this species in lakes Mauda and Pobłędzie. The confirmed occurrence of the relatively large signal crayfish population in Lake Hańcza excludes this lake as a possible site for native noble crayfish (Astacus astacus L.) restoration.

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Introduced alien signal crayfish (Pacifastacus leniusculus) in Finland − uncontrollable expansion despite numerous crayfisheries strategies

Knowledge and Management of Aquatic Ecosystems ◽

10.1051/kmae/2018016 ◽

2018 ◽

pp. 27 ◽

Cited By ~ 3

Author(s):

Timo J. Ruokonen ◽

Rosanna Sjövik ◽

Esa Erkamo ◽

Jouni Tulonen ◽

Fabio Ercoli ◽

...

Keyword(s):

Alien Species ◽

Current Distribution ◽

Management Strategies ◽

Pacifastacus Leniusculus ◽

Water Bodies ◽

Distribution Area ◽

Limited Effect ◽

Signal Crayfish ◽

Noble Crayfish ◽

Present Distribution

In Finland, massive signal crayfish introductions started towards the end of 1980s, with an estimated total of 2.2 million signal crayfish been stocked before year 2016. During that period, Finnish fisheries authorities have implemented three national management strategies setting guidelines for the crayfish introductions. The main aims of the strategies have been conservation of native noble crayfish stocks and a controlled spreading of the alien signal crayfish within a designated region. In this study, we report the current distribution of signal crayfish in Finland in comparison to the guidelines set in these three national strategies. The present distribution area of the signal crayfish covers most of the Southern Finland. The signal crayfish has been introduced with a stocking permits to over 480 water bodies. In addition, there have been numerous stockings without permits, which are often next to the region designated for the signal crayfish. Based on the results, we conclude that crayfish management strategies adopted in Finland have only had limited effect on the spread of signal crayfish. We presume that main causes for the uncontrolled spreading of the signal crayfish in Finland have been lack of strict official supervision and general lack of awareness about the risks associated with the alien species spreading.

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