Does the introduced signal crayfish occupy an equivalent trophic niche to the lost native noble crayfish in boreal lakes?

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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Relaxed attitude towards spreading of alien crayfish species affects protection of native crayfish species: case studies and lessons learnt from a Fennoscandian viewpoint

Freshwater Crayfish ◽

10.5869/fc.2020.v25-1.039 ◽

2020 ◽

Vol 25 (1) ◽

pp. 39-46

Author(s):

Japo Jussila ◽

Lennart Edsman

Keyword(s):

Competitive Advantage ◽

Pacifastacus Leniusculus ◽

Astacus Astacus ◽

Signal Crayfish ◽

Aphanomyces Astaci ◽

Noble Crayfish ◽

Native Crayfish ◽

Chronic Carrier ◽

Highly Virulent ◽

Crayfish Species

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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Divergent temperature-specific metabolic and feeding rates of native and invasive crayfish

Biological Invasions ◽

10.1007/s10530-021-02687-1 ◽

2021 ◽

Author(s):

T. J. Ruokonen ◽

J. Karjalainen

Keyword(s):

Native Species ◽

Ecological Impacts ◽

Metabolic Rates ◽

Feeding Rates ◽

Cold Temperatures ◽

Signal Crayfish ◽

Climatic Scenarios ◽

Invasive Crayfish ◽

Noble Crayfish ◽

The Impact

AbstractTemperature is one of the most important factors governing the activity of ectothermic species, and it plays an important but less studied role in the manifestation of invasive species impacts. In this study, we investigated temperature-specific feeding and metabolic rates of invasive and native crayfish, and evaluated how temperature regulates their ecological impacts at present and in future according to different climatic scenarios by bioenergetics modelling. We conducted a series of maximum food consumption experiments and measured the metabolic rates of cold-adapted native noble crayfish (Astacus astacus) and invasive signal crayfish (Pacifastacus leniusculus) originally from a warmer environment over a temperature gradient resembling natural temperatures in Finland. The maximum feeding rates and routine metabolic rates (RMR) of native noble crayfish were significantly higher at low temperatures (< 10 °C than the rates of invasive signal crayfish. The RMRs of the species crossed at 18 °C, and the RMRs of signal crayfish were higher at temperatures above 18 °C. These findings indicate that the invader’s thermal niche has remained stable, and the potential impacts per capita are lower at suboptimal cold temperatures than for the native species. Our bioenergetics modelling showed that the direct annual predation impact of noble and signal crayfish seem similar, although the seasonal dynamics of the predation differs considerably between species. Our results highlight that the temperature-specific metabolic and feeding rates of species need to be taken into account in the impact assessment instead of simple generalisations of the direction or magnitude of impacts.

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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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The trophic niche of sculpins Cottus spp. in forage fish assemblages of boreal lakes

Journal of Fish Biology ◽

10.1111/jfb.14188 ◽

2019 ◽

Vol 96 (1) ◽

pp. 92-101

Author(s):

Christina M. Mozzon ◽

Gretchen L. Lescord ◽

Pascale‐Laure Savage ◽

Thomas A. Johnston

Keyword(s):

Fish Assemblages ◽

Trophic Niche ◽

Boreal Lakes ◽

Forage Fish

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Signal crayfish in Lake Saimaa could be maladapted to the local conditions due to Aphanomyces astaci infection: A seven-year study

Freshwater Crayfish ◽

10.5869/fc.2016.v22-1.53 ◽

2016 ◽

Vol 22 (1) ◽

pp. 53-60 ◽

Cited By ~ 6

Author(s):

Japo Jussial ◽

Vesa Tiitinen ◽

Lennart Edsman ◽

Harri Kokko ◽

Ravi Fotedar

Keyword(s):

Commercial Fishery ◽

Total Catch ◽

Trap Catch ◽

Local Conditions ◽

Signal Crayfish ◽

Aphanomyces Astaci ◽

Commercial Grade ◽

Noble Crayfish ◽

Crayfish Population ◽

Lake Saimaa

Abstract We conducted a seven-year survey (years 2009 - 2015) of the Lake Saimaa signal crayfish population. Lake Saimaa is the largest single waterbody in Finland, with a productive fishery and crayfishery. The signal crayfish were introduced to Lake Saimaa in mid-1990’s and a commercial fishery was initiated in the mid-2000s. At first, there was a small proportion of noble crayfish among the catch, but after 2007, an acute crayfish plague epidemic eradicated them, and the signal crayfish stock started showing frequent gross symptoms of chronic crayfish plague infection (e.g., melanised lesions, eroded uropods and pleopods, lost appendages with melanised stumps). This stock now shows gross symptoms of the infection at a rate of 45% to 79% of the annual trap catch, in addition to showing signs of eroded swimmeret symdrome (ESS) at a rate of 2.8 to 15.4%. The CPUE has remained rather low, between one and three crayfish throughout the survey, while the proportion of the commercial grade catch has been between 35% and 68% of the total catch. The signal crayfish populations in Lake Saimaa are still rather fragmented, and production is low. It appears that the Lake Saimaa signal crayfish population has developed slowly and is producing less than expected.

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Publisher Correction: Diet and trophic niche of the invasive signal crayfish in the first invaded Italian stream ecosystem

Scientific Reports ◽

10.1038/s41598-021-00571-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Fabio Ercoli ◽

Daniela Ghia ◽

Laura Gruppuso ◽

Gianluca Fea ◽

Tiziano Bo ◽

...

Keyword(s):

Trophic Niche ◽

Signal Crayfish ◽

Stream Ecosystem

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