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1

The signal crayfish Pacifastacus leniusculus – distribution and invasion in the Southern Baltic coastal river

100%
Dobrzycka-Krahel A., Skora M. E., Raczynski M., Szaniawska A.
Polish Journal of Ecology
|
2017
|
tom 65
|
nr 3
The signal crayfish Pacifastacus leniusculus (Dana, 1852) of North American origin was introduced to Europe (to Scandinavia) in the 1960s. Since that time due to translocation to many countries, biological features and ecological plasticity, it became widespread, invasive and displaced native species. The paper reports first multi- point colonization of P. leniusculus in the Polish rivers. The aim of the study was to determine the current distribution of the signal crayfish in the coastal Baltic tributary (the River Wieprza) after 20 years of deliberate releases in its drainage area. During sampling at 28 sites with use of the “Pirate” crayfish traps and hand collection methods in spring and summer 2014, 127 P. leniusculus individuals were found at 8 sites in the Wieprza and its two tributaries, both away from and close to known sites of their introduction in 1995 and 1996 in the Wieprza River drainage area. The species spreads via the Wieprza River towards the Baltic brackish waters. With such expansion of this species, it is expected to be found in Polish coastal waters of the Baltic Sea and in other coastal rivers in the near future. The conflict between legal aspects of the signal crayfish farming, colonization by the species of the natural aquatic ecosystems and the expectations of consumers is discussed.
2

Estimated population abundance of catchable signal crayfish [Pacifastacus leniusculus [Dana]] and spiny-cheek crayfish [Orconectes limosus [Raf.]] in lake Pobledzie [Northeastern Poland]

100%
Krzywosz T., Ulikowski D., Traczuk P.
Archives of Polish Fisheries
|
2006
|
tom 14
|
nr 1
In 2004, monitoring catches were performed on signal crayfish, Pacifastacus leniusculus (Dana) and spiny-cheek crayfish, Orconectes limosus (Raf.), in order to estimate the abundance of the catchable populations in Lake Pobłędzie (northeastern Poland). Catches were performed using 58 Evo traps along a part of lake with an area of 1.65 ha. In catches conducted on September 6 and 7, a total of 479 specimens of signal crayfish and 29 spiny-cheek crayfish were caught, marked, and released. After twelve days, repeat catches were conducted during which 476 specimens of signal crayfish, including 66 marked specimens, and 36 specimens of spiny-cheek, including 5 marked specimens, were caught. The average total length of the caught signal crayfish was 11.7 ± 1.06 cm (7.6 - 15.0 cm), while that of the spiny-cheek species was 9.3 ± 0.65 cm (7.5 - 10.7 cm). The average catchable population abundance per unit of studied surface area was calculated at 2094 specimens ha⁻¹ for signal crayfish and 127 specimens ha⁻¹ for spiny-cheek crayfish. Taking into consideration that this method underestimates the population abundance of crayfish from the lower size classes, it is estimated that the actual catchable population abundance in Lake Pobłędzie might be higher by about 25%.
3

Observations of the signal crayfish Pacifastacus leniusculus [Dana] in a Lake in the Eastern Suwalki Lake District

100%
Krzywosz T., Krzywosz W.
Archives of Polish Fisheries
|
2002
|
tom 10
|
nr 2
The aim of the study was to identify the characteristics of a population of signal crayfish Pacifastacus leniusculus (Dana) which were introduced into the lake eleven years ago. In 1992, 1,100 one-year-old signal crayfish specimens were released into the lake. The lake has a surface area of 57.6 ha, an average depth of 5.9m and a maximum depth of 15.4m and is currently in a moderately advanced trophic state. The lake was inhabited by numerous populations of the noble crayfish Astacus astacus (L.) until 1988 when they were poisoned. The catch rate statistics of crayfish fishermen have indicated that the growth in the signal crayfish populations has been progressive since 1996. In 1998, the sixth year they inhabited the lake, the size of the catch population, which occurred in that and in following years, was formed. Specimens measuring from 11 to 14 cm dominated in this population, while only a very few crayfish specimens reached a length of approximately 16 cm. As the crayfish specimens increased in body length, the male body weight predominance over female body weight also increased. While for specimens 10 cm long this figure was as high as 17.5%, for 16 cm long specimens it peaked at 33.6%. Noble and narrow-clawed crayfish have also been observed in control catches since 1999. The signal crayfish had similar weights at the same body lengths to those of the noble and narrow-clawed crayfish Astacus leptodactylus Esch. and were heavier than the spiny-cheek crayfish Orconectes limosus (Raf.). The signal crayfish reproduce in late September and early October, which is at least two weeks earlier than indigenous crayfish.
4

Evaluation of changes in the abundance of three catchable crayfish species in lake Pobledzie [Northern Poland]

80%
Krzywosz T.
Archives of Polish Fisheries
|
2006
|
tom 14
|
nr 1
The aim of the study was to learn about the character and dynamics of changes in the abundance of the catchable population of the signal crayfish, Pacifastacus leniusculus (Dana), the spiny-cheek crayfish, Orconectes limosus (Raf.), and the noble crayfish, Astacus astacus (L.), that all inhabit Lake Pobłędzie (northern Poland). During the study period of 1996 - 2005, the effectivity of crayfish catches conducted with Evo traps in the lake rose from 1.30 to 5.67 specimens trap⁻¹ night⁻¹. This indicates that crayfish abundance increased progressively. The noble crayfish was observed only in the 1999 - 2002 period and succumbed to growing pressure from both of the American species. Studies have excluded the existence of the crayfish “plague” caused by Aphanomyces astaci Schikora. The abundance of the signal crayfish, which was introduced in 1992, increased throughout the study period. The abundance of the spiny - cheek crayfish rose from 1999 to 2002. Although a slight decrease was noted in 2003, not until 2004 was a rapid decline noted in this species. A similarly dramatic decline has been noted since 2002 in the abundance of spiny-cheek crayfish in many other Polish waters. This was probably the result of an outbreak of an infectious disease particular to this species. The catch effectivity of signal crayfish (99.5% share of catches) in 2005 was 5.00 specimens trap⁻¹ night⁻¹ and was higher than the catch effectivity achieved with this species in Californian and Swedish lakes.
5

Czy warto zainteresowac sie hodowla rakow?

61%
Serafin J.
Biuletyn Informacyjno-Handlowy. Ośrodek Doradztwa Rolniczego Boguchwała
|
1999
|
nr 11
13-14
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