ABUNDANCE OF NARROW-CLAWED CRAYFISHES (Astacus leptodactylus Eschscholtz, 1823) AND ITS TRENDS IN LAKE SEVAN, ARMENIA

Öz

The narrow-clawed crayfish (Astacus leptodactylus Eschscholtz, 1823) is an indigenous spe­cies in Arme­nia. In 1980s it was occasionally introduced in Lake Sevan where its population started to grow. There is a large scale fishery of the crayfish in the Lake, as its demand remains high. Industrial stock of crayfishes at the Lake monitored annually, shows statistically sig­nifi­cant decline in the 2004-2011 period. This decline can be described by logarithmic model y = -577.5ln(x) + 2158, F = 50.27, P<0.001. The catch rate of crayfish net-boxes also shows loga­rithmic decline F = 9.27, P<0.05 in the 2004-2011 period. Since the net boxes are designed to catch the larger size crayfishes only, the decline indicates a decrease of average size among crayfish population. The female fertility does not show statistically significant correlation with the in­dustrial stock of crayfish. It does, however, show neg­ative correlation with the catch rate of the net boxes: r_Pearson = -0.686, P<0.05; ρ_Spearman = -0.647, P<0.05. The correlation can be ex­plained as the big animals are actively removed through harvesting, while small­er animals are not captured; meanwhile the remaining smaller animals produce fewer eggs. Decline of cray­fish stock cannot be explained by diseases and inva­sive species, but can be explained by over­harvesting. Continuation of harvesting aimed at supplying the ex­isting demand might result to population decline of more than 70% during next 17 years.

Anahtar Kelimeler

• Narrow-clawed crayfish,Astacus leptodactylus,Abundance,Lake Sevan,Armenia

Kaynakça

1. Aydin, H., Harlıoğlu, M.M., Deniz, T. (2012): Harvest, export and economic status of freshwater crayfish (Astacus leptodactylus Esch.1823) in Turkey. African Journal of Agricultural Research, 7(16): 2463-2468.
2. Badalyan, N. (2012a): The growing features of Pontacus Leptodactilus Eshch. of lake Sevan. Biological Journal of Armenia, 1(64): 108-110.
3. Badalyan, N. (2012b): Characteristics of narrow-clawed crayfish (Pontastacus leptodactylus Eschscholtz, 1823) of the Lake Sevan under raising of the Lake’s level. Dissertation seeking for the Academic Degree of Candidate of Biological Sciences with specialization 03.00.08 –“Zoology”, 101 pp.
4. Budnikov, K.N., Tretyakov F.F. (1952): Rechnie raki i ikh promysel. M, Pishpromizdat, 96 pp.
5. Dartay, M., Atessahin, T. (2013): A Study on Catching Freshwater Crayfish, Astacus leptodactylus Eschscholtz 1823, and Its Some Population Characteristics. Turkish Journal of Science & Technology, 8(2): 125-130.
6. Dorn, N.J., Wojdak, J.M. (2004): The role of omnivorous crayfish in littoral communities. Oecologia 140: 150-159.
7. Fedotov, V.P., Bykadorova, S.V., Kholodkevich, S.V. (1998): Crayfish situation in the North-West of Russia. In: Trond Taugbøl (ed.), Nordic-Baltic Workshop on Freshwater Crayfish Research and Management. Eastern Norway Research Foundation and Estonian Ministry of Environment.
8. Gabrielyan, B. (1987): Investigation of Spawning Migrations of Khramulja Varicorhinus Capoeta Sevangi (Filippi) by the Method of Marking with Active Dyes. Biological Journal of Armenia, 40(1): 79-82.

9. Gabrielyan, B., Ghukasyan, E. (2007): Ecological consequences of introduction of hydrocoles in Lake Sevan. Proceedings of the International Conference “Natural and invasive processes of forming the biodiversity of aquatic and terrestrial ecosystems”, Rostovna-Donu, 81-82.
10. Ghukasyan, E., Badalyan, N., Hovhannisyan, R., Dallakyan, M. (2006): On the changes of biological parameters of crayfish in the Lake Sevan. Biological Journal of Armenia, 3-4(58): 321-324.
11. Ghukasyan, E., Badalyan, N., Gabrielyan, B., Sahakyan, D., Dallakyan, M. (2011): Reproduction peculiarities of narrow-clawed cray¬fish in Lake Sevan. Proceedings of the International Conference “Biological Diversity and Conservation Problems of the Fauna of the Caucasus”, September 26-29, Yerevan, Asoghik, 105-108.
12. Ghukasyan, E., Badalyan, N., Sahakyan, D. (2010): Ecological peculiarities of narrowclawed crayfish in Lake Sevan and dynamics of its industrial stock. in Ecology of Sevan in the period of raising its level. Study results of Russian-Armenian biological expedition on hydro-ecological survey of Lake Sevan (Armenia) (2005-2009), Makhachkala. Nauka DNC, 224-228.
13. Ghukasyan, E., Badalyan, N., Sahakyan, D., Dal¬lakyan, M. (2008): Influence of fishery on the population of narrowclawed crayfish in Lake Sevan. Proceedings of the International Conference “Importance of ecology and nature protection in the perspectives of sustainable development” November 20-21, 2008. Yerevan, 65.
14. Ghukasyan, E., Gabrielyan, B., Badalyan, N. (2007): Dynamics and some biological parameters of narrowclawed crayfish introduced to the Lake Sevan. Proceedings of Southern Scientific Center of Russian Academy of Sciences “Biodiversity and transformation of mountain ecosystems of Caucasus”. Rostovna-Donu. SSC RAC Press. 3, 114-118.
15. Güner, U., Harlıoğlu, M.M. (2009): Status of freshwater crayfish distribution in Thrace region of Turkey. Reviews in Fisheries Science, 18(1): 1-6.
16. Harlıoğlu, M.M., Güner, U. (2007): A New Record of Recently Discovered Crayfish, Austropotamobius torrentium (Shrank, 1803), in Turkey. BFPP/Bull. Fr. Pêche Piscic., 387, 01-05.
17. Harlıoğlu, M.M. (2004): The present situation of freshwater crayfish, Astacus leptodactylus (Eschscholtz, 1823) in Turkey. Aquaculture 230: 181-187.
18. Harlioğlu, M.M., Harlioğlu, A.G. (2004): The harvest of freshwater crayfish, Astacus leptodactylus (Eschscholtz, 1823) in Turkey. Reviews in Fish Biology and Fisheries, 14(4): 415-419.
19. Harlioğlu, A.G. Harlioğlu, M.M. (2009): The Sta¬tus of Freshwater Crayfish (Astacus leptodactylus Eschscholtz) Fisheries in Turkey. Reviews in Fisheries Science, 17(2): 187-189.
20. Holdich, D.M., Reynolds, J.D., Souty-Grosset, C. Sibley, P.J. (2009): A review of the ever increasing threat to European crayfish from nonindigenous crayfish species. Knowledge and Management of Aquatic Ecosystems, 394-395: 1-46.
21. Hovhannisyan, R. (1998): Ecological peculiarities narrow-clawed crayfish in Lake Sevan. Dissertation seeking for the Academic Degree of Candidate of Biological Sciences by specialization 03.00.08 –“Zoology”, 94 pp.
22. Hovhannisyan, R., Ghukassian, E. (1996): Some ecological peculiarities of Lake Sevan higher Crustacea PontAstacus leptodactylus Eschholtz. Lake Sevan: problems and strategies of action. Proceedings of the international conference. Sevan, Armenia, 13-16 October. 1996, 99-101.
23. Kholodkevich, S.V., Shumilova, T.E., Fedotov, V.P., Zhuravlev, D.A. (2005): Effects of the Astacus astacus L. Population on Biomass of Macrophytes in a Fresh Water Body. Russian Journal of Ecology, 36(4): 271-276.
24. Kireev, I.A. (1933). Hydrographic works at the Lake Sevan. Materials on the study of the Lake Sevan and its watershed. Tiflis, 5: 65-87.
25. Kokko, H., Koistinen, L., Harlioğlu, M.M., Mak¬konen, J., Aydın, H., Jussila J. (2012): Recovering Turkish narrow clawed crayfish (Astacus leptodactylus) populations carry Aphanomyces astaci. Knowledge and Management of Aquatic Ecosystem, 404: 12.
26. Longshaw, M. (2011): Diseases of crayfish: A review. Journal of Invertebrate Pathology, 106(1): 54-70.
27. Lozán, J.L. (2000): On the threat to the European crayfish: a contribution with the study of the activity behaviour of four crayfish species (Decapoda: Astacidae). Limnology, 30: 156-161.
28. Momot, W. (1995): Redefining the role of crayfish in aquatic ecosystems. Reviews in Fisheries Science, 3(1): 33-63.
29. Momot, W., Gowing, H., Jones, P. (1978): The Dynamics of Crayfish and Their Role in Ecosystems. American Midland Naturalist, 99(1): 10-35.
30. Nyström, P., Brönmark, Ch., Graneli, W. (1996): Patterns in benthic food webs: a role for omnivorous crayfish? Freshwater Biology, 36(3): 631–646.
31. Souty-Grosset, C., Holdich, D.M., Noël, P.Y., Reynolds, J.D. Haffner, P. (2006): Atlas of Crayfish in Europe. Muséum national d’Histoire naturelle, Paris.
32. Statistical yearbook of Armenia. (2008): National Statistical Service of the Republic of Armenia, Yerevan, 2008, 589 p.
33. Statistical yearbook of Armenia (2012): National Statistical Service of the Republic of Armenia, Yerevan, 2012, 567 p.
34. Svoboda, J., Kozubíková, E., Kozák, P., Kouba, A., Bahadir Koca, S., Diler, O., Diler I., Policar, T., Petrusek, A. (2012): PCR detection of the crayfish plague pathogen in narrowclawed crayfish inhabiting Lake Eğirdir in Turkey, Diseases of Aquatic Organisms, 98(3): 255-259.
35. Pagano, M., Gauvreau, K. (1993): Principles of biostatistics. Duxury Press, Belmont, CA. 524 pp.
36. Púky, M., Reynolds, J.D., Schád, P. (2005): Native and alien Decapoda species in Hungary: distribution, status, conservation importance. Bulletin Francais de la Pêche et de la Pisciculture.
37. Reports of Institute of Hydroecology and Ichthyology of SCZH of NAS RA. (2010): Scientific Center of Zoology and Hydrobiology and Sevan National Park, Yerevan. 6 pp.
38. Reports of Institute of Hydroecology and Ichthy¬ology of SCZH of NAS RA. (2011): Scientific Center of Zoology and Hydrobiology and Sevan National Park, Yerevan. 10 pp.
39. Wayne, D.W. (2009): Biostatistics: A Foundation for Analysis in the Health Sciences, 9th Edition. John Wiley & Sons, Inc. 956 pp.