Crayfish Resources

PUBLICATIONS

WEBSITES

PODCASTS

VIDEOS

TVO video about Marbled Crayfish

My Crayfish Publications . 

Hamr P. and Schryer B. (2026). Field Guide to Crayfishes in Canada. Invading Species Awareness Program and Fisheries & Oceans Canada. First edition. pp. 1-109.

Hamr P. (2026). Red swamp crayfish in Ontario: Biology, Management and Impact. Report for the Biodiversity and Invasive Species Section, Ministry of Natural Resources, Peterborough Ontario. Pages 1-51.

Hamr P. and Schryer B. (2025). The expansion of the white river crayfish (Procambarus acutus) in Ontario, Canada. Freshwater Crayfish 30 in press.

Edelsparre, A., McCarter, J., White, R., Aarts, M., Beauclerc, K., Choquette, J., Crowley, J., Davy, Ch., Fotherby, H., Gillingwater, S., Feltham, J., Hamr, P., Maddalena, M., Mullen, J. Quinn, J., Siu, J, Urquhart, J., Watt, C. and Pulfer, T.

(2025). Forecasting species at risk conservation: Addressing recovery actions through multi-agency broad scale sampling. Ecological Solutions 6 (4)1-10.  https://doi.org/10.1002/2688-8319.70168.

Hamr P. (2025). Red Swamp Crayfish in Ontario: Biology, Management and Impact. Report for The Biodiversity and Invasive Species Section, Ministry of Natural Resources, Peterborough Ontario. Pages 1- 50.

Hamr P. and Schryer B. (2025). Guide to Ontario’s Crayfishes. Invading Species Awareness Program & Fisheries and Oceans Canada. Second edition. P. 1-79. Updated  2nd edition.

https://www.invadingspecies.com/download/guide-to-ontarios-crayfishes/#

Hamr P. (2024).  The Real and Potential Impacts of Invasive Crayfish in Ontario Canada: A Review.

Freshwater Crayfish 29 (1):9–22.   https://doi.org/10.5869/fc.2024.v29-1.9

Filice, P., W. Budnick, R. Feagley, B. Roth, and L. Nathan. (2024). Great Lakes Almanac to Invasive Crayfish: Identification and Reporting.  URL: invasivecrayfish.org/almanac  (illustrations by P. Hamr).

Hamr P. and B. Schryer (2024). Guide to Ontario’s Crayfishes.  With OFAH/DFO. Contributions of text and illustrations. 1st edition.

Hamr P. (2024). INVASIVE SPECIES RISK ASSESSMENT GUIDANCE DOCUMENT: VIRILE CRAYFISH (Faxonius virilis).  BC Inter-Ministry Invasive Species Working Group. Pp. 1-20.

Hamr P and B. Schryer (2023). New Records of White River Crawfish (Procambarus acutus) from Ontario Canada.

Crayfish News 45 (3-4): 6-9.

Hamr P., Schryer B., Lake C. (2023). Oral presentation and Abstract First record of the first wild marbled crayfish (Procambarus virginalis) population in North America/Canada and subsequent eradication efforts

International Association of Astacology Symposium 24. Zagreb Croatia.

Hamr P. (2023). First Record of The Marbled Crayfish in Canada.  Crayfish News 45(1-2): 1-2.

Hossie T. J. and Hamr P. (2023). Non-native White River Crayfish on Pelee Island: Habitat Use and Possible Threats to Imperilled Taxa. Poster Presentation OCTWS Conference.

Hamr P. (2022). The Life of a Rusty Crayfish (Faxonius rusticus) in Pictures. Crayfish News 44, Issue 3-4.  

e-ISSN: 2150-9239 (online)  

Hamr P. (2022). Chimney Crayfish RElocation. Report for Beacon Environmental Consulting. August 2022.

Hossie T.J. and Hamr P (2022). First Records of White River Crayfish (Procambarus acutus) in Ontario/Canada on Pelee Island, Ontario, with Notes on Other Crayfish Species Present and Their Habitats. Freshwater Crayfish 27(1): 9-16. https://doi.org/10.5869/fc.2022.v27-1.9

Hamr P and Verhoeff N (2022). The Life History of the Rusty Crayfish (Faxonius rusticus) in a Small Southern Ontario Stream. Freshwater Crayfish 27(1): 17-25. https://doi.org/10.5869/fc.2022.v27-1.17

Hamr P. (2022) Invasive Crayfish Impacts in Ontario.  Report for The Biodiversity and Invasive Species Section, Fish and Wildlife Policy Branch, Ministry of Natural Resources and Forestry, Ontario. Peterborough, Ontario.

 Hamr P (2021). An Update of the Classification, Status, and Distribution of Canadian Freshwater Crayfishes.

  Freshwater Crayfish 26(2): 119-125.

Hamr, P (2020).  The Classification, Status and Distribution of Canadian Crayfishes: An Update. Crayfish News 42: 1-5.    

 Hamr, P., Hoel M. and K. Eales (2019).  The distribution and conservation of the white colour morph of the Northern         Clearwater Crayfish (Faxonius  propinquus) in Lake Simcoe, Ontario,  Canada.   Freshwater Crayfish 24(1): 33-38. https://doi.org/10.5869/fc.2019.v24-1.33

Yaziciouglu B., Hamr P., Kozak P., Kouba A. & Niksirat H.  (2016). Fine structure of the spermatozoon in three species of Cambaridae (Arthropoda: Crustacea: Decapoda) Cambarus robustus, Orconectes propinquus and Orconectes rusticus : A comparative biometrical study.   Zoomorphology. PeerJ 4:e2363; DOI10.7717/peerj.2363

Hamr, P and Hoel M. (2015).  Searching for Canada’s rarest crayfish. 2015 Crayfish News 37(2): 4-5.

Hamr, P., Hamr J. and Hoel M. (2015).  The crayfishes of Manitoulin Island. Freshwater Crayfish 20 (1) 87-91. doi: 10.5869/fc.2014. v20-1.87

Richman N.I. , M. Böhm, S.B .Adams , F. Alvarez, E.A. Bergey, J.J.S. Bunn , Q. Burnham, J. Cordeiro, J. Coughran , K.A. Crandall , K.L. Dawkins , R.J. Distefano , N.E. Doran, L. Edsman , A.G. Eversole, L. Füreder, J.M. Furse, F. Gherardi, P. Hamr , D.M. Holdich , P. Horwitz , K. Johnston, C.M. Jones, J.P.G. Jones, R.L. Jones, T.G. Jones, T. Kawai , S. Lawler, M. López-Mejίa, R.M. Miller , C. Pedraza-Lara , A.M.M Richardson, M.B. Schultz, G.A. Schuster, P.J.Sibley, C. Souty-Grosset , C.A. Taylor , R.F. Thoma , J. Walls , T.S.Walsh  and B. Collen (2015). Multiple drivers of decline in the global status of freshwater crayfish (Decapoda: Astacidea). Philosophical Transactions of the Royal Society B: Biological Sciences 370(1662): 1–11. doi: 10.1098/rstb.2014.0060

Kozák P., Buřič M., Kanta J., Kouba A., Hamr P., Policar T. (2012).  The effect of water temperature on number of moults and growth of juvenile signal crayfish Pacifastacus leniusculus    Czech Journal of Animal Science. 54, 286-292.  https://doi.org/10.17221/1727-CJAS

Hamr, P. (2011).  Long-Term Monitoring of Crayfish Populations in the Credit River at the Upper Canada College    Outdoor School Freshwater Crayfish 18 (1) 83-86.

Hamr, P. (2010). The biology, distribution and management of the introduced Crayfish Orconectes rusticus in Ontario, Canada. Freshwater Crayfish 17: 85-90. doi: 10.5869/fc.2010.v17.85

Hamr, P. (2010). Method for Quick Assessment of Ovary Maturation in Crayfish Crayfish News 32(3): 6.

Kozak P., Buřič M.,  Kanta J.,  Kouba A., Hamr P.  and Policar T. (2009). The effect of water temperature on the number of moults and growth of juvenile signal crayfish Pacifastacus leniusculus Dana.  Czech Journal of Animal Science: 54(6): 286–292.

Hamr, P. (2008). Life History of the Crayfish Astacopsis franklinii (Parastacidae) in streams on Mount Wellington, Tasmania.  Freshwater Crayfish 16:155-164.  Griffiths University. Queensland, Australia. 978-0-9805452-0-3 online

Hamr, P. (2007). Sampling Protocol for Rusty Crayfish Orconectes rusticus in Ontario.  Report for the Ontario Ministry of Natural Resources and Ontario Federation of Anglers and Hunters.

Hamr, P. (2007). Summer 2007: Ontario Crayfish Distribution Report.  Report for the Ontario Ministry of Natural Resources and Ontario Federation of Anglers and Hunters.

Hamr, P. (2005). Giant freshwater crayfish (Astacopsis gouldi) recovery plan review. Report for The Threatened Species Unit, Department of Primary Industries, Water and Environment, Hobart, Tasmania.

Taylor, R. M., Hamr, P. & Karstaad, A. (2005). Bait Guide for Eastern Canada, the Great Lakes Region and Northeastern United States.  G. Winterton ed. University of Toronto Press.

Taylor, R. M., Hamr, P. & Karstaad, A. (2005). Chapters 10 –13 (Crayfishes, pp. 222-317) in The Comprehensive Bait Guide for Eastern Canada, the Great Lakes Region and Northeastern United States.  G. Winterton ed. University of Toronto Press.

Hamr, P. (2005). The Distribution and Conservation Status of Burrowing Crayfishes Fallicambarus fodiens and Cambarus diogenes in Canada.  Freshwater Crayfish 15:1-13 . London. England.

Hamr, P. (2003). Conservation Status of Burrowing Crayfishes in Canada. Report for the Endangered Species Unit, World Wildlife Fund Canada. pp. 1-34. UCC Press. Toronto, Canada.

Hamr, P. 2002. Orconectes. Chapter 15 in Biology of Freshwater Crayfish.  D. Holdich editor. Blackwell publishing. Oxford. UK.

Hamr, P. (2000). Impact of Introduced Freshwater Crayfish in Canada. Proceedings of the 10th International Aquatic Nuissance Species and Zebra Mussel Conference. Toronto. Ontario.

Hamr, P. (1999).  The commercial harvest of the exotic Rusty crayfish (Orconectes rusticus). Summer 1998. pp 1-9. Report to the Ministry of Natural Resources, Peterborough Region. Peterborough, Ontario, Canada.

Hamr, P. (1998). Conservation Status of Canadian Freshwater Crayfishes. Report for the World Wildlife Fund Canada. pp. 1-80. WWF Toronto, Canada.

Hamr, P. (1997).  A giant’s tale: The life history of Astacopsis gouldi (Decapoda: Parastacidae), a freshwater crayfish from Tasmania. Freshwater Crayfish XI. W. Momot editor. International Association of Astacology. LSU Graphic Services. Louisiana State University. Louisiana USA.

Hamr, P. (1997).  The potential for the commercial harvest of the exotic Rusty crayfish (Orconectes rusticus). A feasibility study. pp 1- 17. Report to the Ministry of Natural Resources, Peterborough Region. Peterborough, Ontario, Canada.

Hamr, P. (1996).  A giant’s tale: The life history of Astacopsis gouldi (Decapoda: Parastacidae), a freshwater crayfish from Tasmania. Presentation at the 11th International Association of Astacology Symposium. August 1996. Thunder Bay, Ontario, Canada.

Jain, A and Hamr, P (1996).  McCraney Creek Report. Science Department Appleby College, Oakville Ontario Canada. pp 1-16.

Hamr, P. (1995).  The Reproductive Biology of the Tasmanian Freshwater Crayfish Parastacoides t. tasmanicus. Freshwater Crayfish VIII. R. P. Romaire editor, International Association of Astacology. Baton Rouge, Louisianna.

Hamr, P and Richardson A. (1994).  The life history of Parastacoides tasmanicus tasmanicus Clark, a

burrowing crayfish from south-west Tasmania. Australian Journal of Marine and Freshwater Research 45: 455-470.

Hamr, P., R. S. Kirby, P. Gillis and K. E, Day (1994). Development of Methodologies for Whole-Sediment Tests with Benthic Invertebrates. Report to Method Development and Application Division Technology Development Branch Environment Canada. AEC (NWRI), CCIW, Burligton, Ontario, Canada. pp 1-70.

Hamr, P. (1993).  Survey of Aquatic Invertebrate Taxa in Oshawa’s Second Marsh; September 1993. Report to the Canadian Wildlife Service, Great Lakes Cleanup Fund, Toronto, Ontario, Canada (pp. 1-23).

Hamr, P (1992).  A Revision of the Tasmanian Freshwater Crayfish Genus Astacopsis Huxley (Decapoda: Parastacidae). Papers and Proceedings of the Royal Society of Tasmania. 126: 91-94.

Hamr, P. (1992). Embryonic and Postembryonic Development in the Tasmanian Freshwater Crayfishes Astacopsis gouldi, Astacopsis franklinii and Parastacoides tasmanicus tasmanicus (Decapoda: Parastacidae). Australian Journal of Marine and Freshwater Research Vol. 43. 861-878.

Hamr, P. (1992).  Rare and Endangered: The Pedder Galaxias. Australian Natural History Vol 23 No 12.

Hamr, P. (1992). Biology of Tasmanian Freshwater Crayfishes: A Review. Inland Fisheries Commission Occasional Report 92-02 (pp. 1-42.). Inland Fisheries Commission, Tasmania.

Hamr, P. (1992). Conservation of Galaxias pedderensis. Inland Fisheries Commission Occasional Report 92-01.(pp. 1-66.). Inland Fisheries Commission, Tasmania.

Hamr, P.  (1991). The Conservation of Galaxias pedderensis" Presentation at the 18th Annual Congress of the Aust. Society for Fish Biology. Hobart, Tasmania, Australia.

Hamr, P.  (1991).  Life history of the Giant Freshwater Crayfish. Inland Fisheries Comission Newsletter Vol 20 No 1.

Hamr, P. (1990). The Life Histories of the Tasmanian Freshwater Crayfishes of the genus Astacopsis (Decapoda: Parastacidae). Memoirs of the Queensland Museum: Proceedings of the International Crustacean Conference, Brisbane, Australia , July 1990.

Hamr, P.  (1990).  Rare and Endangered: Tasmanian Giant Freshwater Lobster. Australian Natural History Vol 23 No 5.

Hamr, P. (1989). Tasmanian Giant Freshwater Lobster Fishing Regulations. Law Reform 1989 Law Faculty, University of Tasmania, Hobart, Tasmania.

Horwitz, P. and P. Hamr. (1988).  An Assessment of the Caroline Creek Freshwater Crayfish Reserve in Northern Tasmania.  Papers and Proclamations of the Royal Society of Tasmania 122: 69-72.

Hamr, P. (1988). "Giant Lobster Tales:The Biology of Astacopsis gouldi." Presentation at the 27th Annual Congress of the ASL. Magnetic Island, Queensland, Australia.                                         

Hamr, P. and M. Berrill. (1985).  The Life Histories of North Temperate Populations of the Crayfish Cambarus robustus and Cambarus bartoni.  Canadian Journal of Zoology 63: 2313-2322.

Hamr, P. and L. Sinclair. (1985).  The Burrowing Activity of the Crayfish Orconectes propinquus (Girard) in Southern Ontario.  American Midland Naturalist 113(2): 390-391.

Hamr, P. (1984).  The Burrowing Activity of Ontario Crayfishes.  Ecology Bulletin 8: 9-13.

Trent University, Biology Dept. Peterborough, Ontario, Canada.