Rusty the Ravager
I spent this past summer working in, what has become for me, my favourite place in the world: Quetico Provincial Park. It is a large wilderness park at the very heart of our continent in Northwestern Ontario, near the small town of Atikokan. I was working as a Biologist Intern with an amazing team of four other people, collecting plant and animal monitoring data for the Park Biologist.
What made this job so great?
Well, motorized vehicles are not allowed in the park, so we had to conduct all of our research from canoes. This meant several 10-day canoe trips, getting paid to look closely at many different plants and animals: MY DREAM.
For my second trip of the field season we paddled down to Basswood Lake, in the South end of the park, right on the Canada-US border. We went to Basswood Lake because there is a particular species of crayfish that has invaded this lake, and has the potential to invade northwards to other areas of the park. Our mission for the trip was to find this crayfish in order to determine its distribution in the lake.
Our intrepid invader is the Rusty Crayfish (Orconectes rusticus, Girard 1952).
The Rusty Crayfish is native to Ohio, but has been introduced to many new areas. Using live crayfish as bait for fishing is the biggest cause of these introductions (Puth and Allen 2005, Hein et al. 2007). Females can lay a lot of eggs (up to 200, Philips 2010), so if one female (that has already mated) gets accidentally dropped from the fishing boat, it may be enough to establish a population in a new area. Yikes!
This is a problem because Rusty Crayfish alter the ecosystems they invade with their really big appetites. And they aren’t picky, they eat EVERYTHING. The presence of Rusty Crayfish has been correlated with decreasing amounts of small bugs and snails that live under rocks and aquatic plants (McCarthy et al. 2006, Olsen et al. 1991, Lodge et al. 1998). This also means that there is less food for smaller, native crayfish, who are also getting pushed out of the better habitat by these larger invasive bullies (Arcella et al. 2014, Capelli et al. 2014). Finally, they are also capable of eating and ripping up entire beds of aquatic plants, which is home to many small bugs and fish (Peters et al. 2008, Maezo et al. 2010). So not good news, especially for a pristine wilderness park like Quetico.
We were most interested in getting presence/absence data, and we spent six days conducting our surveys. There were two methods we used to figure out where the Rusty Crayfish were in the lake. First, we set out minnow traps (baited with wet catfood, bass, or sardines) for at least 12 hours for each set.
Our second method for collecting crayfish was to do walking (or swimming) transects. It was pretty cold for the first couple of days, but then it warmed up, and this part of the research became a lot more fun! We basically swam in straight lines, flipping over rocks and cobble, trying to find and catch crayfish.
The data that we collected wasn’t good news for the park. We found that the Rusty Crayfish had invaded all the way up into North Bay (see map above). We also didn’t find ANY native crayfish. That doesn’t mean that there aren’t any native crayfish in Basswood Lake (our sampling methods were not extensive enough to say that), however it probably means that the native crayfish populations are not doing well.
So what can we do about this?
Well first and foremost, we need to stop using Rusty Crayfish as live bait. This is accomplished through education (tell your fishing friends!), and creating ‘No Live Bait’ laws for local areas. All live and dead organic bait is already banned from Quetico (only artificial bait can be used). But since waterways are connected, we need more of these kinds of regulations, especially around protected areas.
You can also tell people about, or donate to, the Quetico Foundation. This is a non-profit organization that does a lot for Quetico, including funding the salary of student researchers like myself every year. Without the Quetico Foundation, it would be impossible to do this kind of research in the park. If eradication of the Rusty Crayfish through heavy trapping and removal is possible, it will be, at least in part, because of the financial support of this great organization.
Comment below! Have you ever seen a Rusty Crayfish?
Arcella, T. E., W. L. Perry, D. M. Lodge, and J. L. Feder. 2014. The role of hybridization in a species invasion and extirpation of resident fauna: Hybrid and breakdown in the rusty crayfish (Orconectes rusticus). Journal of Crustacean Biology 34:157–164.
Capelli, G. M. 1982. Displacement of Northern Wisconsin Crayfish by Orconectes rusticus (Girard). Limnology Oceanography 27:741–745.
Hein, C. L., M. J. Vander Zanden, and J. J. Magnuson. 2007. Intensive trapping and increased fish predation cause massive population decline of an invasive crayfish. Freshwater Biology 52:1134–1146.
Lodge, D. M., R. O. Y. A. Stein, K. M. Brown, A. R. Covich, C. Bronmark, J. E. Garvey, and S. R. Klosiewski. 1998. Predicting impact of freshwater exotic species on native biodiversity : Challenges in spatial scaling. Australisan Journal of Ecology 23:53–67.
Maezo, M. J., H. Fournier, and B. E. Beisner. 2010. Potential and realized interactions between two aquatic invasive species: Eurasian watermilfoil (Myriophyllum spicatum) and rusty crayfish (Orconectes rusticus). Canadian Journal of Fisheries and Aquatic Sciences 67:684–700.
McCarthy, J. M., C. L. Hein, J. D. Olden, and M. Jake Vander Zanden. 2006. Coupling long-term studies with meta-analysis to investigate impacts of non-native crayfish on zoobenthic communities. Freshwater Biology 51:224–235.
Olsen, T. M., D. M. Lodge, and G. M. Capelli. 1991. Mechanisms of impact of an introduced crayfish (Orconectes rusticus) on littoral congeners, snails and macrophytes. Canadian Journal of Fisheries and Aquatic Science 48:1853–1861.
Peters, J. A., and D. M. Lodge. 2013. Habitat, predation, and coexistence between invasive and native crayfishes: prioritizing lakes for invasion prevention. Biological Invasions 15:2489–2502.
Phillips, I. D. 2010. Biological Synopsis of the Rusty Crayfish (Orconectes rusticus). Pages 1–99.
Puth, L. M., and T. F. H. Allen. 2005. Potential Corridors for the Rusty Crayfish, Orconectes Rusticus, in Northern Wisconsin (USA) Lakes: Lessons for Exotic Invasions. Landscape Ecology 20:567–577.