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The Risks of Not Having a Plan for Rainbow Trout

Another weekly post for you! This week, PEIISC member and West River Watershed Coordinator, Megan Harris, takes a look at the risks of not having a plan for Rainbow Trout.

I talk to many avid anglers on the Island about getting rid of rainbow trout and they all suggest that I’m being too extreme. Eradication isn’t necessary – we can have our cake and eat it too. How many times have we learned that lesson the hard way?

Rainbow trout (Oncorhynchus mykiss) were introduced to maritime freshwaters from both intentional stocking and as aquaculture hatchery escapees. In PEI, they are now in over 20 rivers that empty to the south and east. They appear to be expanding toward north shore river systems.

So why should we be concerned about rainbows? Anglers love them because they fight well when hooked. The large sea-run fish, called steelhead, are also a draw for off-Island fishing traffic. Yes, they are beautiful. They also make the top 100 list of worst global invaders, published by the IUCN’s Invasive Species Specialist Group – they currently sit at number 63. They are native to the Pacific coast of North America, but now occupy many rivers across Canada, the U.S. and are established on all continents except Antarctica.

They threaten native freshwater fishes and ecosystems via several mechanisms: hybridization, disease transmission, predation and competition for habitat. They are a highly adaptable predator, more tolerant of warm water than our native brook trout and competing for fast-flowing spawning waters with native Atlantic salmon. The adults eat insects, molluscs, fish eggs and young fish, while the young eat zooplankton.

On the Island, brook trout are struggling in some rivers while Atlantic salmon have been in decline for decades. Habitat degradation is a big contributor, but rainbow trout represent an additional pressure to populations of native species. In other jurisdictions where they’ve worked to control this invasive species, it has usually been accomplished through angling regulations – allowing only rainbow trout to be kept and no native fish. In Great Smoky Mountains National Park, the antibiotic antimycin is used to kill rainbow trout in an effort to protect the native brook trout.

Today, we don’t have a plan to control rainbow trout in Island rivers and there is no consensus on whether we need to be thinking about it. What do you think?

- Megan Harris, PEIISC Member and West River Watershed Coordinator

Native Brook Trout. Photo by: Taylor Main
Native Brook Trout. Photo by: Taylor Main
Invasive Rainbow Trout. Photo by: Taylor Main
Invasive Rainbow Trout. Photo by: Taylor Main