Science on the Stream: Tracking the Northern Pike

Photo Credit: Kevin Gallant, Assistant Researcher at Maine Department of Inland Fisheries and Wildlife

Paddling along Pushaw Stream or any other Maine waterway in the spring can feel almost perfect. You may notice fresh buds and green leaves on trees, birds flying over with nesting material, and frog calls throughout as you drift along—everything can seem so calm. But if you’re someone interested in ecology, you know that just below the surface, there is always a host of changes occurring, especially in spring. Temperatures are rising, there’s been an incredible increase in nutrients from snowmelt and rainfall, migrations have begun, and fish populations are shifting. One particularly aggressive newcomer, the invasive northern pike, is making waves in more ways than one.

What is the issue?

While northern pike (Esox lucius) do originate from parts of North America, including Canada and areas in the northern U.S. like Minnesota and even New York, they are not native to Maine's lakes and rivers. Known for being aggressive and large, they were illegally introduced to our waterways as a means of creating more sport fishing opportunities. While some introduced species can be benign to our ecosystem—petunias, for example—this has not been the case for northern pike. Unfortunately, once established, they spread rapidly through connected waterways and are now found in several river systems where they weren’t historically present, and where they threaten native fish populations.

They are quite impressive opportunistic carnivores, eating just about anything they can catch. Pike are known to feed on small mammals, amphibians, and even birds. However, fish seem to be the most common food item in the diet of pike in Maine. This includes native fish like brook trout and landlocked salmon—species already facing pressure from changing habitats. In addition to feeding on native fish, they can outcompete those fish for resources, disrupting long-established food webs.

Since they’ve spread widely through Maine’s waterways, researchers are now working to map out exactly where these invasive fish have established themselves. The Maine Department of Inland Fisheries and Wildlife (MDIFW) is currently one of the organizations making an effort to monitor pike movements and determine where they may go next.

How is this being studied?

To find out more about northern pike, MDIFW is trapnetting during the spring season for live spawning pike. The fish caught in these traps are measured and released with a special tag. If you traveled to paddle at Hirundo early this spring, you may have spotted the buoys attached to these nets at their research sites along Pushaw Stream! Once the fish are back in the waterway, the team relies on anglers to catch and report them.

The tags placed on the fish, called floy tags, have a unique number on each one so that when a fish is caught, the number can be reported back to MDIFW. Along with the tag number, anglers are asked to answer a handful of questions—such as where the fish was caught, its length, and whether it was kept or released. Anglers are welcome to leave their contact information if they are interested in learning the original capture information on that fish or if they have questions.

Why does this work matter?

You may wonder why tracking the movement and location of pike is the main goal at this time. Kevin Gallant, Assistant Regional Biologist at MDIFW, shared with us that “Monitoring the movement of invasive fish can help us prepare to limit future impacts on native and stocked fisheries.” Once there is a better understanding of their movement patterns, management tools to prevent them from establishing in new areas can be explored. These tools may include modifying or blocking fish passageways to selectively allow native species through, using targeted removal efforts, or in some cases, applying chemical treatments to reclaim affected waters. Once they know where pike are and where they’re likely to spread, management efforts can be more focused and efficiently directed toward implementing the appropriate tools.

Monitoring the movement of invasive fish can help us prepare to limit future impacts on native and stocked fisheries.

What can we do to help?

If we have you on our hook (pun intended) and you are interested in supporting this research there are direct actions you can take to support this research in Maine, especially if you are someone who fishes.

1. See a tagged fish, report a tagged fish. If you find a tagged fish you can report it to MDIFW through their site or contact Kevin at kevin.gallant@maine.gov or 207-794-1029.

2. You can also always report any strange findings or actions you observe while fishing. View the MDIFW department directory.

3. Keep a voluntary angler book for MDIFW. If you often fish directly for pike along Maine’s waterways, especially along Pushaw or Pushaw Stream, you can keep a voluntary angler book for MDIFW. Contact kevin.gallant@maine.gov to learn more!

If you are not an angler, there are many non-fishing ways to still support the Maine Department of Inland Fisheries and Wildlife (MDIFW) and help researchers and conservation efforts:

• Buy Official MDIFW Merchandise or Make a Donation: Support outreach and education by shopping their online store for apparel, drinkware, and more, or make a donation.

• Volunteer Your Time: Check out volunteer opportunities at the Maine Wildlife Park or with citizen science programs like the Heron Observation Network.

• Share their work & goals: Follow them on Facebook and Instagram, and share the work they are doing. Spread the word about their efforts and needs.

By staying proactive and using the right combination of tools, we can help protect the health of our native and stocked fisheries. Continued monitoring and response will be key to staying ahead of the problem. We’re grateful to the researchers at MDIFW for their ongoing efforts to track and manage invasive species, and we appreciate their willingness to share their work with us. We wanted to highlight this project because it's exciting research happening right here at Hirundo. It's important to us that our community knows about the science and conservation work taking place at the refuge.

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Resources:

Kevin Gallant, Assistant Researcher at Maine Department of Inland Fisheries and Wildlife

Brautigam, F., & Lucas, J. (2001). NORTHERN PIKE ASSESSMENT. In Maine Department of Inland Fisheries & Wildlife, Maine Department of Inland Fisheries & Wildlife. https://www1.maine.gov/ifw/docs/strategic-management-plans/northernpike.pdf

Northern Pike: Species information: Fisheries: Fish & Wildlife: Maine Dept of Inland Fisheries and Wildlife. (n.d.). https://www.maine.gov/ifw/fish-wildlife/fisheries/species-information/northern-pike.html