- Lampreys, lampreys everywhere…some are part of nature
- Native species vs invasive species are always a concern for understanding
- Lampreys live in the Great Lakes, isolated northern lakes, the Mississippi River, other places
By Mike Schoonveld
A couple of years ago I fished for sturgeon on the Rainy River in Minnesota, just upstream from where it flowed into Lake of the Woods. As luck would have it, I caught one and it came with a surprise.
Last fall I fished for largemouth bass on the Mississippi River near LaCrosse, WI and one of the bass we caught that morning also came with a surprise. Each of these fish flopped on the deck with a lamprey clinging to their side.
I have not lived a fish-sheltered life. I’ve fished every Great Lake and dozens more not quite so great lakes. I’ve studied, fished for, and caught nearly every game fish available in these waters. When I landed that Minnesota sturgeon, the tag-along lamprey was an unexpected surprise.
As a Great Lakes fisherman, I am very familiar with sea lampreys, an invasive species from the Atlantic Ocean, now present in all five Great Lakes, as well as New York’s finger lakes.
It’s not a surprise when I catch a trout or salmon with lamprey scars, or even with a live lamprey still attached.
My Rainy River surprise was a mystery. How had sea lampreys moved from the Great Lakes to Lake of the Woods and why hadn’t I ever heard about them damaging the fish populations there as they do in the Great Lakes?
Mystery solved; it wasn’t a sea lamprey. The lamprey suctioned to the sturgeon I caught was most likely a silver lamprey, one of four native species of lampreys found in Minnesota, Michigan, Wisconsin and the other Great Lakes states. Two of them, like sea lampreys, are parasites. Chestnut lampreys – the other native parasitic lamprey – have been found in Minnesota, but have not been seen in Lake of the Woods.
I identified this silver lamprey after the fact. I was trying to get a grip on it so I could treat it the same way I treat the sea lampreys which come on my boat attached to a salmon or trout. They come aboard in one piece; they go back to the lake in two parts. Lampreys are slick and squiggly, and the sturgeon-sucker squiggled back into the river before I could decapitate it.
Neither silver or chestnut lampreys are protected species in Minnesota so that I wouldn’t have been in trouble had I put it on the chopping block. Since then, I have now learned they don’t deserve to be hacked into pieces as do sea lampreys in the Great Lakes.
By the time the lamprey came on board the boat with me on the mighty Mississippi, I knew better. It could have been either a silver or chestnut lamprey. Both are endemic to the big river. I released it, all in one piece, soon after snapping a photo (shown here).
NATIVE VS. INVASIVE
Why was I so soft-hearted about the bass-sucking lamprey encountered on the Mississippi River and why am I so ruthless about the sea lampreys “vampiring” on lake trout in the Great Lakes? Aren’t the silver, chestnut and sea lampreys all doing similar things? Aren’t all of them blood-sucking parasites potentially and probably injuring or killing the fish they attack?
Absolutely! The difference is the silver lampreys in Lake of the Woods and the chestnut lampreys in the Mississippi River have never wiped out entire populations of fish where they have been found. Invasive sea lampreys did that in the Great Lakes and would still be doing it if not for lamprey control programs in the US and Canada. Even with silver and chestnut lampreys there is still plenty of sturgeon in Lake of the Woods – along with walleye, lake trout, pike, crappies and other fish. There is still plenty of fish in the Mississippi River as well.
Native lampreys and native fish all evolved together and co-developed a host/parasite relationship and achieved a natural equilibrium. The long and short of it is through a complex web, which involves many more species than just bass or sturgeon and lampreys, there aren’t ever enough native lampreys in a system to overwhelm the fish on which they feed. Nature is a savage place. Big fish eat little fish, herons and ospreys eat bigger fish. For the most part, nature is always interacting to maintain the balance. Native lampreys parasitizing native fish are as much a part of that balance as an osprey snatching a pike.