The winter 2012 issue of “UMaine Today” contains a brilliantly fascinating article about Maine sea lampreys, which this column has also covered in the past, a good thing. This parasitic, cartilaginous, snake-like species needs plenty of positive publicity to offset two strikes against them.
Sea lampreys look like a creature from a horror movie, giving them a bad rap.
After the St. Lawrence Seaway let lampreys into the Great Lakes in the 1950s, this fish lived out its entire life cycle in freshwater, where it fed heavily on native salmonids, pretty much extirpating them. On the other hand, except for rare exceptions, Maine’s sea lampreys spend the parasitic phase of their adult life in the ocean.
Many youngsters and sadly adults along Maine’s coastal rivers, streams and brooks can easily catch lampreys by hand during the annual spawning runs in late May and early June, and they may kill them, thinking they are doing a good deed by helping rid the water of this parasitic fish.
However, as a general rule, sea lampreys don’t prey on inland salmonids and have a symbiotic relationship with trout and salmon that serves an integral, multipurpose function. I have firsthand experience with lampreys on the Sheepscot River and watched the three-part story unfold
First, in spring, lampreys run up coastal waters like the Sheepscot and its tributaries, where they build nests in suitable gravel bottoms to lay eggs. As they move bottom debris around — everything from tiny pebbles to softball-sized rocks — silt and whatnot washes downstream and helps clean gravel for salmonids to spawn later in fall.
Second, when lampreys change the gravel bottom each spring, they dislodge invertebrates, etc. that in turn feed baitfish, tiny game fish and carnivorous invertebrates. Bigger fish, mammals, reptiles, amphibians and avian predators also get into the foraging spree, thanks partly to lampreys.
Third, after spawning, lampreys soon die, and the decaying bodies add nutrients to the water. No one should underestimate this point, either, and the following anecdote underscores its effectiveness.
In college, I drove a Volkswagen Beetle that illustrated just how much nutrients leach into the water in late May and early June after lampreys die and start rotting. After fishing the Sheepscot, I’d put my wet waders into the trunk, located in the vehicle’s front because the motor was in the rear. As I traveled down the road, the dead-lamprey odor that coated the rubberized canvas blew back into the car and smelled badly enough to choke a skunk.
In my youth and early adulthood, the old Department of Inland Fish and Game allowed mature lampreys to run the Sheepscot, and as the theory went, lampreys did not feed on fish during the spawning runs. Like many fish species that run upriver from the ocean, including Atlantic salmon, nature shuts down their feeding, or they would clean a river out of most of its forage within days.
After lampreys lay eggs, they hatch and spend three to 17 years in rivers, living in mud. In most drainages, juvenile lampreys run back to the ocean before they start feeding on fish. On the Sheepscot River, though, as anyone knows who fished there in the 1960s and ’70s, that theory has a flaw.
If a drainage has a deep-water impoundment — and the Sheepscot River does … 150-foot deep Sheepscot Pond — then it holds juvenile lampreys that feed on salmonids in the drainage. Many of us on the river in the 1970s caught trout and salmon with a small, blackish lamprey attached to their sides, extracting fluids, or at least with circular, lamprey scars.
Circa the late 1970s, the Department of Inland Fisheries and Wildlife, started blocking upstream lamprey migration on the Sheepscot to curtail predation, and a strange thing happened — strictly my anecdotal evidence.
Each fall for most of my life, I bird-hunted the Sheepscot from Sheepscot Pond in Palermo to the Route 105 bridge in Somerville. When lampreys ran the river in my youth, salmonid spawning was quite heavy there. It was nothing to see trout and salmon on gravel nests in bird-hunting season. When lampreys no longer ran that section and cleaned gravel, spawning sightings declined significantly. I have always wondered if there was a correlation and think the topic needs scientific research.
Lampreys have a round mouth, rasping tongue and teeth that help them attach to the side of fish to extract bodily fluids, and they do feed heavily in this manner at sea. In the old days, though, circular scars from lampreys on Sheepscot salmonids were common and proved juvenile lampreys were feeding on landlocked trout and salmon. It also underscored that many salmonids survived the intrusion. Blocking the spawning run made these marks quite uncommon, though.
Yes, fisheries-management issues can keep biologists awake at night. If my opinion interests anyone, particularly biologists, I say let the lampreys run the river. They’ve done it for millennia, a natural part of this river.
Here’s another little Sheepscot tidbit, too. In my youth, I lived for the March brown (Stenonema vicarium) hatches on this river, a large mayfly that drives big trout wild. S. vicarium needs clean gravel to flourish, but I haven’t seen this bug on the river since the very early 1980s.
Ken Allen of Belgrade Lakes is a writer, editor and photographer. He can be contacted at: