Whachu Know About Sea Lampreys?

Note: This is a long one…something like 1,700 words. But it was fascinating learning about one of the Great Lakes’ most formative invasive species as well as the people who lead the way in what is hands down the most successful control program of any Great Lakes invasive species thus far. In fact, did you know that the sea lamprey population has declined to just 1/10 of what it was at its peak in the 50’s? Thanks to the research coming out of Hammond Bay, that number will only continue to get smaller, and the lake trout population can then continue to rebound from its catastrophic decline in the late 50s.

Tucked into a rocky bay area on Lake Huron — just off of Highway 23 between the towns of Rogers City and Cheboygan — is the Hammond Bay Biological Station. There’s a gas station down the road, but little else that would justify identifying Hammond Bay as a “town.” Yet on the cedar-lined dirt road leading to the station, you at once feel as if you’re in a remote seaside village, bustling with activity, existing seemingly independent from the rest of world.

The research station was once inhabited by a branch of the United States Coast Guard, and as such is flourescently white, with a tell-tale red roof reminiscent of storybook lighthouses. The perfectly nautical color combination and Lake Huron stretching endlessly beyond the facility makes arrival at the station feel like a teleportation to an East Coast postcard — of a Maine fishery or a New England village with the word ‘Cape’ in its name.

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When you get closer to the building, you see the remnants of multiple renovations, repaints and additions made to the space, which now accommodates lab facilities for state-of-the-art sea lamprey control and management research in place of equipment and living spaces for Coast Guard servicemen. The facility began operating as a research station in the late 50’s, on the heels of one of the most detrimental — and borderline catastrophic — declines in the Great Lakes lake trout population ever recorded. The culprit? Sea lampreys, which found their way to the Great Lakes via shipping canals from the Atlantic, and which can lay as many as 100,000 eggs per female while killing nearly 40 pounds of fish in a lifetime. Lake Superior was the only lake in which the lake trout population wasn’t entirely extirpated with the arrival of sea lamprey,  and as such, sea lamprey control researchers and biologists were able to accommodate a rebound in the lake trout populations. That was in the late 50s.

Now, a highly successful sea lamprey control program — coordinated by the Great Lakes Fishery Commission in partnership with the U.S. Fish and Wildlife Service and Fisheries and Oceans Canada — has diminished lamprey numbers to 1/10 of what they were at their peak in the mid 60s, while also allowing for a considerable recovery in the Great Lakes lake trout population. Research at the Hammond Bay Biological Station, which operates through a partnership between the Great Lakes Fishery Commission and the U.S. Geological Survey-Great Lakes Science Center, has played a critical role in the development of sea lamprey control methods used to keep the populations in check. According to Scott Miehls, a research biologist working at the station, the annual success rate for lamprey control is 90 percent of the population. That is, the research coming out of Hammond Bay is contributing to a 90 percent decline of lamprey numbers through the application of various methods, such as barriers to concentrate spawning sites, luring and trapping, and lampricides.

“Based on population estimates from [when sea lamprey control wasn’t in place] compared to population estimates from now, we are holding the sea lamprey population at about 10 percent of where it was back then,” Miehls said. “The management program essentially removes 90 percent of the lamprey from the Great Lakes every year. If you think about the control program that’s in effect now, the combination of barriers to block lamprey from getting to spawning grounds, the lampricide to kill the larvae from lamprey that did find an area to spawn and in the trapping effort to remove lamprey from streams, we’re wiping out 90 percent of the population on an annual basis. It is really close to our targets.”

And while Miehls said these methods have put them close to their intended targets annually, the 10 percent of lamprey still existing in the Great Lakes are a continual cause of concern, and Miehls knows they have a long way to go before the population is at a point of total collapse.

“We’re getting really close,” Miehls said. “But as far as an end in site — a complete eradication of lamprey from the Great Lakes — it’s something that is always being looked at on the research side of things, but we focus our efforts mostly on management because it’s obtainable and it’s cost effective.

“But that’s sort of where we come in here at Hammond Bay — we’re constantly trying to come up with better tools for control,” he added.

For now, Miehls and the rest of the biologists, researchers, students and myriad of others working on sea lamprey control are focusing their efforts on the tried-and-true methods of lamprey management. Among those methods is simply trapping the lampreys, which requires much more effort than one would expect.

As compared by Michigan State University research graduate student Cory Brant, who has been working in the lab since he did a half-summer internship at the station a few summers ago, a lamprey needs a reason to go into a trap in the same way a mouse does — with something enticing. In the case of researchers at Hammond Bay, a natural scent compound referred to as a pheromone is used to achieve a cheese or peanut butter-like effect with the lampreys. Both pheromones employed by Brant and his co-researchers occur naturally in areas with sea lamprey populations, is extracted in the lab from water that once contained lampreys, and relies solely on scent as a luring mechanism. The presence of one such pheromone — released by healthy larval lamprey in stream beds — is correlated with a good spawning site by spawning adult lampreys, and as such, lures them in. Another — the aptly-nicknamed ‘love pheromone’ — is simple the scent of male lampreys, which females are drawn to in the spring while finding a location to spawn.

“I spent just half a summer up here and I became nuts about it [lamprey research],” Brant said. “All [of their] behaviors can be induced with just a smell, which is super useful for integrating a trap or any type of control — they’re basically possessed because the only way they’ll be successful in life is by following this smell at this stage in life.”

And while this is his last summer at this particular research facility, Brant said he is and will remain deeply passionate about lamprey behavior and it’s connection to naturally-occurring scents.

“The pheromone stuff blew my mind,” he said. “It’s just like, ‘I’m going to be successful [through spawning], and I’m with the guy of my life right here…this is going to be awesome!’ but the females are on the nest with the male odor and no actual male there at all.”

Besides pheromones, lampricides are used on an annual basis in most watersheds with lamprey populations, which includes the Burt and Mullett Lake waterways in addition to rivers running directly into a Great Lake.

Lampricide use has been incredibly effective — nearly 99 percent of lamprey’s exposed to the chemical die from it — but reaching more remote populations has proved difficult. Still, the original lampricide used in the 50s to stop the rampant growth of the sea lamprey population is being used to this day, with no sign of the target organimsm developing a resistance to the chemical cocktail used in lampricide.

“We’re sort of limited on how far and wide we can spread the application of lampricide simply for cost reasons, and the lamprey themselves — the biology and way they behave in the lake — has sort of led to this safe population,” Miehls said. “The same happens with pest management in an agricultural situation. If you’re spraying for pests in a fruit orchard, typically growers will leave a patch unsprayed so that you have a population of the pests that’s never exposed to the chemical so they don’t develop a resistance. The same thing sort of happens here,  but it’s less of an intended design and more of a logistical constraint that we have.”

According to Miehls, Lampricide use does not affect other species living in rivers and streams fatally, though it is attributed to raising stress hormones in some aquatic animals. Otherwise, the lampricide employed by researchers is incredibly selective to lampreys for one significant reason — their lack of evolutionary development compared to other native fish species.

“The reason this compound is toxic to lamprey and not other fish is that lamprey are such an ancient fish — they actually predate the dinosaurs and are less developed than our native fish in the Great Lakes,” Miehls said. “They’re not able to process the lampricide and remove it from their bodies. Other fish treat it as a toxin and it’s filtered out of their blood and excreted back into the stream, but lamprey accumulate the toxin and have no way of excreting it from their bodies. Lamprey and hagfish are the only two living species still in the Agnathnan family, and they’re sort of living fossils.”

Miehls’ passion for lampreys and their management has grown since 2009. With a background in fisheries management, Miehls moved to Michigan to be near his wife Andrea — a communications associate at the station — and ended up with a job in sea lamprey control.

“I got to know people in the program, and gain a feel for what the program was all about,” he said. “I absolutely became absorbed by it and the family that is the sea lamprey control program.”

However, he said he was most enticed by the almost immediate effect that sea lamprey research has on Great Lakes ecosystems, which when working with environmental issues like invasive species, is a hard thing to come by.

“One of the former station directors here at Hammond Bay was retiring, and one of the comments he made kind of struck home,” Miehls added. “[He said] it’s kind of a rare thing when you’re working in this field that you get the sort of instant gratification that you do working here, where you can see all the efforts that you’re putting forth having an immediate impact.

““You can spend your whole career working on fishery research before seeing an impact on a fishery. Here, you can see it right out the windows when the fishing boats go by and there are steelhead in the rivers — it’s a cool feeling to be involved in a program that’s having such a huge and positive impact on the Great Lakes as a whole.”