Science: Sea Lampreys

Washington Post staff writer Kari Lydersen will be online Monday, Sept. 24 at Noon to discuss methods for controlling the sea lamprey population in the Great Lakes.

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Sea Lampreys have a slimy snake-like, muscular body capped by a suction-cup mouth ringed in teeth - along with a sharp probing tongue. They are one of nine non-mammalian organisms chosen for genetic sequencing - along with slime mold and round worms - by the National Human Genome Research Institute to identify benchmarks on the evolutionary timeline.

Submit a question or comment now or during the discussion.

Read more about the sea lamprey in today's story, Taking Measures to Control an Invasive Species, and learn about their life cyele in this interactive graphic.

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Philadelphia, Pa.: Are sea lampreys safe to eat? If so, why did the King die from eating them?

Kari Lydersen: As they say, everything in moderation. It sounds like it was the "surfeit" that did him in. Yes, sounds like they are totally safe to eat. Though like most fish, chances are the ones in the Great Lakes accumulate mercury in their tissue...

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Hampton, Va.: That is one ugly fish.

Kari Lydersen: Yes, it is!

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Arlington, Va.: So... what does Sea Lamprey taste like? Eel? If it's the Queen of England's favorite delicacy, then I'm sure it's absolutely awful. British food is miserable.

Kari Lydersen: Hmm, I've heard it described as oily and gamey -- probably quite different than eel -- but to each their own. As a side note, though it looks kind of similar to an eel, they are not closely related animals.

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Herndon, Va.: I'm impressed by the creative management techniques deployed against the sea lampreys, but I wonder why you don't use the one proven tactic to reduce a species: eating it. Isn't the sea lamprey protected in the UK because of overfishing? Couldn't we unleash fishermen on this monster by creating a market for it?

Kari Lydersen: From what I've heard some researchers were talking about pushing sea lamprey as a delicacy, but those in charge of the eradication program were adamant that this is a bad idea because if sea lampreys did become a delicacy here, it there would be a commercial incentive to be sure they are NOT eliminated.

Kari Lydersen: There's a similar debate regarding Asian carp -- another voracious invasive species which is making its way up toward the Great Lakes via the Mississippi River and Chicago Sanitary and Ship canal. There have been efforts to promote Asian carp as a delicacy here like it is in China, but most scientists oppose that plan for the same reasons as with sea lampreys.

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Toronto, Canada: By gosh, it's hard to believe that anyone would consider such an ugly thing as a lamprey to be a delicacy. How have the stocks of sport and commercial fish in the Great Lakes faired since the 1960s, when lamprey numbers were at their peak?

Kari Lydersen: As the sea lamprey populations have been reduced to about a quarter of their peak, lake trout and other sportfish have certainly rebounded. There was a point where fishery officials did not even bother stocking sea lamprey-infested lakes, because they knew most of the fish would just be decimated by the lampreys. The USGS says lake trout "spawning potential" has increased six-fold just since 1995 thanks to sea lamprey control.

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Chicago, Ill.: Kari, I am a H.S. Biology teacher from Bethesda who has relocated to Chicago to teach in the North Shore Suburbs. My students just finished an activity on Lake Michigan Food webs, and invasive species like the Sea Lamprey were an important part of our discussion.

My question for you, which many of my students asked, is what native species are most affected by the sea lamprey in lower Lake Michigan and what steps can people take to ensure more native species don't begin to inhabit our lake? Thank you, Shayda, New Trier H.S., Winnetka, Ill.

Kari Lydersen: Lower Lake Michigan is actually apparently the part of the Great Lakes least affected by sea lampreys; there isn't much in the way of sea lamprey trapping or controls in the bottom half of Lake Michigan; though last summer more than 1,000 pounds of poison called "lampricide" was poured in streams in the Chicago area. So though there may not be a highly visible effect from the lampreys in lower Lake Michigan, of course the health and ecology of all the lakes is linked, and it's still something for your students to be aware of, especially as a symbol of what havoc could be wreaked by future invasive species.

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zebra mussels: how is the war against the zebra mussels faring in the Great Lakes? are they more damaging then the lamprey in your opinion?

Kari Lydersen: They have fairly different effects; sounds like the "war" on zebra mussels is a losing or lost battle, they cost the power industry and municipalities tens of millions of dollars a year, mainly because they clog the pipes of water intake systems. From what I understand there is little that can be done to effectively reduce zebra mussel populations; it's a problem we have to live with. Sea lampreys on the other hand have been controlled effectively -- in fact one scientist described sea lampreys as the only invasive species that can actually be contained and possibly even eventually eradicated. Which is "worse" probably depends on who you are -- a trout fisherman or power company manager!

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other problems in the Lakes: I heard about a large non-native carp that seems to be making headway in the Great Lakes at the expense of all the sport fish. did you come across this in your reporting?

Kari Lydersen: Yes, I've done separate stories on the Asian carp which you're referring to. This fish escaped from fish farms, where it had been brought to clean up algae and gunk, a number of decades ago, and they have been slowly making their way up the Mississippi River toward the Great Lakes ever since. It is now about 30 miles from Lake Michigan, via the Illinois River and the Chicago Sanitary and Ship canal. The Army Corps of Engineers has installed an electric barrier (a much larger version of ones also used to control lampreys) in the canal to keep the Asian carp out, but permanent funding for the completion and operation of the barrier is not yet secured. If the Asian carp (big head and silver carp, specifically) get into the Great Lakes, they could have a devastating effect, eating everything in sight.

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Invasive Carp: any chance the lamprey will take out the invasive carp? if they do, i hope it doesn't give them enough food to reproduce more. everyone should go to youtube and google 'jumping carp' just to see how invasive these things are.

Kari Lydersen: Haha, these two species haven't met yet as far as I know, but would be an interesting showdown...(the Asian carp are not yet in the Great Lakes).

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Annandale Dude: These Agnathans are one ugly group of fish. When I'm fishing along the great lakes and I catch a fish with a lamprey attached, what should I do with it? Drop a rock on it or throw it on shore?

Kari Lydersen: Fishery staffers throw their dead lampreys in landfills...removing one probably won't make a big difference one way or another, but might as well put it somewhere other than back in the lake, where it won't stink too much.

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Asian Carp: Hi Kari, Could you speak for a moment on Asian carp. How much damage could they do to the Great Lakes fishing industry? Is the Chicago Ship Canal Barrier really going to work on these beasts?

Kari Lydersen: The barrier is a controversial issue...apparently it has performed well in tests, keeping other fish from crossing. (The Asian carp haven't yet reached the barrier). If it is operated as planned, it looks promising it could keep the Asian carp at bay. But it will cost one million dollars a year to operate, and it is not decided whether Illinois or the federal government will foot the bill. Plus funding for the completion of the barrier isn't finalized, and there is still testing going on because of concerns humans could be shocked if they fell in the water.

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San Diego, Calif.: Are there any natural predators which could be used to control the lamprey?

Kari Lydersen: Whatever predators the sea lampreys would have in the open ocean -- salt water -- probably would be unlikely to survive in the Great Lakes; it's possible parasites that affect the sea lampreys in the ocean could be introduced to the Great Lakes, but experience has shown that introducing another species to try to control a problem species is the last thing we want to do -- the unexpected ripple effects and ecological impacts of the "solution" could be far worse than the problem.

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off topic: But what is the state of the Zebra Mussel situation. I was on MS river, and thought I saw tons of them. though they could have been some other little shell fish

Kari Lydersen: Zebra mussels are throughout the Mississippi River basin. THey are surprisingly small...and an ironic side effect is that they make water in lakes look clear, clean and beautiful. Though it is said they give Chicago's drinking water -- which comes from Lake Michigan -- a distinctive taste.

Photos and more information can be found here.

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Norfolk, Va.: Whether or not we can control Sea Lampreys, the future seems clear: because we live in a borderless world, all the world's species are borderless, too (by hitching a ride with us). So haven't we created a situation where all the sea creatures share a very small pond, and the most aggressive/strongest will dominate globally?

Is there really any hope of protecting a "local" ecosystem as long it's connected to us humans globally?

Kari Lydersen: Those are good points...I think the main lesson to be taken from all the harm done by invasive species is that at the very least we should try to lessen our impact as far as spreading and introducing existing and new invasive species -- there is a huge debate going on now regarding proposed federal and state legislation which would place limits on ocean-going ships with ballast coming into the Great Lakes -- ballast water is the main way invasives are spread to the Great Lakes. The shipping industry has sued the state of Michigan over a law regulating their ballast practices. Environmental and outdoors groups have proposed banning ocean-going vessels from the Great Lakes altogether.

Individual boaters and fishermen also need to be extra careful to clean their equipment and boats so as not to spread invasives.

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Arlington, Va.: Do Sea Lampreys latch on to humans? If so, any chance we can let some loose in Congress?

Kari Lydersen: Haha...I did have the chance to feel a lamprey trying to latch on to my palm, and it took some force to pull it off. But apparently they don't want to suck humans' blood...and unlike fish, we can pull them off if they try to hitch a ride.

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Blacksburg, Va.: I suppose it's easy to gin up support for destroying Sea Lampreys because they're so ugly -- much easier than eradicating cute bunny rabbits in Australia, I guess -- but aren't they a unique species worth protecting even if they did hitch a ride into these environments in the first place?

Kari Lydersen: Yes, and though sea lampreys are ugly, they are one of the most primitive living creatures -- they should get some points for that. I don't think anyone's saying they should be wiped out worldwide; but their unrestrained presence in the Great Lakes did previously and could still have the potential to devastate the populations of various other organisms along the food chain. For example in the past when they knocked out trout, which eat alewives, alewives had an unsustainable population explosion followed by a massive die-off, which left the shores of the Great Lakes covered in heaps of rotting, stinking alewives. That's just one small example of a domino effect, the chain reaches much further...

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Encinitas, Calif.: Who really decides on the level of funding for the eradication program? Is it something like Game and Fisheries, or is it an "earmark"?

Kari Lydersen: I'm not an expert on the funding situation but from what I understand, federal funds allocated for aquatic invasive species control are managed by a coalition of state, federal, tribal and Canadian bodies called the Great Lakes Fishery Commission which makes most of the decisions on how to break down the resources. (There are exceptions as with the Asian carp barrier where federal legislation directly addresses a specific invasive species).

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Hampton, Va.: I don't know if the spread of invasive species is really inevitable. With all the the genetic research going on, is it impossible to believe we couldn't eventually genetically alter Sea Lampreys so they're less effective?

Kari Lydersen: There is actually research ongoing into genetically altering sea lampreys to have a "daughterless gene," so that they would only bear male offspring and hence their populations would eventually decrease to nothing. But as with introducing any new factor into the environment, there could be unintended consequences. For example there are fears the "daughterless gene" could "migrate" into other aquatic species.

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Washington, D.C.: Is there any evidence of sea lampreys invading the Chesapeake Bay, and what are the most worrisome invaders in local waters (and what sportsfish do they impact the most)?

Kari Lydersen: I came across articles mentioning sea lampreys found in the Chesapeake Bay, though I don't know that they're seen as a problem there. Many invaders in the Bay, as in the Great Lakes, came through ballast from ocean-going ships, including the Rapa whelk and the Asiatic clam. Other invasives mentioned in the Chesapeake Bay area -- also prevalent in the Great Lakes region -- are the plant phragmites and purple loosestrife.

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Encinitas, Calif.: Although sea lampreys are native to salt water, they can do just fine in fresh water? What about other fresh water rivers and lakes throughout the world? Can they just swim up a river, or do they need ships to carry them? Are they big problems in other lakes? Or is there something special about the Great Lakes?

Kari Lydersen: Sea lampreys are not strong swimmers - they need to ride on fish to move long distances. They need streams to spawn in, so the many tributaries of the Great Lakes do make the Great Lakes ideal for them. I haven't heard of them in other lake systems in the US -- since they originally came from the ocean that would mean most land-locked lakes would have to get them from boaters or fishermen.

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Harford Co., Md.: We have them in our creek in Harford Co., Md., most every spring - we look for them at the time when buttercups bloom. I've heard that our species is not the same as the invasive pest of the Great Lakes...do you know if this is true? Some people make sport of shooting them with pistols. I wonder if our species is good to eat.

Kari Lydersen: Interesting...there are several species of native freshwater lampreys which are not considered pests and in fact are protected.

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Didymo: whats the scoop (no pun intended) on Didymo infestations around the lakes?

Kari Lydersen: The phosphorus blooms which feed didymo algae -"green slime" -- are a big problem in the lakes and down the Mississippi River basin...though various environmental programs aimed at curbing farm run-off and treated sewage disposal -- the main sources of phosphorus -- hope to address this.

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