Why, those slimy, blood-sucking... Sea lampreys!

Ladies and gentlemen... The sea lamprey.

The sea lamprey (or Petromyzon marinus) is a parasitic eel-like fish that sucks on other fishes' blood and body fluids to survive. On average, it's said that a staggering 6 of 7 fish won't survive a sea lamprey attack. With these creatures in our Great Lakes, our native fish and biodiversity wouldn't stand a chance.

Sea lampreys are an invasive species from the Atlantic Ocean. People first started spotting them in the Great Lakes in the 1830's and speculation began that they were accidentally introduced to Lake Ontario via man-made canals. They spread to the other Great Lakes by 1939. At the time, lake trout were the most predatory species, so the sea lampreys would choose them as hosts (image to the right) and as a result, the population greatly decreased. They actually became extinct in Lakes Ontario, Erie, and Huron (except some inlets of Georgian Bay).

If the extinction of one species wasn't bad enough, take into consideration the change in biodiversity and the food chain. The absence of the predatorial lake trout led to increases in population of other foreign species (ie rainbow smelt, alewife). These large numbers still threatened the native species. Continually, sea lampreys were still present. Soon, our biodiversity would not be very diverse..

Luckily, in the whole lifetime of a sea lamprey, only one year is used for parasitic feeding. When they are physically mature enough, they migrate into streams to spawn. It sounds like there shouldn't be a problem, but a female lamprey will spawn an average between 60 and 70 thousand eggs. Even considering the chances of fertilization, that is a huge number.

Some may say this problem was our fault as human beings (man-made canals), but so is the solution. There are a few different paths being taken.

Lampricides are very selective and have little to no impact on other fish or wildlife. The lampricide is put into the streams to kill off the sea lampreys while they are still in larvae form.

Barriers are built to prevent spawning lampreys from reaching their destination. Don't worry though, they don't obstruct the paths of other fish.

Traps are usually placed near the barriers (it only makes sense, because there will be a larger concentration making them easier to catch). The females are mostly used for research, while the males are brought in for the sterile-male-release-technique.

Sterile-Male-Release-Technique -- males are sterilized, then released back into the water. You should remember that by this age, the lampreys don't go into parasitic feeding frenzies.

Thankfully, these actions are helping, as research tells us that ongoing efforts have lowered the population by 90%. These organizations aren't even killing them off, they're just preventing future spawns. Humans may be the cause for many environmental problems, but we can also be the solution.

**All images are hyperlinked to source**

Sources:
Eastern Michigan University
Fisheries and Oceans Canada
Great Lakes Fishery Commission
Minnesota Sea Grant
USGS Great Lakes Science Center

I commented on...:
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