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Great Lakes Invasive Species


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#1 Poliwog

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Posted 13 September 2006 - 04:31 PM

I decided to dive the “Raleigh”, a Lake Erie wooden freighter shipwreck that went down in 1911. It’s an easy dive—only about half a kilometer (quarter mile) off shore in about 9 meters (27 feet) of water. Visibility was about 7 meters (25 feet) at best.

While the “Raleigh” is an unremarkable shipwreck by most measures, as it has been smashed into a pile of lumber by successive winter ice jams since its’ sinking, I just couldn’t get over the sheer abundance of this little critter. These little buggers were everywhere! I would estimate this one wreck alone was holding a population of at least 5000 Gobis.

This little guy (or girl) is a Neogobius melanostomus, commonly known around these parts as a “Round Gobi” and hales from the Black and/or Caspian Sea.

Foreign ocean going vessels traversing the Great Lakes are suppose to empty and flush their ballast tanks before entering the Great Lakes watershed in an effort to prevent the introduction of animal and plant species not indigenous to the Great Lakes from establishing breeding populations. Apparently, not many of the ships entering the Great Lakes do this, as this is only one of approximately 182 invasive species now competing for the same limited resources as indigenous species are.

While Neogobius melanostomus grows to a maximum of 25 to 26cm (10 inches), it is a particularly nasty fish in that it is an aggressive and voracious feeder that can forage in complete darkness. It also takes over prime breeding grounds used by native species and displaces them to less desirable locations. This critter has no natural predators in the Great Lakes to keep the population in check.

About the only thing I can say about the fish is that it is very approachable and stationary making picture taking quite easy.

If there was ever to be a “poster child” for strong environmental laws, and vigorous enforcement of said laws, the Neogobius melanostomus has got to be it, followed the Zebra Mussel (Dreissena polymorpha) in a very close second place.

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#2 SeaDogDiver

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Posted 14 September 2006 - 03:41 PM

Yes, they are everywhere in the Great Lakes, and we're not talking about our little colorful friends from the warm water that we love!

I run many wreck charters in Lake Michigan every year, and they can sometimes be like locusts.......try tapping your hand on a deck plate or on the bottom for a moment, and in the blink of an eye you are surrounded by them.......kind of like a scene from "The Birds" by Hitchcock.

We also often come accross many dead ones rolling around on the bottom. Unfortunately, they seem to thrive and in some areas have all but displaced many of the native species that I grew up with. In fact, they don't even see to be of intrest as a food source to most of the predator fish.

First Zebra mussels, and now these weird guys.......what next??