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"Threespine sticklebacks eat zooplankton, oligochaetes and chironomid midge larvae and mosquito larvae." While not new to the Great Lakes, the two- to three- inch fish is showing up with more frequency, causing some anglers to scratch their heads when it appears in their smelt nets or on their fishing lines. So what is this fish and should we be worried about it? Threespine sticklebacks are commonly found off the Atlantic and Pacific coasts of North America. Opinion is split on how they got to the Upper Great Lakes, but biologists assume they entered through the St. Lawrence Seaway in the ballast water discharge of ocean-going ships, or that they traveled via natural migration through the Hudson Bay watershed. Since 1980 they have spread to Lake Michigan and are now found in Lake Superior. Minnesota Sea Grant Exotic Species Information Center Coordinator, Doug Jensen, remembers when threespine sticklebacks first appeared locally in LTV Steel's cooling water tanks in Taconite Harbor, MN, in 1994. "When I first confirmed the sighting, I was not very concerned. Based on the published literature, the species appeared to be of little threat," said Jensen. " Even after Dennis Pratt of the Wisconsin DNR reported that he found them in the Duluth-Superior harbor, we came to the same conclusion 'so what?' Since then, I've become more concerned due to recent reports from southern Lake Michigan where the infestation has rapidly grown." Jensen is hearing stories from anglers who shore fish there for yellow perch that paint a bleak picture. Anglers catch threespine sticklebacks and round gobies, but few yellow perch or native fishes. |
"One time last year, 12 anglers fishing for five hours caught about
1,000 fish made up of just round gobies and threespine sticklebacks,"
said Jensen. "Anglers report these sticklebacks are so aggressive
that they will attack a penny dropped into the water. Not even the aggressive
goby goes after the penny. If this stickleback is that aggressive and
becoming that abundant, perhaps there should be more concern and research
devoted to them." Little is known about its biology or potential environmental impacts.
Threespine sticklebacks are easy to identify, with three spines on the
dorsal fin and large eyes. The first two spines are very pronounced, the
third is much smaller. They inhabit shores of larger lakes. Shallow, sandy
bottomed areas are their preferred habitat. In spring, the males construct an elaborate underwater nest from algae,
sticks and plant fragments which resembles an oriole's nest. The nest is
usually attached to emergent aquatic plants, but sometimes it is built
on the bottom itself. After the female lays the eggs, the male guards them
until they hatch and then watches over the fry until they disperse. Threespine sticklebacks may compete with native sticklebacks for food.
They eat zooplankton, oligochaetes and chironomid midge larvae and mosquito
larvae.
To learn more about exotics visit the MN Sea Grant Field Guide To Exotic Species on the Great Lakes, or play an Exotics Species Slide Show from USEPA
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Construction begins on fishing reefs to be made from stadium debris
About 15,000 tons of concrete debris from the demolished stadium will be used to build two artificial fishing reefs in Lake Erie.
Cleveland's Mayor Michael R. White and officials from the Cuyahoga County Port Authority and the Ohio Sea Grant Program participated in a ceremony Wednesday to mark the start of construction.
``The new artificial reefs, which are environmentally safe, will improve the ecology of Lake Erie with unlimited opportunities for offshore fishing for Cleveland citizens,'' said White.
The reefs will be built about one-half mile offshore and will be 600 feet long, up to 15 feet high and at least 15 feet underwater. They are expected to be completed by December of 1997.
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Officials with the Ohio Sea Grant Program, a cooperative effort designed to enhance use, development and wise management of Lake Erie resources, has said that an artificial reef can attract as many as 60 times more fish than normally would be in the area. Such reefs provide hiding and spawning locations.
Jeff Reutter, director of the program, said Wednesday that the reefs will provide housing for smallmouth bass, yellow perch and walleye.
The stadium debris has been stored on lakefront docks. The structure was demolished last spring to make way for a stadium that will become the home in 1999 of a football team to replace the Cleveland Browns. |
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