According to the Minnesota Department of Natural Resources in an email to the Minnesota Stop Carp Coalition:
A bighead carp was captured on Tuesday, September 16 at the mouth of the St. Croix River by a commercial angler under DNR contract. The fish was 901 mm long and weighed 21 lbs 5 oz.
Because a bighead carp had previously been found in the area, the DNR is not issuing a press release. The fish caught this week is not a silver carp, the species notorious for leaping out of the water when boats pass, and which was found in the Mississippi near the St. Croix earlier this summer, but the DNR says their impacts can be severe:
They eat huge amounts of plankton and detritus. Because they feed on plankton, these fish compete for food with native organisms including mussels, larval fishes, and some adult fish such as paddlefish. This competition for food could result in fewer and smaller sport fish.
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The St. Croix has miraculously escaped many of the ravages to which almost all rivers have succomed. The fact that it has the largest native mussell population of any major river in the WORLD makes this river entirely unique. But the pressures on the lower St. Croix have increased exponentially with the building of the St. Croix Crossing and the potential of non-native species invasion from the MIssissippi and other outside ecosystems via human activity. The bridge will dramatically increase the amount of unfiltered run off over concrete surfaces that will challenge the largest beds of mussels DIRECTLY UNDER THE BRIDGE. Sprawl associated with increased development as a result of the bridge and the upgrading of HW 36 to a major corridor will exacerbate that. Additionally, those native mussell beds were right in the way of bridge piers that proliferated during the design process and required the difficult and almost always futile moving of those beds. Adding invasive species onto these pressures will be a double whammy. We must support efforts to keep invasives out of the St. Croix. It is probable that the bridge building process will result in an acute invasion of zebra mussells from construction activies, as equipment is extremely hard to keep cleansed on that huge scale. With such changes, the St. Croix has never been more vulnerable to rapid deteriorating change that will impact water quality and the presence of native species.