Lake Michigan Salmon In Big Trouble - Prey Fish Numbers Down To 1/3 Of 2005 Levels - Free Press

[hatrack]

Lake Michigan anglers can expect to catch fewer chinook salmon this summer, and those that are caught likely will be smaller. Prey fish numbers have decreased for the third year in a row to about one-third of 2005 levels (and only 8% of the peak in 1989), and salmon will find it tougher to locate the alewives that are their primary food source.

What researchers don't agree on is whether Lake Michigan's chinook can hang on at present levels or if the new data presage an imminent collapse of the salmon fishery like the one that occurred in Lake Huron three years ago. The key to the lake's future is held by a nickel-sized mollusk called a quagga mussel, another invader from Europe that has nearly eliminated earlier-invading zebra mussels in both Lakes Michigan and Huron.

Quaggas can colonize sand and mud bottoms (zebra mussels need rock or other substrate) and live much deeper than zebra mussels (now past 300 feet and still going down). They're bigger and more efficient filter feeders than zebras, removing more nutrients from the water, and in Lake Michigan their numbers are an astonishing seven to eight times greater than they were in Lake Huron when the salmon fishery collapsed there.

Quagga break the food chain by eliminating tiny creatures that provide food for huge numbers of small crustaceans and fish from many species, including the alewives that are the chinooks' nearly exclusive prey base. Energy that once moved up the links of the food chain through invertebrates to baitfish to salmon is now locked up on the lake bottom in mussel shells, which are eaten in small numbers by only a few fish.

EDIT

http://www.freep.com/apps/pbcs.dll/article?AID=/20080207/SPORTS10/802070406/1058

[mike_c]

1. quaggas are very bad news....

The great lakes are undergoing an invasive species meltdown, in which each successive invader alters the habitat and facilitates the next wave of invasion.

[GliderGuider]

2. You know,

I'm trying really, really hard to keep an optimistic demeanour, so that people like losthills and OKIsItJustMe won't yell at me. You're so not helping.

[phantom power]

3. Be sure to let me know how that goes.