Dam construction changes both the character and the fish populations of the upper Mississippi River. The skipjack herring essentially disappeared here when a dam, lock, and powerhouse was built at Keokuk, Iowa in 1913, blocking the skipjack’s upstream spawning run. High spring water levels can allow the skipjack to return to its full historic range but the right conditions for a significant migration have occurred only once (1986) since this historic dam on the Mississippi River was completed.
The skipjack herring still lives in the lower reaches of the Mississippi River where it is the preferred prey for walleye, catfish and other predator species. It is relatively common where populations still exist.
The disappearance of the skipjack herring from the upper Mississippi River is also eliminating what was once the most abundant mussel in the upper Mississippi River. Because the skipjack herring hosts the larval state of the ebonyshell mussell, this mollusk that once supported America's button industry no longer reproduces here. Individual long-lived specimens are still found today but the ebonyshell is now a Minnesota endangered species.
Key ID Features: The skipjack herring is a silvery, flat-sided fish with a single dorsal fin, no lateral line, and a belly keel. It is typically 10 - 17 inches long and rarely more than 2 pounds.
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Last updated: November 22, 2019