Alosa chrysochloris (Rafinesque, 1820)
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Basis for Listing
Skipjack herring were abundant in the early part of the twentieth century in the Mississippi River as far north as Minneapolis, and adults and juveniles were once common in Lake Pepin. They reached Big Stone Lake in the Minnesota River and Taylors Falls in the St. Croix River (Eddy and Underhill 1974). However, dam construction along the Mississippi River, beginning with the one completed in 1913 at Keokuk in southeastern Iowa, blocked the skipjack herring's pre-spawning migration route to the upper sectors of the river (J. T. Hatch, University of Minnesota, pers. comm.). Consequently, populations declined dramatically. The species went unreported in Minnesota for decades and was considered extirpated.
The skipjack herring has a slender, compressed body and reaches a maximum total length of 53 cm (21 in.). Its large, terminal mouth and pointed snout with projecting lower jaw, are distinctive. Teeth are present in both jaws and in 2-4 rows on the tongue. Skipjack herring are gray on back, and silver or white on sides and bottom.
Skipjack herring occur in deep, clear, fast-flowing areas over sand or gravel in large rivers.
Biology / Life History
The skipjack herring's diet includes small fishes and larval and adult insects. Schools of skipjack herring drive minnows to the surface for easy capture (Trautman 1981) and often leap out of the water when feeding. They often congregate in large numbers below dams in the spring (Becker 1983), presumably attempting to migrate upstream to spawn. When it does occur, spawning is believed to be between late April and early July. Skipjack herring are the sole host for the larval stages of two state endangered species of mussel (ebonyshell and elephant-ear), permitting these species to complete their life cycles.
Conservation / Management
Further research into the species' life history and ecological requirements is needed. It is known that lock and dam structures hinder migration of skipjack herrings during the early spring. If the skipjack herring is to be reestablished in Minnesota, fish passage features such as ladders or lifts will be required on Mississippi River lock and dams between Minneapolis and Keokuk, Iowa, and on dams on the Minnesota River to its source at Big Stone Lake. Temporary stocking would need to follow until natural reproduction could be confirmed in Minnesota waters. Recovery of this species would also restore the host for two of Minnesota's endangered mussels species, the ebonyshell (Fusconaia ebena) and the elephant-ear (Elliptio crassidens).
Conservation Efforts in Minnesota
The construction of a fish passage facility is being considered at U.S. Lock and Dam 3 near Redwing and could help skipjack herring migration in the Mississippi River drainage. The Minnesota DNR Division of Ecological Services received a State Wildlife Grant to conduct surveys for rare fish species in the Mississippi River from the Twin Cities to the Iowa border. These surveys were conducted from 2006-2008 (Schmidt and Proulx 2009), and while the skipjack herring was a targeted species, none were found.