Paddlefish (Polyodon spathula) COSEWIC assessment and status report: chapter 7

Population Sizes and Trends

In Canada, the paddlefish was designated as Extirpated by COSEWIC in 1987, and re-confirmed in 2000, as no specimens have been seen since 1917. Although there have been no targeted surveys, there have been numerous Great Lakes sampling events as part of routine inventories by the Ontario Ministry of Natural Resources and the monitoring of commercial fish harvests. A fish with such unique characteristics could hardly fail to be noted in routine inventories, or if taken by an angler.

Very few specimens were ever collected in Canada, therefore it is difficult to determine if these were part of a once larger population, or if they were stray fish that had made their way into the Great Lakes (Reid et al. 2007). However, several authors (Hubbs and Lager 1958; Eddy and Underhill 1974; Burr 1980; Trautman 1981; Cooper 1983; Hubbs et al. 2004) have suggested that they were once part of the fauna of the Great Lakes basin, although they were known with certainty only from Lake Erie (Trautman 1981). Others (Greene 1935: cited in Becker 1983; Cavender 1987; Hubbs et al. 2004) have argued that their presence in (at least the lower) Great Lakes was as a result of migration through canals built in the late 1800s to join Lake Erie and the Ohio River, and the Mississippi River to Lake Michigan. Trautman (1957) favoured a pre-Columbian invasion, with a small, relict population in Lake Erie, since the presence of the species there seemed to pre-date canal building, but Cavender (1987) indicated that the lack of paddlefish fossils in northern Ohio was suggestive of its being rare in Lake Erie, or introduced after European colonization.

The species remains widespread (though less so than historically) in the Mississippi and Gulf Slope drainages of the U.S. (Figure 2), but since the early 1900s has disappeared from all peripheral areas, including Ontario, Michigan, Pennsylvania, New York, Maryland, and North Carolina (NatureServe 2007). More recently, paddlefish have been shown to be in decline in much of the range, and populations have disappeared from other peripheral areas in Texas, Louisiana, Tennessee, Wisconsin, Virginia and West Virginia (NatureServe 2007). Of the 22 states with extant populations, it is presently ranked as secure only in Kentucky and South Dakota (NatureServe 2007).

Paddlefish have been shown to have aquaculture potential (Perschbacher no date), and many states have implemented stocking programs to supplement existing stocks or undertake recovery programs (Pflieger 1997; NatureServe 2007).

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