Paddlefish (Polyodon spathula) COSEWIC assessment and status report: chapter 4

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Distribution

Global range 

The paddlefish lives in the slow-flowing waters of the Mississippi Valley and adjacent Gulf of Mexico drainages, as well as the Missouri, and Ohio River systems (Figure 2) [Burr 1980; Parker 1987, 1988], and was historically found in the Great Lakes (Halkett 1913; Trautman 1957). Paddlefish was never common in the Great Lakes; it was known with certainty only from Lake Erie, where there were at least two well-authenticated records, both before 1910 (Van Meter and Trautman 1970).

Canadian range 

The occurrence of this species in Canadian waters (Figure 2) is based on reports of specimens collected in Lake Huron, near Sarnia (2 specimens), in the Spanish River, a tributary of Georgian Bay (1 specimen), and in Lake Helen on the Nipigon River (Halkett 1913). There is also mention of records from the Lake Superior drainage basin (1 specimen) from the late 1800s and early 1900s (Halkett 1913). The last Canadian record is from 1917 (Parker 1988; Reid et al. 2007). Records from Lake Erie (Trautman 1957) are derived from the waters of the American side of the lake. Authentication of these records is problematic and some have questioned their validity (Parker 1988).

There have been no records of the species in Canadian waters over the past 90 years and it is presumed extirpated from Canada. At this time, it is impossible to know the true extent of its occurrence in Canada, but it would have undoubtedly been greater than 100,000 km² [estimated from a polygon of best fit (see COSEWIC 2007) applied to the known former range], which represents approximately 3% of the global range. Given the lack of information on its actual distribution and habitat preferences in Canada, it is impossible to determine the area of occupancy, but it would probably have been less than 100,000 km².

Canada never was a significant part of the distribution, but in the U.S. the species has also been extirpated in Maryland, Michigan, New York, North Carolina and Pennsylvania (Graham 1997), as well as from the Great Lakes basin, all highly peripheral areas, which probably never represented a significant part of the range (Cooper 1983). It is also considered to be imperiled, or critically imperiled in other peripheral areas such as Montana, Minnesota, and Ohio (NatureServe 2007).