Lake Ontario and Great Lakes kiyi COSEWIC assessment and status report: chapter 8
Limiting Factors and Threats
The decline of kiyi in lakes Huron, Michigan and Ontario was likely the result of commercial overfishing (Moffett 1957, Smith 1964, Berst and Spangler 1973, Christie 1973; Miller et al. 1989). Commercial fishing of deepwater ciscoes, including kiyi, no longer occurs in the American waters of the Great Lakes, but still takes place in the Canadian waters of lakes Huron and Superior. The chub quota for eastern Lake Superior was 220 tonnes in 2002, below the estimated mean exploitable biomass of 440 tonnes, and well below the 2,211 tonnes estimated to be present in Lake Superior; therefore, overfishing is unlikely to be a major ongoing threat (Petzold 2002). In addition, the kiyi are also known as “black chub” and have lower marketability than other cisco species (Petzold 2002), and the current demand for chubs is low (K. Cullis, OMNR, pers. comm.).
It has been suggested that remnant kiyi populations may have competed with, or have been predated by, introduced fish species. Although, these interactions may have been a factor in the decline of deepwater ciscoes in lakes Huron and Ontario (Berst and Spangler 1973, Christie 1973; Miller et al. 1989), they were likely unimportant in Lake Superior, as the deepwater cisco decline pre-dated the colonization of the lake by sea lamprey, alewife and rainbow smelt (Osmerus mordax).
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