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Bloater Research 


Deepwater ciscoes are a diverse group of species that once comprised an integral part of the native fish community of the Laurentian Great Lakes. Currently, most deepwater ciscoes are extinct or have suffered local extirpations that restrict them to Lake Superior and/or Lake Nipigon, while the shallow-water form of cisco (Coregonus artedi) persists throughout the extent of the Great Lakes. An exception to this is bloater, a deepwater disco that inhabits Lakes Huron, Michigan, Superior, and Nipigon. Until the mid-1950s, C. hoyi were an abundant forage fish in Lake Ontario but became scarce in the 60s as a result of a dramatic population decline associated with overharvesting and invasive rainbow smelt (Osmerus mordax), alewife (Alosa pseudoharengus), and sea lamprey (Petromyzon marinus). Attempts to re-establish a self-sustaining population of deepwater ciscoes in Lake Ontario have consisted of stocking small numbers (16-35 thousand/year) of hatchery-reared juveniles raised from fertilized Lake Michigan bloater eggs. Upon more efficient collection of wild eggs and improved brood development, a total of 500,000 juvenile bloater will be stocked in Lake Ontario every year. The issue remains that we are unaware of what happens to these stocked fish following their introduction into the lake; in reality this is an issue for the 25 million juvenile fishes stocked in the Great Lakes every year.

Acoustic Telemetry

The objectives of this research project are to determine the post-release behaviour, habitat use, and survival rates of stocked bloater in Lake Ontario through the use of acoustic telemetry, building on a successful pilot study in 2015-2016. Juvenile bloater (19 months old, 20-100 g) are surgically implanted with acoustic transmitters that provide information about location, depth, and temperature and then released as part of a normal stock in the St. Lawrence Channel located in eastern Lake Ontario. A total of ~100 acoustic receivers have been deployed in the St. Lawrence Channel to detect the presence and absence of tagged bloater.

Relevant Lab Members –Natalie Klinard (M.Sc. – alumni), Scott Colborne (PDF – alumni), Eddie Halfyard (PDF – alumni)


Establishing a population of deepwater ciscoes will help to achieve healthy lake ecosystem by restoring fish native to the lake and increasing biodiversity. A substantial population of forage fishes would improve food web stability through providing a trophic link between benthic production and top predators and reduce the potential for invasive species to colonize the niche that bloater would will. Successful reestablishment of hatchery-reared fish resulting from studies done using acoustic telemetry would also provide a foundation that can be used as the basis for reintroduction and management of other native species throughout the Great Lakes.

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