Round whitefish

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

The round whitefish (Prosopium cylindraceum) is a freshwater fish in the salmon family. It lives in northern North American waters—from Alaska to New England, including the Great Lakes (except Lake Erie)—and in some Arctic areas of Asia, such as Kamchatka and the coasts of the Sea of Okhotsk.

What it looks like and how big it gets
Round whitefish have an olive-brown back with silvery sides and belly. They are deep-bodied, cylindrical fish that usually grow about 9 to 19 inches long (23 to 48 cm). They can live up to about 12 years. Males show color changes during spawning.

Habitat and range
They prefer cold, clear waters and can be found in post-glacial lakes, rivers, and some brackish areas. They typically inhabit depths of roughly 180 to 700 feet (55–213 m). They tolerate low-salinity in Arctic regions and have a wide northern range.

What they eat
Round whitefish are bottom feeders. Their diet includes invertebrates, crustaceans, insect larvae, and fish eggs. They are opportunistic, meaning their exact food changes with what’s available in their habitat and season.

Reproduction and life cycle
Round whitefish migrate to freshwater tributaries to spawn. Spawning occurs in fall, usually between October and November, when water temperatures are at or below about 2.5 °C (36.5 °F). Maturity happens around age seven, and not all individuals spawn every year. Eggs are laid in pebble beds and other spaces between rocks in the flowing water, where they hatch as streams begin to run with spring.

Conservation and threats
The IUCN lists the round whitefish as Least Concern. It is not a primary target for fisheries, and there are few dedicated round whitefish fisheries. In some places, numbers have declined due to habitat changes, water quality issues, acid rain, sedimentation, and warming water from climate change. Predation by larger fish (like yellow perch, smallmouth bass, and rainbow smelt) and competition for food in younger life stages can also affect populations. Local protections exist in some states where the species is less abundant.

Other notes
The round whitefish has several common names, including Menominee, pilot fish, frost fish, round-fish, and Menominee whitefish. The name is sometimes used for other whitefish as well.