The rudd is a European member of the minnow family that has been introduced to many parts of North America. It is believed that bait-bucket dumping has been the primary way that rudd have spread. Although the rudd is not a legal baitfish in Ontario, it has invaded our waters today likely originating from the United States where they have been commonly used as baitfish.

Characteristics

The rudd is a large, deep-bodied minnow that can grow to a length of 35cm (14 inches) and weight of approximately 1.8 kg (2.5 - 3 lbs). The mouth of the rudd is steeply angled with a protruding lower lip. Adult rudd look like golden shiners but have a fully scaled belly (native golden shiners have a fleshy "keel" strip along their belly) and differing fin colour and scale patterns. The pectoral, pelvic and anal fins of the rudd are bright reddish orange and the dorsal and forked tail fins are reddish-brown. The scales on the back are olive colour and the sides are brassy yellow, tapering to a silvery-white belly. When waters warm to 14° - 20° C, females can lay between 100,000 to over 200,000 eggs/year over submerged vegetation in shallow waters close to shore. The eggs hatch in 7-14 days depending on water temperature.

The rudd inhabits quiet, heavily vegetated waters and can adapt to a wide range of environmental conditions, including poor water quality. Adults feed mainly on aquatic vegetation (which they do not process well) and on insects, which they capture at the surface. Young feed on algae and small invertebrates.

Distribution

In Ontario, rudd were first found in the St. Lawrence River in 1990. They were found at several locations in the river in the 1990s and in 1997 were discovered in western Lake Ontario and in eastern Lake Erie. It is believed that rudd were first intentionally used as baitfish in Wisconsin in the 1920s and used in the Hudson River drainage in 1936. Since that time, rudd has been introduced in over 20 U.S. states.

 Download the Rudd distribution map

Impact

The impacts of the rudd on native species are not completely known. The rudd can hybridize with the native golden shiner, which could pose a risk to this important baitfish species. Over time, the unique genetics of the native golden shiner could be lost. Young rudd could also compete with native fish for food and habitat resources. Unlike most native fish, the adult rudd is omnivorous, which means it can change its diet from insects to plants. Rudd eat large amounts of aquatic vegetation around the shoreline, which could degrade spawning and nursery habitats for young fish. Northern pike, muskellunge, yellow perch, and alewife use shoreline vegetation for nesting and as nursery areas for their young. Rudd do not process the large amounts of vegetation it eats efficiently and this results in more nutrients being released into the water. This increased nutrient flow can result in increased algal blooms, lower levels of dissolved oxygen and reduced water clarity and quality.

Prevention

Once introduced rudd are difficult to control, therefore, it is vital to prevent their spread to other waterbodies. Bait bucket release is the primary mechanism by which rudd have gained access into open waters. Never use rudd as baitfish. Always be careful to never take live bait from one waterbody and release it into another which includes collecting baitfish from the Great Lakes to use in inland waters. It is illegal to release baitfish from one waterbody to another. Remember to dump your bait bucket on land before leaving a waterbody.

If you catch a rudd, destroy it. Do not throw it back. If you catch a rudd in an area not shown on the distribution map, preserve the fish in alcohol or freeze it and call the Invading Species Hotline at 1-800-563-7711 or contact your local MNR office.