Distribution

Physical Characteristics

The white sucker has the following characteristics:

• a torpedo-shaped fish distinguished by its sucker-like mouth, which is located on the underside of its blunt, rounded snout; its mouth has thick lips covered with little fleshy bumps (papillae);
• its colour varies from grey to coppery brown to almost black on the back and upper sides, becoming lighter on the lower sides to white on the belly;
• during spawning, the darkness on the back intensifies and the body becomes more golden in colour;
• spawning males develop coarse bumps (nuptial tubercles) on the anal fin and lower tail (caudal) fin;
• it has relatively large scales, one dorsal fin, no adipose fin and the lateral line is complete;
• young white suckers 5-15 cm (2-6 in) in length usually have three large dark spots on the sides. >
• They can grow to 63 cm (25 in) and more than 3.2 kg (7 lb) but reach about 46 cm (18 in) in Nova Scotia.

Spawning migrations of white suckers can be numerous and very dense-500 have been known to swim upstream past a single point in five minutes.

Although most fish are aged by examining the growth rings on their scales, this method is not always reliable for suckers older than five years. They are best aged using sections of their pectoral fin rays.

Natural History

The white sucker can adapt to a wide range of environmental conditions but generally lives in the warm, shallow waters of lakes and quiet rivers. They prefer summer temperatures of 24øC. In streams they are most abundant in pool areas with ample underwater debris, streamside vegetation, and water depth to provide cover.

In lakes, they are usually found in the upper 6.2-9.2 m (20-30 ft) of water, moving to shallows to feed. They browse the bottom, sucking in aquatic insects, small clams, and snails, and then spitting out the inedible sand and gravel. They feed mostly at dawn and dusk and are active year round.

White suckers spawn in the spring (May and June), migrating upstream to spawning areas (small streams and tributaries) when water temperatures are 10-18øC. Suckers typically spawn in shallow gravel riffles where the water is up to 30 cm (1 ft) deep and where the flow is moderate. Lake populations of white suckers with limited access to streams will occasionally spawn on gravel shoals where there are waves. Although some spawning occurs in daytime, most takes place at sunrise and sunset. One female spawns with several males. Females usually produce 20,000-50,000 eggs, but can produce up to 139,000 eggs. Suckers do not build a nest, but scatter their eggs, which stick to the bottom or drift downstream and attach elsewhere.

The eggs hatch in 8-11 days, depending on the temperature (10-15øC). The young remain in the gravel for one or two weeks and then migrate downstream at a size of 12-17 mm. Sometimes only 3% of white sucker eggs survive to this stage. Young suckers in lakes are found along shorelines with sand or gravel bottoms. In streams they prefer sand and gravel shallow areas with moderate currents.

At first white suckers do not feed on the bottom. Their mouth is at the end of their snout, and they feed near the surface of the water on plankton (tiny organisms suspended in the water). When they grow to about 16-18 mm (0.6-0.7 in), their mouths shift to the underside of the head and they begin taking food from the bottom. White suckers grow most rapidly during their first year and can reach a length of 17.9 cm (7 in). Growth rates vary considerably in different areas, but in all populations females grow more rapidly than males, reach larger sizes, and live longer. They usually mature at ages 5 to 8, and males mature a year earlier than females. Suckers can live up to 17 years.

Although there is evidence that suggests the white sucker can compete for food with other sport fish, they can be a major food item in the diet of other fish such as Atlantic salmon, brook trout, pike, and bass. They are also eaten by birds and mammals.

Published With Funding from the Canada-Nova Scotia Cooperation Agreement on Economic Diversification, Resource Competitiveness Program.