Abundance, growth, and food supply of white suckers (Catostomus commersoni) in relation to lake morphometry and pH

Associations between the abundance, body growth, and food supply (chironomid and ephemeropteran larvae) of white suckers, and lake morphometry and water chemistry were determined for eight Ontario lakes. White sucker abundance was low in three deep–acid lakes, intermediate in two deep–circumneutral lakes, and high in three shallow–acid lakes. Abundance was negatively correlated with both maximum lake depth (r = −0.71) and mean lake depth (r = −0.67) and positively correlated with the morphoedaphic index (r = 0.67). Generally, 4-year-old white suckers were largest in deep–acid lakes, intermediate in size in deep–circumneutral lakes, and smallest in shallow–acid lakes. Fork length and somatic weight at age 4 were negatively correlated with white sucker abundance (r = −0.76 and −0.80, respectively), positively correlated with density of chironomid larvae (r = 0.62 and 0.68, respectively), and negatively correlated with pH (r = −0.67 and −0.70, respectively). The von Bertalanffy estimates of maximum attainable fork length (Lx) for both sexes were substantially larger in both deep–acid and deep–circumneutral than in shallow–acid lakes. Correlations indicated that oligotrophic lakes contain white suckers with a large Lx, the strongest correlation being with maximum lake depth (female Lx, r = 0.84; male Lx, r = 0.89).