2001 Sportsman Lake Stock Assessment Survey: The Warmwater Fish Community of an Isolated Island Lake

In fall 2001, we used standard electrofishing and netting techniques to sample fishes of the littoral zone of Sportsman Lake, San Juan Island. Three species were found including (in order of decreasing abundance) largemouth bass, pumpkinseed, and yellow perch. Largemouth bass as old as age 10 and measuring up to 430mm total length (TL) were captured. Individuals measuring 300mm TL or longer captured while electrofishing comprised 23% of largemouth bass measuring 200mm TL or longer (i.e., PSD = 23). However, individuals less than 200mm comprised 88% of all bass sampled. Smaller largemouth bass were highly abundant and displayed a trend of increasing growth and condition up to approximately 200mm TL. Growth and condition then fell to below average levels, suggesting a predator-crowded population. Fish larger than 350mm TL, though still below average in growth, showed improved relative weight. Large numbers of young-of-year largemouth bass and yellow perch were sampled and may represent strong, future year classes. Age 1 and 2 yellow perch occurred in low densities, were fast growing and well fed, but older fish were absent from our samples. While catch rates for pumpkinseed measuring 80mm TL and longer were higher than state averages, few young-ofyear fish were found, suggesting a year class failure possibly due to predation by other fish. Smaller pumpkinseed were abundant and showed symptoms of stunting, while larger, older fish displayed faster than average growth. Management options include: mechanical removal of stunted size classes of both largemouth bass and pumpkinseed, management of the lake as a panfish fishery, promoting a juvenile panfish derby, introduction of black crappie to diversify the fishery, introduction of a super predator such as tiger muskellunge to reduce over abundant smaller fish, conducting a creel survey, conducting detailed aquatic plant and water quality surveys, and implementing boat ramp improvements.