Effects of Clam Shrimp on Production of Walleye and Northern Pike, and a Review of Clam Shrimp Control Strategies

Abstract

The dynamics of clam shrimp, Caenestheriella belfragei, populations in fish culture ponds were studied to evaluate their effect on yield of fingerling northern pike, Esox lucius, or walleye, Stizostedion vitreum. The studies were carried out on twenty-three 0.64-ha ponds during the culture season for northern pike and on 19 of the same ponds during the season for walleye. Ponds were filled between April 26 and May 12, 1992. The ponds were drained after 3 to 4 weeks to harvest the pike, then refilled after 0 to 4 days (mean = 1.5 days) to raise walleye. Adult clam shrimp were observed in 12 of the 23 ponds during northern pike culture and in 10 of the 19 ponds during walleye culture. Northern pike were cultured up to 29 days in ponds with clam shrimp, while pike were cultured a maximum of 22 days in ponds without clam shrimp. Survival and yield (fishha) of northern pike were significantly (P < 0.05) lower in ponds with clam shrimp, compared with survival and yield in ponds without clam shrimp. Similar differences, although not significant, were seen in walleye culture ponds. Northern pike and walleye were cultured longer in ponds with clam shrimp, implying that fish growth is reduced in culture ponds with clam shrimp. The majority of large clam shrimp found during the walleye culture season were most probably hatched during northern pike culture. When used in tandem to raise northern pike and walleye, ponds should be thoroughly dried between culture periods to prevent development of clam shrimp during the walleye culture.