Sea Lamprey Control in Lake Champlain

Abstract

In 1990, the United States Fish and Wildlife Service (USFWS) and state agencies initiated an 8-year experimental sea lamprey ( Petromyzon marinus) control program on Lake Champlain to reduce parasitic phase sea lamprey and increase sport fish survival and growth. Twenty-four 3-trifluoromethyl-4-nitrophenol (TFM) treatments were conducted on 13 tributary systems, and nine Bayluscide treatments were conducted on five deltas. Most tributaries received two rounds of treatment, 4 years apart. Trap catches of spawning-phase sea lamprey in three monitored tributaries declined by 80–90% from 1989 to 1997, but nest counts were reduced by only 57% during the same period. Sixteen of 24 TFM treatments reduced ammocoetes to less than 10% of pre-treatment levels. Eight of nine Bayluscide treatments resulted in mean ammocoete mortality rates over 85% in caged test animals. Nontarget effects were noted among amphibians, mollusks, macroinvertebrates, native lamprey, and other fishes, and were higher for Bayluscide treatments than TFM. Recovery of delta taxa occurred within 4 years after treatment. Wounding rates on lake trout and Atlantic salmon were reduced in the Main Lake basin. Catches-per-unit-effort (CPUE) and estimated angler catch of lake trout increased. A moderate (25%), statistically significant increase in survival of 3–4 yr lake trout was noted. Returns of Atlantic salmon (Salmo salar) to tributaries increased significantly after treatment, and there was an estimated 3-fold increase in returns to the Main Lake sport fishery. Angler catches of brown ( Salmo trutta) and rainbow trout ( Oncorhynchus mykiss) were higher in 1997 than in 1990. Economic analysis of the program indicated a 3.5:1 economic benefit: cost ratio. Results indicate that the experimental control program was successful, and provide justification for continuing sea lamprey control on Lake Champlain.