USE OF MOBILE BIOASSAY EQUIPMENT IN THE CHEMICAL CONTROL 

 OF SEA LAMPREY 



INTRODUCTION 



The use of selective larvicides in the control of 

 sea lamprey in the Great Lakes began in 1958 when 

 11 streams tributary to Lake Superior were treated 

 with 3-trifluormethyl-4-nitrophenol (TFM). This 

 material was one of several discovered by the Bureau 

 of Commercial Fisheries, under contract with the 

 Great Lakes Fishery Commission, at the Hammond 

 Bay Laboratory, Millersburg, Michigan, (Applegate, 

 Howell, and Smith 1958; Applegate et aL, 1961). 



The early testing and application of TFM re- 

 vealed that the degree of selectivity between lam- 

 prey larvae and stream fishes may vary from stream 

 to stream and also with season in the same water. A 

 determination must be made, therefore, prior to each 

 application, of the minimum concentration of larvi- 

 cide required to kill all lamprey larvae and the max - 

 imum concentration that can be used without causing 

 significant mortality to game fishes of the streams. 



The nearest bioassay facility for making these 

 determinations in 1958 was at the Hammond Bay Lab- 

 oratory, Millersburg, Michigan. Transportation of 

 water from Lake Superior streams to this laboratory 

 was costly and caused delay in obtaining results. Ex- 

 pansion of the chemical-treatment program to all 

 Lake Superior tributaries infested with sea lamprey 

 obviously required a faster method of obtaining re- 

 sults of bioassays. This need was met by installing 

 bioassay equipment in a housetrailer which could be 

 moved from stream to stream. The present report 

 describes the equipment of this mobile laboratory, 

 outlines bioassay procedures, and reviews uses of the 

 results. 



BIOASSAY FACILITIES 



The equipment was installed in a standard 18- 

 foot housetrailer. Fixtures furnished with the trailer 

 shell were a 30, 000 -B. T. U. gas furnace, four over- 

 head fluorescent lights, conveniently placed elec- 

 tric outlets, and two 10 -inch exhaust fans in the 

 ceiling. 



A waterproof power -inlet fixture was mounted 

 on the outside and connected to a fuse box on the in - 



side wall. A voltmeter was placed in the input 

 line to provide a constant check on voltage since a 

 considerable amount of electrical equipment was 

 installed. 



Two water troughs (10 by 2 feet and 1 foot deep) 

 of 20 -gauge galvanized sheet steel, were framed with 

 2- by 4 -inch boards and fastened to the trailer walls 

 (fig. 1). The troughs and framing were further sup- 

 ported by a table of 2- by 12 -inch boards with 4- by 

 4 -inch wooden legs. A 2 -inch thickness of fiberglass 

 insulated the sides of the troughs to prevent conden- 

 sation. 



A centrifugal -type, water -circulating pump with 

 2 -inch suction and 1-inch discharge and powered by 

 a 1/2-horsepower electric motor was mounted in the 

 laboratory to pump water directly from the stream to 

 the trailer through a rubber hose. An intake basket 

 covered with fine -mesh screening filtered debris from 

 the incoming water. This basket contained a check 

 valve to prevent loss of water from the hose when the 

 pump was not running. 



Water was piped to the troughs by 1/2 -inch cop- 

 per tubing. A shutoff valve was provided for each 

 trough. Standpipes, 2 inches in diameter and 7 inch- 

 es high, at the end opposite the water source con- 

 trolled water depth. The standpipes were connected 

 to a drain beneath and at the rear of the trailer. A 

 hose attached to this drain returned overflow water 

 to the stream. Valves were installed at low points 

 in the water system to permit complete drainage when 

 the laboratory was not in use. 



The troughs contained space for 22 individual 

 test containers each, or a total of 44 in the two. Each 

 container was provided with a controllable supply of 

 compressed air to maintain oxygen concentrations 

 in the test solutions at or near saturation. 



Air for the test jars was furnished by two tank- 

 mounted, air-cooled, single-stage compressors, pow- 

 ered by 1/3 -horsepower motors. The primary supply 

 lines from the compressors were interconnected. In 

 the event one compressor failed, the opening of a 

 stopcock allowed the remaining compressor to furnish 

 air to all test jars. Air was distributed to the individual 



