ESTIMATING PRODUCTION 



Figure 21. — The scap net has many uses about the hatchery. 



texture so as to prevent injury to 

 the fish being handled (fig. 21). 



Care of collecting gear 



Nets should be carefully inspected 

 for holes, repaired when holes ap- 

 pear, and thoroughly dried after 

 each use. Nets should be stored 

 in a cool, dry place with a good 

 circulation of air. If they are fre- 

 quently used in waters rich in or- 

 ganic matter, it is well to have the 

 nets treated occasionally with a pre- 

 servative, such as tannin or copper 

 oleate. It is not desirable to use 

 tar as a preservative for minnow 

 nets because this substance has a 

 tendency to harden the fibers, and 

 tlius introduces conditions which 

 may be injurious to the fish being 

 handled. Nylon nets do not require 

 a preservative. 



Small hand nets, such as dip nets 

 and scap nets, used daily in and 

 about a bait dealer's establishment, 

 when not in use, should be kept in 

 a sterilization bath consisting of a 

 weak chlorine solution. In this 

 way, disease organisms will not be 

 carried from one tank to another by 

 the nets. One formula used in 

 Michigan hatcheries consists of 26 

 fluid ounces of cleanser (3-percent 

 available chlorine) to 30 gallons of 

 water. As chlorinated solutions de- 

 teriorate rapidly in the presence of 



organic materials or when exposed 

 to air, the bath must be strengthened 

 about once a week by adding 13 

 ounces of cleanser. Once a month 

 the entire solution should be dis- 

 carded and a new bath prepared. 

 A word of caution : chlorine is toxic 

 to fish, and discretion should be 

 used when disposing of old steril- 

 izing solutions. 



ESTIMATING PRODUCTION 



As soon as a tankload of fish has 

 been seined and transferred to the 

 live box, the fish should be weighed 

 (fig. 22), and carried in a pail of 

 water to the tank. The usual pro- 

 cedure is to hang the scale from a 

 tripod set in several feet of water. 

 A half -bushel metal basket is partly 

 filled with clean water. Ten pounds 

 of fish are weighed and carried to 

 the truck. By weighing 10 pounds 

 of fish at a time it is easy to keep 

 account of the fish taken, or the 

 production of a pond. Fish han- 

 dled in these amounts will not be 

 too crowded or easily injured. If 

 the operator is interested in know- 

 ing the number collected, he can 

 weigh and count the fish in 1 pound. 



Another method of measuring 

 minnows that is not destructive of 

 the fish is the wet gallon measure. 

 A 5-gallon pail is marked off from 

 the li/^-gallon level to the top in 



37 



