INVESTIGATIONS UPON THE DETERIORATION OF NETS IN LAKE ERIE 



By A. C. Robertson, Associate Technologist, Bureau of Fisheries, and W. H. 

 Wr[GHT, Late Associate Professor of Agricultural Bacteriology, University of 

 Wisconsin 



CONTENTS 



Page 



I ntroduction 249 



Effect of "red slime" on netting 151 



Effect of bacteria on netting 152 



Description of attacking bacteria 152 



Morphology of bacteria " I53 



Colony formation and growth characteristics 154 



Occurrence of the bacteria 15g 



Bacterial action on the individual fiber 15g 



Distribution of the bacteria and their environment 160 



Preservative treatments * lg2 



Tests of preservative treatments in the laboratory 163 



Tests of preservative treatments in the lake " 165 



Practical fishing tests I7I 



Summary ~ j74 



Bibliography ~~ j^g 



INTRODUCTION 



The Great Lakes, and particularly Lake Erie, contribute appre- 

 ciably to the catch of the American fisheries. In 1927, 81,326,550 

 pounds of fish worth $6,794,891 were caught in the Great Lakes, of 

 which Lake Erie supplied 23,796,462 pounds, worth $1,831,284. From 

 these data it can be seen that Lake Erie plays an important part in 

 the fishery industries of the country. The productivity of the water 

 IS about 10 pounds of fish per acre per year,^ which exceeds that of the 

 other lakes. Lake Ontario, for instance, produces but 1.1 pounds of 

 fish per acre and Lake Superior only 0.6 pound per acre. This low 

 yield for the latter is no doubt due to the unusual coldness of its 

 waters and the extensive areas of deep water. 



The large productivity of Lake Erie makes it an excellent fishing 

 ground. However, the cost of keeping nets in good condition con- 

 stitutes a heavy expense to the fishermen. Surveys show that about 

 $3,000,000 worth of gear is used in the "interior waters," of which a 

 large amount (about $920,000 in 1922)^ was used in Lake Erie. Part 

 of this gear, such as gill nets, etc., scarcely maintains good working 

 strength over a year's time, and the rest (trap nets, etc.) seldom lasts 

 over three years without extensive repairs. 



for pubSfoI,""r° Tm7°'^ °^ *^® ^' ^- Commissioner of Fisheries for 1930. B. F. Doc. 1083. Submitted 

 rimw ^''-^ Industries of the United States 1926, by Oscar E. Sette, Appendix V to the Report of the U S 

 S th„ i.'^L°°^'' ''^ Fisheries for 1927. Average catches for years 1913-1925, inclusive, are divided by the area 

 Ont'a^rif f.iTp^nds Je'rcretfleaf '°"°"= ^^'''' '■''' ^'^'•"°' '■''' ^^^^^^--^-^^^ SuperKcS; and 

 CommSe°rt'^tL°Hes'foV 19^^^^^ S.' ''''' ''^ """""' ^^ ''"'' '"'"'''"''' ''' '" '"' ^«P°^* "' ^^« "" ' ^■ 



149 



