30 



COMMERCIAL FISHERIES REVIEW 



Vol. 28, No. 8 



Fig. 1 - Alewife catch made by M/V Kaho in IS-minute drag in- 

 side Chicago Harbor, 



Alewife landings increased from a few 

 hundred pounds in 1956 to about 15 million 

 pounds in 1965. Bureau of Commercial Fish- 

 eries investigations, closely associated with 

 the industry during this period of growth, 

 have furnished evidence of the great magni- 

 tude of the resource, of the almost year-a- 

 round availability of alewife to otter (bottom) 

 trawls, of the economic feasibility of pro- 

 ducing alewife at a landed value as little as 1 

 cent a pound, and of the suitability of alewife 

 for making high-quality pet food and fish meal. 



Even with the 30 -percent increase in ale- 

 wife production expected again this year, the 

 stocks available for harvesting will be hardly 



touched. According to the present condition 

 and distribution of Lake Michigan alewife 

 populations, a production of 200 million pounds 

 a year is a reasonable goal. 



Continued Bureau research will maintain 

 close surveillance of the alewife stocks, es- 

 tablish relationships to other important fish 

 species, and strive to improve the economic 

 utilization of this valuable resource. 



Further evidence of the increasing num- 

 bers of alewife in Lake Michigan in spring 

 1966 came from such sources as municipal 

 water supply systems, electricity generating 

 utilities, and steel mills. Alewife plugged 

 water intake screens more than ever this 

 year- -causing production cut-backs. One ex- 

 ception was the City of Chicago's Central 

 District Filtration Plant, the largest facility 

 of this type in the world, which experienced 

 no difficulty even though large schools moved 

 through the area for a period of about 5 weeks. 

 A special deterent net, built according to Bu- 

 reau recommendations, was set around the in- 

 take area and is credited with preventing 

 serious problems during the alewife runs. 



The primary objective of the cruise was to 

 supplement data on the seasonal availability 

 and bathymetric distribution of alewives, 

 chubs, yellow perch, and smelt. Secondary 

 objectives were to collect fish for botulism 

 studies, monitor the growth rates and distri- 

 bution of newly-planted lake trout, collect 

 depth -frequency data on chubs, alewife, and 

 perch, and collect fish for food studies. 





gBltfWM»i» M i M»«a»M - 



Fig. 2 - Chicago Central District Filtration Plant which supplies water to 2,5 million Chicagoans. Faint white streak near shore at left 

 is the air bubble curtain in operation--used to prevent alewife plugging of water intake screens. 



