404 U. S. BUREA.U OF FISHERIES 



ment of Commerce, on the United States import and export trade in 

 fishery products during 1927; and the collection and publication here- 

 with of the 1927 fishery statistics of Lakes Keokuk and Pepin. 



The special statistical observations on the mackerel fishery have 

 been of particular interest and are beginning to bear fruit of unusual 

 importance to the industry. The project involves the collection of 

 data on the size, date, and locality of capture of each fare of mackerel 

 landed at the principal mackerel-receiving ports; also the measuring 

 of a sample of 20 or more fish from each fare. These data, together 

 with biological analyses, in which the division of scientific inquiry has 

 had an important share, have made possible an understanding of the 

 fluctuations in abundance of this notoriously erratic species. During 

 the years 1925, 1926, and 1927 the commercial catch has been domi- 

 nated almost completely by fish of the 1923 spawning season. In 

 other years either spawning has been a failure or infant mortality 

 has been so high as to have virtually prevented significant contribu- 

 tion to the stocks of mackerel in the sea. Knowing that for three 

 years the commercial fishery has been drawing on a stock of mackerel 

 that has had virtually no increase from natural reproduction it is 

 possible to estimate the trend for at least a year in the future. The 

 1923 year class came into commercial importance in 1925, and the 

 consequent increase in abundance caused a commercial catch exceed- 

 ing any since 1885. In 1926 the catch was still larger, but m 1927 

 the catch decreased about 12 per cent. Evidently, mortahty, both 

 natural and artificial (removal of the commercial catch from the 

 stocks in the sea), by that time had offset the increase due to growth 

 in size of individual mackerel. Thus it has been possible to predict 

 that the 1928 catch wifi fafi below the 1927 catch by more than 12 

 per cent. Such predictions will be of inestimable value to fishermen 

 and fish dealers when their reliability has been tested sufficiently 

 through a number of years. 



TECHNOLOGICAL INVESTIGATIONS 



The technological work of the bureau is directed toward the elimi- 

 nation of loss in fishery industries by the utiUzation of material 

 generally wasted, by making existing processes more economical 

 or replacing them with new methods, or by making investigations 

 and spreading information concerning new uses of fishery products. 

 To do these things, the bureau supplies the industry with the best 

 scientific information available and conducts investigations that 

 promise to be of general importance and that are of such nature that 

 the bureau can hope to prosecute them profitably with the per- 

 sonnel and funds available. It has been necessary, however, to point 

 out to the industry that there are problems that the bureau is quafified 

 to attack and can do so properly, but that there are other problems 

 that industry must solve for itself. The latter generally are not of a 

 technological nature but are purely matters of management, whereby 

 great savings may be effected by applying sound business principles. 

 The' technologists are fitted to point out to the industry the sources 

 of loss in a plant, but the solution of these problems is an individual 

 matter best solved by the persons involved. 



A prominent feature of this year's work is the greater number of 

 contacts made in the field, through which the problems of the industry 



