BIOLOGY AND NATURAL HISTORY 113 



North Carolina's production dropped from about nine million pounds in 

 1897 to less than one million in 1940. In fact, the annual production since 

 1930 has averaged less than a million pounds. North Carolina has produced 

 from 8 to 15 per cent of the total U. S. catch. 



Much has been said and written regarding the causes of the decline in the 

 shad fishery. Overfishing, pollution, and dams are generally considered the 

 three important factors involved. At first, it was thought that overfishing 

 was chiefly responsible; therefore about 1880 a large-scale program of 

 artificial propagation was initiated in an attempt to restore the shad popula- 

 tion. Early indications were that the planting of small shad was accomplish- 

 ing its purpose (a gradual increase in supply of adults from 1880 to 1896) 

 but improvements in fishing methods and greater fishing intensity were not 

 considered in accounting for such increases. Then after 1896, while planting 

 was continued, the shad decreased at a rapid rate. Artificial propagation did 

 little, if any, demonstrable good; at least it could not maintain the supply. 



The effect of overfishing, or even the possibility of overfishing, is not com- 

 pletely understood. Huntsman (1944) summarizes one of the current at- 

 titudes toward overfishing (of fish in general) as follows: 



Frequently the possibility is advanced that overfishing has resulted in under- 

 replacement of the stock through decrease in the numbers of spawning fish. 

 Since most species have a high reproductive capacity, this does not readily occur. 

 Exclusion of anadromous fish from their spawning grounds by impassable dams 

 definitely prevents replacement of the stock. Conceivably, overfishing might 

 prevent full replacement of stock, but it is desirable to have carefully docu- 

 mented experiments to establish the need for restriction of the fishery to assure 

 replacement. Leaving out of account such forms as the amphibious walrus of 

 the Atlantic and fur seal of the Pacific, which are particularly vulnerable on 

 their breeding grounds, we have as yet been unable to learn of a clear, docu- 

 mented case of under-replacement through overfishing for this continent. 

 Information on this would be welcomed. It is proposed to undertake somewhat 

 precise experiments to determine in particular cases how many spawners are 

 required for replacement of the stock, so that the full surplus may be taken for 

 human use if desired. 



It is also difficult to place the full responsibility for the shad decline on 

 overfishing, in the light of the Greenfield fishery data referred to above. This 

 fishery, as were most other fisheries, was inoperative for four years during 

 the Civil War, 1862-1865 inclusive. If the breeding stock previously had 

 been maintained at too low a level, this four-year period should have provided 

 ample time to increase the stock. Yet the annual production for the five-year 

 period following the war was only 14 per cent higher than the five-year pre- 

 war period (41,746 fish as compared with 36,609). The take for the next 

 five-year (1871-1875) period was about the same, but the following five 



