182 U. S. BUREAU OP FISHERIES 



SIGNIFICANCE OF FLUCTUATIONS IN YIELD 



As has been stated before, the object of this inquiry is to discover, 

 if possible, whether or not the fisheries of Texas are suffering from 

 depletion by overfishing. Depletion of a fishery usually is under- 

 stood to mean a decreasing yield in relation to the effort involved; 

 and although no single adequate test for depletion has been devel- 

 oped, the various lines of evidence by which the condition may be 

 recognized have been summarized admirably by W. F. Thompson. 4 

 It is conceded generally by fishery investigators that the amount 

 per boat of the commercial catch is a reliable index to the relative 

 abundance of the stock of fish in the sea. A progressive decline in 

 the average catch per boat thus would indicate a decline in abun- 

 dance; but this can be determined only by an examination of records 

 collected in such a manner as to show the catches of each boat day 

 by day and calls for extensive fishery statistics. Moreover, a decline 

 in abundance may be brought about by natural causes outside of 

 human control and must be distinguished from overfishing. Bio- 

 logical studies may be depended upon to aid in distinguishing between 

 the possible natural and artificial causes of depletion. Changes in 

 the method of fishing and in the locality of the fishing grounds, as 

 well as such economic factors as demand, market competition, dis- 

 tribution, etc., also must be be considered when studying the records 

 of the yield. 



The available records of past development of the Texas fisheries 

 are inadequate to demonstrate whether depletion is going on. Both 

 State and Government statistics are not only contradictory to a 

 degree and unreliable as to fact, but are in such form that they are 

 useless for determining the relative abundance of the fish supply. 

 The trend of the total yield of the shore fisheries, as shown by the 

 Federal records, has been almost horizontal for the 33-year period 

 since 1890, but the records of the State show a rise in the yield. 



Despite the possible slight increase in the total yield, it is evident 

 that the supply has not kept pace with the demand. The population 

 and hence the potential demand, has increased at a greater rate than 

 has the production of food fish. 5 To meet the local demand, the sup- 

 ply has been augmented by shipments of fish from the eastern Gulf 

 States and from California. From this fact alone one might con- 

 clude that the fisheries had reached their fullest development and 

 were on the decline because of overexploitation, were it not for the 

 complicating factor of legal restrictions, which undoubtedly operate 

 to reduce the annual yield. 



In the older fisheries, where depletion of the more desirable species 

 is taking place, the market is being supplied with increasing quantities 

 of the smaller and less desirable species. An example of such a 

 shifting from the better to the cheaper classes of fish, characteristic 

 of a declining fishery, is found in the larger catches of black drum. 

 (See Table S.) The yield of six species of cheaper fish that average 

 4 cents per pound rose from 6.9 per cent of the total yield of all food 

 fish in 1890 to 33.1 per cent in 1918, and still amounted to 23.5 per 



* In " California Fish and Game," vol. 8, July, 1922, p. 172. 



« The population of Texas in 1920 was 100.8 per cent greater than in 1890, while the yield of food fish in 1923 

 was only 6.5 per cent greater than in 1890, as shown by the records of the Bureau of the Census and the Bu- 

 reau of Fisheries. The population of Texas in 1890 was 2,235,527; 3,048,710 in 1900; 3,896,542 in 1910; and 

 4,663,228 in 1920. 



