BIOLOGY AND NATURAL HISTORY 81 



seems reasonable to believe that those species which are now at a low point 

 in production or abundance may be expected to increase in the future. 



Long-term geographic shifts in the population of fishes from one region to 

 another are well known to the fishing industry. The weakfish or gray trout 

 was absent from northern New England waters from before 1800 to 1838, 

 then became abundant in the late i8oo's, reaching a peak from 1901 to 1904; 

 it declined rapidly after 1904, and was again practically absent from these 

 waters by 1909. Bluefish were absent from New England waters during the 

 period 1764 to 18 10, but since that time they have supported a continuous 

 but fluctuating fishery. The centers of abundance of the North Carolina 

 species, gray and spotted trout, bluefish, and croakers, seem to have shifted, 

 so that their relative abundance in the State and in the neighboring States 

 has changed much from time to time. Notwithstanding the fluctuations in 

 abundance of many or all the species, the total production of the food fishes 

 as a whole in North Carolina shows no consistent trend, upward or downward. 



Changes in the abundance of the several species are thus undoubtedly 

 the result of natural factors even though fishing may also have some effect. 

 Heavy fishing may reduce a population, but the fishery arrests itself auto- 

 matically as it becomes unprofitable and is discontinued or much diminished 

 long before any species is totally "fished out." 



While in most cases a decline in production is followed by an increase, 

 there are certain instances where changed conditions may prevent subsequent 

 increases. This seems true of the shad in nearly all of the Atlantic coast 

 streams. Obstructions, pollution, sedimentation, and soil erosion have made 

 many of the rivers unsuitable for shad spawning and survival of young. This 

 problem is discussed in greater detail in the sections dealing with the species. 



The relationship between legislation and fluctuations in abundance is 

 interesting and important. Restrictive laws are generally made when a 

 fishery is declining or when it has reached a low point in the usual cycle; 

 and when subsequently the species increases in abundance, the restrictive 

 measures are given credit for having produced the increase. The same chain 

 of events has occurred in the case of artificial propagation, although recent 

 research has cast serious doubt on the ability of fish plantings to increase 

 the population of sea or coastal fishes to a measurable degree or even to 

 sustain it where it naturally tends to decline. Considerable research needs 

 to be done to determine whether the fish need the protection they are now 

 given, and whether the inconveniences of restrictive measures to the fisher- 

 men are justifiable from an economic or biological viewpoint. 



It is indicated in Part III of this Survey that economic improvement in 

 the fishing communities is not to be expected from advance in prices, but 

 it must come from the production and sale of more fish and from increased 

 efficiency and lower cost. Is the State capable of producing substantially more 



