HERRING IN PRINCE WILLIAM SOUND, ALASKA 
273 
Table 7. — Vertebral count samples of the 1926-year class from Macleod Harbor 
Since the material is apparently homogeneous McClure Bay, which differs by 3.19 
standard errors from Naked Island and 2.34 standard errors from Eshamy Bay, 
giving probabilities of 0.002 and 0.02, respectively, may have an independent stock 
of herring, but can not be definitely said to differ without further data. 
CONDITIONS OF THE SUPPLY 
FACTORS INFLUENCING THE DETERMINATION OF ABUNDANCE 
The principal aim of this investigation has been to determine the trend of abun- 
dance as influenced by the present intensive fishery. Our determinations of this trend 
are, and must be, imperfect, as the only index to the abundance of the herring is 
contained in the records of the commercial fishery. Even supposing this fishery 
obtained a representative sample of the total population (which it does not, due to 
selective schooling and the selective action of the gear used) there would still be some 
doubt as to the adequacy of our sampling of this commercial catch. Even if the size 
and age composition of the population were accurately known, there would still be 
the question of its abundance. The only available unit of fishing effort — the seine 
boat — is not standardized; and, if it were, we would still be confronted with changes 
in the availability of the fish at different seasons, and in fluctuations of this availability 
at the same period in different years owing to factors not yet understood. In spite 
of these handicaps the following analysis has been made, using the available data, and 
a few important facts have been discovered. 
As aforementioned, the changes in the abundance of the supply of fish may be 
caused by natural conditions such as the presence of dominant year classes, or they 
may be caused by the artificial conditions brought about by an intensive fishery. 
The availability of the fish, apart from their abundance, may be subject to seasonal 
variations, and is influenced by regulations restricting the length of the season or 
limiting the areas to be fished. The intensity of the fishery depends not only on the 
number, size, and efficiency of the fishing boats, but also indirectly on the size and 
type of shore plants, inasmuch as the quantity, size, and condition of the fish on 
delivery to the plant is dependent on the purpose for which the fish are to be used, 
and governs the effort expended in securing them. Considerable difficulty is met 
with in showing the relation existing between these various factors and the total catch 
from year to year, on account of the data being insufficient, especially for the earlier 
years of the fishery, to give a proper measure of the effects of each factor. 
