PROGRESS IN BIOLOGICAL INQUIRIES, 1926 567 
mackerel. Swordfish present a slight upward trend and Spanish mackerel 
(including cero) show a distinct downward trend. 
Among the demersal fishes (fig. 8), cod and halibut show a general downward 
trend (more severe in the case of halibut), haddock show a general upward 
trend, as do also snappers and groupers, flounders show a most decided upward 
trend, and hake showed a slight upward trend until 1897 and thereafter a 
moderate downward trend. 
All of the important anadromous fishes (fig. 9) show trends distinctly upward 
in the early years and downward in the later years. Shad and sturgeon reached 
peak productions earliest (1897) and declined most rapidly thereafter. Smelt 
reached peak production as early but declined less consistently. Striped bass 
and alewives, though showing a declining yield, have not fallen as rapidly and 
consistently as the others. 
Among the shore fishes (fig. 10), four species—whiting, butterfish, spots, 
and croakers—show very marked upward trends. Scup and kingfish seem to 









4 
O 
Tn 
MMII 

XN 

MILLIONS OF PouNDS 
ny Pp 2S 
AL LE | U 
) TT 
- 

1880) 
¢ 8 
Fic. 7.—Changes in the yield of several important pelagic species on the 
Atlantic seaboard (on a logarithmic calc 
1895 
1900 
905) 
210 
\O15 
1920 
have maintained their yield at a fairly constant level. Squeteague and mullet 
grew in yield until 1902, and have since maintained it at nearly the same level. 
Herring and pollock show a rise and fall of considerable magnitude. 
If we group the species that have declined most seriously in recent years 
(bluefish, cod, halibut, shad, and sturgeon), we find that they are all fish that 
were highly prized during early years and have been subject to intensive fishing 
for the longest time. Also, if we group those showing greatly increased yield 
in recent years (flounders, Spanish mackerel, haddock, snappers, groupers, 
croakers, spots, butterfish, and whiting), we find that they are species less in 
demand in former years but that have been exploited more lately. It would 
seem that in general the yield on the Atlantic coast has been held at a high 
level by replacing the staple fish of former days with new species, which were 
not greatly in demand in the earlier years. In some cases this may have been 
due to economic factors. The cod, for instance, among those that have declined, 
apparently has been affected by the decreased salt-fish trade; but in most cases 
the declining yields seem to be the result of depletion, and the total yield of 
