FISHERIES AND GUANO INDUSTRY OF PERU. 337 
No fishes ascend the upper courses of the rivers and the very few species 
found in the lower parts are very small and of negligible economic value. 
These little rivers are of great importance to the fisheries, however, as the habitat 
of the most important shellfish of the country, the excellent ‘“‘cameron de rio.’’@ 
This fresh-water shrimp is a most highly and deservedly prized product, the 
equal in quality of any crustacean form. ‘The rivers are also significant, since 
in the time of flood the most important of the food fishes, the large ‘‘corbina,”’ 
is found in greatest numbers in the neighborhood of the mouths, probably feeding 
upon the small crustacea which find their way out of the river. The season of 
“agua nueva” (new water) is a propitious one for the fishermen. 
Consequent upon the absence of large rivers and the steepness of the coast, 
there are few good bays or harbors. Most of the ports are upon a more or less 
exposed shore, where embarkation must be effected through the surf, unless a 
long pier has been built out beyond the ordinary breakers. Even in compara- 
tively calm weather, the great swells rolling into the open bays often assume 
such proportions as to make landings impracticable even with the use of long 
steel piers. Fortunately, the coast is entirely free from storms; but the fisheries 
as well as commerce are seriously handicapped at such ports as Eten, Salaverry, 
Cerro Azul, and Mollendo, where for days at a time communication between sea 
and land is rendered impossible by the prevalence of ‘‘la mar brava”’ (the wild 
sea). ; 
Untropical as is the coast of Peru in its aspect as described above, it is 
equally so as regards the temperature of the ocean water. There is no more 
significant feature of the coast than the Humboldt or Peruvian current which 
flows northward and northwestward along the west coast of South America, 
bringing the cold antarctic waters down to the equatorial region. ‘To find 
upon the coast of the United States a summer temperature of the ocean water 
corresponding to that of Callao at 12° S. one would go to about the latitude 
of New York on the Atlantic side (41° N.) or Monterey on the Pacific (36° N.). 
The Peruvian current, in conjunction with other factors, particularly the 
constancy of the winds on the coast, produces a relative uniformity of tempera- 
ture conditions. There is little variation in the water temperature from hour 
to hour during the day, little difference from month to month during the year, 
and a relatively small change from latitude to latitude. It is probable that 
such variations as are found are due more to very local conditions, or to the 
swinging of the current, than to seasonal changes or differences of latitude. 
At Callao (12° S.) the water in early summer was at 15-19° C. (59-66° F.) and 
in early winter from 16.5 to 19° C. (61-66° F.); at Paita (5° S.), in April, 
records from 15.5° to 20.5° C. were taken, with an average of 17.5°C. (63.5° F.); 
@ Bithynis cementarius gaudichaudi (Milne-Edwards). 
B. B. F. 1908—22 
