"Oyster City," Yaquina Bay, Oregon.
As the result of an application through official sources, re-enforced possibly by the results of a biological survey made by this department during the preceding summer, twenty-two barrels of Eastern oysters were, on November 7, 1896, deposited on a portion of Oysterville Flat, so called, in Yaquina Bay, Oregon, seven miles and a half from the ocean. The oystermen of that section have agreed to abstain from tonging for native oysters upon the portion of the flat thus reserved until sufficient time has elapsed to justify an opinion as to the result of the experiment. These introduced oysters were of two varieties—the long, slender East Rivers and the more oval, fan-shaped, and ribbed Princess Bays. Their journey of twelve days across the continent, in sugar barrels, from New York to San Francisco and thence to Oregon without water did not cause the mortality one might expect, for in strewing them over the bed from the scows of the oystermen very few dead individuals were observed—certainly not one half of one per cent.
An Experimental Spawning Float.
This alien oyster has much to contend with here. It was realized that the cold and salt water rushing in from the Pacific—colder and salter by far than in their Atlantic home at the same time—if it did not entirely prevent spawning would at least make the survival of the young embryos a matter of doubt; yet it was hoped that perhaps, after a number of years, the oysters might become acclimated, as it were, and their spawn, inheriting their parents' acquired hardiness, we might present to the people of the State a new form of Oregon product in the shape of Eastern oysters hatched and grown in the waters of this bay. Notwithstanding the fecundity of this oyster, a female producing in the vicinity of sixty million eggs at a spawning, it must be remembered that even under the most favorable conditions in its own home, where the water has in summer a fairly constant temperature of over 70° F. and a salinity of 1.012 on an average, but a very small proportion of this multitude survive. How much more unlikely is its survival in the waters of Yaquina Bay, Oregon, where the writer has seen the water change from a temperature of 70° F. and a saltness of 1.012 to a temperature of 55° and a salinity of 1.022 within six hours! It was to save the young embryos from exposure to these and kindred dangers that I, as a volunteer employee of the United States Fish Commission during the summers of 1897 and 1898, among other things resorted to the artificial fertilization of the eggs in a temporary laboratory, carrying the delicate embryos to the swimming stage and dumping them by thousands into the bay. Given some clean crocks, a microscope, dissecting instruments, tumblers, rubber tubing, thermometers, and instruments to test the saltness of the water, and innumerable embryos can be cared for without much trouble. The process, as practiced by Brooks, Ryder, Nelson, and others in America, is too well known to need repeating here. Its efficacy is well established, and, in spite of the incredulity of the oystermen, who wished to see the oysters spawn "spontaneous," as they expressed it, an incredulity amounting almost to opposition, the writer has persevered in this work for two seasons and intends to continue it the coming summer.
1, native oyster spat on clam shell; 2, same on inside of oyster shell; 3, 4, 5, native spat (Ostrea lurida) on Eastern oyster shells; 6, showing size and appearance of native spat one or two months old.
The native oyster of this Northwest coast (Ostrea lurida), smaller and by many preferred to its Eastern congener, while it is far less fruitful in its spawning than the latter, retains its young within the parent shell until long after they have passed the tender stages, when they leave the mantle cavity of the parent to swim for themselves. This oyster could rightly be called viviparous, while the Eastern oyster is oviparous. On account of its nurse-acting proclivities this West-coast oyster has an immense advantage here over the introduced species. The latter's eggs have to run the following gantlet: (1) Not meeting with a fertilizing cell and perishing in consequence; (2) sinking, before or after fertilization, in the fatal mud; (3) being eaten by small fish and other minute animals; (4) being killed by sudden changes in the temperature and density of the water. Artificial fertilization and the rearing of the embryos in the laboratory largely eliminate these dangers. We have adopted other methods to insure success. A few of the oysters were removed from the Government plant and deposited two miles farther up the bay, nine miles and a half from the ocean, where it was thought the water was warmer, less salt, and less variable than on Oysterville Flat. Some, during the breeding season, were placed on spawning floats and anchored near the shore, where the shallow water is thoroughly warmed by the sun. It was in one of these floats that the oystermen had an opportunity to see the oysters spawn "spontaneous," for the water therein, reaching 70° F., became milk-white with spawn or milt within an hour after the oysters had been taken from the plant. This was really our first proof that the introduced oyster would spawn here. Some were placed in sloughs adjoining the bay, with the hope that favorable conditions would be met with there. Others were placed in artificially constructed salt ponds somewhat after the style used by the French.
