Popular Science Monthly/Volume 56/December 1899/Eastern Oyster Culture in Oregon
|EASTERN OYSTER CULTURE IN OREGON.|
By F. L. WASHBURN, A. M.,
STATE BIOLOGIST AND PROFESSOR OF BIOLOGY IN THE UNIVERSITY OF OREGON.
DURING the past two years the United States Fish Commission, with characteristic enterprise, has been carrying on experiments in the propagation of Eastern oysters in the bays of the Oregon coast. Work of a similar nature is now being undertaken in the State of Washington.
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
"Oyster City," Yaquina Bay, Oregon.
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.
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.
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
An Experimental Spawning Float.
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 loss variable
Eastern Oysters in Oregon. The lower row shows size when planted in 1896; the upper row represents their appearance in 1898.
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.
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.
What has been the outcome? The oysters, particularly the Princess Bay variety, have grown enormously and are in excellent condition. Until this spring no Eastern spat or young Eastern oysters had been discovered; this, of course, is the crucial point in the experiment; we know they will spawn, but will the spawn develop? Recently, much to our encouragement, a few young oysters, apparently of last summer's spawning, have been found and forwarded to Washington, proof positive that the oyster will propagate here, but not certain evidence of the practical outcome of the experiment. It is too early to predict results as yet; two years more are really required to tell the story.
For thirty years Eastern oysters have been shipped to San Francisco by enterprising firms of that city, planted there in the bay until a large size is attained, and then sold at an immense profit. These firms have always claimed that the Eastern oyster did not reproduce there. As far as can be ascertained from a reliable source, the shipments in recent years have rather increased than diminished, this fact being used as an argument to support the above statement. It is nevertheless a known fact that much Eastern spat and many adult oysters undoubtedly hatched there have been found by members of the United States Fish Commission and others. Moreover, with increasing trade one would naturally expect more shipments, even though the introduced oyster did propagate to some extent.
Ostrea lurida, the toothsome little native oyster which years ago was so abundant at Yaquina Bay, affording support to many families, has decreased in numbers to such an alarming extent that unless some radical measures are soon taken to prevent, the native oyster industry of this locality will be a thing of the past. This decrease in the size and numbers appears to be due to several causes. In the first place, there has been a very persistent tonging on a somewhat limited area. This might have been counterbalanced by proper precautions to insure a future supply, but, with characteristic lack of foresight, such precautions have been neglected, and the beds have been culled year after year, until the comparatively few oysters now marketed from Yaquina Bay are of very questionable size. Each oysterman has two acres of flats for private use. Three natural beds in the bay afford sources of supply for these private beds. The larger oysters tonged on the natural beds are marketed, and the smaller specimens spread on the private ground referred to. Beyond strewing clean shells on these private beds, no provision is made to collect the swimming embryos during the spawning season, and multitudes must be carried away and lost. The writer has urged upon the oystermen the need of collectors of brush or tile, by the use of which the oysters which they have acquired may be largely increased in numbers, and will endeavor to demonstrate, by the use of tile collectors, that hundreds of young spat may be saved and raised to marketable age. Our native oyster structurally and physiologically resembles the European oyster (Ostrea edulis), and, like it, could be propagated in artificial oyster ponds. The practicability of such work on the West American coast depends, of course, on the market price of the resulting product as compared with the outlay required for labor.