A 1-inch clam will grow in one year to a size between 2 and 3 inches. Under fairly favorable conditions, with a moderate current, a 1-inch clam will increase to 2½ inches, or a gain of 900 per cent, in volume. For every quart planted, the yield in one year will be 9 quarts. For beds without current, 1-inch clams average about 2 inches, or a gain of 500 per cent.; i.e., five quarts for every quart planted. Beds under exceptionally fine conditions have shown the amazing return of 15 quarts for every quart of 1-inch clams planted. Clams increased in these beds from 1 to 3 inches in length. Therefore, by planting clams 1 inch or over, under favorable conditions a marketable clam can be produced in one year.
What is the maximum production per square foot?
The number of clams per square foot that can be raised to the best advantage depends upon the location of the flat in respect to natural conditions. Clams thickly planted (15 to 20 per square foot) in favorable locations may show a greater growth than when thinly planted (5 per square foot) in less favorable locations; therefore, no definite statement can be made which will apply in all cases. The only rule that can be given is that a flat with a current will produce a greater number of clams per square foot than one without a current. On good flats clams can be planted conveniently and economically from 10 to 15 per square foot, or even a larger number.
What results can be obtained by planting on barren flats?
There are two groups of flats which come under the term barren: (1) flats which once produced clams in great numbers, but now are practically barren, except for an occasional clam here and there; (2) flats which never have produced clams, and on which for physical reasons clams can never grow. The first group of flats is alone considered in this answer.
Experimental beds were planted on certain flats in the Essex River which come within the first group of barren flats. These once productive flats had been cleaned out in the past, and for some reason had not seeded naturally. Forty beds were laid out under all kinds of conditions, with the object of finding a way to make these once more productive. Results have been all that could be hoped for. Only 4 poor beds were found, out of the 40 laid out; 36 beds were in thriving condition. It should be noted that no attempt was made to choose the best places, but all conditions were tried. Over two-thirds of the clams were re-dug, the increase averaging, in terms of 1-inch clams, over 1,000 per cent., or 10 quarts for every quart planted the year before.
If many acres of Massachusetts flat, idle at present, are capable of such a yield, should such economic waste be allowed? Why should not the towns, by the expenditure of a little money, restock flats such as these for the benefit of their inhabitants? I do not say that all flats can be made productive in this way, as I know of many cases where the mere sowing of seed clams will not restock a flat; but I do say that Massachusetts possesses enough flats of the former nature, which should be made a profit to her clammers. Clam set occurs, as Mr. Stevenson shows in his report, in large quantities; the transportation of seed clams is easy; planting requires little labor, the practical way being to sow the clams, which burrow readily; while the yield in proportion to the labor is enormous.
What sized clams are best for planting?
The size best adapted must be determined for each flat. Shore flats with little current will allow the planting of any size, from ¼ inch up; flats with a swift current necessitate a larger clam (1 to 1½ inches), as the smaller will be washed out of its burrow; soft mud also demands a larger clam, as the smaller will be stifled by the oozy silt.