While the main cause of the decline of the natural clam, quahaug and oyster beds is overfishing by man, the decline of the scallop fishery cannot be so considered. The scallop has a short life, hardly 25 per cent. passing the two-year limit; so it does no harm to capture the marketable scallops which are over sixteen months old, as the scallop spawns when one year old, and dies a natural death usually before it reaches a second spawning season. When only old scallops are taken, as is generally the case, it is probably impossible for man to exterminate the scallops by overfishing. Unfortunately, in certain localities in the past there has been a large capture of the "seed" scallop, viz., the scallop less than one year old, which has not spawned. This has worked the ruin of the scalloping in these localities. The capture of the spawners for another year merely makes the next year's set so much smaller, and causes a rapid decline.
As a rule, it is hardly profitable to catch the "seed" scallop, owing to its small size. But a direct relation can be established between a high market price and the capture of seed. When the market price is high and scallops scarce, it becomes profitable to catch the young "seed." The present scallop law now defines a "seed" scallop, and forbids its capture. By protecting the "seed" scallop the State has done all that at present appears expedient to insure the future of the industry; the rest lies in the hands of the towns.
So, while the scallop has declined in certain localities, and the decline has been hastened by unwise capture of the "seed" scallop, the main decline of the fishery cannot be attributed to wholesale overfishing, as it is impossible to overfish if only the old scallops (over one year old) are taken; for, unlike most other animals, the scallop usually breeds but once, and its natural period of life is unusually brief. These scallops, if not taken, will die, and prove a total loss; so every fisherman should bear in mind that, as long as the "seed" scallops are protected, severe fishing of large scallops is not likely to injure the future scallop industry.
The principal causes of the decline of the fishery, besides the inroads of man, are best termed "adverse physical conditions." Severe winters, storms, anchor frost, etc., work destruction upon the hapless scallop. The "infant mortality" is especially great.
As the scallop dies before reaching its second birthday, only one set of scallops spawn in any one season. There are never two generations of scallops spawning at one time. I quote from Ernest Ingersoll in this connection:—
This represents a case where the generations follow one another so rapidly that there are never two ranks, or generations, in condition to reproduce their kind at once, except in rare individual instances, since all, or nearly all, of the old ones die before the young ones have grown old enough to spawn. If such a state of affairs exists, of course any sudden catastrophe, such as a great and cold storm during the winter, or the covering of the water where they lie for a long period with a sheet of ice, happening to kill all the tender young (and old ones, too, often) in a particular district, will exterminate the breed there; since, even if the older and tougher ones survive this shock, they will not live long enough, or at any rate, will be unable to spawn again, and so start a new generation.[10]
The set of young scallops is abundant in shallow water upon the eel-grass flats, which often, as is the case of the Common Flats at Chatham, are exposed at extremely low tides. A severe winter often kills off all the "seed" thus exposed. In this case no spawn is obtained the following summer, causing the suppression of the scallop fishery in that locality for at least a few years, and possibly its permanent extinction.
III. Improvement; restocking Barren Areas.—The scallop industry, unlike the clam and quahaug, offers but little inducement to private enterprise. For successful private culture small bays or coves would be needed, and suitable areas are very scarce. The scallop offers better opportunity for communal culture, i.e., by towns.
There is but one way now known of artificial propagation for the scallop industry, and that is by transplanting in the fall the abundant set from the exposed places to the deeper water before the seed is killed by the winter. It is merely assisting nature by preventing a natural loss, and in no sense can properly be termed propagation. It is merely a preventive, and money used in this way to preserve the scallops is well expended. Usually the set is abundant, and can be transferred in large numbers. This is the only practical method now known of increasing our scallop supply, though it is hoped in the future that other methods may be devised.