In general the cause of their moving in together from the offshore depths is their sexual development. I have heard the speculation that this is affected by the increase in light at this stage of the season, but unfortunately know no more about it. In any case at the age of four, or sometimes three, they are ready to spawn, to follow out the new force that is in them, on an old track. Their timing, when to migrate, is a question of generation, a decision that has to be made once again in the earth’s timeless schedule. Perhaps there is a comparison to be made once more with the weather, in which the element of surprise is constant during the usual course of the season, the intangible variant still plaguing prediction. The turns to storm or sunshine have their own order in the years beyond the immediate one. Who knows when anything will happen? Suddenly the cicadas start to sing in the August trees. Why that day or hour? Because “conditions are just right”? Perhaps, if we could ever track down all the conditions. Natural acts may be repetitive, but no flight, or song, or new growth has ever existed before at exactly the same time, pitch, or ratio. They are part of the indefinite context of generation. What about the alewives during their years in the sea? Very little seems to be known. According to _Fishes of the Gulf of Maine_ by Bigelow and Schroeder: “The alewife is as gregarious as the herring, fish of a size congregating in schools of hundreds of individuals (we find record of 40,000 fish caught in one seine haul in Boston Harbor) and apparently a given school holds together during most of its sojourn in salt water. But they are sometimes caught mixed with menhaden, or with herring. Alewives, immature and adult, are often picked up in abundance in weirs here and there along the coast, and it is likely that the majority remains in the general vicinity of the fresh-water influences of the stream-mouths and estuaries from which they have emerged, to judge from the success of attempts to strengthen or restore the runs of various streams.... But it is certain that some of them wander far afield, for catches up to 3,000 to 4,000 pounds per haul were made by otter trawlers some 80 miles offshore, off Emerald Bank, Nova Scotia at 60 to 80 fathoms, in March 1936.” They also say, with circumspection: “It seems likely from the various evidence that the alewives tend to keep near the surface for the first year or so in salt water, and while they are inshore when older. But practically nothing is known of the depths to which they may descend if (or when) they move offshore, there being no assurance that those taken by trawlers were not picked up, while the trawls were being lowered or hauled up again.”