The probable yield of his fish trade was always carefully calculated, even when the pressure of national affairs required his absence from home. From Philadelphia we find him writing to his manager about a fish merchant's offer: "Ten shillings per hundred for shad is very low. I am at this moment paying six shillings apiece for every shad I buy." He usually tried to get at least twelve shillings a hundred for his shad, which were salted prior to marketing, although there were instances when he let them go for as little as one pence apiece. The extraordinary price of six shillings for one shad cited by him in Philadelphia is hard to explain. It probably referred to a fresh one caught early in the season and prepared especially for his table. Though records of the average weight of shad in those days are lacking, seven pounds is a fair estimate, and it may have been greater. The weights now seldom exceed three or four pounds, because in the more recent years of intensive fishing, shad have been widely caught up as they returned from the ocean to spawn for the first time. Shad, along with other anadromous, or "up-running," fish are born near the head-waters of rivers, and seek the ocean for feeding and growth. Unlike salmon they do not perish after one spawning and the oftener they return, the larger they are. What conservationists call "escapement," or the freedom to get back to the ocean from the rivers, is considered vital to their survival in quantity. All through the two-score years of fishing at Mount Vernon, Washington suffered, judging by his unceasing preoccupation with minor details, from the lack of a fishing foreman to whom he could entrust the operation with any confidence. Letters toward the close of his life bearing on this subject are still replete with reminders concerning trifles which would have been routine for any competent boss. The fish runs start about March; therefore, in January he finds it necessary to write; "It would be well to have the seines overhauled immediately, that is, if new ones are wanting, or the old ones requiring much repair, they may be set about without loss of time." He must even look beyond his own help for the skill necessary to put his nets in order. "I would have you immediately upon the receipt of this letter send for the man who usually does this work for me.... Let him choose his twine (if it is to be had in Alexandria) and set about them immediately." Abundance of fish created a bottleneck: In the height of the fishery they are not prepared to cure or otherwise dispose of them as fast as they could be caught; of course the seines slacken in their work, or the fish lie and spoil when that is the only time I can make anything by the seine, for small hauls will hardly pay the wear and tear of the seine and the hire of the hands. However, then as now, fishing was a gamble: