With the growth of the ranch to three hundred ninety acres and the imminent purchase of another seven hundred acres, Jack had talked to his stepsister Eliza, now separated from her husband, Captain James Shepard, into moving to the ranch as his business manager. This was one of the wisest decisions Jack ever made. Eliza proved to be a near perfect ranch superintendent. She came to the ranch in 1910 and functioned as superintendent until her death in 1939. She lived at Madrone Lodge on the Fish Ranch until Jack built her a house near his cottage.

It is difficult for most people to realize that, as little as Jack was on the ranch, he was still responsible for all that was done. Jack and Eliza were an unbeatable combination. Loyal to the very heart of her being, Eliza faithfully carried out everything that Jack planned with amazing ability. Letters and coded telegrams told her exactly what he wanted done. Whenever he returned to the ranch, he found things exactly as he had instructed. She never failed in even the smallest details.

When Jack died in 1916, Charmian kept her on in the same job. When Eliza died in 1939, her son, Irving, took over; and when Charmian died in 1955, the ranch and the literary estate went into the hands of Irving Shepard. Upon the latter's death in 1975, it was left to his wife and children.

Today the ranch and the Jack London literary estate are in the capable administrative hands of Irving's son, Milo Shepard.