Heavy fishing removes the larger animals and does not give young lobsters a chance to grow to their potential size. Most of the large lobsters in the inshore fishery were caught during the 1800s and early 1900s. Lower fishing pressure on the offshore lobster stocks allows more lobsters to grow to a larger size, but even there the size range is much reduced from the early days of the fishery. The largest lobster ever recorded was a 51 1/2 pound lobster caught in Maine in 1926.
Growth overfishing is much more common than recruitment overfishing, but it does not receive the attention given to recruitment overfishing because it does not pose such a serious threat to the continued existence of the resource. But growth overfishing still reduces the potential yield from a fishery, and thus the economic and other benefits that could be obtained from the stock.
Growth overfishing occurs when animals are harvested at an average size that is smaller than the size that would produce the maximum yield per recruit. The total yield from the fishery is therefore less than it would be if the fishing mortality rate, or percent of the stock removed each year, were lower. In such a case, less fishing would produce higher landings. This is the essence of fishery conservation, and holds true even when the resource is abundant.