Exploitation-Related Changes in the Growth and Reproduction of Tilefish and the Implications for the Management of Deepwater Fisheries
Patrick J. Harris, Sandra M. Padgett, and Paulette T. Powers
Abstract.—Deepwater fisheries throughout the world appear to be particularly susceptible to extremely rapid overexploitation, with many species exhibiting signs of overfishing. The “boom and bust” nature of these fisheries, particularly as it applies to specific locations, often means a fishery may be overfished before management can react. The rapid removal of fish from a previously unexploited population could have significant effects on the life history of the species. Only 15,275 kg of tilefish Lopholatilus chamaeleonticeps were landed in the southeastern United States in 1980, but by 1983, landings peaked at 1,596 metric tons. Tilefish were collected for life history analysis from 1980 to 1986 and 1996 to 1998 from the southeastern coast of the United States. Samples were obtained from fishery-independent research cruises and from commercial catches. We documented the life history parameters between the two time periods to determine if the rapid increase in fishing mortality had any impact on the life history of tilefish. We found a significant decrease in the mean length at age for most age classes between the two time periods for males and females. The size at maturity decreased between 1980 and 1986 and 1996 and 1998, and the size and age of reproductively active tilefish decreased between the two periods. We suggest “satellite” females may occur in the tilefish population where females smaller than a limiting size are unable to maintain a reproductive territory and do not reproduce, even though they are mature. This reduction in length at age and mean size of fish may reduce the potential reproductive output of the population, thereby limiting the recovery potential. The reduced fecundity of the population, combined with continued fishing mortality, slow growth, and limited habitat presents a unique and difficult conundrum for fishery managers to solve, which may apply to many deepwater fisheries.