Managing a fishery under moratorium: Assessment opportunities for Virginia's stocks of American shad

Virginia's river fisheries for American shad have been under moratorium sin ce 1994. The moratorium is partial since the three stocks (in the James, Yo rk, and Rappahannock rivers) are harvested to an unknown degree in an offsh ore mixed-stock fishery. Current research efforts have three objectives: (1 ) to determine current status of the stocks relative to historical levels, (2) to determine appropriate target catch-rate levels for restoration, and (3) to develop new assessment tools so that a future moratorium can be avoi ded. Current status is being evaluated by monitoring catch rate of commerci al fishers who are paid to fish with historical methods in historical locat ions; the contemporary catch rates are compared to those recorded in logboo ks completed voluntarily by fishers prior to the closure. We propose to def ine restoration targets in terms of historic catch rates recorded in logboo ks. This requires determination of relative catching power of historic (mul tifilament) and modern (monofilament) nets. Two novel assessment methods ar e being evaluated: index-removal and change-in-ratio methods. These are bas ed on comparing the catch rate and catch composition, respectively, of ripe ning fish and spent fish near the mouth of the river. During a moratorium, the parameters should be the same for ripening and spent fish, thus providi ng a critical check on the model assumptions. Maturity information is neede d to forecast recruitment but previous estimates of maturity-at-age schedul es are biased. Improved estimates can be obtained using anew statistical me thod which requires that there be a moratorium. It is unfortunate for socie ty when a fish population declines to the point where a moratorium must be declared but a moratorium can provide important opportunities for testing m ethods and estimating parameters.