Shad Restoration

Since the 1970s, American shad and hickory shad populations have declined drastically in the Chesapeake Bay due to over-fishing, poor water quality and stream blockages. A 1980 fishing moratorium, habitat improvements, pollution mitigation and fish passage construction has not resulted in recovery, primarily due to lack of adult spawners. In 1994, Maryland DNR Fisheries Service and several partners began a program to reintroduce shad spawning runs to selected tributaries through restorative hatchery stocking. Traditional strip spawn culture methods require access to large numbers of ripe adults. We developed a new technique to induce spawning in broodfish collected from the Susquehanna River using synthetic reproductive hormone implants and tank spawning systems (Mylonas et al. 1995). Fertilized eggs can be produced from any migratory pre-spawned female. Larvae and juveniles are marked and stocked in target tributaries. Surveys are conducted to sample larval, juvenile and adult shad. From 1994 to 2008 the program has stocked 25.9 million american shad and 95.1 million hickory shad in the Choptank River, Patuxent River, Patapsco River and Nanticoke River.

In 1999 we documented the first appearance of hatchery-produced adult American shad in the Patuxent River. The proportion of hatchery fish caught in adult surveys increased in 2000 and 2001 as fish from the 1994 and 1995 stocking events reached full recruitment to the migrating spawning stock.

No juvenile American shad were collected in the Patuxent River from 1960 to 1993. From 1994 to 1997 we captured hundreds of hatchery juveniles. The first wild juveniles were captured in 1998 and the wild component of the juvenile population increased from 1% in 1999 to 8% in 2000. Wild fish represented 11% of the juvenile population in 2001.

As hatchery-produced adult spawning stocks increase, the wild component of the juvenile population should exhibit corresponding growth. Restoration goals will be realized when natural reproduction overwhelms the contribution of hatchery-produced fish in the juvenile population.