Spawning Of American Shad (Alosa Sapidissima) And Striped Bass (Morone Saxatilis) In The Mattaponi And Pamunkey Rivers, Virginia

In the Atlantic coastal region, AmeriAmerican shad deposit semidemersal can shad (Alosa sapidissima) is highly eggs in the freshwater portions of the prized for its flesh and roe. Spawning estuaries in the spring, usually begin­ runs have been heavily fished and ning in March and ending by early since the late 1800s, landings have June with peaks in April (Klauda et shown steady declines to the extent al., 1991). American shad have histori­ that Maryland declared a fishing cally ascended farther upriver than moratorium in 1980, and Virginia folat present, within tributaries where lowed in 1994 for Chesapeake Bay and obstructions to movements upstream its tributaries (ASMFC, 1999). Shad now exist. Prior to dam building in the restoration projects are underway to 1800s on the James River, large num­ restock depleted spawning runs, espebers of American shad traveled over cially in regions where stream impedi335 miles from Chesapeake Bay into ments have been or are being removed. the Jackson and Cowpasture rivers Coastal ocean intercept gill-net fisher(Mansueti and Kolb, 1953). ies have remained in place despite The York River, a coastal plain trib­ criticism and speculation about their utary located in the Chesapeake Bay impact on populations, particularly watershed, is formed by the conflu­ those river systems stocks that are ence of the Pamunkey and Mattaponi depleted. The Atlantic States Marine Rivers at West Point (Fig. 1). The Fisheries Commission Shad Board Pamunkey River has a larger water­ (ASMFC, 1999) adopted a fishery manshed (3768 km2) and average spring agement plan for American shad and discharge rate (47.5 m3/s) than the river herring that included a five-year Mattaponi River (2274 km2; 27.2 m3/s, phase-out of the ocean fishery and that respectively). Watershed sizes are required states to develop an approved based on U.S, Geological Survey digital fishing or recovery plan for each stock line graph data (DLG) at 1:100,000. under restoration. In Virginia, this On these unobstructed rivers, annual requirement applies to the James and releases of hatchery-reared American York rivers. shad approximate two to four million Although the roe fishery for Amerifry through efforts of the Virginia Game can shad has historically been imporand Inland Fisheries (VGIF) and an es­ tant, there is little information about timated 2.5 to 3 million fry are released the specific spawning locations of by the Pamunkey tribal government. In these broadcast spawners. American addition there are unknown contribu­ shad are anadromous fish native to the tions from the Mattaponi tribal governAtlantic coast of North America, with ment (Gunther1). Current monitoring a range extending from southeastern of adult catches indicates that the York Labrador to the St. Johns River, FlorRiver supports the strongest runs of ida. In Chesapeake Bay tributaries, shad in Virginia (Olney and Hoenig2). American shad in the York River are used as the source stock for hatchery ef­ forts in the James and Potomac rivers. Thus, the restoration efforts in Virginia are dependent on the productivity of the York River. Within the freshwater tidal portions of the Mattaponi and Pamunkey riv­ ers, numerous other species spawn, including striped bass (Morone saxati­ lis) (McGovern and Olney, 1988; Grant and Olney, 1991). The Chesapeake Bay stock has rebounded after severe declines in the 1970s and early 1980s as a result of successful management and several years of successful re­ production (Olney et al., 1991; Field, 1997). The extent of the spawning area for both American shad and striped bass is in part a function of salinity and temperature. Striped bass spawn from the limit of brackish water to freshwater in the rivers of Chesa­ peake Bay from early April through the end of May (Setzler-Hamilton et al., 1981), and American shad spawn in freshwater (Leim, 1924). McGov­ ern and Olney (1996) noted that the lower limit of striped bass spawning followed the 1 ppt salinity contour, and Secor and Houde (1995) postulated that the freshwater-saltwater inter­ face may act as a down-river barrier to striped bass egg and larval advection. Based on suitable temperature ranges (12–24°C for striped bass [SetzlerHamilton et al., 1980; Rutherford and Houde, 1995] and 12–25°C for Ameri­