Striped Bass. The following account of the life history of striped bass was adopted from Flagg:53The striped bass, Moronesaxatilis, is known by a variety of local names such as striper, rock, rockfish, linesides, or roller. These names refer to the general description or habits of the striped bass. "Rock" or "rockfish" is a name commonly used in the Chesapeake Bay and south Atlantic states. The name "linesides" refers to the longitudinal black or dusky colored strips along the sides of the striper. This feature readily distinguishes the striper from the closely related white perch.
The sea bass family, or Percicthyidae, is an extremely numerous tribe of fishes but is represented by only four species in the Gulf of Maine. These are the striped bass, white perch, sea bass, and wreckfish. The striper is easily differentiated from the others by seven or eight longitudinal black or dusky colored stripes along the sides. There are two well-developed dorsal fins (each of about equal length with the first being spiny and the second soft-rayed), and a moderately stout forked tail. Three spines form the front part of the anal fin and the base of the tail fin (caudal peduncle) is moderately stout. The striper has a projecting lower jaw, a head almost as long as the fish is deep, and a mouth which gapes back to the eye. The separation of the two dorsal fins definitely distinguishes it from the white perch in which the two dorsal fins are attached. The color is dark olive green to bluish on the back, with pale sides and a silvery ventral surface. The general form is elongated with the body 3 1/3 to 4 times as long as it is deep. There are other finer characteristics which distinguish the striper, but the above description suffices to distinguish it from other Gulf of Maine fishes.
With respect to growth, striped bass are generally 4-6" long at the end of the first summer, 10-12" at age 2, 14-15" at 3, 18-20" at 4, 21-23" at 5, 24-27" at 6, and 43-47" at 14. Striped bass angled in Maine are comparable in size and weight for a given age to those of Chesapeake Bay.
The spawning habits of striped bass have been well documented and observed, both on the east and west coasts. Spawning seasons are generally governed by water temperatures with spawning known to occur at temperatures ranging from 50-75oF. Shannon and Smith54 have found that the optimum temperature for egg incubation and larval development is 65oF. Incubation time is dependent on water temperatures, with eggs hatching in 30 hours at 72oF and 74 hours at 58oF. Eggs subjected to temperatures exceeding 75oF result in such rapid development that a high proportion of malformed fry occurs.
The spawning areas range from head-of-tide in Chesapeake Bay to small tidal river systems 12 miles upstream to 80 miles above tidewater on the Roanoke River in North Carolina and 200 miles above tidewater on the St. John River in Canada. The location of spawning is probably an adaptation of certain stocks to the water temperatures at the time of spawning. Upriver spawners are probably early run fish while tidal river spawners would probably be late run spawners in order for egg incubation times to coincide with availability of freshwater flow. This would allow for adequate incubation time before the fry reach high salinity waters. Studies by Rathjen and Miller55 demonstrated that live striped bass eggs in the Hudson River were not found in areas of salinity in excess of 1:1,000. Therefore, upriver and near head-of-tide stocks of striped bass have to be very temperature sensitive in order to accommodate egg incubation time with extent of freshwater flow. The high egg production per female also compensates for the very restrictive requirements for egg incubation and fry development.
During the spawning act, single females are surrounded by several to many males. Spawning usually occurs in slow to moderate currents and near the mid-channel of the river. Miller and McKechnie56 provide an accurate observation of striped bass spawning in California's Sacramento River. Females roll on the surface and as eggs are extruded males fertilize them. The newly fertilized eggs expand to about 1/8" in diameter and become semi-buoyant, requiring a current or water turbulence to remain suspended in the water column. Because of these requirements of fresh flowing water and minimum incubation time of 24-30 hours, it would appear that the best spawning areas would be large coastal rivers of moderate gradient, slow to moderate current, and stable flow during the egg incubation and larval development period. The large expanse of low salinity water in Chesapeake Bay and Albemarle Sound of North Carolina lend themselves as ideal spawning habitats for striped bass. The low range in tidal fluctuations in the middle Atlantic states lessen the possibilities of high salinity intrusions which could cause high mortality of eggs and larvae. With respect to Maine, striped bass populations would appear to be more restricted in spawning habitat because of high salinity gradients in the tidal portions of most Maine rivers. The exception to this situation is Merrymeeting Bay, where the restricted access of tidal intrusion at "The Chops" (a constriction at the seaward end of Merrymeeting Bay) and large volumes of freshwater discharge from the Kennebec and Androscoggin Rivers creates an extensive freshwater estuary.