Transactions of the American Fisheries Society 121:524-537. 1992 © Copyright by the American Fisheries Society 1992 Maturation and Fecundity of Roanoke River-Albemarle Sound Striped Bass ERIK J. OtSEN 1 AND ROGER A. RUUFSON Institute for Coastal and Marine Resources, and Department of Biology East Carolina University, Greenville, North Carolina 27858-4353, USA Abstract.—Since the early 1940s, several investigators have determined age-at-maturity sched- ules for female striped bass Mor one saxatilis at various locations along the Atlantic coast of the USA. These researchers have used one of two sets of criteria to determine whether a female is sexually mature; however, recent work suggests that these methods may underestimate the number of females entering the spawning population at an early age (e.g., ages 3 and 4). The objectives of our study were (1) to compare three methods and criteria for establishing sexual maturity and (2) to use all three methods in establishing a maturity schedule for female striped bass. Also, we estimated potential fecundity of the fish as a function of size, weight, and age. Two hundred sixty- five female striped bass were collected from the Roanoke River-Albemarle Sound system of North Carolina during the prespawning and spawning seasons (March-May) of 1989 and 1990. Females ranged in size from 344 to 1,172 mm fork length and in age from 2 to 16 years. Age-3 females produced approximately 200,000 eggs. The relationship between fish age and the number of eggs produced was statistically linear; one age-16 female produced approximately 5,000,000 eggs. Ma- turity estimates based on three methods were not significantly different; they indicated that about 44% of age-3 females were sexually mature and that all females examined were mature by age 6. These data suggest that female Roanoke striped bass may mature at an earlier age than striped bass in other systems. The proportion of females reaching sexual maturity by age 3 appears to be increasing in the Roanoke-Albemarle system; however, viability and year-class contribution of eggs spawned by age-3 females are unknown. The cause of the apparent downward shift in the maturation schedule is undetermined; environmental stress, fishing pressure, and genetic changes are possible factors. Until the viability and recruitment potential of eggs spawned by age-3 females can be ascertained, we recommend that management agencies consider age-4 females to be the first age-class that contributes to formation of Roanoke-Albemarle year-classes. During the 1970s, there was a drastic reduction Carolina and its economic importance, congres- in numbers of striped bass Morone saxatilis bar- sional monies were designated in 1988 for study vested along the Atlantic coast of the USA. In of this system to be administered by a North Car- 1979, the U.S. Congress passed an amendment to olina Striped Bass Study Management Board. Our the Anadromous Fish Conservation Act (Public maturation and fecundity study is one of several Law 96-118, 16 U.S.C. 757g) establishing the studies funded by the Board to assess status of the Emergency Striped Bass Study (ESBS) to examine stock and develop a strategy for stock restoration, stock status, identify causes for decline in pro- The age at which striped bass females mature duction, and determine the economic impacts is an important consideration for developing bar- caused by the decline in harvest (Chafee 1980). vest quotas and size limits for a fishery. If a pop- Legislative action in 1984 created The Atlantic ulation is depressed, a slot limit (under which fish Striped Bass Conservation Act (Public Law 98- of intermediate size may be harvested but not 613); an amendment to the Act in 1986 (Public larger or smaller fish) may allow more females to Law 99-432) authorized implementation of a fed- survive to first spawning, thereby increasing the eral moratorium on striped bass fishing for those number of eggs spawned each year. Results of pre- states failing to comply with a coastwide manage- vious investigations to determine maturation rates ment plan (USDOI and USDOC 1987). Because of female striped bass have been quite variable of the large population of striped bass within the and wide ranging: 0-18% at age 3, 0-97% at age Roanoke River-Albemarle Sound system of North 4, and 17-100% at age 5 (Specker et al. 1987). The ____ wide range of maturation rates may be manifes- i r»- jj ^JT- « j r ^ tations of different genotypes present within the • Presen t address: Grand Traverse Band of Ottawa _. ,. ., , ,, v, ,._ and Chippewa Indians, Biological Services, Fishery group of individuals sampled, of different cntena Management Building, Route 1, Box 135, Suttons Bay, used * n maturation studies, or of a combination Michigan 49682, USA. of these aspects (Specker et al. 1987). Merriman 524