Reproduction of Black Drum, Pogonias cromis, from the Chesapeake Bay Region

Abstract

Ovaries of black drum, Pogonias cromis, collected fromthe Chesapeake Bay region in 1992, were used to describe reproductive strategy and fecundity. Histological examination showed that black drum spawn in the Chesapeake Bay region from April through early June. Distributions of oocyte diameter showed distinct oocyte-developmental groups indicating that Chesapeake Bay black drum are group-synchronous batch spawners. Female black drum are extremely fecund ranging from 414,000 to 3,736,000 hydrated oocytes (mean = 1,389,000) per batch with a spawning periodicity of 3.8 days. Estimates of spawning strategy, spawning periodicity, and batch fecundity for black drum from the Chesapeake Bay region were similar to reported estimates from the Gulf of Mexico. INTRODUCTION In U.S. waters, where the primary range for black drum, Pogonias cromis, in the Northwest Atlantic is from the Delaware .Bay south to Florida and through the Gulf of Mexico (Welsh and Breder, 1923; Hildebrand and Schroeder, 1928; Silverman, 1979), there are at least two known populations: one along the U.S. East Coast and one or more in the Gulf of Mexico (Gold et al. 1995; Jones and Wells 1998). Many essential elements of the reproductive life history are well understood for stocks in the Gulf of Mexico (Fitzhugh et al. , 1993; Nieland and Wilson, 1993; Saucier and Baltz, 1993; Fitzhugh and Beckman, 1987). Specifically, black drum fromthe Gulf of Mexico mature at five years, are group-synchronous spawners, with a batch fecundity of 1.4 to 1.6 million hydrated oocytes, and have a spawning periodicity of 3 4 days (Fitzhugh et al. , 1993; Nieland and Wilson, 1993). In contrast to the Gulf of Mexico black drum, littl~ is known about the reproductive biology of black drum along the U.S. East Coast. Studies of adult black drum in Eastern Florida and in the Chesapeake Bay have been limited to estimating the age at maturity and spawning season. Murphy and Taylor (1989) showed that the age at first maturity is five to six years and the spawning season along Northeast Florida is from January to May with peak spawning in March and April, while Alshuth and Gilmore ( 1995) found a more protracted spawning season from October to late March. In Virginia waters Bobko (1991) observed a spawning season of April through May, and noted that all fish were mature by age six. Although the length of the spawning season and age of maturity have been documented, spawning strategy has not been described nor batch fecundity estimated for black drum from along the U.S. East Coast. Estimates of batch fecundity are essential to understanding life-time reproductive output. However, this information is difficult to obtain because an age-specific migration pattern exists for this population. Although black drum of all ages are present E-mail : bkwellswork@cs.com