Reproductive Biology of the Bay Anchovy in Chesapeake Bay

Abstract

Eggs in plankton samples from lower Chesapeake Bay indicated that the spawning season of the bay anchovy Anchoa mitchilli in 1988 extended from early May to mid-September. Oocyte stages in adults were used to determine daily spawning time and frequency as well as batch fecundity. Spawning was temporally synchronized and lasted for about 1.5 h each night. Spawning time became later each month (2000 hours on 6 June to 2330 hours on 31 August). Spawning frequency per individual was every 4 d in early June and every 1.3–1.9 d in other months. Batch fecundity was a linear function of fork length and of body weight; regression slopes on 6 July and 4 August were significantly higher than those on 6 June and 31 August. Estimated mean total spawnings per female in 1988 was 54. Total egg production for a fish of average size was 45,110, which is equivalent to 346% of body biomass energy. Age determinations based on lagenar otoliths showed that some fish spawned when as young as 2.5–3 months. The bay anchovy has a greater reproductive potential than is known for other anchovy species.