Spawning Periodicity and Reproductive Behavior of Fundulus heteroclitus in

The Mummichog, Fundulus heteroclitus, is a widely distributed fish that has been extensively researched in the southern portion of its range (south of Cape Cod, MA). During the summers of 2003 and 2004, we studied the reproductive ecology of F. heteroclitus in a northern population (Northeast Creek, Mount Desert Island, Maine). Our direct observations show that unlike more southern populations, northern F. heteroclitus spawns daily during its two-month spawning season, with no preference for spring tides over the entire season. However, within consecutive semidiurnal tides significantly more spawning was associated with the higher high tide. Spawning occurred on bare gravel and on mud associated with the grass Spartina patens. Spawning was highly promiscuous with males typically spawning in groups with females in very shallow water during receding tides. These temporal and spatial patterns of oviposition caused eggs to be deposited in a much broader range of habitats than in southern populations of this species. We present and evaluate critically several hypotheses that may explain the variation in spawning patterns observed in this species. spawning is a well-documented pattern of INTERTIDAL reproduction in marine and estuarine fishes, occurring in at least nine orders and 26 families of fishes (DeMartini, 1999). Many of these fishes appear to spawn on lunar or tidal cycles, including many temperate species that spawn in salt marshes such as the Atlantic Silverside, Menidia menidia (Middaugh, 1981; Conover and Kynard, 1984; Conover and Heins, 1987; Conover, 1992), and the Mummichog, Fundulus heteroclitus (reviewed in DeMartini, 1999; Taylor, 1999). These temporal patterns of lunar or tidal spawning will influence spatial patterns of egg deposition in intertidal spawners. Spawning in the intertidal