Latitudinal variability in lunar spawning rhythms: absence of a lunar pattern in the northern mummichog Fundulus heteroclitus macrolepidotus

In this study, the natural spawning season of the northern mummichog Fundulus heteroclitus macrolepidotus was examined from May to July in the lower St John River, New Brunswick, Canada (45 degrees N), through measurements of gonado-somatic index (I(G)), liver-somatic index (I(L)) and condition factor (K). I(G) increased during the prespawning phase (mean +/-s.e. 5.49 +/- 0.20%), peaked during the spawning phase (14.68 +/- 0.51%) and dropped …