Lunar Synchronization of Fish Reproduction

Abstract

Lunar‐synchronized spawning has been reported in four orders of fish. Salmoniform, atheriniform, and tetraodontiform species spawn intertidally on spring tides, leaving their eggs exposed to air between tidal inundations. This spawning mechanism may be essential to survival of species that are residents of areas such as tide marshes where dissolved‐oxygen concentrations in the water column can be near zero. Spawning cycles of both lunar and semilunar periods have been reported in coral‐reef fishes of the Perciformes. Reproduction by these fishes does not include aerial incubation of eggs. It has been hypothesized that the spawning cyclicity in these fishes synchronizes reproduction with moonlight or current conditions that enhance parental care or predator avoidance. The intertidal spawners that have been studied display cyclic changes in gonad maturity consistent with a semilunar periodicity in recruitment of oocytes into final maturation. Oocytes in the early stages of vitellogenesis are present throughout the spawning season. In the mummichog Fundulus heteroclitus, this periodicity is generated by an endogenous mechanism that operates in the absence of diurnal, lunar, or tidal periodicities in light or water movement. Indirect evidence exists for the involvement of both light‐and tide‐related phenomena in synchronization of semilunar reproductive rhythms in fishes.

Detecting lunar cycles in marine ecology: periodic regression versus categorical ANOVA

“…Environmental cycles (e.g., tidal water movement, moonlight) entrain endogenous reproductive cycles, synchronizing gamete release within a population and ensuring that movement, feeding and reproduction occur under favourable conditions (Taylor 1984, Omori 1995. Lunarsynchronized spawning, for example, is commonly documented for species of shallow waters with large tidal fluctuations (Korringa 1947, Taylor 1984.…”

“…Reef fishes often mass in spawning aggregations on a specific lunar and seasonal cycle (Johannes 1981, Robertson et al 1990). In addition, lunar cycles have been detected in spawning and settlement of intertidal (Taylor 1984) and pelagic-spawning fish and invertebrates (Crabtree 1995, Robertson et al 1999. Lunar cycles in fish behaviour have long been recognized and exploited by artisinal and commercial fisheries (Johannes 1981, Parrish 1999.…”

Hatching Dates of the Japanese Flounder Settling at Yanagihama Beach in Nagasaki Prefecture, Japan

“…23,24) Presently, it is difficult to judge which interpretation is correct. Otolith studies of the pelagic larvae collected widely from Nagasaki waters and of the larvae settling at several other beaches facing Goto Nada should provide an answer.…”

Waiting for a sign: extended incubation postpones larval stage in the beach spawning California Grunion Leuresthes tenuis (Ayres)

“…Like many fish (Taylor 1984), L. tenuis spawn and hatch only during the highest semilunar tides associated with the new and full moons. Eggs spawned at the falling tide of one full or new moon typically hatch during the next rising spring tides, within two weeks, considered the primary hatching time (Walker 1952).…”