Nassau groupers aggregate to specific spawning sites on the full moon during December and January. This peculiar timing is of particular interest to scientists, who have suggested that, like other marine mammals, the gravitational pull of the moon at this specific time of year inspires migration to breeding grounds. Spawning aggregates can be as large as 100,000 individuals. Like other groupers, Nassau groupers are considered monandric protogynous hermaphrodites, meaning juveniles contain immature gonads for both genders and then directly mature as either male or female.
Mating System: polygynandrous (promiscuous)
Nassau groupers congregate once a year at the edge of reef shelves in shallow water to spawn. They are strictly loyal to their spawning sites. This species changes its coloration when receptive to mating, usually becoming bicolor, darker, or incorporating a white belly. Dark coloration is though to be characteristic of males, while bicoloring and dark coloring typically correspond to submissive behaviors. Spawning peaks 3 to 5 days after the full moon, but can continue up to 8 days after. Eggs hatch 23 to 48 hours after fertilization and mature slowly, reaching reproductive maturity between 4 and 8 years of age (average 5 years of age). In captive populations, maturity occurs much sooner, which has been attributed to more abundant food sources and less environmental stress. In captivity, the average hatchling length of the notochord is 1.8 mm.
Breeding interval: Nassau groupers breed annually.
Breeding season: Spawning of Nassau groupers lasts 8 days and begins on the full moon of December or January.
Range time to hatching: 23 to 48 hours.
Range age at sexual or reproductive maturity (female): 2 to 7 years.
Average age at sexual or reproductive maturity (female): 5 years.
Range age at sexual or reproductive maturity (male): 2 to 7 years.
Average age at sexual or reproductive maturity (male): 5 years.
Key Reproductive Features: seasonal breeding ; sequential hermaphrodite (Protogynous ); fertilization (Internal ); oviparous
Nassau groupers do not invest energy in their offspring post-fertilization.
Parental Investment: no parental involvement
- NOAA. Synopsis of biological data on the Nassau grouper, Epinephelus striatus (Bloch, 1792), and the Jewfish, E. itajara (Lichtenstein, 1822). NMFS 146. July 1999: U.S. Department of Commerce. 1999.
- Dineen, J. 2004. "Epinephelus striatus" (On-line). Smithsonian Marine Station at Fort Pierce. Accessed February 03, 2011 at http://www.sms.si.edu/irlspec/epinep_striat.htm.
- Kobara, S., W. Heyman. 2008. Geomorphometric patterns of Nassau Grouper (Epinephelus striatus) spawning aggregation sites in the Cayman Islands. Marine Geodesy, 31: 231-245.
- Semmens, B., M. Boardman. 2004. Observations of a Nassau grouper, Epinephelus striatus, spawning aggregation site in Little Cayman, Cayman Islands, including multi-species spawning information. Environmental Biology of Fishes, 70: 305-313.