Camouflage Grouper Spawning – Late Night Mating Madness
Like many grouper species, camouflage groupers (Epinephelus polyphekadion) aggregate to spawn. Camouflage grouper spawning aggregations have been reported from Fiji, Indonesia, Malaysia, Solomon Islands, Tahiti, the Seychelles and Palau.
In Palau, camouflage groupers aggregate in select reef passages for several days during the new moon period in the summer months. Males compete for and pair with females during the daylight hours.
Spawning begins after dark. The first pair races several meters up into the water column, releasing milt and eggs, then bolts back down to the safety of the reef. This event lasts little more than a few seconds. Less than a minute later the second pair races up in unison. Then the third and the forth. Within minutes the reef erupts into a firework display of sperm and eggs.
Females can easily be distinguished from males (before they spawn) by their massively swollen belly filled with eggs.
Sharks hunt the groupers as they rise from the reef.
The mayhem is over in less than 30 minutes.
Although the camouflage grouper is widely distributed, it’s populations are easily exploited. At least five camouflage grouper spawning aggregations have disappeared in Palau since the 1970s – due to overfishing. Consequently, it is now illegal to fish camouflage grouper spawning aggregations in Micronesia as well as New Caledonia and the Solomon Islands.
Worldwide threats facing this species include commercial and recreational fishing and habitat degradation of coral reefs. The IUCN lists worldwide camouflage grouper populations as near threatened.
Unique Dive Expeditions in Palau recently worked out the camouflage grouper’s spawning pattern. Check out the Science and Conservation of Fish Aggregations (SCRFA) to learn more about spawning aggregations and how to protect them.