So How Do Female Grouper Get Mates?

To find out how grouper get mates for five years researchers attempted to launch a submarine in 300 feet of water on the Oculina coral reef northeast of Fort Pierce to watch female grouper search for big male grouper mates. They were trying to safely launch and recover so they could maybe spend a few hours observing groupers mating on a newly discovered coral reef mating site. As life would have it, heavy seas prevented safe operations most of the time. They some how managed 75 dives totaling over 200 bottom hours watching grouper interact socially.

They observed aggregations of hundreds of groupers, the most prominent species was scamp, gag, speckled hind as well as snowy and Warsaw grouper in the mix. There were no Nassau, red or black grouper in this depth of water. But the grouper that did show up to mate did put on a great show.


Scamp grouper had definite territories on the reef, each territory was patrolled by an aggressive male swimming just above the reef and at will diving on a female, which caused his head to turn gray, his body black with white belly blotches and his tail white. See, Scamps are usually covered with small brown spots.

The females were definitely in a pecking order with the alpha female displaying a pattern like a cat's paw, just as if a cat had walked across the fish with paint on it's paws. All the other females appeared to be a combination of light or dark brown, with the light phase more prominent than the dark brown. It looked as if they could turn these dark and light brown colors off at will in seconds. The odds were ten to fifteen females to each male in his harem and all of this happens when grouper get mates!

The male Scamp grouper are caught more often than the female because of their aggressive nature. Here lies the problem. If there are no big males the females have no one to spawn with. It's been proven that Scamp grouper change sex from female to male. So how long does take for a female Scamp grouper to change into a male? The next question is does it ruin or deplete the male spawning numbers for the females in the harem?

We now know that scamp grouper meet in late summer and fall to determine if there is a shortage of male grouper so all grouper get mates.

When the expected large male grouper doesn't show up, one of the female grouper in the harem must change her sex.

She has to change into a male in order to protect the female harem before the next spring spawning season so grouper get mates.

The grouper social hierarchy is complicated, they show mental capabilities that's rarely seen in the fish world.

However, most grouper spearfishing on Florida's east coast takes grouper in shallow aggregations when and where they often meet to determine which female is going to be the one to change sexes. This messes up the social order and probably the spawning the next spring spawning season.

Not many fishermen understand that groupers are very sophisticated and they have a social order with each "pecking order" and that the sex reversal, when the female turns into the dominating male, happens just before the spawning season typically by social selection.

Sadly, the scamp, gag, Warsaw, snowy and speckled hind groupers are largely missing from these spawns these days. One solution could be to map all sites where select grouper get mates gather to determine the sex reversal, or to spawn. We need to limit spearfishing of grouper at these gathering sites during these sex reversal periods and when the spawning is actually happening. If we don't, more grouper will be missing for the mating season.



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