As the full moon of the year’s shines down on a Caribbean coral reef of the Belize, 10,000 brown and white fish congregate 100 ft (30 m) beneath the water surface, where the reef drops down into the sea depths. They are Nassau groupers that have come to the spawn. On arrival, the 5-20 lb (2.3-9 kg) groupers form themselves into a small group and flash their colored pattern body at each other. This it is though is probably the way males impress the females and see off rivals and could also be a way of determining the balance of the males and the females in the group. Nassau groupers can changes sex from female to male, so if during one spawning season there are too many females, some older females can change sex for the next.
The eggs carried by the females begin to ripen before the matting season starts, and are usually ready to be released on the third night after the full moon. Just before the spawning, the shoal of the courting fish descends to 120 ft (37 m). Then, at the sunset exactly, they rush to the surface in a groups of 30-40, the females releasing their eggs at a depth of 80 ft (24 m) and the males shedding their milt (sperm). For the next few night other group follows the same ritual. By the time of the new moon, all the fish have returned to their respective territories around the West Indian reefs and resumed their solitary way of life. Groupers spawn in these particular spots because the reef itself is a dangerous place to deposit eggs. Seldom is anything particularly nutritious eggs left uneaten for long, for the waters of the tropical coral reefs, unlike the nutrient rich water of temperate seas, are eggs. Damselfish guard them until they hatch. Jaw fish incubate their eggs in their mouths.
The strategy of the Nassau groupers is to spawn on the edge of the reef so that the tide will carry the eggs well away from the reef to develop where there has a better change of the survival. The groupers all time their spawning by the full moon, as the chances of a some eggs surviving is better where there is a large number. The fish also favor sites around underwater projections, where the water turbulence creates movement that will help to carry away the eggs and the larvae. As the full moon of the year’s shines down on a Caribbean coral reef of the Belize, 10,000 brown and white fish congregate 100 ft (30 m) beneath the water surface, where the reef drops down into the sea depths. They are Nassau groupers that have come to the spawn. On arrival, the 5-20 lb (2.3-9 kg) groupers form themselves into a small group and flash their colored pattern body at each other. This it is though is probably the way males impress the females and see off rivals and could also be a way of determining the balance of the males and the females in the group. Nassau groupers can changes sex from female to male, so if during one spawning season there are too many females, some older females can change sex for the next.
