Nassau Grouper: A Beautiful Fish at Risk
The Nassau Grouper, a strikingly colored, large iconic Caribbean reef fish, was once one of the mostly heavily fished species in the region. Due to unsustainable exploitation practices, however, it is now scarce in many coral reef ecosystems throughout its native range. In 1996, after an estimated 60% population decline in just thirty years, the
Photo Credit: http://appliedecology.cals.ncsu.edu/
Unfortunately for the Nassau Grouper, its reproductive strategy contributes to its downfall. During most of the year, the grouper are homebodies living under coral ledges and reef structure, barely moving more than a few hundred meters from their home in a day. Over winter full moons, however, when it is time to reproduce, they migrate great distances – often over 100 miles – to specific locations where they meet up with thousands of other Nassau Grouper who have also travelled great distances to reproduce. These meeting areas are known as spawning aggregations. At these spawning aggregations, the grouper change color and engage in beautiful, complex courtship rituals timed to occur within minutes of the sunset. Their eggs, fertilized in the water, float to the surface and drift with the currents for up to 40 days, when the next generation of Nassau Grouper, as tiny larval fish, swim down and settle in the safety of shallow coastal habitats such as seagrass beds and mangrove forests.
Photo Credit: Shedd Aquarium/Chuck Knapp
Annual grouper spawning aggregations are so precisely located and timed that they are quite predictable. This is a good reproduction strategy when a species is distributed over hundreds of miles of coral reefs. It’s a bad strategy when fishermen know where and when it happens. And they do. Historically, at spawning aggregations throughout the Caribbean, fishermen have caught thousands and thousands of grouper in just a few days, each year, with very —> Read More