Luiz Rocha, the curator of ichthyology at the California Academy of Sciences, writes from Belize, where he conducts research on the social wrasse, one of the world’s most endangered fish.
Tuesday, Dec. 17
Four lionfish found inside Belize’s barrier reef. This invasive species is predating the social wrasse, a native to the area that helps maintain the health of the reef ecosystem.
The weather is much better, and we were able to do several dives and get a good grasp on just how bad the lionfish invasion in Belize really is. They are everywhere. We saw and collected them in all habitats we visited, including coral reef, sea grass and mangrove. Finding them in the last two is especially disheartening, as they are nursery habitats for many coral reef species. Lionfish are eating young reef fish before they can even get there.
In the morning we dove along the barrier reef to estimate lionfish abundance there. During a 45-minute dive, we counted more than 20 of them. For perspective, we were a group of five divers, swimming slowly over the edge of the barrier reef. Collectively we would see a lionfish on average every two minutes.
Even though this area of Belize has some spectacular diving, it is relatively far from the main airport, and there are no major scuba dive centers. In addition, the main fisheries here are for queen conch and lobster, so nobody is actively fishing the lionfish. Without any control from divers or fishermen, the lionfish population has been allowed to grow unchecked.
Carole’s hand was still swollen from the lionfish sting the previous day and she could not use a spear, so Diane Pitassy from the Smithsonian was my dive buddy and helped handling the lionfish. This time we used a wire that went through the gill and out the mouth of the lionfish to carry them instead of the catch bag. The change in strategy worked — no accidental jabs and searing pain this time around.
The writer held a wire with about 10 lionfish captured during one afternoon dive.
We collected 18 more lionfish in social wrasse habitat, and most of them had social wrasses in their stomachs. We cannot make a precise estimate of how much this is influencing the social wrasse yet. This is mostly because many of the unidentifiable fish remains that we are getting from some lionfish may also be social wrasses. But we do know the number is high.
We also found more signs of social wrasse habitat degradation and destruction. Most dive sites in the inner barrier reef — closer to coastal development — had very poor underwater visibility and a lot of silt in the water. This is probably a result of sand and mud runoff from the islands after the mangrove is cut down. The complex network of mangrove roots serves as a trap for sediments that run off from both the coast and the island, and as the roots are taken out and replaced by artificial beaches, the water quality deteriorates. Large expanses of mangroves were and continue to be cut down to give room to exclusive resorts or large houses. Boat traffic is intense.
An island inside the social wrasse habitat where mangrove was destroyed to make way for a hotel.
The social wrasse is being hit from all directions. From the top, humans are destroying mangroves and contributing to habitat degradation; from the bottom, the social wrasse seems to be one of the main components of the diet of the invasive lionfish. We really hope that with this blog and more research papers planned for the near future we can influence decision making in Belize and help protect this, and other, Belizean reef fishes.