Scientist at Work Blog: For the Social Wrasse, News, Good and Bad

Luiz Rocha, the curator of ichthyology at the California Academy of Sciences, writes from Belize, where he conducts research on one of the world?s most endangered fish, social wrasse.

Saturday, Dec. 15

After hours on airplanes and in airports ? with a last leg by boat ? I finally arrived at Carrie Bow Key. It was late afternoon and there was no time to dive. But what I found on the Pelican Keys early the next morning was not encouraging. Invasive lionfish lurked around the islands. And after catching a few of them, I went for a walk in the mangroves and found trash strewn along the shore.

I had come to Belize to assess the potential threats to a small, but important, member of the reef ecosystem. And by Day 2, I had found two major threats to the social wrasse.

Now for the good news: The lionfish population is not large. And I saw many social wrasses, although they were only juveniles and females. Their schools were, as expected, high in the water column feeding on plankton, dutifully capturing nutrients from the water and transferring them to the reef.

The few lionfish that our team observed seemed to prefer a high-relief habitat with big rocks and overhangs. Those types of habitats are hard to find here.

We captured two lionfish and both of their stomachs were empty, but they were well-nourished. We may have just been unlucky, catching them between meals. Of course, we will keep capturing more lionfish during the next few days.

Many islands in the Caribbean are doing a good job in keeping the lionfish population in check. They are quite tasty once you get past the poisonous spines and good marketing has made them popular in restaurants. There are now lionfish tournaments and in some places even tourists are encouraged to spear them. But none of this will be enough to eradicate the species. Lionfish have very broad habitat requirements and some have been spotted from submersibles as deep as 1,000 feet. Even if divers control them at shallow depths there will always be more deeper down.

Recognizing that humans can?t possibly catch all of these new invaders, some dive shops are resorting to a slightly more controversial tact. In Mexico, Barbados and a few other places in the Caribbean, people are ?training? groupers, sharks, morays and other large reef fish to eat lionfish.

While at first this practice seems to be the logical thing to do, there is no evidence that these larger fish are actively trying to catch live lionfish. Rather, they are learning that divers in the water mean ?free handouts,? and becoming very aggressive when divers don?t give them their lionfish snack.

Whether it?s effective to try to sic fish on fish is unclear, but the strategy remains a heavily debated topic in the scientific literature. And regardless of our efforts to control this spiny exotic, it?s clear that the lionfish is here to stay. And it?s up to us to figure out what they are doing to their new home because maybe then we can devise better ways to mitigate their impact on the reef and the social wrasse.

Source: http://scientistatwork.blogs.nytimes.com/2012/12/17/for-the-social-wrasse-news-good-and-bad/?partner=rss&emc=rss

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