Thursday, December 10, 2009

Lionfish. They're Here.


Making casual conversation in a dive shop at West End, Roatan, I commented on a poster requesting info on lionfish Pterois volitans/miles sightings, and was astonished by the response.

Oh yes, the store personnel said, that newsletter is from October, when we had about fifty, but we had a lot more last month. In the last couple months it's suddenly gotten much worse. We've seen them while snorkeling in 4 feet of water, and way down deep, and everywhere in between. They went on to theorize that a large number of fertilized eggs, or juvenile fish, had drifted from sites further east in the Caribbean.

In case this issue has flown beneath your radar, the story is that lionfish, natives to the Pacific, probably escaped from a Florida aquarium during Hurricane Andrew. They've been coming for some time, and now, according to this map, they're everywhere.

These fish might have trouble overwintering in colder areas, but the guys in the dive shop told me in Roatan's waters, they spawn 30,000 eggs at a time and can breed monthly. They eat the juveniles of numerous reef species, including the ones who keep the reef clean, compete for resources, and have a nasty venomous spine which makes them unattractive to the human fishers. In fact, if you do get stung, you probably won't die, but you will be in pain for a month, and the best remedy is to pour hot water on the site. Lionfish are said to be tasty, if you cut out the poison sac under the spine. They apparently just sit still and look at you, so aren't particularly hard to get.

I'm certain it's a terrible thing, but there are so many terrible things of the same nature. The Burmese python in Florida, the giant carp approaching the Great Lakes, just for starters. A person could begin to suffer from Terrible Thing Overload Syndrome.

What particularly interested me was the response. "Does everyone carry spear guns to shoot them with on sight?" I asked. No, ma'am, they do not. There seem to be three reasons why not. One, they don't want spear guns in the marine park, although presently the divemaster is allowed to have one on the boat. Two, they are there to conserve and preserve, and blasting fish in front of paying scuba divers is not the ideal image. Three, they, or someone in the larger reef management world, are concerned about humane treatment of the fish. The recommended method is to catch the fish - this involves a plastic bag behind the fish, and a stick in front of the fish - and put it in ice water to numb it before it actually dies.

I can just see it now.

In Bonaire I gather they're sending out fish-killing patrols. Maybe they're doing the same here and just not admitting it. I hope so. They do hope to keep the marine park free of lionfish, but I don't think the pooper-scooper approach is going to work.

UPDATE: I met a woman involved in reef statistics who told me that a lot of the sightings were of juveniles, 1-3 inches, so you can see why they might not be spear gun material, and that they are not at this moment spewing 30,000 eggs per month. Even the intermediates, 5-6 inches, can be caught in a net, if you happen to be carrying one. But there were also a few larger fish of reproductive age. And of course, right up there with death and taxes are time and sex!
I also know snorkelers who found a lionfish on the reef in Belize. They thought it was one of the most attractive fish they had ever seen. They'll go back out next time planning to shoot to kill, but with regret.
I also noticed that the first result on my Google search was about keeping lionfish in aquariums.

Here's a little more detail on what's so terrible about these fish. The entire website is worth reading if you're interested in the issue.
Recent research by Albins and Hixon (2008) provides the first evidence of negative effects of lionfish on native Atlantic coral-reef fishes. The recruitment of coral-reef fishes was studied during the 2007 recruitment period (July-August) on small patch reefs in the Bahamas with and without a single lionfish. Over the five week period, net recruitment (i.e., accumulation of new juvenile fishes via settlement of larvae) was reduced by 79% on reefs with lionfish compared to reefs without lionfish. Stomach content analyses and observations of feeding behavior showed that reductions in native fish density were almost certainly due to predation by lionfish. ... In addition, lionfish have the potential to decrease the abundance of ecologically important species such as parrotfish and other herbivorous fishes that keep seaweeds and macroalgae from overgrowing corals.
from the Nonindigenous Aquatic Species site of the USGS

1 comment:

Passport said...

We saw these guys in the Abacos last year. Although there our dive instructor took a spear out with us in case we encountered any. Of course we didn't while he had the spear. It seems to me that five minutes of education for the divers would show how very important it is to control the lion fish population. Maybe they should have a lionfish hunting tour!