As everyone in the dive world knows by now, the Caribbean has been invaded by lionfish – reef fishes indigenous to the Indo-Pacific region. Sightings have been reported from the mid-Atlantic U.S. coast all the way to S. America and through much of the Caribbean.
That much is scientific fact. But what are the long-term impacts of this unforeseen event? Will lionfish simply turn out to be just another interesting fish for reef divers to watch, or will the entire fish population of the Caribbean eventually be reduced to one single lionfish about the size of Aruba waiting patiently for the next cruise ship to pass by?
Speculation runs amuck, and the purpose of this article is to shed some hard light on what is known and what is not regarding the great lionfish invasion.
Impacts of Concern
The main expressed concerns posed by Caribbean lionfishes can be summarized as follows:
1. Ecosystem Change: Because lionfish are highly piscivorous, they may have the capacity to reduce the recruitment of juvenile fishes to reef areas. This has been experimentally confirmed by short-term studies on a few small Bahamian patch reefs. Such impacts could (in theory) lead to declines in Caribbean reef biodiversity, disruption of normal ecological processes, and possibly the local extinction of select species.
2. Economic Impacts: By reducing populations of grouper and other commercially valuable species, lionfish may damage the economies of island communities dependent upon fishing. Lionfish may also impact local tourism, an economic mainstay of many Caribbean island nations.
3. Human health: Lionfish are highly venomous, with the capacity to inject neurotoxins dangerous to humans (and other animals) from stout spines on several of the main fins. As lionfish populations continue to increase, so does the likelihood of human injuries. Lionfish envenomation is considered a serious injury requiring immediate professional medical evaluation and treatment.
Evaluating the Impacts
While the lionfish is undoubtedly here to stay, this author’s evaluation of the threat is, for the most part, not as dire as some others might believe.
The threat to human health is real and unquestioned, but the number of actual injuries is likely to be relatively small and rarely (if ever) life threatening.
The economic threat to tourism will likely be minimal. In terms of general tourism, the main impacts will probably occur from parents understandably reluctant to allow children to wade or snorkel in reef areas. But that alone will not deter family travel to the Caribbean. In terms of dive tourism, based upon the propensity of the dive industry to capitalize on “thrill tourism” (e.g., shark feeding), it is likely that this opportunity will also be used to attract rather than repel scuba divers (e.g., “help count lionfish”; “see a new species”, etc.).
In terms of ecological and commercial fisheries impacts (referred above), the concerns expressed are legitimate. Nonetheless, it should be kept in mind that the scientific basis for these concerns is minimal at best, based upon one or two published short term studies from small patch reefs in a limited area. How these results might extrapolate to large reef areas throughout the region is purely speculative at this time.
Finally, from the broad perspective we must keep in mind that for millions of years lionfish have been widespread throughout a vast oceanic region that contains at least ten times the biodiversity of the Caribbean.
While fears that modern Caribbean reef communities have never before been exposed to lionfish are not unfounded, it is also true that the Caribbean reef fauna is derived from Pacific reef communities that have “only” been isolated for some three million years. Most populations of these animals certainly have the capacity to rapidly undergo adaptive changes (i.e., evolution) to face new situations.
In any event, only time will tell what the real threat of the great lionfish invasion really amounts to.
William S. Alevizon, Ph.D.