[Coral-List] Do goliath grouper eat lionfish?

[Sarah Frias-Torres]

Rachel and coral-list
that is the 64 million dollar question.
For those in Coral-list not aware of this, goliath grouper (Epinephelus itajara) include in their diet a number of poisonous fish, from those with venom-spines (catfish) to those with venom on their skin (Diodontidae, puffers and the like). It is obvious that the goliaths, somehow, have evolved to deal with deadly toxins and associated spines.
The anecdotal evidence Rachel refers to is basically found in Florida, where thanks to a federal and state fishing ban, goliath groupers have been protected since 1990. Elsewhere in tropical and subtropical Atlantic, the species is critically endangered due to overfishing and habitat destruction.In Florida reefs, where the presence of adult goliath groupers is slowly (very slowly) increasing every year, we see that there are lower abundances of lionfish, if we compare to other reefs in the Caribbean, where there are zero goliaths, and many, many  lionfish.
So a logical conclusion is to assume that goliath groupers are eating the lionfish.
However, nobody has found yet a lionfish inside the stomach of a goliath grouper. 
As we speak, Chris Koenig and team (Florida State University) are doing a limited study on goliath grouper stomach contents, using stomach lavage (not killing the groupers). I'm not sure if they are taking samples through an extended size range. Juggling a 6 foot long goliath is not easy. 
The idea of goliath groupers eating lionfish is not a crazy one. Besides the information I mentioned above, we know that in their natural Indo-Pacific habitat, lionfish are in the menu of big groupers and sharks. It is interesting to note that there are two big groupers in the Indo-Pacific which occupy a similar niche to that of goliath grouper in the Atlantic: the giant grouper, also known as Queensland grouper (Epinephelus lanceolatus) and the potato grouper/potato cod (E. tukula). Both seem to eat lionfish. 
Here is the tricky part: if goliath grouper is indeed a predator of lionfish, it will be the only known native predator of the invasive Indo-Pacific lionfish. And keeping a healthy population of goliath grouper, as well as allowing goliaths to recover where they are critically endangered or commercially extinct (most of the Atlantic), might be one of the most powerful strategies we have to fight the lionfish invasion.... now, there was a little study published on a Reef Site [Maljkovic et al  Reefs (2008) 27:501] reporting predation of lionfish by tiger grouper (Mycteroperca tigris) and Nassau grouper (E. striatus). Whether this is anecdotal, or is a common occurrence, I don't know (these groupers have diet requirements/adaptations very different from those of goliath grouper), but it sets the same argument for the need to reconstruct the overfished grouper populations of the Atlantic/Caribbean, as an essential tool to fight the lionfish invader..
Well, that's my five cents. If anyone wants to team up to answer this question (specially goliath grouper vs lionfish) , please let me know.

Sarah Frias-Torres, Ph.D. Postdoctoral Scholar &Schmidt Research Vessel Institute Postdoctoral Fellowhttp://independent.academia.edu/SarahFriasTorresOcean Research & Conservation Association 1420 Seaway Drive, 2nd Floor Fort Pierce, Florida 34949 USA http://www.teamorca.org



> From: rgraham at wcs.org
> To: coral-list at coral.aoml.noaa.gov
> Date: Wed, 15 Sep 2010 18:30:47 +0000
> Subject: [Coral-List] Do goliath grouper eat lionfish?
> 
> Hello Coral Listers and fellow goliath grouper researchers,
> 
>  
> 
> Do we have any direct evidence yet of lionfish being eaten by goliath
> grouper? It would make sense that they would and I have taken out many a
> ray/catfish spine or old hook from a GG stomach but I have not yet come
> across any lionfish spines - and we have a LOT of lionfish in Belize now. I
> can't seem to find any evidence for GG preying on the lionfish aside from
> anecdotal reports of lower abundances of lionfish in locations of high GG
> abundances.
> 
>  
> 
> Any confirmations of predation would be greatly appreciated.
> 
>  
> 
> Best
> 
>  
> 
> Rachel
> 
>  
> 
>  
> 
>  
> 
> Dr. Rachel T. Graham
> 
> Ocean Giants Program
> 
> Wildlife Conservation Society
> 
> PO Box 76
> 
> Punta Gorda
> 
> Belize
> 
> t: +501 722 0063
> 
> e: rgraham at wcs.org
> 
>  
> 
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