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LIONFISH RESEARCH

The sanctuary research team works closely with other government and non-government agencies across the Gulf of Mexico and Caribbean to better understand the invasive lionfish problem and work toward solutions.

A freshly dissected, headless lionfish laid out on a cutting board with a pair of dissecting scissors and a ruler
Lionfish dissections give us data that is helpful in understanding the lionfish problem. Photo: FGBNMS/Drinnen

As part of this effort, a certain amount of data collection is conducted with each specimen removed from the sanctuary. Initially, all of the following data was collected from each specimen, but as the volume of specimens increases, only a certain percentage receive the full work-up.

Once captured, lionfish are placed in labeled bags noting when and where each specimen was collected. The specimens are then frozen until ready for processing.

6 ice chests full of thawed, dead lionfish in plastic bags.
317 lionfish were thawed in tubs and coolers for processing in September 2015 following the first Lionfish Invitational. Photo: FGBNMS/Drinnen

Once thawed, weight and length data is collected on every lionfish removed from the sanctuary. This includes two measurements--total length and standard length (from the nose to the point where the tail attaches to the body).

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Lionfish being weighed in a plastic container on a small electronic scale.
A lionfish being weighed on an electronic scale (weight in grams). Photo: FGBNMS/Drinnen

Person using a flexible plastic ruler to measure the total and standrad lengths of a lionfish, in centimeters.
A lionfish being measured, in centimeters.
Photo: FGBNMS/Drinnen

The lionfish's head is removed and sent off to a researcher who is sampling the otoliths (ear bones) of lionfish to determine their ages. Since otoliths are very small (about .5 cm), it is easier and less time-consuming to send the whole head.

Scientist's hand holding a lionfish head with the recently extracted otolith displayed on the hand. The word "otolith" is depicted with a line leading to the object on the hand.
A researcher displays an otolith on her hand after extracting it from the lionfish head on the right. Photo: FGBNMS/Drinnen

By examining the growth rings in the ototliths, researchers can tell how old a fish is. When coupled with the weight and length data, this helps us understand how quickly lionfish are growing in their invasive range.

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Close up look at the small, oblong otolith displayed on the researcher's hand
Close up view of an otolith on the researcher's hand. It measures about .5 cm. Photo: FGBNMS/Drinnen

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Fin clips are taken from either the dorsal and/or anal fins to be sent off for research on lionfish genetics.

A researcher using scissors to clip off a section of the soft rays on a lionfish's dorsal fin.
A researcher clips a small section from the soft part of the dorsal fin. Photo: FGBNMS/Drinnen

Genetic data tells us how lionfish are related throughout the invasive range. So far, scientists can trace all of the lionfish from the Western Atlantic/Caribbean/Gulf of Mexico back to 10 original females!

A woman places fin clips into small vials with a liquid preservative so that they can be safely shipped for testing.
Researcher Michelle Johnston places fin clips in small vials with liquid preservative. Photo: FGBNMS/Drinnen

A single small vial with a lionfish fin clip in ethanol standing on a table next to a box full of sample vials with other fin clips
Each fin clip is preserved in ethanol in a small, labeled vial. (Image: FGBNMS/Drinnen)

The abdomen is cut open to reveal the sex of the fish and allow us to examine the gut contents.

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Gloved hands using scissors to cut open the belly of a lionfish.
Researcher Marissa Nuttall cuts open the belly of a lionfish. Photo: FGBNMS/Drinnen

Most lionfish that we examine have globs of fat in their guts, an indication that these fish are overeating and becoming obese.

A dissected lionfish belly with congealed fat clumps pulled outward.
Off-white clumps of fat are often found surrounding the organs of a lionfish. Photo: FGBNMS/Drinnen

The stomach is cut open to see what the lionfish has been eating.

Using tweezers to pull a fish from the cut open stomach of a lionfish
Extracting a small fish from the stomach of a lionfish.
Photo: FGBNMS/Drinnen

A gloved hand holding the fish extracted from a lionfish stomach in the preceeding photo.
A blenny extracted from the lionfish stomach pictured above. Photo: FGBNMS/Drinnen

Some of the gut contents are fairly recent additions and relatively easy to identify. Those that are not are sent off for genetic analysis.

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Three partially digested cardinalfish extracted from the stomach of a dead lionfish.
Three partially digested cardinalfish taken from a lionfish stomach. Photo: FGBNMS/Drinnen

So far, the most fish we have found in a single stomach is 15--11 damselfish and 4 blennies! The level of digestion indicated that they were all eaten at about the same time.

A dissected lionfish carcass displayed next to the 15 fish extracted from its stomach.
15 fish were taken out of the stomach of a lionfish about 9 inches long. Photo: FGBNMS/Drinnen

Each animal extracted from the lionfish stomach is recorded along with its size.

A dead damselfish being measured in the palm of a gloved hand.
Michelle Johnston measures a relatively large damselfish (about 5.5 cm) found in the stomach of a lionfish. Photo: FGBNMS/Drinnen

Larger vials containing fish samples taken from lionfish stomachs
Fish and invertebrates that cannot be identified are preserved in ethanol and sent off for DNA identification.
(Image: FGBNMS/Drinnen)

All of this data on the the lionfish prey allows us to determine what life stages of which species are being affected by the invasion.

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Gloved hands measuring a small fish on a cutting board.
Measuring a small fish removed from a lionfish stomach. Photo: FGBNMS/Drinnen

Lionfish Stomach Contents
Common Name Family/Class Percent Composition
Red Night Shrimp Rhynchocinetidae

31.12

Other Shrimp Species Penaeoidae
17.63
Wrasse Labridae
8.47
Blenny Blenniidae
3.58
Damselfish Pomacentridae
3.27
Cardinalfish Apogonidae

1.70

Parrotfish Scaridae
1.44
Goby Gobiidae
.65
Crab Crustacea
.39
Surgeonfish Acanthuridae
.35
Basslet Grammatidae
.31
Snapper Lutjanidae
.26
Grouper Serranidae
.22
Jack Carangidae
.17
Drum Sciaenidae
.13
Unidentifiable Fish  
16.02
Empty Stomach  
8.08
Chyme (digested mush)  
6.20
A listing of the most common fish and invertebrates found in lionfish gut contents.

When a specimen is large enough, we filet the fish to get at least 100 grams worth of meat to send off for ciguatera testing. Since the sanctuary is a hotspot for ciguatera, we want to make sure lionfish aren't dangerous to eat.

Taking a filet of meat from a lionfish
Michelle Johnston filets a larger lionfish specimen so that meat samples can be sent for ciguatera testing.
Photo: FGBNMS/Drinnen

Each time we process lionfish, local Sea Aggies are invited to participate. This helps us with the large amount of data processing and provides valuable hands-on experience for marine biology students.

Two Texas A&M Galveston students assist with lionfish dissections
Sea Aggies helping with lionfish dissections in October 2014. Photo: FGBNMS/Drinnen

Two Texas A&M Galveston students helping with lionfish dissections
Sea Aggies helping with lionfish dissections in September 2015. Photo: FGBNMS/Drinnen

Processing hundreds of lionfish is hard work, but it is also rewarding knowing that we are contributing to a bank of knowledge that may some day help us overcome this invasion.

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Michelle Johnston posing with a lionfish head, both she and the fish with mouths wide open.
Science is fun! Photo: FGBNMS/Drinnen

For more information on the lionfish problem, please visit our Invasive Lionfish page.




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