Why Are Lionfishes (Pterois, Scorpaenidae) So Rare
In Their Native Ranges?
Terry J. Donaldson, David Benavente and Roxie Diaz
University of Guam Marine Laboratory
UOG Station
Mangilao, Guam 96923 USA
email: [email protected]
What is Rarity?
• Species with low abundance
• Species with small geographic ranges
• Species that may be found only in a few
specialized habitats
• These components are not mutually exclusive
A Fourth Definition
• Species with wide geographical ranges but low
adult abundances at any given locality
Cheilinus undulatus
(Labridae)
Photos: J.E. Randall
Bolbometopon muricatum
Labridae: Scarinae
What Causes Species to be Rare?
• Relationship between body size and range size
• Relationship between body size and abundance
• Environmental adaptations resulting from range
size variability at higher latitudes
• Habitat requirements and resource availability
• Poor ability to exploit marginal habitats or other
resources
• Poor mobility
• Low reproductive effort
• Poor recruitment
After Gaston (1994); Jones, Munday and Caley (2002)
The Unusual Suspects:
Lionfishes (Pterois, Scoraenidae)
Pterois antennata
Photographs: J.E. Randall
Pterois radiata
Pterois volitans
Why Are Scorpionfishes So Rare?
Photographs: J.E. Randall and R.E. Myers
Tropical and Subtropical Scorpionfishes
• Some have a high degree of habitat specificity
• Strong site fidelity because of poor mobility
• Behavior
• Ambush or hunting predators
• Long larval life but poor recruitment?
• Prey of larger predators limits abundance of adults and
juveniles?
• Sampling artifacts: cryptic and/or nocturnal
Visual surveys at selected Pacific localities (n = 632 transects)
Transect Type and Number
Locality
Guam
Northern Mariana Islands (limestone)
Northern Mariana Islands (volcanic)
Palau
Southwest Palau Islands
Yap-Ulithi, Micronesia
Chuuk, Micronesia
Kosrae, Micronesia
Kwajalein, Marshall Is.
Majuro, Marshall Is.
American Samoa
Sta. Ysabella, Solomon Is.
Visayas, Philippines
Total
Timed Swim GPS Timed
63
43
5
0
65
21
0
11
6
3
0
22
12
251
7
0
0
0
0
0
0
0
0
0
0
0
3
10
Belt
157
4
0
11
0
8
55
0
7
7
122
0
0
371
Number of transects out of a total of 632 transects where lionfishes
were observed. Pant = Pterois antennata; Prad = P. radiata;
Pvol = P. volitans.
Transect type
Pant
Prad
Timed GPS
0
0
0
Timed swim
3
5
23
Belt
3
0
3
Total
6
5
26
0.8%
4.1%
Percent
1.9%
Pvol
What Causes Species to be Rare?
• Relationship between body size and range size
• Relationship between body size and abundance
• Environmental adaptations resulting from range
size variability at higher latitudes
• Habitat requirements and resource availability
• Poor ability to exploit marginal habitats or other
resources
• Poor mobility
• Low reproductive effort
• Poor recruitment
Body Size, Range Size and Abundance
• Species with wide geographical ranges but low
adult abundances at any given locality
Cheilinus undulatus
Photos: J.E. Randall
Bolbometopon muricatum
Habitat
Pterois antennata
Pterios volitans
Pterois radiata
Pterois volitans
Resource Use and Behavior
• Lionfishes are social
• Shelter together
• Hunt cooperatively
Resource Use: Being a Predator
• Adults are piscivorous but also feed upon crustaceans
• Nocturnal predators but also feeding during daylight
and crepuscular periods (dusk and dawn “switchover”)
• Prey limited?
Doubtful.
Long Larval Life and Poor Recruitment
• Morphological and life history specializations of
larvae facilitate long larval periods and greater
dispersal
• Wide geographic ranges
• Why poor recruitment?
Many larvae lost in “vastness” of the IndoWest Pacific?
Predation upon larvae, post-larvae and small
juveniles promotes low abundance locally?
Prey of Larger Predators?
• Largely anecdotal information or small sample
sizes
• Scorpaenids found in stomachs of groupers
(some groupers not much larger than their prey)
• Moray eels will prey opportunistically upon adults
• But, how much larger? What preys upon postlarval juveniles?
Poor Mobility and High Site Fidelity
Scorpaenopsis macrochir
Pterois volitans
Pterois antennata
Rarity, “crypticity”, nocturnal behavior and
sampling error
Turning the Question Around:
Why Aren’t Lionfishes Rare in the
Western Atlantic?
Some Possible Explanations (But Not All)
• Lack of effective predators upon adults
• A surfeit of suitable habitat (= disturbed habitat)
• The geography and physics of larval distribution
• Lack of effective predators upon post-larval juveniles
• Competitive release as invasive species
• Altered states: shifts in life history strategies that promote
rapid growth, early maturity and reproduction
Acknowledgments
• Jack Randall- B.P. Bishop Museum (photographs)
• Robert Myers- Coral Graphics (photographs)
• Surveys funded or supported directly or indirectly by:
NOAA, U.S. Fish and Wildlife Service, U.S. National
Park Service, U.S. Navy, The Nature Conservancy, and
the University of Guam Marine Laboratory