ANSRP Bulletin, Vol-04-1 February 2004 Suckermouth : Threats to Aquatic Ecosystems of the United States? by Jan Jeffrey Hoover, K. Jack Killgore, and Alfred F. Cofrancesco

Introduction In appearance and in habits, the suckermouth catfishes or “plecos” of South and Central America () are markedly different from the bullhead cat- of North America (Ictaluridae). Bullhead catfishes are terete and naked, with a terminal mouth and a spineless adipose fin. They are free-swim- ming predators that feed on invertebrates and other fishes. Suckermouth catfishes, in con- trast, are flattened ventrally, their dorsal and lateral surfaces covered Figure 1. Suckermouth catfishes from the San Antonio River at Lone Star with rough, bony plates forming Boulevard, San Antonio, Texas. These are sailfin catfishes and are believed to represent three species: anisitsi (foreground), flexible armor (Figure 1). Be- P. disjunctivus (middle), P. multiradiatus (background) cause of this armor, suckermouth catfishes are sometimes referred Figure 2. Mouth of a sailfin . The thick, fleshy lips form a sucking to as “mailed” catfishes (Norman disc for attaching to rocks and 1948). The mouth is inferior and grazing on the lips surrounding it form a benthic, adhering to streambeds sucking disc (Figure 2). The and rocks with their mouths. adipose fin has a spine. The They are vegetarians feeding on caudal fin is frequently longer detritus and algae. Feeding is ventrally than dorsally. Pectoral done by plowing along the sub- fins have thick, toothed spines strate and using the thick-lipped, which are used in male-to-male toothy mouth to scrape plant combat and locomotion (Walker materials (filamentous algae, 1968). Suckermouth catfishes are diatoms) from hard surfaces or to

In this Issue: Suckermouth Catfishes: Threats to Aquatic Ecosystems of the United States? ...... 1 Risk Assessment, Decision Analysis, and Invasive Species ...... 10 suck up fine sediments. Speci- into two different camps: “splitters,” mens in aquaria may live more principally Europeans, who divide spp. than 10 years. Suckermouth the group into multiple genera and Armadillo del Rio catfishes are capable of breathing numerous species, and “lumpers,” air by swallowing it and extract- principally Americans, who divide Armadillo del rio (Figure 3) ing oxygen through the gut lining the group into fewer genera and were introduced to Texas and (Norman 1948). fewer species.1 Confounding the Florida rivers in the mid-1950s/ With more than 550 species, problem of taxonomic resolution early-1960s and other locations suckermouth catfishes constitute is the co-occurrence of multiple shortly thereafter (Nico and Fuller the largest family of catfishes in species in a single location and 1999). Reproductive populations the world (Robins et al. 1991). the possibility of interspecific exist in Nevada and Hawaii and Popular with home aquarists hybridization. For example, three isolated specimens have been because of their distinctive ap- recognizably distinct forms occur reported from at least five other pearance, hardiness, and propen- at a single location in the San states (Arizona, Colorado, Con- sity for cleaning algae from all Antonio River in Texas (Figure 1). necticut, Louisiana, and Pennsyl- submerged surfaces (including These conform to characteristics vania). In Texas, the San Antonio vascular plants), suckermouth of three of the species known to River population was apparently catfishes have been commonly exist in the United States, but established after individuals imported into the United States their close abundance and co- escaped from the San Antonio since the mid-20th century (Innes occurrence suggest the possibility Zoo in 1962. Armadillo del rio 1948) and the number of taxa of future hybridization.2 At were used in the zoo as a biologi- imported has increased during present, several species, in two cal control for nuisance growths recent decades (Robins et al. genera, are known to be well- of hair algae (Barron 1964). 1991). Consequently, it is not established in U.S. waters (Page Other populations in the United easy, at present, to precisely and Burr 1991). Some specimens, States resulted from farm identify specimens of however, have unusual pigmenta- escapees or releases. suckermouth catfishes when they tion suggesting hybridization Fishes in the genus Hypostomus are found in U.S. waters. (e.g., Nico and Martin 2001). (Plecostomus in older references) of this group has been described as “relatively primitive” and for some genera as “a mess” (Page and Burr 1991; Armbruster 2000). As a result, species-level identifications are tenuous. Forums exist for identi- fying specimens from photo- graphs (e.g., http://www. planetcatfish.com) and some taxonomic resources are available on the Web, such as those for Loricariidae at the Auburn Uni- versity Website (Armbruster 2000), but comprehensive taxo- nomic keys to species are not yet readily available to resource managers. Also, taxonomists working with sucker-mouth Figure 3. Armadillo del rio from the San Antonio River at the San Antonio Zoo. catfishes are themselves divided The small dorsal fin has a single spine and seven rays

1 Personal Communication. 2003. Pete Liptrot, Bolton Museum , Art Gallery, and Aquarium; United Kingdom. 2 Personal Communication. 2003. Larry Page, Florida Museum of Natural History, University of Florida.

2 ANSRP Bulletin, Vol-04-1, February 2004 are readily distinguished by their gess 1989). There are approxi- comparatively small dorsal fin Pterygoplichthys spp. mately 22 species (Armbruster with fewer than nine (usually Sailfin Catfishes 1997). Pigmentation, within and seven) rays, a snout with a smooth among species, is highly variable. margin, and fused opercular bones Sailfin catfishes were con- Four species are known from U.S. (Burgess 1989). They frequently firmed from waters in Texas, waters (Table 1). A fifth species, have patterns of spots and they Florida,and Hawaii after 1970 P. gibbiceps, the leopard pleco or range in size from 14-50 cm (e.g., Ludlow and Walsh 1991; acari pedra, is frequently imported depending on age and species. Page 1994; Edwards 2001). Early but has not yet been collected in Texas specimens have been introductions may have gone North America (Smith 1981; collected that approach the maxi- unnoticed because of superficial Burgess 1989; Sandford and Crow mum known size for the taxon. similarities to armadillo del rio. 1991). There are approximately 116 Most populations of sailfin cat- Like armadillo del rio, these species (Burgess 1989), but one, fishes were probably started from fishes construct burrows in the Hypostomus plecostomus, is the aquarium releases. banks of the rivers and lakes in most geographically widespread, Fishes of the genus Pterygop- which they live (Figure 5). Bur- occurring in tropical South lichthys (Liposarcus in some row width approximates that of America, Panama, and Trinidad; literature) are readily distinguished the occupant fish (i.e., width H. plecostomus is also the most from the armadillo del rio by their between extended pectoral fins), frequently imported species comparatively wide dorsal fin burrow length is typically 0.5 to (Walker 1968). At least six other with more than 10 rays (Figure 4), 1.0 m, and shape is variable species, however, have been used their snout with a granular margin, although the tunnel usually ex- as ornamental fishes and can be and an articulated interopercular tends downward into the bank distinguished (and putatively bone with evertable spines (Bur- (Devick 1988). These burrows are identified) based on pigmentation (Walker 1968). Taxonomic status of populations in the United States has not been determined definitively, but three morphologi- cally distinct species are estab- lished (Page and Burr 1991). These fishes construct branch- ing, horizontal burrows in stream or pond banks that are 120-150 cm deep (Burgess 1989). Burrows are used as nesting tunnels and are guarded by the males until free-swimming larvae leave the burrow. Some species are salt- tolerant. Although salinities in which they have been collected are not reported, waters have been described as “quite brackish.” Introduced populations can become locally abundant in a short period of time. Prior to 1989, the estimated number of individuals in U.S. waters was 7 million. Figure 4. Sailfin catfish from Espada Lake, Texas. The large dorsal fin has a single spine and 11 rays.

ANSRP Bulletin, Vol-04-1, February 2004 3 used for reproduction but also allow survival during drought (Figure 6). Eggs are laid in the burrow and are guarded by males; fish can survive in the moist micro- habitat even when water levels fall far below the opening to the chambers (Bur- gess 1989; Sandford and Crow 1991). The authors have observed San Antonio River fish that are, for all appearances, “dead” in the dry burrows above de-watered reaches of the river, but which are, in fact, very much alive (Figure 7). Such fish, when returned to the water, recover after a short time and swim away. Burrows may also be used as refugia during cold weather (Nico and Martin 2001). These traits enable sailfin catfish to thrive in their natural and Figure 5. Burrows of sailfin catfishes in the San Antonio River, Texas in unnatural habitats. Dense populations of sailfin catfishes (hundreds to thousands per water body) have been observed in natural parts of their range (Burgess 1989) and in Hawaii, Puerto Rico, and Florida (Devick 1988; Nico 1999a; Bunkley-Williams et al. 1994).1 Growth is rapid during the first two years of life (more than 35 cm) and fecundity high (472-1283 mature eggs/ female) especially in larger individuals (Devick 1988, 1989). Consequently, introduced populations can become abun- dant in a very short period of time. The population of Pterygoplichthys multiradiatus in Wahiawa Reservoir (Oahu, Hawaii) was established in 1986 (or shortly before), was characterized by Figure 6. Sailfin catfish in de-watered burrow

1 Personal Communication. 2003. Joe Gallo, Southwind Lakes Homeowners Association, Boca Raton, FL.

4 ANSRP Bulletin, Vol-04-1, February 2004 more than 2,000 burrows at three locations in 1987, and more than 10,000 burrows at those same locations in 1988 (Devick 1989). In 1989, it was one of the more abundant fish species in the impoundment, and by 1991 had spread throughout nearby streams and reservoirs (Devick 1991).

Environmental Effects The distinctive feeding and reproduc- tive behaviors of suckermouth catfishes, coupled with large size and high popula- tion densities, constitute significant threats to native fish communities and to aquatic Figure 7. Sailfin catfish extracted from de-watered burrow. Eyes are habitats of the United States. Potential and sunken into the sockets and surface is dry to touch indicating documented impacts of suckermouth prolonged aerial exposure. Specimen recovered, however, when catfishes include: returned to the river, ventilating and moving almost immediately, and swimming off into deep water several minutes later Disruption of aquatic food chains Grazing on benthic algae and detritus by suckermouth catfishes alters and reduces food and physical cover available for the aquatic insects eaten by most North American stream fishes. Feeding on mud and silt (Walker 1968) could result in resuspension of sediments and/or changes in substrate size. In addition, nutrients are prematurely diverted from the “consumer” components of food webs and transformed into feces available only to scatophags and decomposers (i.e., bacterial, fungi). Food chain disruption is not limited to stream channels, as some species (e.g., P. gibbiceps, P. pardalis) also forage on floodplain detritus (Smith 1981).

Impacts to native species Figure 8. Central stoneroller, Campostoma anomalum, a native Native herbivorous North American herbivore threatened by suckermouth catfishes. The ventrally fishes, like the central stoneroller positioned (inferior) mouth has a cartilaginous ridge on the lower jar used to scrape off attached algae on which the fish feeds. The (Campostoma anomalum) and the Florida hooked horns on the dorsal surface of the head are breeding flagfish (Jordanella floridae), are small tubercles of the male, which will be lost shortly after spawning (less than12 cm) minnows or minnow-like fishes, with comparatively short lifespans mentally tolerant species that large, they may displace (less than 4 years), low fecundity, and feed on the same foods that smaller or less aggressive limited resistance to hypoxia and desicca- they do. Because they are benthic fishes (e.g., darters, tion (Figure 8). Consequently, they are at bottom feeders, suckermouth madtoms, bullhead catfishes). a competitive disadvantage when con- catfishes may incidentally Declining abundance and fronted by larger (greater than 15 cm), ingest eggs of native fishes. restricted occurrences of the longer-lived, highly productive, environ- Because they are benthic and central stoneroller in the San

ANSRP Bulletin, Vol-04-1, February 2004 5 Antonio River system, for ex- colony” in which several dozen variety of species in each of the ample, were coincident with occur in very close proximity to genera suggests that certain taxa increasing abundance and ex- each other (Nikolsky 1963). (or hybrids) in successive genera- panding distributions of These colonies can compromise tions will acclimatize to sub- suckermouth catfishes believed to shoreline stability, increasing tropical and mild-temperate threaten the native minnow erosion and suspended sediment climates, becoming more cold (Hubbs et al. 1978). loads (Nico 2000a). Siltation, tolerant over time. It is probable then that Mortality of endangered bank failure, head-cutting, and suckermouth catfishes will readily shore birds elevated turbidity are likely impacts. In Wahiawa Reservoir, disperse through eutrophic waters Suckermouth catfishes, be- burrows excavated in 1988 were (including those that are hypoxic cause they are large, sedentary, estimated to have displaced 150 and turbid), through high water and palatable, are attractive prey tons of silt (Devick 1989). In one velocities, and through brackish to fish-eating birds. Their defen- south Florida community, erosion water. Overland travel has been sive erection of dorsal and pecto- of catfish-infested shorelines is reported anecdotally when envi- ral spines, however, poses mortal estimated at 0.6-1.3 m following ronmental conditions are extreme danger to birds attempting to each substantial rainfall or 4 m/yr.1 and short terrestrial excursions swallow whole fish. Twenty seem likely if ground is suffi- brown pelicans (Pelecanus ciently moist (Walker 1968).2 occidentalis) are known to have Systems at Risk Inter-drainage dispersal via strangled after feeding on upland stream cross over and P. multiradiatus but many more Based on their biology and coastal or inter-coastal waterway deaths are suspected (Bunkley- commercial appeal, the likelihood migration is inevitable. Sucker- Williams et al. 1994). of continued dispersal of mouth catfishes are commercially suckermouth catfishes in North Changes in aquatic plant valuable for their tasty flesh, their American waters is high. They roe (suitable for caviar), and as communities are tolerant of (and likely to live specimens for aquaria. Conse- Suckermouth catfishes “plow” benefit from) eutrophication and quently, the risk of deliberate, the bottoms of streams, occasion- other forms of aquatic distur- anthropogenic introductions of ally burying their heads in the bance, as evidenced by their fish into other uncontaminated substrate and lashing their tails occurrence in nutrient-rich Lake drainages exists and is likely to (Walker 1968). These behaviors Thonotosassa and Lake Maggiore, increase as more people become can uproot or shear aquatic Florida (Page 1994; Nico 1999b). aware of the species. plants. This would impact native Armadillo del rio are highly Several geographically dispar- plant species by reducing their resistant to high water velocities. ate ecosystems are at immediate abundance in beds of submersed In laboratory swim tunnels, they risk from recent (after 1990) aquatic vegetation and creating can maintain station and move introductions (or discoveries) of mats that could shade them from freely in water velocities greater sucker-mouth catfishes: sunlight. Making “cuttings” at than 1 m/s (personal observation). ¾ Kissimmee River, Florida – the water’s surface available for Cold tolerance is unknown but under restoration by the Army dispersal by water movement, movements into thermal refugia Corps of Engineers. boat propellers, and aquatic birds (i.e., springs and seeps during ¾ Lake Okeechobee, Florida – the would benefit non-native nui- winter) seem likely based on perimeter of which is contained sance plant species. seasonal disappearances in the by earthen levees. spring-fed San Antonio River, ¾ San Antonio River, Texas – Bank erosion Texas (personal observation) and under restoration by the Army The nesting burrows of apparent utilization of sewage Corps of Engineers. suckermouth catfishes sometimes outflows in Houston area (Nico ¾ Reservoirs, Puerto Rico and form a large group or “spawning and Martin 2001). Also, the Hawaii – operated by the Army

1 Personal Communication. 2003. Joe Gallo, Southwind Lakes Homeowners Association, Boca Raton, FL. 2 Personnal Communication. 2003. Leo Nico, USGS Geological Survey, Gainesville, FL.

6 ANSRP Bulletin, Vol-04-1, February 2004 Corps of Engineers or other tude from a single group of Turbulence, bubbles, or sound, governmental resource agencies. introduced fishes have not yet however, may provide some level been seen in this country. of containment due to the fishes’ Unprecedented sensitivity to underwater vibra- tions and sounds. Suckermouth Levels of Threat Recommendations catfishes, like all catfishes and minnows, possess a series of Suckermouth catfishes present In the early 1990s, bighead and bones (i.e., the Weberian appara- a cumulative series of threats to silver carps were viewed largely tus or Weberian ossicles) connect- aquatic ecosystems unprecedented as a localized and innocuous ing the inner ear to the swim in recent history. Previously phenomenon of the lower Missis- bladder and providing better introduced fishes have had signifi- sippi Basin. Little effort was sound discrimination and percep- cant effects on a limited number made to study, contain, and tion than other fishes (Burgess of ecosystem characteristics. manage those species. Today they 1989). Pulses or curtains of such Some species degrade physical threaten the upper Mississippi disruptive stimuli will be avoided habitats (e.g., common carp via Basin and the Great Lakes. In by fish, but the threshold levels turbidity, grass carp via aquatic recent years, suckermouth cat- and habituation responses of vegetation removal). Others fishes have appeared in a greater suckermouth catfishes have not compete directly with native number of locations and in greater been determined. taxonomic diversity than ever fishes for space (e.g., round goby Bank stabilization (e.g., to before. Failure to promptly with sculpins) or for food (e.g., minimize nesting), water diver- contain and manage them could bighead carp with paddlefish). sion (to minimize contamination result in a similar range expansion A few prey on native fishes (e.g., of uninfested waters), population with potential for disastrous pike killifish on native topmin- augmentation of native herbivores, environmental consequences. nows, sea lamprey on several and removal of suckermouth To effectively control these Great Lakes fishes). Suckermouth catfishes can also be implemented species, innovative barriers, man- catfishes, however, affect all of proactively or as damage control agement techniques, and public these ecosystem components and techniques. Burrows of sailfin awareness programs are required. processes. They degrade physical catfishes in south Florida are Electrical barriers, effective at habitats (i.e., removing algal sometimes clumped, suggesting containment of some other fishes cover, uprooting aquatic plants, that certain substrates, or loca- (Stokstad 2003), may not be effec- altering bank topography), com- tions within water bodies are tive on suckermouth catfishes, the pete directly with native fishes preferred. If these areas were adults of which are capable of (i.e., small herbivorous fishes, stabilized (e.g., bank armor), sudden bursts of speed carrying larger crevice-dwelling fishes), erosion would be reduced and them substantial distances in and could prey on native fishes nesting discouraged simulta- seconds (personal observation). (i.e., via incidental ingestion of neously. Likewise, if infested Hydraulic barriers provide natural demersal eggs). However, they water bodies could be isolated containment of many fishes and can also affect ecosystems at lower during periods of fish movement be used to contain some exotic and higher trophic levels. By (e.g., flap gate culverts), some species (Hoover et al. 2003), but ingesting mud and grazing, they level of containment could be may be difficult to create for this impact primary productivity (e.g., achieved. Native fish communities group of fishes. Suckermouth via changes in sediment size and could be enhanced by stocking catfishes are specially adapted for algal standing crops) and second- waterways with native herbivores resisting high water velocities, both ary productivity (e.g., bypassing (minnows, killifishes, tadpoles). behaviorally (via substrate consumer levels of food webs). They could also be enhanced by appression and rapid swimming) By serving as prey for aquatic the promotion of fishing for and morphologically (via suctorial birds, they threaten endangered suckermouth catfishes. Sucker- mouths, winglike pectoral fins, populations of keystone predators mouth catfishes are larger than rough surfaces, and flattened (e.g., pelicans). Multi-level most species of native freshwater impacts of this variety and magni- bellies).

ANSRP Bulletin, Vol-04-1, February 2004 7 fishes and in some streams (e.g., photographs. Joe Gallo provided sources, Hawaii Department of Land San Antonio River), they may be information on suckermouth and Natural Resources. Devick, W. S. (1991). “Patterns of the largest fishes present. Com- catfish populations and their introductions of aquatic organisms to mercial fishermen could be con- impacts on shorelines in Boca Hawaiian freshwater habitats.” New tracted (and could generate addi- Raton, Florida. Preliminary directions in research, management tional revenue for contractors from research on sailfin catfishes was and conservation of Hawaiian freshwater stream ecosystems. the sale of meat and eggs). Recre- funded by the U.S. Army Engi- Proceedings of the 1990 symposium ational fishermen could participate neer District, Fort Worth, and by on freshwater stream biology and in fund-raising “rodeos” or “round- the Aquatic Nuisance Species fisheries management. Division of ups” sponsored by local govern- Research Program. Permission to Aquatic Resources, Hawaii Depart- ments (and could be eligible for publish this document was ment of Land and Natural Resources, 189-213. cash prizes or bounties). granted by the Chief of Engineers. Edwards, R. J. (2001). “New additions Educational materials (e.g., and persistence of the introduced CDs, Webpages, flyers, posters), fishes of the upper San Antonio River, similar to those used for other Literature Cited and Bexar County, Texas,” Texas J. Sci. 53(1), 3-12. aquatic nuisance species and for Internet Sources Hoover, J. J., Adams, S. R., and Killgore, endangered species, could be K. J. (2003). “Can hydraulic barriers Armbruster, J. W. (1997). “Phylogenetic developed to inform people of the stop the spread of the round goby?,” relationships of the sucker-mouth ERDC/TN ANSRP-03-1, U.S. Army dangers posed by these seemingly armored catfishes (Loricariidae) with Engineer Research and Development innocuous fishes. The United particular emphasis on the Center, Vicksburg, MS. Ancistrinae, , and States Geological Survey pro- Hubbs, C., Lucier, T., Garrett, G. P., Neoplecostominae,” Unpubl. Ph.D. duces detailed species “fact Edwards, R. J., Dean, S. M., and dissertation, University of Illinois, Marsh, E. (1978). “Survival and sheets” for all exotic fishes in Urbana-Champaign. abundance of introduced fishes near U.S. waters (e.g., Nico 1999a, Armbruster, J. W. (2000). Loricariid San Antonio, Texas,” Texas J. Sci. Home Page. Auburn University 1999b, 2000a, 2000b) and the 30(4), 369-376. Museum. http://george.cosam. U.S. Army Corps of Engineers has Innes, W. T. (1948). Exotic aquarium auburn.edu/usr/key_to_loricariidae/ fishes. Innes Publishing Co., Phila- a Web-page devoted to its own lorhome/lorhome.html delphia, PA. Aquatic Nuisance Species Re- Barron, J. C. (1964). “Reproduction and Ludlow, M. E., and Walsh, S. J. (1991). http://www.wes. apparent overwinter survival of the search Program ( “Occurrence of a South American suckermouth armor catfish, army.mil/el/ansrp/ansrp.html). armored catfish in the Hillsborough Plecostomus sp., in the headwaters of These, or similar materials, could River, Florida,” Fla. Sci. 54, 48-50. the San Antonio River,” Texas J. Sci. Nico, L. (1999a). “Pterygoplichthys be incorporated into public out- 16(4), 449-450. anisitsi. Nonindigenous aquatic reach programs (e.g., for schools, Bunkley-Williams, L., Williams, E. H., species fact sheet 766,” United Jr., Lilistrom, C. G., Corujo-Flores, I., youth groups), news coverage States Geological Survey. (e.g., in newspapers, local publi- Zerbi, A. J., Aliaume, C., and http://nas.er.usgs.gov.queries/ Churchill, T. N. (1994). “The South SpfactSheet.asp?speciesID=766 cations), and in science-oriented American sailfin catfish Liposarcus Nico, L. (1999b). “Pterygoplichthys events (e.g., at nature centers and multiradiatus (Hancock), a new exotic disjunctivus. (Weber 1991). established in Puerto Rican fresh natural history museums, at Nonindigenous aquatic species fact waters,” Carrib. J. Sci., 1-2: 90-94. meetings of aquarium societies). sheet 766,” United States Geological Burgess, W. E. (1989). An atlas of Survey. http://nas.er.usgs.gov.queries/ freshwater and marine catfishes – A SpfactSheet.asp?speciesID=767 preliminary survey of the Nico, L. (2000a). “Pterygoplichthys Siluriformes. TFH Publications, Acknowledgments multiradiatus (Hancock 1828). Neptune City, NJ. Nonindigenous aquatic species Devick, W. S. (1988). “Disturbances and Neil Douglas, Steven George, fact sheet 766,” United States fluctuations in the Wahiawa Reservoir Bradley Lewis, and Catherine Geological Survey. ecosystem,” Project F-14-R-12, Job 4, Murphy provided assistance in the http://nas.er.usgs.gov.queries/ Study I. Division of Aquatic Re- SpfactSheet.asp?speciesID=768 field. Tyler Strange assisted in the sources, Hawaii Department of Land Nico, L. (2000b). “Pterygoplichthys and Natural Resources. laboratory. Bob Edwards and pardalis (Castelnau 1855). Devick, W. S. (1989). “Disturbances and Larry Page suggested identifica- Nonindigenous aquatic species fluctuations in the Wahiawa Reservoir fact sheet 766,” United States tions for San Antonio River ecosystem,” Project F-14-R-13, Job 4, Geological Survey. specimens based on the authors’ Study I. Division of Aquatic Re-

8 ANSRP Bulletin, Vol-04-1, February 2004 http://nas.er.usgs.gov.queries/ SpfactSheet.asp?speciesID=769 Nico, L., and Fuller, P. (1999). About the Authors: “Hypostomus sp. Nonindigenous aquatic species fact sheet 766,” Jan Jeffrey Hoover is a research fishery biologist in the United States Geological Survey. Environmental Laboratory at the U.S. Army Engineer http://nas.er.usgs.gov.queries/ Research and Development Center (ERDC) in Vicksburg, MS. He holds a B.S. degree in biology from Florida Atlantic SpfactSheet.asp?speciesID=762 University, an M.A. degree in zoology from Florida Atlantic Nico, L. G., and Martin, R. T. (2001). University and a Ph.D. in zoology from the University of “The South American suckermouth Oklahoma. Dr. Hoover’s research expertise is in the natural armored catfish, Pterygoplichthys history of fishes. His professional experience includes fish anisitsi (Pisces: Loricariidae), in surveys in bottomland hardwood systems reflecting Texas, with comments on foreign fish variable anthropogenic impact. Contact: 601-634-3996, introductions in the American [email protected]. southwest,” Southwestern Naturalist 46, 98-104. Nikolsky, G. V. (1963). The ecology of fishes. (translation by I. Birkett). K. Jack Killgore is a research fishery biologist in the Environmental Laboratory at the U.S. Army Engineer Academic Press, London [1978 Research and Development Center (ERDC) in Vicksburg, Edition, TFH Publications, Inc., MS. He holds a B.A. degree in zoology from the University Neptune Ciuty, NJ]. of Arkansas, an M.S. degree in fishery biology from Sam Norman, J. R. (1948). A history of Houston State University, and a Ph.D. in fish ecology from fishes. A. A. Wyn, Inc., New York. the University of Mississippi. Dr. Killgore has been involved Page, L. (1994). “Identification of in research concerning fish ecology of large river systems. sailfin catfishes introduced to Contact: 601-634-3397, [email protected]. Florida,” Fla. Sci. 57(4), 171-172. army.mil. Page, L. M., and Burr, B. M. (1991). A field guide to freshwater fishes – North America North of Mexico. Houghton Miflin Company, Boston, Dr. Alfred F. Cofrancesco is a research entomologist MA. and Branch Chief, Aquatic Ecology and Invasive Species Robins, C. R., Bailey, R. M., Bond, C. E., Branch, Environmental Laboratory at the U.S. Army Brooker, J. R., Lachner, E. A., Lea, R. Engineer Research and Development Center (ERDC) N., and Scott, W. B. (1991). “World in Vicksburg, MS. His studies focus on integrated pest fishes important to North Americans management, in particular, biological control of noxious exclusive of species from the conti- and nuisance plants. Dr. Cofrancesco holds B.S. and M.S. degrees and a Ph.D. in Biology from the University nental waters of the United States and of Southern Mississippi. Contact: 601-634-3182, Canada,” American Fisheries Society, [email protected]. Bethesda, MD. Sandford, G., and Crow, R. (1991). The manual of tank busters. Tetra Press, Morris Plains, NJ. Smith, N. J. H. (1981). Man, fishes, and the Amazon. Columbia University Press, New York. Stokstad, E. (2003). “Can well-timed jolts keep out unwanted exotic fish?” Science 301, 157-158. Walker, B. (1968). “The fish with the folded mouth,” The Aquarium Series II 1(10), 4-5, 36-43.

ANSRP Bulletin, Vol-04-1, February 2004 9 Risk Assessment, Decision Analysis, and Invasive Species Barry S. Payne and Andrew C. Miller

Williams 2002). Although com- phasizes the need for new data. Introduction prehensive and standardized, the Risk assessment (e.g., Bartell et method is purely qualitative. The world is much more inter- al. (1992); U.S. Environmental More quantitative approaches are connected now than just a few Protection Agency (USEPA) being developed that explicitly decades ago. Consequently, the 1998) and decision-making combine theoretical ecology and frequency of biological invasions methods (e.g., Clemen and Reilly invasive species management (e.g., worldwide has increased. Such 2001) can be used to maximize Bartell and Nair, in press). How- invasions have threatened bio- existing data and strategically ever, rigorously quantitative and diversity, ecosystem structure and guide new data acquisition. data-rich approaches tend to be less function, national economies, and Existing information and knowl- accessible to managers making even human health (Simberloff et edge always should be used to the invasive species decisions. Further- al. 2000). International and maximum extent possible. Higher more, most issues cannot be re- national priorities have made levels of uncertainty accompany solved using scientific information invasive species an urgent issue. less data-rich aspects of risk alone. Data are never as compre- Risk assessment and decision- assessment and decision analysis. hensive or clear as desired, yet in- making methods allow systematic However, decisions, uncertainty, vasive species management deci- yet rapid consideration of invasive and preferences still can be sions still must be made. Experts’ species management options. modeled. Certainly, such methods opinions always remain part of the Risk assessments of invasive can point data acquisition at those process. Also, public and social species are emerging in several aspects of a decision that are least values play important roles. Tools forms. The Aquatic Nuisance clear, most important, and can be of formal decision analysis offer Species Task Force, under the improved with new or more ways of combining scientific authority of the Nonindigenous information. Too often additional information, opinion, and values Aquatic Nuisance Species Act of studies are poorly aimed at critical in risk assessments of invasive 1990 and the National Invasive aspects of uncertainty that, if species (e.g., Maguire, in press). Species Act of 1996, recently better elucidated, can improve This bulletin combines the use developed a qualitative screening decision-making. of risk assessment and decision protocol for application to species With respect to invasive species analysis with existing information of interest (Risk Assessment issues, a great deal of existing and approaches, which should Management Committee 1996). knowledge and understanding of yield more objectively structured This qualitative procedure consid- life history mechanisms, control and quantitative evaluations than ers seven elements (pathway, methods and strategies, can be those presently guided by the survival in pathway, establish- applied without delay. This is not qualitative screening procedure ment, spread, etc.), and then to suggest that all details of the recommended by the Aquatic guides both the assignment of a problem are known, but simply Nuisance Species Task Force. risk level (high, medium, low) to that there is a relevant collective each element and a confidence wisdom. Formal risk or decision statement concerning each risk Improving Invasive analysis methods begin not with a level estimate. Detailed species search for new data, but rather profiles subsequently have been Species Risk systematic organization of exist- published for a few invasive Assessment and ing information and knowledge in species that incorporate brief risk Management a fashion directly tied to manage- assessments that have relied on ment decisions that must be made this qualitative approach (e.g., The process of environmental (e.g., Maguire, in press). Prob- Nico et al. 2001; Courtenay and impact assessment often overem- abilities can be assigned to areas

10 ANSRP Bulletin, Vol-04-1, February 2004 of knowledge that are poorly expert opinion allow limited estimates of the risk of establish- understood. Ultimately, decisions objective information to be used ment and management options to are made that are transparent in a more defensible way than reduce risk. Metapopulation (nothing is hidden in the process) unstructured use of such opinion models (e.g., Akcakaya 2000b; and repeatable. Uncertainties are (Maguire, in press). Litvaitis and Villafuerte 1996; fully displayed. Improvements that aim at Kindvall 2000) and exposure- Decisions about management making qualitative assessments of response models (e.g., Pastorok of invasive species are difficult for invasive species issues more et al. 2001; Bartell and Nair, in reasons typically addressed by quantitative fall mostly in the area press) might help quantify risk formal decision analysis: uncer- of probability modeling. Various and uncertainty in relation to tain outcomes, multiple and approaches or tools hold consider- spatial scale. Retrospective analysis conflicting objectives, and many able promise for application to of life history and physiological interested parties with differing invasive species predictions. For ecology of successful and unsuc- views on both facts and values example, stochastic matrix mod- cessful invaders has allowed (Maguire, in press). Decision els, widely used for viability recognition of attributes that analysis involves modeling of analyses of rare or endangered might predict success of future decisions, uncertainty, and prefer- species (e.g., Akcakaya 1991, invaders (Kolar and Lodge, in ences (Clemen and Reilly 2001). 2000a; Cox and Engstrom 2001; press). Tools of formal decision analysis Maguire et al. 1995; Root 1998) Table 1 summarizes approaches (e.g., decision trees, influence also can be applied to invading that are especially relevant to diagrams, probability trees, values populations, and can address invasive species risk assessments structuring, uncertainty propaga- influential factors such as life and management plans and have tion, and additive utility func- history parameters, catastrophes potential to make such assessments tions) offer much for invasive and environmental fluctuation, and plans more thorough, clear, species risk assessment and and habitat spatial patterns and and quantitative. management. For example, connectivity. Neutral landscape probability modeling integrates models and percolation theory scientific information into the (Gardner et al. 1987) may provide ANSRP Initiative decision process. Nevertheless, greater insight into thresholds for expert judgments often remain species establishment. Discrete- The Corps of Engineers necessary. However, opinions can time versions of classic PDE Aquatic Nuisance Species Re- vary unacceptably among differ- models are applicable to quantita- search Program (ANSRP) is ent groups of experts using essen- tive predictions of spread rates developing risk assessment and tially the same information. (Henson 1998). Spatial scales of decision-making methods for Structured methods of eliciting assessment are probably crucial to invasive species. These methods

ANSRP Bulletin, Vol-04-1, February 2004 11 will structure the analysis of purely qualitative approach different groups of experts, with management alternatives, data, suggested by the the Aquatic different values and biases, to assumptions, and uncertainties, Nuisance Species Task Force follow the same procedure to and result in species management (Risk Assessment Management approximately the same outcome. plans that can be both clearly Committee 1996). This approach Tools of decision analysis are communicated and rapidly imple- is suitable mainly for screening or now applied mostly to business, mented. The success of this early planning studies and is not legal, and industrial efficiency or research depends on development especially rigorous. In contrast is quality control issues, but have of methods that are: a highly rigorous and quantitative great potential for ecological risk ¾ Accessible by managers. approach such as that applied in a assessments, including those ¾ Coherent, transparent, and recent risk assessment of the needed to improve invasive easily reproduced or modified. Asian Longhorn Beetle (Bartell species management. ¾ Able to quantify ecological, and Nair, in press). Such a risk These tools are not constrained economic, and social risks and assessment is difficult to commu- to qualitative assessments. Applied rewards of management options. nicate and may be difficult for to either approach they offer Future bulletins and technical managers to readily use, but means of clarifying choices, notes will present specific appli- admirably aspires to a more highlighting crucial consider- cations of risk assessment and objective and quantitative assess- ations and uncertainties, and decision analysis tools, relying on ment. A third approach, exempli- concisely summarizing conse- the methods listed in Table 1, to fied by Maguire’s (in press) quences of different alternatives. invasive species management application of formal decision The discipline of formal decision issues and decisions. These will analysis to feral pigs in Hawaii analysis offers much to ecologists tend to address particular taxa, yet represents an intermediate option. and engineers dealing with provide examples applicable to Decision analysis tools offer a invasive species risk assessment commonly encountered invasive means of achieving clarity of and management. species issues. communication and ease of use while still incorporating rigorous quantitative modeling components. Literature Cited Future Directions During the next few years, It is noteworthy that govern- relatively qualitative approaches Akcakaya, H. R. (1991). “A method for simulating demographic ments, agencies, and the public are likely to continue to dominate stochasticity.” Ecological Modelling tend to deal with biological invasive species risk assessments. 54, 133-136. invasions at the species level. The coherence of relatively Akcakaya, H. R. (2000a). “Population Thus, development of more qualitative assessments can be viability analyses with demographi- structured and quantitative risk substantially improved using cally and spatially structured mod- els,” Ecological Bulletins 48, 23-38. assessment procedures for one or some of the tools of formal deci- Akcakaya, H. R. (2000b). “Viability a few high priority species is sion analysis. However, those analyses with habitat-based sensible. aspects of decision analysis that metapopulation models,” Population Three important and recent relate to decision, uncertainty, and Ecology 42, 45-53. Bartell, S. M., Gardner, R.H., and approaches to species-specific preference or value modeling are O’Neill, R. V. (1992). Ecological risk approaches have been reviewed also accommodated by quantita- estimation. Lewis Publishers, that are especially instructive. tive methods. When existing data Chelsea, MI. The first is represented by bio- are plentiful, decision analysis can Bartell, S. M., and Nair, S. K. “The accommodate rigorously quantita- establishment of invasive species: An logical profiles with risk assess- interface between risk analysis and ments that were recently devel- tive methods. When supporting theoretical population ecology,” Risk oped for the Snakehead Fish data are scarce and expert judge- Analysis (in press). (Courtenay and Williams (2002)) ment increases in importance, Clemen, R. T., and Reilly, R. (2001). and Black Carp (Nico et al. decision analysis can also accom- Making Hard Decisions with Decision Tools. Duxbury Press, Belmont, CA. 2001)). This approach to risk modate less rigorous quantifica- Courtenay, W. R., and Williams, J. D. assessment strictly follows the tion. The value structuring aspects (2002). Snakeheads (Pisces: reasonably comprehensive yet of decision analysis may allow Channidae): A biological synopsis

12 ANSRP Bulletin, Vol-04-1, February 2004 and risk assessment. USGS Florida Litvaitis, A. J., and Villafuerte, R. Risk Assessment Management Commit- Integrated Science Centers, Centers (1996). “Factors affecting the persis- tee. (1996). “Generic nonindigenous for Aquatic Resource Studies, tence of New England cottontail aquatic organisms risk analysis Gainesville, FL. metapopulations: The role of habitat review process (for estimating risk Cox, J., and Engstrom, R. T. (2001). management,” Wildlife Society associated with the introduction of “Influence of the spatial pattern of Bulletin 24, 686-693. nonidigenous aquatic organisms and conserved lands on the persistence of Maguire, L. A. “What can decision how to manage for that risk),” Report a large population of red-cockaded analysis do for invasive species to the Aquatic Nuisance Species Task woodpeckers,” Biological Conserva- management?” Risk Analysis (in Force, U.S. Government Printing tion 100, 137-150. press). Office: 1998-693-132/62087 Region Gardner, R. H., Milne, B. T., Turner, Maguire, L. A., Wilhere, G. F., and No. 10. Dated October 1996. M. G., and O’Neill, R. V. (1987). Dong, Q. (1995). “Population Root, K. V. (1998). “Evaluating the “Neutral models for the analysis of viability analysis for red-cockaded effects of habitat quality, connectivity broad-scale landscape pattern,” woodpeckers in the Georgia Pied- and catastrophes on a threatened Landscape Ecology 1(1), 19-28. mont,” Journal of Wildlife Manage- species,” Ecological Applications Henson, S. M. (1998). “Leslie matrix ment 59, 533-542. 8(3), 854-865. models as “stroboscopic snapshots” Nico, L. G., Williams, J. D., and Herod, Simberloff, D., Mack, R.N., Lonsdale, of McKendrick PDE models,” Journal J. J. (2001). Black Carp W.M., Evans, H., Clout, M., and of Mathematical Biology 37, 309-328. (Mylopharyngodon piceus): A Bazzaz, F. (2000). “Biotic invasions: Kindvall, O. (2000). “Comparative Biological synopsis and updated risk Causes, epidemiology, global conse- precision of three spatially realistic assessment. USGS Florida Carribbean quences and control,” Issues in simulation models of metapopulation Science Center, Gainesville, FL. Ecology No. 5, Ecological Society of dynamics,” Ecological Bulletins 48, Pastorok, R. A., Bartell, S. M., Ferson, America. 101-110. S., and Ginzburg L. R., ed. (2001). USEPA. (1998). “Final Guidelines for Kolar, C. S., and. Lodge, D.M. “Eco- Ecological modeling in risk assess- Ecological Risk Assessment,” EPA/ logical predictions and risk assess- ment: Chemical effects on popula- 630/R-95/002F, April 1998. ments for alien species,” Science (in tions, ecosytems, and landscapes. press). Lewis Publishers, Boca Raton, FL.

About the Authors:

Dr. Barry Payne is a research Dr. Andrew Miller is a research biologist in the Environmental limnologist in the Environmental Laboratory at the U.S. Army Laboratory at the U.S. Army Engineer Engineer Research and Research and Development Center Development Center (ERDC) in (ERDC) in Vicksburg, MS. He holds a Vicksburg, MS. He holds a B.S. B.A. degree from Olivet College in degree from The University of Michigan, an M.S. degree from Central Texas at Arlington and a Ph.D. Michigan University, and a Ph.D. from from Syracuse University. the University of Louisville. Dr. Miller’s Dr. Payne leads a research research interests include freshwater team that focuses on the physio-logical ecology of molluscs, endangered species, freshwater invertebrates in relation to environmental techniques for creating aquatic habitats, issues associated with water resource projects. His and methods for measuring effects of water resource projects. research focuses on the life history, population Contact: 601-634-2141, [email protected]. dynamics, and physiological ecology and stress tolerance of freshwater molluscs, aquatic habitat and bioassessment procedures, and aquatic ecosystem sustainability and restoration. Contact: 601-634- 3837, [email protected].

ANSRP Bulletin, Vol-04-1, February 2004 13 Aquatic Nuisance Species Research Program

This bulletin is published in accordance with AR 25-30 as one of the information dissemination functions of the Environmental Laboratory of the Engineer Research and Development Center at the Waterways Experiment Station. It is principally intended to be a forum whereby information pertaining to and resulting from the Corps of Engineers’ nationwide Aquatic Nuisance Species Research Program (ANSRP) can be rapidly and widely disseminated to Corps District and Division offices and other Federal and State agencies, universities, research institutes, corporations, and individuals. Contributions are solicited, but should be relevant to the management of aquatic nuisance species, providing tools and techniques for the control of problem aquatic nuisance species in the Nation’s waterways. These management methods must be effective, economical, and environmentally compatible. The contents of this bulletin are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. This bulletin will be issued on an irregular basis as dictated by the quantity and importance of information to be disseminated. Communications are welcomed and should be addressed to the Environmental Laboratory, ATTN: Mr. Glenn G. Rhett, U.S. Army Engineer Research and Development Center (CEERD-EM-W), 3909 Halls Ferry Road, Vicksburg, MS 39180-6199, or call 601- 634-3717.

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