Ichthyomyzon gagei

Southern Brook lamprey
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Cephalaspidomorphi
Order:	Petromyzontiformes
Family:	Petromyzontidae
Genus:	Ichthyomyzon
Species:	I. gagei
Binomial name
Ichthyomyzon gagei C. L. Hubbs & Trautman, 1937

The Southern Brook Lamprey (Ichthyomyzon gagei) is a lamprey found in the southern United States including Arkansas, Louisiana, Mississippi, Alabama, and Georgia. It is a jawless fish with a sucking mouth on one end of it (like a leech.) It can appear to be a small eel, since it is rarely longer than 1ft.

Ichthyomyzon gagei, the Southern Brook lamprey, is a non-parasitic fish native to distinctive aquatic habitats in North America which must be protected in order for this species to continue to thrive. This paper incorporates strategies aimed at protecting the distinct microhabitats of I. gagei from human interference, including pollution and habitat degradation. I. gagei inhabits a geographic area stretching from southern Mississippi, Georgia, and Florida along the Gulf Coast west to Oklahoma and Texas and have been reported as far north as Minnesota and Wisconsin (Beamish 1982) (Cochran 2000). I. gagei inhabits specific types of microhabitats at different morphological phases of its life cycle which consists of two distinct stages. During the larval stage, I. gagei are most often found burrowed into fine sandy creek substrate, but are also occasionally found burrowed among dense clusters of leaves or other aquatic vegetation (Beamish 1982). Ammocoetes, or larval stage lampreys, feed on diatoms and other organic particles collected mainly off the substrate (Gallaway 1977). I. gagei larvae typically undergo metamorphosis after 3 years; however, some ammocoetes stay in the larval stage for an additional year (Beamish 1982). Following metamorphosis from the larval stage, the adult stage is reached. During this phase, I. gagei does not eat; rather, it obtains energy from stored fat reserves collected as ammocoetes and also migrates from slow moving streams to faster moving water with slightly larger pebbles as opposed to fine sandy substrate (Gallaway 1977). This fasting behavior continues until spawning during which adult lampreys come together from late April to early May and spawn in habitats consisting of small, shallow ripples with 17-21°C water (Cochran 2000). Although I. gagei populations have been found to be generally stable, due to the strict habitat requirements during each phase of its life cycle, the quality of each of these habitats must be preserved in order to ensure that the specific niche filled by the southern brook lamprey is protected.

Geographic Distribution

Ichthyomyzon gagei occurs in slow moving rivers and streams from Florida to southern Mississippi, Georgia, and Arkansas along the Gulf Coast west to Oklahoma and Texas (Beamish 1982). I. gagei ranges as far north as Minnesota and Wisconsin. Specifically, I. gagei have been reported to occur in the Chattahoochee river system and the Conecuh river system in Alabama, the Sabine river system in Texas and Louisiana, the Illinois river system in Oklahoma, and the Neches river system in Texas. I gagei was thought to be restricted to the southern United States; however, Becker observed I. gagei in Wisconsin in 1983 (Cochran 2000). I gagei has also been reported to occur as far north as the Spruce river and the Tamarac river in Wisconsin and Minnesota (Cochran 2012). Unpublished findings have also shown that I. gagei inhabits tributaries of Choctawhatchee Bay and the Ochlockonnee river system in Florida, the Chattahoochee river system in Georgia, and the Trinity and San Jacinto river systems in Texas (Dendy 1953).

Ecology

The diet of I. gagei changes as it undergoes metamorphosis during its life cycle from one phase to the next. The diet of larval I. gagei consists mainly of organic detritus. Studies that focused on closely related lamprey species (I. fossor) found that the stomach contents of larval lampreys contained 97.9% organic detritus, 2.12% algae, and 0.09% bacteria (Bowen 1994). After metamorphosis into the adult phase, southern brook lampreys do not feed but rely on stored fat reserves accumulated during the larval stage for energy and nutrients. Studies have found that the digestive tract of the southern brook lamprey actually shrinks and becomes functionally useless as larval lampreys enter the adult stage. I. gagei encounters a wide range of predators in its natural habitat (Gallaway 1977). The eggs of adult lampreys are preyed on by various species of fish and crayfish (Renaud 1997). Southern brook lampreys in the larval stage serve as prey for a wide range of fish and bird species (Renaud 1997). Adult forms of the Southern brook lamprey are preyed upon by larger fish species such as the Northern pike (E. lucius), perch species, the European chub (S. cephalus), and the mudpuppy (N. maculosus). I. gagei shares similar habitats and resources with many species of shiners (Notropis), the longnose dace (Rhinichthys cataractae), Johnny darters (Etheostoma nigrum), and mottled sculpins (Cottus bairdi) (2012. Minnesota Department of Natural Resources). I. gagei fills a very specific niche in the river systems that it occupies. Any daramtic increase in predators or decrease in food availability may result in a decline in the number of I. gagei found in these systems.

Life History

The southern brook lamprey’s life cycle consists of two main stages: larval and adult. During the larval stage, I. gagei inhabits a distinct micro habitat involving relatively slow moving water and a sandy substrate (Gallaway 1977). The consistency of the substrate is vitally important to the Southern brook lamprey because during the larval stage, I. gagei burrows into the substrate using its oral disk as an anchor (Beamish 1994). I. gagei secretes mucous from its body to form a tube leading to the entrance of the burrow and to provide support for the burrow (Beamish 1994).The formation of this larval burrow relies on the composition and size of the substrate available. The combination of both small and large particles and coarse and fine sand grains allow I. gagei to construct a suitable burrow that allows enough water to flow through the burrow to ensure proper respiration (Beamish 1994). The substrate in which larval I. gagei burrow must not contain too many fine silt and clay particles as this would inhibit respiration while too many particles of coarse sand would hinder proper burrow construction (Beamish 1994). The larval stage is complete after approximately three years (Beamish 1982). Following the larval stage, I. gagei undergoes metamorphosis into the adult form. Adult I. gagei are found in crevices and cracks between large rocks in deeper, faster moving water than the habitat occupied during the larval stage (2012. Minnesota Department of Natural Resources). After completing the metamorphosis to adults, I. gagei come together in groups to spawn and, once spawning is complete, the adults die (Williams 2006). Spawning usually occurs between April and May and takes place in another distinct microhabitat consisting of shallow riffle areas with rocky substrate with a water temperature falling between 17°C to 21°C (Cochran 2000). Fecundity of I. gagei averages between 1,000 to 3,264 oocytes (Beamish 1983). Human factors have been found to influence the available habitat for spawning I. gagei. Southern brook lampreys have been recorded using shallow areas under bridges as spawning grounds possibly to help conceal spawning aggregations from visual predators.

Current Management

The Southern Brook Lamprey is currently listed as a species of “least concern” in the United States by CN Red List (Oldsberg 2011). I. gagei has also not been given any status regarding endangerment by the US Federal List or CITES (Oldsberg 2011). Currently there are no conservation plans in action specific to I. gagei nor laws or protected waterways aimed at conservation (Oldsberg 2011). No evidence of biological factors has been found that would contribute to a decline in the abundance or the range of I. gagei, in fact, the biggest threat to I. gagei and closely related species is human induced alteration of suitable microhabitats (Renaud 1997). In order to preserve these specific types of microhabitats used by I. gagei during each phase of the life cycle, habitat preservation and rehabilitation of affected microhabitats are essential (Renaud 1997). Microhabitats used by I. gagei during all life stages must have a certain water temperature, substrate composition, and water quality in order for I. gagei to successfully inhabit and spawn in these areas (Beamish 1994). These factors can be regulated by protecting designated areas from pollution and interfering human activity.

Management Recommendations

In order to monitor both the state of suitable habitats and population dynamics of I. gagei, sampling of both the numbers of individuals present and the conditions of their habitat is needed. I would recommend sampling populations of I. gagei both in regions where they are known to occur and regions where they could potentially occur. Sampling would be most effective if performed twice annually, once in the spring during spawning to find the numbers of spawning adults, and once in the fall to measure the abundance of larval lampreys. At these sampling times, the quality of the habitat from which I. gagei are sampled should also be assessed. The water temperature should be recorded, the composition of the substrate should be noted, and the water quality (pH, salinity, and other water quality measurements) should be analyzed and documented. Congregations of spawning adult lampreys could be easily sampled using Trap or Fyke nets as adult lampreys usually spawn in open, shallow riffle sections of rivers and streams. Non-lethal traps, such as minnow traps, could also be used to sample adult I. gagei populations. Larval populations are harder to sample as I. gagei remains burrowed in the substrate during the larval phase. Snorkeling may be the most effective way to sample these populations. In addition to sampling of populations and habitat quality, certain areas should be protected from human trespassing and pollution to ensure that the range of I. gagei does not become reduced. These protected areas should include some parts of waterways in each state that I. gagei occurs as to keep its current range intact and also in areas where I. gagei has become rare, such as the Tennessee River (Mettee 2004).

Literature Cited

• Beamish, F.W.H. 1982. Biology of the Southern Brook Lamprey. Environmental Biology of Fishes. (7) p.305-320.
• Beamish, F.W.H., Jebbink, J. 1994. Abundance of Lamprey Larvae and Physical Habitat. Environmental Biology of Fishes. (39) p. 209-214.
• Bowen, S.H., Sutton, T.M. 1994. Significance of Organic Detritus in the Diet of Larval Lampreys in the Great Lakes Basin. Canadian Journal of Fisheries and Aquati Sciences. (51). p. 2380-2387.
• Cochran, P.A., Fago, D., Lyons, J. 2000. Wisconsin Fishes 2000: Status and Distribution. http://www.seagrant.wisc.edu/greatlakesfish/lyons.html. 18 November 2012.
• Cochran, P.A., Pettinelli, T.C. 2012. Northern and Southern Brook Lampreys (Ichthyomyzon fossor and Ichthyomyzon gagei) in Minnesota. Minnesota Department of Natural Resources. http://files.dnr.state.mn.us/eco/nongame/projects/consgrant_reports/1987/1987_cochran.pdf. p. 1-12.
• Dendy, J.S., Scott, D.C. Distribution, Life History, and Morphological Variations of the Southern Brook Lamprey, Ichthyomyzon gagei. Copeia. (3). p. 152-162.
• Gallaway, B.J., Moshin, A.K.M. 1977. Seasonal Abundance, Distribution, Food Habits, and Condition of the Southern Brook Lamprey, Ichthyomyzon gagei, In an East Texas Watershed. The Southwestern Naturalist. (22) p.107-114.
• Mettee, M. F., O’Neil, P.E., Pierson, J.M. 2004. Fishes of Alabama and Mobile Basin. http://www.outdooralabama.com/fishing/freshwater/fish/other/lamprey/so/ . 14 November 2012.
• Oldsberg, R. 2011. Ichthyomyzon gagei. http://animaldiversity.ummz.umich.edu/accounts/Ichthyomyzon_gagei/ 18 November 2012.
• Renaud, C.B. 1997. Conservation Status of Northern Hemisphere Lampreys (Petromyzontidae). Journal of Applied Ichthyology. (13) p. 143-148.
• Williams, J., Zellers, R.2006. Arkansas Fish .p10. www.agfc.com/resources/Publications/ar_fish.pdf. 14 November 2012.

2012.

• Minnesota Department of Natural Resources. http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=AFBAA01040. 18 November 2012.

References

• IUCN 2007. 2007 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 28 September 2007.
• Northern and Southern Brook Lampreys (Ichthyomyzon fossor and Ichthyomyzon gagei)in Minnesota.^[1]
• Metamorphosis of the Southern Brook Lamprey.^[2]
• Distribution, Life History, and Morphological Variations of the Southern Brook Lamprey, Ichthyomyzon gagei.^[3]
• Conservation Status of Northern Hemisphere Lampreys (Petromyozontidae).^[4]
• An Analysis of Tennessee's Jeopardized Fish Taxa.^[5]