The chestnut lamprey is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of lamprey

Lamprey

Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers...

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Abstract

The following is a management plan description for the Chestnut Lamprey (Ichthyomyzon castaneus). This lamprey is one of the North American native parasitic species of lamprey, and can be found in rivers along the eastern United States and Canada. During their early years the larval lampreys settle in the bottom of slow flowing water and filter feed on desmids, diatoms, and protozoans. As adults, these animals attach and feed off a host, such as trout. Recent research gives reason to believe that species including the Chestnut lamprey (I. castaneus) remain attached to their host during the winter. As with many lampreys the Chestnut Lamprey (I. castaneus) breeds only once during it’s lifetime, producing thousands of eggs (Lanteigne, 17). Many attempts have been made to control the spread of the lamprey. Keeping track of these parasite numbers requires traps or aid from local fishermen. In some areas of Canada numbers of many lamprey species are measured by observing the scars on caught fish. In some areas the Chestnut Lamprey (I. castaneus) is considered an invasive species and steps are being taken to control their numbers. Since lamprey numbers can spread quickly careful management is required. One possible way to manage these parasites in the future is egg collection where lamprey activity is high. Any diseases that can be transmitted through feeding must be monitored in order to prevent dwindling fish numbers and human health problems. The Chestnut Lamprey (I. castaneus) must be monitored, while ensuring their numbers do not drop too low.

Geographic Distribution

One of the first known sightings of the chestnut lamprey (I. castaneus) was in Canada in 1898 by E. S. Thompson. This discovery supports the assumption that the chestnut lamprey is a native species to North America The range of the chestnut Lamprey (I. castaneus) extends from Lake Winnipeg and the Hudson bay down the Mississippi river to the Central and Eastern United States, this includes any large lakes or reservoirs where large host fish are present. In Canada, studies indicate that this species of lamprey has been found in Saskatchewan, Manitoba, Ontario, and Quebec. It is possible that the lamprey has expanded its range from Canada to the Eastern United States due to remaining attached to a migrating fish species. Another hypothesis is the animals must travel downstream in order to cope with changing temperatures during the season. While the exact method of migration is unknown, evidence of the chestnut lamprey’s (I. castaneus) increased range is present.

Ecology

The Chestnut lamprey (I. castaneus) can be distinguished by a maximum length of around 345 millimeters, 325 millimeters in Canada, with dark grey to olive skin color, blue-black after spawning, and with five to eight bicuspid laterals around its mouth. Adults are parasitic and feed on larger species of fish to support their body. It was widely presumed that this fish did not feed during the winter, but recent research in Wisconsin has revealed some lampreys remain attached to their host during the winter months; one fisherman caught a sturgeon with a chestnut lamprey (I. castaneus) still attached. If these animals have learned to survive in cold temperatures their lifespan may increase. Observation of this species has revealed that they are primarily a nocturnal animal and they seek out shade during daylight. This intolerance of light may cause difficulty for future management practices. These lampreys are beneficial to the rivers and lakes, due to their natural control of local fish populations. The loss of these animals can lead to overpopulation of another fish species. One potential problem that humans can have on these animals is pollution; by polluting the waters young lamprey that must filter feed to survive will have trouble if any large particles block their mouth filters.

Life History

During the egg stage of the lamprey’s life, it is most vulnerable to predators that prefer to eat fish eggs. Predation by other fish helps keep the lamprey numbers under control. When the lamprey has hatched from its egg into the larvae stage, it is limited to pools or backwater areas with a sand or sandy mud bottom. The young lampreys filter feed for food for around five to seven years until they are large enough to attach themselves to a host species. Spawning of this species of lamprey occurs from June to July when the animals are around seven to nine years old and migrate to tributaries to protect the young from predators, though most spawning activity has been observed in mid-June. During the mating process, one female would begin moving rocks from a suitable area for eggs; afterward she attaches herself to a rock while hopeful males attach to her and stroke her tail attempting to mate. The eggs are then covered with a rock, presumably to shade the young lampreys at birth and to keep any predators from devouring the young. After studying a number of male lampreys, researchers have discovered that the males have the ability to produce 15a-hydroxilated steroid, which some believe drives the male hormones for mating. The steroid hormome may explain why so many males gather around one female during the mating season. As with most lampreys, the chestnut lamprey (I. castaneus) only mates once during its entire life and dies shortly after. Adult lampreys put all their energy into ensuring a future for the next generation. With this species only producing eggs once in a lifetime and the potential predators, there is a small chance of an overpopulation of chestnut lampreys (I. castaneus).

Current Management

Findings of the animals clinging to game fish have raised questions of how to control the species numbers. Unlike its sea lamprey (Petromyzon marinus) the chestnut lamprey (I. castaneus) is not considered an invasive species; therefore not much attention has been given to management. During the winter research in Wisconsin scientists observed species of game fish, such as lake sturgeon (Acipenser fulvescens), that were caught by area spear fishermen for any lampreys or scars. Practicing this method allows wildlife officials to keep track of lamprey activity. If the study is done on migratory fish, the lamprey wound could have been the result of a lamprey from another North American area and the results may become bias. One study of chestnut lampreys (I. castaneus) in Michigan involved using traps baited with live white suckers (Catostomus commersoni) and lampreys were caught in every month except January. These studies led to the conclusion that as long as the lamprey’s temperature remained high the animals can continue to feed during the winter. If the host fish was observed as well, the possibility of a lamprey receiving higher body temperature from another fish can be studied. Local Michigan fisherman have also reported of chestnut lampreys (I. castaneus) swimming up to a hole he cut through the ice in a portion of the impounded river. Reason for this action taken by the lampreys has yet to be determined, but this may be the result of desperation for warmer temperatures or food. Even though much attention has been given to the sea lamprey (P. marinus) all species of lamprey, including the chestnut, must be observed in order to maintain a stable environment.

Management Recommendations

Population of Chestnut Lamprey (I. Castaneus) must be continuously monitored to insure this parasitic species does not become a threat to game fish or any endangered species. Continuing observation with aid from area fisherman will aid in keeping track of the population. This animal’s sensitivity to light might result in planning difficulties for nocturnal observation. Using underwater cameras with night vision capabilities will help in observing their activities. Research on lamprey attachments during the winter months may reveal new adaptations and benefits these animals have acquired. Some researchers have hypothesized that feeding during the winter months allows the lampreys to travel to their breeding grounds easily or improve their chances of avoiding winter hazards like ice scourging. Feeding during the winter months may result in a number of adaptations. Because they are not an invasive species, like their sea relatives, there is not a need for lampricide or any kind of control. The population numbers must still be continuously monitored in order to ensure that neither the lampreys nor their host fish decline in numbers. With the damming of rivers and the majority of the population near the Mississippi river, the spread of the lamprey is likely to be cut off from the rest of the United States. Captured lampreys can be observed in order to find out whether or not any diseases are transmitted from lamprey to host fish. While there has been no indication of virus transmission by the chestnut lamprey (I. castaneus) there is a chance of disease that has yet to be discovered. Continuous monitoring of the chestnut lamprey (I. castaneus) is needed to better understand its importance to the enivironment and its affect on the fish it lives off.