One of the first known sightings of the chestnut lamprey 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 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 increased range is present.
The chestnut lamprey can be distinguished by a maximum length of around 345 millimetres (13.6 in), 325 millimetres (12.8 in) 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 still attached. Observation of this species has revealed that they are primarily a nocturnal animal and they seek out shade during daylight. These lampreys may be beneficial to the rivers and lakes, due to their natural control of local fish populations. Human populations can pose threats to these animals through pollution, siltation, and dredging. Larval lamprey that must filter feed for numerous years and are vulnerable to changes in their environment during this time. For instance, larval lampreys will perish if large particulate regularly blocks their mouths because they are filters.
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 hormone may explain why so many males gather around one female during the mating season. As with most lampreys, the chestnut lamprey 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.
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 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 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 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 all species of lamprey, including the chestnut, must be observed in order to maintain a stable environment.
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- Bryan, Mara B.; Bayer, Jennifer; Close, David A.; Li, Weiming; Robinson, T. Craig; Semeyn, Jesse; Young, Bradley A. (2006). "Comparison of synthesis of 15α-hydroxylated steroids in males of four North American lamprey species". General and Comparative Endocrinology. 146: 149–156. doi:10.1016/j.ygcen.2005.11.003.