The brown lamprey, or Ichthyomyzon castaneus, is a fascinating but unpopular species among sport fishermen in Quebec. Unlike its more invasive cousins like the sea lamprey, the brown lamprey is native and plays an important ecological role. It is mainly found in the rivers and lakes of southern Quebec, particularly in the watersheds of the Saint Lawrence and Outaouais rivers. Its interest lies more in scientific and ecological study rather than sport fishing, as it does not provide a notable fight. However, it is fascinating for those interested in aquatic biodiversity and species interactions. Its distribution is quite localized, making it a species to observe rather than capture for pleasure.

The brown lamprey is distinguished by its elongated, eel-like body, which is scale-less, making it smooth to the touch. Its color ranges from light brown to dark brown, often with yellowish highlights on the ventral side. Its mouth is circular and suction-like, equipped with keratinized teeth that allow it to attach to its hosts, as it is partially parasitic. The dorsal fins are double and located toward the back of the body, while the caudal fin is rounded. Young lampreys, called ammocoetes, are lighter in color and live buried in the substrate. In adulthood, the differences between males and females are minimal, although during the spawning period, males sometimes develop papillae on their heads.

The brown lamprey is primarily found in the rivers and lakes of southern Quebec, particularly in the watersheds of the Saint Lawrence and Outaouais rivers. It is relatively abundant in moderate-flowing waterways with sandy or muddy bottoms. Unlike the sea lamprey, it does not migrate to saltwater and remains confined to freshwater habitats. Its range is limited compared to other fish species, making it less visible to the average fisherman.

The brown lamprey prefers freshwater with a moderate current, often found in rivers and streams with sandy or muddy bottoms. It likes well-oxygenated waters and can be observed in areas where aquatic vegetation is abundant, as ammocoetes bury themselves there to feed. The species tolerates some turbidity in the water and can be found at depths ranging from a few centimeters to several meters, depending on the bottom structure and food availability.

The reproduction of the brown lamprey occurs in spring when the water temperature reaches around 10 to 18 °C. Adults migrate upstream to spawning areas, where males build a nest by moving stones with their mouths. The female lays her eggs there, which are then fertilized by the male. Ammocoetes, the young lampreys, hatch after a few weeks and burrow into the substrate where they feed on suspended organic matter. They stay there for several years before metamorphosing into adults and becoming partially parasitic. Spring: Spawning → Summer: Ammocoete development → Fall: Growth → Winter: Hibernation in the substrate.

The brown lamprey is generally solitary, except during the spawning period when it gathers for reproduction. It is not particularly territorial, but ammocoetes may group in favorable areas to feed. This species is sensitive to changes in light, preferring shaded waters or low-light times to move. It reacts moderately to variations in atmospheric pressure and temperature, seeking refuge in the substrate during unfavorable conditions.

The dietary habits of the brown lamprey vary according to its life stage. Ammocoetes feed on suspended organic matter and microorganisms, filtering water through their gills. Adults, now partially parasitic, attach to other fish to consume their blood and bodily fluids. This parasitic behavior is more frequent in spring and summer when host fish activity is at its peak. In fall and winter, feeding activity decreases, and it can survive by reducing its energy needs.

The brown lamprey is mainly active in spring and summer when water temperatures are ideal for reproduction and feeding. In spring, it migrates to spawning areas, and this is the best time to observe it. In summer, it actively seeks hosts to feed on. During fall, its activity slows down as it prepares for winter by reducing its metabolism. In winter, it remains buried in the substrate, entering a state of semi-hibernation. The best times for observation are early morning or late afternoon, especially on overcast or rainy days, as it avoids direct sunlight.

Although the brown lamprey is not a target for traditional sport fishing, if you wish to observe or study it, use lures that mimic host fish to attract its attention. In clear water, favor natural colors like brown and green. In murky water, opt for brighter shades. Surface lures can help locate host fish, thus facilitating the observation of lampreys.

For observation in the wild, use a light rod, 6 to 7 feet long, with a fast action for precise control. An open-faced reel with a 6 to 8 lb line is sufficient for general conditions. If you're using nets for scientific sampling, choose fine mesh to capture ammocoetes without harming them. Hooks are not necessary for this species, except for studying host fish.

If you capture a brown lamprey for study, handle it carefully. Use wet gloves to avoid damaging its delicate skin. Return it to the water immediately after observation to minimize stress. For photography, keep it in the water as much as possible and only take it out briefly.

The main predators of the brown lamprey include carnivorous fish such as pike and walleye. Aquatic birds, such as herons and ospreys, may also feed on it when it is close to the surface or shores.

The brown lamprey is not considered threatened in Quebec, but it plays a crucial role in the ecosystem. Its management focuses on the conservation of its natural habitats and monitoring its populations. There is no specific regulation for its fishing, as it is not targeted for sport. Catch and release is recommended for any accidental capture.