Lake trout, scientifically known as Salvelinus namaycush, is a remarkable species of freshwater char that thrives predominantly in lakes across northern North America. Renowned by various names such as mackinaw, namaycush, lake char, touladi, togue, and grey trout, this remarkable fish holds significance both as a prized game fish and a delectable food source. In this comprehensive article, we delve into the taxonomy, range, description, life history, and commercial aspects of lake trout, showcasing its unique attributes and highlighting why it deserves recognition in the realm of North American freshwater fishing.
Lake trout, belonging to the subgenus Cristovomer, represents a distinct taxonomic lineage within the Salvelinus genus. It stands as the sole member of this subgenus, displaying a more derived evolutionary position when compared to the subgenus Baione. The latter encompasses the brook trout (S. fontinalis) and silver trout (S. agasizii), forming the basal clade of Salvelinus. Therefore, the lake trout showcases a distinctive position within the broader framework of the Salvelinus genus.
From a zoogeographical perspective, lake trout possess a relatively narrow distribution, primarily inhabiting the northern regions of North America. Their native range spans across Canada, Alaska, and to a lesser extent, the northeastern United States. However, lake trout have also been intentionally introduced into non-native waters throughout North America, as well as various parts of Europe, South America, and select regions in Asia. Notably, in Yellowstone National Park, the introduction of lake trout into Yellowstone Lake during the 1980s has labeled them as an invasive species, posing ecological challenges to the park's natural balance.
Lake trout holds the distinction of being the largest among the char species. It boasts an impressive record weight of nearly 102 pounds (46 kg) when netted, measuring around 50 inches (130 cm) in length. While fish weighing 15–40 pounds (6.8–18.1 kilograms) are relatively common, the average length of lake trout falls within the range of 24–36 inches (61–91 centimeters). An exceptional catch, recognized by the International Game Fish Association (IGFA), weighed 72 pounds (33 kg) and was reeled in from Great Bear Lake in 1995, measuring an impressive 59 inches (150 cm) in length.
Lake trout thrive in cold, oxygen-rich waters, typically occupying the pelagic zone during the period of summer stratification in dimictic lakes. Their preferred habitat lies at depths of 20–60 meters (66–197 feet), providing them with optimal conditions for sustenance and survival. As a species, lake trout exhibit slow growth rates and delayed maturation, characteristics commonly associated with oligotrophic waters. Unfortunately, their populations are highly susceptible to overfishing, and many native lake trout communities have suffered severe damage due to a combination of excessive hatchery stocking and overharvesting. Additionally, acidification poses a significant threat to lake trout, adversely impacting their populations through direct harm and the subsequent reduction of prey populations, including Mysis relicta.
Within the lake trout species, three distinct subspecies have been identified: the common lake trout (Salvelinus namaycush namaycush), the siscowet lake trout (Salvelinus namaycush siscowet), and the lesser-known rush lake trout (Salvelinus namaycush huronicus). Notably, some lakes lack pelagic forage fish during the summer stratification period, leading lake trout to adopt a planktivorous feeding strategy. In such environments, lake trout populations thrive abundantly, albeit with slow growth and maturation at relatively small sizes. Conversely, in lakes hosting deep-water forage, lake trout assume a piscivorous diet, resulting in accelerated growth, larger size upon maturation, and reduced population density. Regardless of their feeding strategy, the biomass density of lake trout remains fairly consistent across similar lakes, irrespective of whether the populations are planktivorous or piscivorous.
Lake Superior serves as a notable habitat where both the common lake trout (S. n. namaycush) and the siscowet lake trout (S. n. siscowet) coexist. Common lake trout generally inhabit shallower waters, while their siscowet counterparts prefer deeper regions of the lake. These two varieties exhibit distinct physical characteristics, with common lake trout being slimmer, earning them the nickname "lean" lake trout, while siscowet lake trout possess a relatively plump physique. Over the years, the siscowet population has faced significant decline due to the extirpation of their coregonine prey and overexploitation. However, successful recovery efforts have been witnessed since the 1970s, aided by effective control of sea lampreys (Petromyzon marinus) and the imposition of commercial fishing restrictions. The sustainability of Lake Superior's lake trout population is dependent on continued lamprey control measures.
Lake trout has been observed to hybridize naturally with the brook trout, resulting in unique hybrids referred to as "splake." While these hybrids are typically sterile, self-sustaining populations have been documented in various lakes. Additionally, hatcheries engage in artificial propagation of splake, subsequently stocking them in lakes to enhance sport-fishing opportunities and promote biodiversity.
Commercial fishing of lake trout in the Great Lakes region enjoyed prosperity until the advent of lampreys, overharvesting, and pollution, which severely depleted their stocks. However, commercial fisheries still persist in certain areas of the Great Lakes, as well as smaller lakes across northern Canada. Notably, Lake Superior permits Ojibwe tribes to engage in lake trout fishing under the regulations established by the Great Lakes Indian Fish & Wildlife Commission (GLIFWC), in accordance with various treaties.
The specific epithet "namaycush" finds its roots in the term "namekush," utilized in some inland Southern East Cree communities to refer to this particular species of fish. Within the East Cree language, similar variations such as kûkamâs[h], kûkamâw, and kûkamesh can be found. Cognate words in Ojibwe, another indigenous language, include "namegos" for "lake trout" and "namegoshens" for "rainbow trout," with the latter directly translating to "little lake trout." These linguistic connections demonstrate the cultural significance attached to lake trout among indigenous communities.