From 1942 to 1972, no deepwater sculpin were captured in Lake Ontario so far as is known. Between 1972 and 2002, only six have been caught there, despite continued government mandated trawls aimed at determining the extent of their extirpation from the Great Lakes. All six were caught in Canadian waters, three in 1972 and three in 1996 (Black et al. 1981).
Despite their disappearance from Lake Ontario and steady decline in the other Great Lakes, the United States Fish and Wildlife Service (USFWS) does not list deepwater sculpin as even being a species of concern for the Great Lakes region (NYSDEC, 2002). They are however, listed by the New York State Department of Environmental Conservation and the Canadian government as being threatened and monitored (NYSDEC, 2002, COSEWIC, 2001). Research efforts are underway to determine how many deepwater sculpin are left in the Great Lakes and the other deep water lakes of Canada. The decline of deepwater sculpin may have been linked to the introduction of two non-native species in the Great Lakes: alewives and rainbow smelt. Both of those fish species eat deepwater sculpin eggs and compete with them for food.
There are currently two known threats to the continued survival of deepwater sculpin. The first is the loss of the amphipod Pontoporeia from the majority of the bottom of Lake Michigan. As one of their main food sources, the loss of this important food source will substantially impact the recruitment of deepwater sculpin. The second threat is the presence of invasive round gobies in off-shore waters that overlap the distribution of spawning sites for deepwater sculpin. Round gobies are fierce fighters, and often out-compete sculpin species in the same area (Jude et al., 2002).
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Predators of deepwater sculpin include lake trout (Salvelinus namaycush) and burbot (Lota lota) (McAllister et al., 1979). By the early 1950s, lake trout and burbot were nearly extirpated from Lake Ontario after falling victim to over-fishing and sea-lamprey parasitism. Shortly after the population declines of these two keystone predators, deepwater sculpin disappeared from Lake Ontario for almost the next 50 years. It is believed that the loss of these keystone predators resulted in huge disruptions to this freshwater fish community and deep population declines of sculpin.
Anti-predation mechanisms have barely been studied in deepwater sculpin. The prickles on the top of the body and the four spines on top of the head may serve as deterrents to predators. In addition, the fact that deepwater sculpin spend most of their time under conditions few other species can withstand, limits their interaction with potential predators.
Known Predators:
Deepwater sculpin have been known to reach 9 inches (23 cm) in length, although the average is between 2 and 5 inches (5 to 10 cm). The body is slender with a large flattened head and blunt snout with a large mouth. Eyes are set close together on top of the flattened head. There are four preopercular spines, the two upper ones so close together as to be mistaken as one (Brandt, 1986). There are two dorsal fins, the second significantly larger than the first. In mature males, this second dorsal fin often overlaps the base of the caudal fin, and is one of the distinguishing characteristics of deepwater sculpin (Page et al., 1991). Although deepwater sculpin have no scales, they do have prickles on top of the body.
Coloration is largely characteristic of what one would expect in a habitat with very little if any light. The dorsal region is gray-brown, while the ventral is several shades lighter. The top and sides are speckled and there are thin oval shaped-marks dotting the back (Page et al., 1991).
Sexual dimorphism is apparent only in sexually mature individuals. The largest fish tend to be the most sexually dimorphic in the development of the fins. “In order of decreasing magnitude, it is most pronounced in the second dorsal, pelvic, anal, first dorsal, pectoral, and caudal fins” (Jacoby, 1953).
Range length: 23 (high) cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
The general method for determining age has been to count the annual ‘rings’ on the otolith. According to data collected in the summer of 1973, the maximum age for deepwater sculpin in the Great Lakes was seven years. More recent research suggests that alternating clear and dark bands on the otolith reflect rapid growth during the summer and much slower growth during the winter.
Typical lifespan
Status: wild: 7 (high) years.
During their first year, deepwater sculpin are pelagic, rather than benthic organisms. They live in the water column feeding on pelagic phytoplankton and small invertebrates. As they age they undergo physiological changes and become benthic organisms.
Adult deepwater sculpin are generally found in waters deeper than 20 meters and are particularly abundant between 70 and 90 meters. In Lake Superior they have been found at depths of 407 meters. Although all adults are benthic, the largest fish of a population are found in the deepest waters. Deepwater sculpin live only in cold water, 40 degrees Celsius or less.
Due to their benthic habitat, deepwater sculpin spend their adult lives in complete darkness where the temperature ranges between 3 and 6 degrees Celsius. At this depth, the bottom substrate is fine particulate matter, mud and clays of a uniform size. When they were much more plentiful, they could also be found on substrates consisting of combinations of sand, silt, clay and mud intermixed with rocks, coal and cinders. During one study in 1952, they were found in the waters off Munising, Michigan, on thick beds of aquatic vegetation (Jacoby 1953).
Range depth: 20 to 407 m.
Average depth: 70-90 m.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: pelagic ; benthic ; lakes and ponds; rivers and streams
Although there are similar Nearctic and Palearctic species, as well as similar European freshwater species, deepwater sculpin, Myoxocephalus thompsonii are limited to North America. Once abundant in the Great Lakes and most deep lakes of Canada (especially Nipigon in Ontario, Great Slave in Manitoba, Waterton in Alberta, and Great Bear in the Northwest Territories), the geographic range of deepwater sculpin is rapidly shrinking.
At present, deepwater sculpin are plentiful in lakes Huron, Michigan and Superior, and rare in Ontario and Erie. Despite their deepwater habitat requirements, they are also found occasionally in the inland waterways that connect the Great Lakes, such as the St. Claire River.
Biogeographic Regions: nearctic (Native )
Data on food preference is based on stomach contents of captured fish. The most prominent food item in all specimens examined was the amphipod Pontoporeia hoyi. Also often consumed were opossum shrimp, Mysis relicta (Black et al., 1981). An overwhelming proportion of the diet of large deepwater sculpins is made up of P. hoyi compared to the diet of smaller sculpins which feed fairly equally on P. hoyi and M. relicta (Brandt, 1986 and Wojcik et al., 1986).
Animal Foods: aquatic crustaceans
Primary Diet: carnivore (Eats non-insect arthropods)
Deepwater sculpin are the number one prey item for lake trout (Salvelinus namaycush), a once widely available, commercially harvested fish found in all the Great Lakes. Although a concerted effort has been made since 1950 to restore lake trout populations to the Great Lakes, success has been spotty and limited. Natural reproduction of lake trout is currently occurring on a widespread basis only in Lake Superior. In Lakes Huron, Michigan and Ontario, only limited natural reproduction has occurred. Of these three, only in Lake Huron do the larval fish survive into adulthood (USGS, 2001).
Due to their role as key forage items for lake trout and burbot and because M. relicta and P. hoyi are their main food sources, deepwater sculpin are thought to be responsible for facilitating the majority of the energy movement from benthic organisms to higher trophic levels. This obscure but critical role is likely to have far ranging influences on the overall productivity of the entire Great Lakes ecosystem.
It may be that competition between sculpin species contributed to a decline in deepwater sculpin. Data on competitive feeding habits of various sculpin species are limited, however, juvenile deepwater sculpin and slimy sculpin (Cottus cognatus) have over-lapping food preferences and habitat use, creating the potential for competition. There is also evidence that slimy sculpin prey on the eggs and larvae of deepwater sculpin.
Deepwater sculpin currently are not seen as having any commercial value or economic importance on a local, national or international scale. They are important members of the native Great Lakes and northern lakes ecosystem.
There are no known negative affects of deepwater sculpin on humans.
Although research is ongoing, due to the deepwater sculpin’s inaccessible habitat, there is little concrete documentation of their developmental stages.
Ontogenetic changes occur during the deepwater sculpin’s first year of life, transforming them from pelagic larva to benthic organisms as juveniles, and eventually as adults (Bruch, 1986).
Size increase is greatest in the first year. During the second and third years of life, size increase is typically three-fifths that of the first year. In successive years, the length increase was less than two-fifths that of the first year. On the other hand, weight gain is inversely related to length increase. Deepwater sculpin put on the least weight in the first year, despite the greatest gain in length. In successive years, as elongation slows, weight gain increases (Selgeby, 1988). The largest fish tend to be the oldest.
Deepwater sculpin live in very dark environments. Little is known about their modes of perception and how they might communicate, but it is likely that they use tactile and chemical perception in their dark habitat.
Perception Channels: tactile ; chemical
Because it is so difficult to study deepwater sculpin, little is known about their mating systems.
Sexual maturity does not occur during the first growing season. Instead, after becoming benthic organisms, gonads begin to develop during the second half of the second growing season. Even at this rate, less than half of this age group is fully mature by fall of their second year. The remainder of the fish become fully sexually mature by the fall of their third year (Selgeby, 1988).
Deepwater sculpin spawn during late fall and winter in the Great Lakes and during summer and early fall in Canada (Black et al., 1981). The average number of eggs found in the ovaries of ripe females (females who are just about to lay eggs) is 481. As in other aspects of sculpin life, size does matter and the largest females have the greatest numbers of eggs. Eggs range in size from 1.5 to 2.2 mm (Jacoby, 1953). In the Great Lakes the eggs hatch at the same time that the ice on the lakes begins to break up.
Breeding interval: Breeding is likely to occur each year.
Breeding season: Breeding occurs in late fall and winter.
Average number of offspring: 481.
Range age at sexual or reproductive maturity (female): 2 (low) years.
Average age at sexual or reproductive maturity (female): 3 years.
Range age at sexual or reproductive maturity (male): 2 (low) years.
Average age at sexual or reproductive maturity (male): 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Like other sculpin species, male deepwater sculpin build nests and guard the eggs.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male)
The deepwater sculpin (Myoxocephalus thompsonii) is a species of freshwater fish in the family Cottidae of order Scorpaeniformes.[2][1] It is a glacial relict, native to a limited number of deep, cold lakes in Canada and the United States.[1][3][4]
The deepwater sculpin was first described in 1851 by Charles Frédéric Girard[2] under the name Triglopsis thompsonii.[5] The description was based on specimens obtained by Spencer Fullerton Baird for the Smithsonian Institution from the stomachs of Burbot caught by fishermen on Lake Ontario.[6] The name Triglopsis referred to its resemblance to the Piper gurnard.[7] The specific epithet honored fellow naturalist Rev. Zadock Thompson of Burlington, Vermont.[6]
The similarity between this species and the Fourhorn sculpin led to some taxonomic discussion. Some authors considered it a subspecies (Myoxocephalus quadricornis thompsonii), while other authors maintained it as a species within the same genus (Myoxocephalus thompsonii).[3] Mitochondrial DNA analysis was able to establish that the two species were distinct while providing additional support for the proposal that the deepwater sculpin evolved from the fourhorn sculpin during the early Pleistocene era.[3]
The deepwater sculpin is a small fish on average between 51–76 millimetres (2.0–3.0 in) in length[3] Its body is generally flattened in shape and tapers from the head to the tail.[3] It does not have true scales.[3] Spines are present on the body and fins.[3] The skin is mottled green, gray and brown on the back and whitish underneath.[3][8] The deepwater sculpin can be distinguished from other freshwater sculpins in its range by a distinct gap between the two dorsal fins.[5][3][8] It is most similar in appearance to the fourhorn sculpin, a fish found in salt and brackish water in the arctic but lacks the four bony spines found on the head of that species.[9]
The deepwater sculpin is found from the Gatineau through the Great Lakes, Manitoba, and Saskatchewan to the Great Slave and Great Bear Lakes. It is also found in Waterton Lake within Waterton Lakes National Park and Glacier National Park.[3][10] Within its range, it is limited to deep, well oxygenated lakes with ties to former Wisconsinan glacial lakes or the Champlain Sea.[4]
The deepwater sculpin inhabits the demersal zone.[2] It prefers water temperatures that remain less than 5 °C (41 °F).[3] In lakes in the southern part of its range, it has been observed only in deep water where the water temperature remains cold year round.[3]
The deepwater sculpin feeds primarily on small crustaceans[2] Mysis diluviana and Diporeia.[3] They will also take chironomid larvae.[3][8] Zooplankton are the likely food of the larval stage.[3]
Deepwater sculpin eggs hatch from November to August, peaking in March. Larvae are initially pelagic, staying in the water column above the reach of their adults. Beginning in July, larvae that have grown to 2 centimetres (0.79 in) go through metamorphosis and settle to the bottom.[8] Fish are thought to reach maturity at three years for females and two years for males.[3]
Deepwater sculpin are a significant food source for other fish including lake trout (Salvelinus namaycush) and burbot (Lota lota).[3][8] They are an intermediate host for the parasites Bothriocephalus cuspidatus, and Proteocephalus sp. which also are found in the crustaceans they eat and the fish species that prey on them.[8]
The deepwater sculpin is an indicator species for the health of the deepwater communities in the lakes where it occurs.[3] It is of special interest to those interested in zoogeography.[3][4]
The deepwater sculpin is classified as of Least Concern by the IUCN based on the apparent stability of the population.[1] In Canada, it is considered a species at risk under the Species at Risk Act. Threats include habitat loss, lake eutrophication, invasive species, and water pollution.[3]
The deepwater sculpin (Myoxocephalus thompsonii) is a species of freshwater fish in the family Cottidae of order Scorpaeniformes. It is a glacial relict, native to a limited number of deep, cold lakes in Canada and the United States.
The deepwater sculpin was first described in 1851 by Charles Frédéric Girard under the name Triglopsis thompsonii. The description was based on specimens obtained by Spencer Fullerton Baird for the Smithsonian Institution from the stomachs of Burbot caught by fishermen on Lake Ontario. The name Triglopsis referred to its resemblance to the Piper gurnard. The specific epithet honored fellow naturalist Rev. Zadock Thompson of Burlington, Vermont.
The similarity between this species and the Fourhorn sculpin led to some taxonomic discussion. Some authors considered it a subspecies (Myoxocephalus quadricornis thompsonii), while other authors maintained it as a species within the same genus (Myoxocephalus thompsonii). Mitochondrial DNA analysis was able to establish that the two species were distinct while providing additional support for the proposal that the deepwater sculpin evolved from the fourhorn sculpin during the early Pleistocene era.
The deepwater sculpin is a small fish on average between 51–76 millimetres (2.0–3.0 in) in length Its body is generally flattened in shape and tapers from the head to the tail. It does not have true scales. Spines are present on the body and fins. The skin is mottled green, gray and brown on the back and whitish underneath. The deepwater sculpin can be distinguished from other freshwater sculpins in its range by a distinct gap between the two dorsal fins. It is most similar in appearance to the fourhorn sculpin, a fish found in salt and brackish water in the arctic but lacks the four bony spines found on the head of that species.
The deepwater sculpin is found from the Gatineau through the Great Lakes, Manitoba, and Saskatchewan to the Great Slave and Great Bear Lakes. It is also found in Waterton Lake within Waterton Lakes National Park and Glacier National Park. Within its range, it is limited to deep, well oxygenated lakes with ties to former Wisconsinan glacial lakes or the Champlain Sea.
The deepwater sculpin inhabits the demersal zone. It prefers water temperatures that remain less than 5 °C (41 °F). In lakes in the southern part of its range, it has been observed only in deep water where the water temperature remains cold year round.
The deepwater sculpin feeds primarily on small crustaceans Mysis diluviana and Diporeia. They will also take chironomid larvae. Zooplankton are the likely food of the larval stage.
Deepwater sculpin eggs hatch from November to August, peaking in March. Larvae are initially pelagic, staying in the water column above the reach of their adults. Beginning in July, larvae that have grown to 2 centimetres (0.79 in) go through metamorphosis and settle to the bottom. Fish are thought to reach maturity at three years for females and two years for males.
Deepwater sculpin are a significant food source for other fish including lake trout (Salvelinus namaycush) and burbot (Lota lota). They are an intermediate host for the parasites Bothriocephalus cuspidatus, and Proteocephalus sp. which also are found in the crustaceans they eat and the fish species that prey on them.
The deepwater sculpin is an indicator species for the health of the deepwater communities in the lakes where it occurs. It is of special interest to those interested in zoogeography.
The deepwater sculpin is classified as of Least Concern by the IUCN based on the apparent stability of the population. In Canada, it is considered a species at risk under the Species at Risk Act. Threats include habitat loss, lake eutrophication, invasive species, and water pollution.
