Deepwater Sculpin Research Articles

Partitioning of food resources by sculpins in Lake Michigan

Resource partitioning was studied in two benthic Lake Michigan fishes, the deepwater sculpin,Myoxocephalus thompsoni, and the slimy sculpin,Cottus cognatus, that exhibit nearly disjunct distributions along a hypolimnetic depth gradient. Fish were collected in an area of sympatry over two 24 h periods. These sculpins exhibited food segregation—slimy sculpins ate primarilyPontoporeia affinis, deepwater sculpins ate bothP. affinis andMysis relicta — and their depth segregation was associated with the reported abundance of these prey. Different feeding behaviors may be responsible for this association, since slimy sculpins consumed intermediate size ranges ofPontoporeia and deepwater sculpins consumedPontoporeia in a pattern similar to the ambient size distribution. Neither fish showed a daily activity cycle, and both appear food-limited.

Disappearance of the Deepwater Sculpin (Myoxocephalus Thompsoni) from Lake Ontario: The Keystone Predator Hypothesis

Disappearance of the deepwater sculpin (Myoxocephalus thompsoni) from Lake Ontario during the early 1950s is unexplained. I suggest that a contributing factor to this local extinction may have been increased competition with or predation on younger deepwater sculpin lifestages by the sympatric slimy sculpin (Cottus cognatus) that was precipitated by the loss of piscivores from the lake. Habitat and diet of adult slimy sculpins and young deepwater sculpins overlap in the Great Lakes and both species were heavily preyed upon by the lake trout (Salvelinus namaycush) and burbot ( Lota lota) in Lake Ontario. It is hypothesized that predation on sculpins may have prevented either species from monopolizing the benthic offshore regions of Lake Ontario.

Food of Deepwater Sculpin, Myoxocephalus Thompsoni, from Southeastern Lake Michigan

Pontoporeia hoyi was the major food consumed by most sizes of deepwater sculpins ( Myoxocephalus thompsoni) during spring and summer, 1981–82, at a 100-m station in southeastern Lake Michigan. There was no apparent seasonality in choices of food or volumes consumed. Mysis relicta made up less than 9% of the total food volume and averaged second to Pontoporeia volumetrically—a result which differed from previous investigations for Lake Michigan. Reduced consumption of Mysis in our study compared to previous work may be a function of lower prey density or station depth; mysids may have been farther above the lake bottom than at previously studied, more shallow stations. Ostracods were important in 6- and 7-cm fish diets. Mysis, chironomids, and fish eggs were only found in sculpins larger than 8 cm. Chironomid larvae, which typically burrow into sediments, and copepod and cladoceran zooplankton constituted a small percentage of the diet of all sculpins. These results indicated that the deepwater sculpins examined were primarily epibenthic predators at the sediment-water interface and apparently did not burrow for food or feed higher up in the water column.

Depth Distribution, Diet, and Overwinter Growth of Lake Trout ( Salvelinus Namaycush) in Southeastern Lake Michigan Sampled in December 1981 and March 1982

Lake trout were collected in graded-mesh gill nets and forage fishes were collected in trawls in mid December 1981 and late March 1982. The length ranges of 317 lake trout caught in December and 138 in March were 280–767 and 286–857 mm, and the age ranges I–XI and II–XIV, respectively. Three year classes (1977–79) made up almost 80% of the catches of lake trout in both sampling periods. Lake trout were most abundant at depth of 18 to 37 m in December (water temperatures, 5.5–6.8°C) and at 28–64 m in March (water temperatures, 1.0–1.3°C). Fish of the 1977–79 year classes completed 9 to 24% of their annual growth in length, and 14 to 39% of their growth in weight, between mid December and late March. Lake trout ate mainly alewives ( Alosa pseudoharengus) especially young-of-the-year, in December, but primarily slimy sculpins ( Cottus cognatus) in March, when alewives were mainly at depths of greater than those occupied by most lake trout. Other important food items were rainbow smelt ( Osmerus mordax) and, in deeper water, deepwater sculpins ( Myoxocephalus thompsoni) Bloaters ( Coregonus hoyi) were eaten only sparingly, although they were abundantly available in both sampling periods. Perhaps this species, which coevolved with the lake trout in Lake Michigan and was important in the native trout's diet, is better able to avoid capture by the trout than are the exotic alewife and rainbow smelt. It may not again become a major forage species unless the other food sources become scarce.

Distribution and Abundance of Larval Burbot and Deepwater Sculpin in Lake Michigan

Samples from seven locations at depths to 21 m, collected over periods of up to 8 years, were used to describe the nearshore distribution and abundance of burbot Lota lota and deepwater sculpin Myoxocephalus thompsoni larvae in Lake Michigan. Based upon power-plant-entrainment samples and field collections, burbot larvae (3.0–7.5 mm) occurred from late March to mid-June, most abundantly in April and May, and most often at water temperatures of 6–12 C. Larvae were collected from the 0.5- to 13.5-m depth strata as far lakeward as the 21-m bottom contour, the limit of offshore sampling. In eastern Lake Michigan, highest densities (up to 843 larvae/1,000 m3) were at the 1-m contour; in Green Bay, up to 24,000 larvae/1,000 m3 were detected near the Bark River. High densities of burbot larvae at bottom depths 3 m and less indicated inshore spawning and river spawning at some sites. Deepwater sculpin larvae first occurred in early February and were common in March and April entrainment samples. Larvae (8.0–22.0 mm) were in nearshore waters usually through May at depth strata of 0.5 to 17 m as far lakeward as the 18-m bottom contour. Most larvae occurred at water temperatures below 6 C. Field densities were low, 5 to 78 larvae/1,000 m3. Deepwater sculpin larvae were pelagic and were dispersed over great distances by currents.

The biology and parasites of deepwater sculpin, Myoxocephalus quadricornis thompsonii (Girard), in Burchell Lake, Ontario

Ninety-five deepwater sculpin, Myoxocephalus quadricornis thompsonii (Girard), sampled from Burchell Lake, Ontario, 12 October 1980, were up to 92 mm long. Ninety-eight percent of the specimens were less than 4 years old. Some 2-year-old males had enlarged testes; all older males and females had enlarged testes and eggs (mean diameter, 1.43 mm), respectively. Spawning probably occurs during late fall or winter.Parasites found included Diplostomulum sp. (metacercariae), Bothriocephalus sp. (immature), Cyathocephalus truncatus (nongravid), Cystidicola cristivomeri (third-stage larvae), and third-stage larvae of a spirurine nematode.

Deepwater sculpin, Myoxocephalus thompsoni (Girard) from a Pleistocene nodule, Green Creek, Ontario, Canada

A nodule containing the cranium of a deepwater sculpin, Myoxocephalus thompsoni (Girard), was discovered in Pleistocene Champlain Sea deposits at Green Creek, 10 km east of Ottawa, Ontario, Canada, and represents the first fossil reported for the species. It provides an additional basis for refuting derivation of the species from a post-Wisconsin marine submergence and suggests an origin at the beginning of the Wisconsin or earlier. Habitat preferences of the species favour an oligotrophic lacustrine environment with bottom summer temperatures below 8 °C in the Champlain Sea or nearby lake basin. The head length of the fossil is 28 mm, the estimated standard length 86 mm. Use of a longwave ultraviolet lamp with the fossil improved contrast between the bones and the clay matrix in photographs. Scanning electron microscopy (SEM) analysis of bone in the fossil failed to detect the presence of strontium.

Vertebral Number in North American Sculpins of the Myoxocephalus quadricornis-Complex

X-rays of 438 North American specimens of the Myoxocephalus quadricornis-complex (Cottidae) showed mean vertebral counts (including urostyle) of 38.433 in the deepwater sculpin which inhabits inland continental lakes; 41.097 in the freshwater relict in lakes on Victoria Island, Northwest Territories; 41.417 in newly discovered freshwater relicts in Nauyuk, Stanwell-Fletcher, and Sophia lakes, Northwest Territories; and 41.821 in the coastal fourhorn sculpin living in brackish and marine coastal waters and certain adjacent fresh waters. Except for the Victoria and the three lake relicts, the vertebral means of all pairs of these groups differed at P <.01 or <.001. Of the coastal fourhorn sculpin and the deepwater sculpin 91% are identifiable using only vertebral number, of the Victoria relict and the deepwater sculpin 68%, and of the Victoria relict and the coastal fourhorn only 10%.Vertebral counts alone permit recognition of the deepwater sculpin as a subspecies, Myoxocephalus quadricornis thompsonii Girard, 1852, distinct from the arctic coastal fourhorn sculpin provisionally referred to M. q. hexacornis (Richardson, 1823) and suggest classification of the Victoria Island, Nauyuk, Stanwell–Fletcher, and Sophia lake relicts with the coastal form, rather than with the deepwater sculpin. Relicts in the latter three lakes are suggested to be postglacial in origin.

Evolution of visual pigments

Rod visual pigments exhibit a variety of absorption maxima, determined partly by the nature of the prosthetic group, retinal or 3-dehydroretinal, and partly by the apoprotein opsin. Some animal taxa exhibit little diversity. On the other hand, selective pressures arising from the different light habitats of aquatic environments are believed to have produced the correspondingly wide range of λ max in fish visual pigments, which often extends over 80 nm. Opsins appear to have similar molecular weights. Latest estimates of molecular weight suggest that they have approximately 315 amino acid residues. Some species, notably members of the salmonidae, have visual pigments with different λ max yet have diverged only during the past several million years. This would indicate a very high rate of protein evolution in circumstances where we should expect that amino acid substitution would be severely restricted. Certain fish species (e.g. the deepwater sculpin, Myoxocephalus) have mixtures of visual pigments with λ max separated by only 6 nm. The physiological usefulness of such a pair is dubious, but it may indicate polymorphism at the gene locus coding for opsin. The use of retinol and 3-dehydroretinol, the basis of rhodopsin and porphyropsin, may vary between quite closely related species. Extraneous factors such as light and hormones are known to be important in amphibian larvae and fishes, but there is also clear evidence for genetic influences, as revealed by the divergent evolution of the system in various populations of originally anadromous smelt after only 10 000 years of isolation.

Brief observations concerning the visual pigments of some selected fishes from Lake Heney, Quebec, a relict of glacial Lake Gatineau

The visual pigments and liver vitamins A of several races of Osmerus eperlanus mordax (rainbow smelt). Coregonus artedii (cisco), Myoxocephalus quadricornis thompsonii (deepwater sculpin). Cottus ricei (spoonhead sculpin) and Salrelinus namaycush (lake charr) have been examined. With the exception of Salvelinus and certain specimens of Osmerus, all were taken from Lake Heney. originally part of glacial Lake Gatineau at the time of the Champlain Sea episode, a marine inundation of the St Lawrence Lowlands that occurred some 9,000–12,000 yr ago. Osmerus has a rhodopsin with λ max at 512 nm and a porphyropsin at 541 nm, the latter practically absent in the sympatric dwarf (including young-of-the-year) and giant races of Lake Heney. Coregonus has a rhodopsin with λ max at 510–511 nm, perhaps with a trace of porphyropsin : Salvelinus has a rhodopsin and porphyropsin in variable amounts with respective maxima at 511 and 540 ± 2 nm. Of the two cottids. Cottus has a rhodopsin with λ max at 503 nm but Myoxocephalus is unusual in having a mixture of two rhodopsins with maxima separated by only 7 nm. located at 508 and 515 nm respectively. All species have the precursor of porphyropsin. 3-dehydroretinol. in their livers in proportions ranging from 17 to 50 per cent of the total liver retinols. These findings are related to observations on kindred species in other habitats or other regions, and the visual pigments of the two cottids are discussed in relation to the recent evolution of these fish.

The Deepwater Sculpin, Myoxocephalus quadricornis thompsoni, New to Alberta, Canada

Specimens of the deepwater sculpin from Upper Waterton Lake provide the first record for Alberta and extend the known range over 450 miles to the southwest.

Recent Changes in the Deep-water Fish Populations of Lake Michigan

Abstract The deep-water fish fauna of Lake Michigan consisted of lake trout (Salvelinus namaycush), burbot (Lota lota maculosa), seven species of chubs or deep-water ciscoes (Leucichthys spp.), and the deep-water sculpin (Myoxocephalus quadricornis). Other species occupied the deep-water zone but were not typically part of the fauna. Lake trout, burbot, and a well established commercial fishery held the chub population in somewhat of a balance until the sea lamprey (Petromyzon marinus) destroyed the lake trout and burbot. Released from predation, one species of chub (L. hoyi) increased until its abundance in 1955 was 347 percent of that in 1930–1933. It is the smallest and most slowly growing of the chubs in the lake. Other chubs were reduced in abundance (1954–1955 abundance only 37 percent of that of 1930–1932) by an increased fishing pressure and by sea lamprey predation which shifted to them when lake trout and burbot became practically extinct. Selective destruction of the large chubs reduced the ave...

Studies of the Fish of Great Slave Lake

A four-year study of the fish of Great Slave Lake was initiated one year before the lake was opened for commercial fishing. Information has been obtained about the composition, distribution and general ecology of the major species. Twenty-one species are listed and the ciscoes, probably of three species, await identification. Lake trout, common whitefish and ciscoes dominate the population and the former two species support an extensive gill-net fishery. The inconnu Stenodus, and the deepwater sculpin, Triglopsis, are of special zoogeographic interest.Sampling was mainly with standardized 300-yard gangs of gill net. In these, some 12,000 fish weighing about 20,000 pounds were taken. Some data were obtained on the selective effect of mesh size. Young and small fish were collected by seining.Great Slave Lake's area of 10,500 square miles includes a large open portion and two great arms, one to the north, the other extending eastward. Part of the north arm is shallow and its fish population is much like that of the main lake. Goldeyes, white suckers and pikeperch are found in the shallow warmer parts of these areas. None of these species are found in the deep and cold east arm, but in it grayling and round whitefish are numerous. The common whitefish is virtually absent from McLeod Bay at the extremity of the east arm.Data concerning growth in length and weight are provided for round whitefish, white sucker, longnose sucker, burbot and pikeperch. Most of these species grow a little slower in Great Slave Lake than in lakes farther south. Growth studies of five other important species have been undertaken by other workers.Analysis of the food of all the larger species shows that the main food chains are plankton→ cisco→ lake trout and plankton→ detritus→ bottom organisms→ whitefish. Pontoporeia, Mysis and cottids are important fish food in the deep water.Twenty-one species of parasites are recorded from ten species of fish.

Description of a new species of deep-water sculpin (Triglopsis ontariensis)from Lake Ontario, with notes on related species

Description of a new species of deep-water sculpin (Triglopsis ontariensis)from Lake Ontario, with notes on related species