Animal Diversity Web

Ge­o­graphic Range

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

Habi­tat

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).

• Habitat Regions
• temperate
• freshwater

• Aquatic Biomes
• pelagic
• benthic
• lakes and ponds
• rivers and streams

• Range depth

  20 to 407 m

  65.62 to 1335.30 ft

• Average depth

  70-90 m

  ft

Phys­i­cal De­scrip­tion

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). (Ja­coby, 1953; Page and Burr, 1991)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike

• Range length

  23 (high) cm

  9.06 (high) in

De­vel­op­ment

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.

Re­pro­duc­tion

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. (Black and Lankester, 1981; Sel­geby, 1988)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • external
• oviparous

• 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

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

Lifes­pan/Longevity

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. (Sel­geby, 1988)

• Typical lifespan
  Status: wild

  7 (high) years

Be­hav­ior

These fish live in cold, deep wa­ters and very lit­tle is known about their be­hav­ior.

• Key Behaviors
• natatorial
• motile

Com­mu­ni­ca­tion and Per­cep­tion

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

Food Habits

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). (Brandt, 1986)

• Primary Diet
• carnivore
  • eats non-insect arthropods

• Animal Foods
• aquatic crustaceans

Pre­da­tion

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

  • lake trout (Salvelinus namaycush)
  • burbots (Lota lota)
  • slimy sculpins (Cottus cognatus)

Ecosys­tem Roles

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. (Brandt, 1986)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

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.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known neg­a­tive af­fects of deep­wa­ter sculpin on hu­mans.

Con­ser­va­tion Sta­tus

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).

• IUCN Red List

  Not Evaluated

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

William Fink (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor, Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Alexan­dra Be­linky (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

"New York State De­part­ment of En­vi­ron­men­tal Con­ser­va­tion" (On-line). Ac­cessed No­vem­ber 19, 2002 at http://​www.​dec.​state.​ny.​us/​website/​dfwmr/​fish/​fishspecs/​endgtext.​html#​deepwatersculpin.

"Sci­en­tific Com­mit­tee on the Sta­tus of En­dan­gered Wildlife in Canada (COSEWIC)" (On-line). Ac­cessed No­vem­ber 19, 2002 at http://​www.​speciesatrisk.​gc.​ca/​media/​back3_​e.​cfm.

Black, G., M. Lankester. 1981. The bi­ol­ogy and par­a­sites of deep­wa­ter sculpin, *My­ox­o­cephalus quadri­cor­nis thomp­sonii* (Gi­rard), in Burchell Lake, On­tario. Cana­dian Jour­nal of Zo­ol­ogy,, vol. 59 (7): 1454-1456.

Brandt, S. 1986. Dis­ap­pear­ance of the deep­wa­ter sculpin (*My­ox­o­cephalus thomp­sonii*) from Lake On­tario: the key­stone preda­tor hy­poth­e­sis. Jour­nal of Great Lakes Re­search,, vol. 12 (11): 18-24.

Bruch, R. 1986. Age and Growth, Mor­tal­ity, Re­pro­duc­tive Cycle and Fe­cun­dity of the Deep­wa­ter Sculpin, My­ox­o­cephalus thomp­sonii (Gi­rard), in Lake Michi­gan. Mil­wau­kee, Wis­con­sin: Uni­ver­sity of Wis­con­sin - Mil­wau­kee.

Cross­man, E., H. Van Meter. 1979. An­no­tated List of the Fishes of the Lake Onatario Wa­ter­shed. Ann Arbor, MI: Great Lakes Fish­eries Com­mi­sion.

Ja­coby, C. 1953. Notes on the Life His­tory of the Deep­wa­ter Sculpin, My­ox­o­cephalus quadri­cor­nis L., in Lake Su­pe­rior. Ann Arbor, Michi­gan: De­part­ment of Fish­eries, School of Nat­ural Re­sources, Uni­ver­sity of Michi­gan.

Momot, W., S. Stephen­son. 1996. Atlas of the Dis­tri­b­u­tion of the Fish within th Cana­dian Trib­u­taries of West­ern Lake Su­pe­rior. Toronto, On­tario, Canada: Uni­ver­sity of Toronto.

Page, L., B. Burr. 1991. A field guide to fresh­wa­ter fishes of North Amer­ica. Boston, Mass­a­chu­setts: Houghton Mif­flin Com­pany.

Sel­geby, J. 1988. Com­par­a­tive bi­ol­ogy of the sculpins of Lake Su­pe­rior. Jour­nal of Great Lakes Re­search,, vol. 14 (1): 45-51.

Wo­j­cik, J., M. Evans, D. Jude. 1986. Food of deep­wa­ter sculpin, *My­ox­o­cephalus thomp­sonii*, from South­east­ern Lake Michi­gan. Jour­nal of Great Lakes Re­search, vol. 12 (3): 225-231.