Animal Diversity Web

Ge­o­graphic Range

Bur­bot, Lota lota, are a ho­l­arc­tic species na­tive to the cold fresh wa­ters of the Nearc­tic and Palearc­tic re­gions found be­tween 40 and 70 de­grees North lat­i­tudes. (Cohen, et al., 1990)

• Biogeographic Regions
• nearctic
  • native
• palearctic
  • native

• Other Geographic Terms
• holarctic

Habi­tat

Bur­bot are de­m­er­sal fish found in deep tem­per­ate lake bot­toms and slow mov­ing cold river bot­toms be­tween 4 and 18 de­grees C (Riede 2004; Cohen et al. 1990). Pri­mar­ily found at depths rang­ing from 1 to 700 m, these fish pre­fer fresh wa­ters but are also found in some brack­ish water sys­tems (Cohen et al. 1990). These fish often dwell among ben­thic refu­gia such as roots, trees, rocks, and dense veg­e­ta­tion (Bil­lard 1997). (Bil­lard, 1997; Cohen, et al., 1990; Mor­row, 1980; Riede, 2004; Scott and Cross­man, 1973)

• Habitat Regions
• temperate
• freshwater

• Aquatic Biomes
• benthic
• lakes and ponds
• rivers and streams
• brackish water

• Range depth

  1 to 700 m

  3.28 to 2296.59 ft

Phys­i­cal De­scrip­tion

Bur­bot are large fish known to grow to as much as 1.5 m in length and 34 kg in mass (Mor­row 1980). These fish are yel­low, light tan, or brown with dark brown or black pat­tern­ing on the body, head and most fins. The un­der­belly and pec­toral fins are pale to white (Cohen et al. 1990; Mor­row 1980). The first dor­sal fin is short and is fol­lowed by a long sec­ond dor­sal fin at least 6 times the length of the first and joined to a rounded cau­dal fin (Mor­row 1980). Bur­bot have nei­ther dor­sal nor anal spines and have 67 to 96 soft dor­sal rays, and 58 to 79 soft anal rays (Cohen et al. 1990). Gill rak­ers are short, pec­toral fins are rounded, and cau­dal fins have 40 rays (Mor­row 1980). Like other cods, bur­bot are also char­ac­ter­ized by a sin­gle bar­bel lo­cated on the chin (Mor­row 1980). (Cohen, et al., 1990; Mor­row, 1980)

• Other Physical Features
• ectothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike

• Range mass

  34 (high) kg

  74.89 (high) lb

• Range length

  152 (high) cm

  59.84 (high) in

• Range basal metabolic rate

  171.6 (high) cm3.O2/g/hr

• Average basal metabolic rate

  73.9 cm3.O2/g/hr

De­vel­op­ment

Bur­bot eggs hatch in the spring be­tween April and June de­pend­ing on lo­ca­tion (Bjorn 1940; Cohen 1990). Time to hatch­ing is de­pen­dent on tem­per­a­ture as well as the par­tic­u­lar pop­u­la­tion and eggs usu­ally take be­tween 30 and 70 days to hatch (Mac­Crim­mon 1959; Bjorn 1940). In four weeks lar­val bur­bot in­crease in length from less than 1 cm to over 2 cm (Ghan and Sprules 1993). Bur­bot in Lake Su­pe­rior ex­hib­ited very fast growth rates dur­ing the first two grow­ing sea­sons, at­tain­ing 42% of total length after 10 grow­ing sea­sons (Bai­ley 1972). (Bai­ley, 1972; Bjorn, 1940; Cohen, et al., 1990; Ghan and Sprules, 1993; Mac­Crim­mon, 1959)

In the Vi­lyuy River Basin, Siberia, bur­bot at­tain sex­ual ma­tu­rity in their 7th or 8th year, with males usu­ally ma­tur­ing 1 year be­fore fe­males (Kir­illov 1988). In Lake Su­pe­rior, bur­bot as young as one year old were sex­u­ally ma­ture (Bai­ley 1972). Though sex­u­ally ma­ture spec­i­mens were found for both sexes in year 1 and older age classes, there was a higher pro­por­tion of sex­u­ally ma­ture males until year 5 when all spec­i­mens of both sexes were sex­u­ally ma­ture (Bai­ley 1972). Ac­tiv­ity of bur­bot in­creases in au­tumn as en­ergy re­serves are con­cen­trated on the growth and de­vel­op­ment of go­nads for the win­ter spawn­ing sea­son (Kir­illov 1988). Mat­u­ra­tion of the go­nads in both sexes oc­curs about 4 months after the fall peak in nu­tri­tional re­serves (Pul­li­ainen and Ko­rho­nen 1990). (Bai­ley, 1972; Kir­illov, 1988; Pul­li­ainen and Ko­rho­nen, 1990)

Re­pro­duc­tion

Bur­bot breed once per year in the win­ter, mi­grat­ing to shal­low water or to a smaller stream to spawn (Cohen 1990). Bur­bot move to spawn­ing areas in­di­vid­u­ally and males tend to ar­rive be­fore fe­males (Mor­row 1980). Spawn­ing oc­curs dur­ing the night when in­di­vid­u­als form a glob­u­lar mass, each fish push­ing to­ward the cen­ter and re­leas­ing eggs or sperm (Mac­Crim­mon 1959; Cahn 1936). Postspawn­ing runs up­stream have been ob­served, most likely for feed­ing (Mac­Crim­mon 1959). (Cahn, 1936; Cohen, et al., 1990; Mac­Crim­mon, 1959; Mor­row, 1980)

• Mating System
• polygynandrous (promiscuous)

Bur­bot are pota­mod­ro­mous, mi­grat­ing up trib­u­taries or smaller stream reaches to spawn (Cohen 1990). They spawn in win­ter, lay­ing their eggs in shal­low water to hatch dur­ing the spring (Kir­illov 1988). Fe­cun­dity varies ge­o­graph­i­cally from slightly above 100,000 in spec­i­mens from Wyoming to over 3 mil­lion else­where in their range (Bai­ley 1972). Av­er­age fe­cun­dity ranges from 700,000 to 800,000 eggs (Kir­illov 1988; Bai­ley 1972). Eggs are yel­low, amber, or or­ange in color, spher­i­cal, and rest on the sub­strate (Koli 1990; Bjorn 1940). Eggs usu­ally hatch in two to four months.

Bur­bot may take sev­eral years to be­come sex­u­ally ma­ture. Pre­sent lit­er­a­ture in­di­cates a cer­tain pro­por­tion of bur­bot pop­u­la­tions fail to ma­ture dur­ing each breed­ing sea­son (Pul­li­ainen and Ko­rho­nen 1990). Some stud­ies have also sug­gested that bur­bot may take one or two years to re­store nu­tri­tional re­serves after a spawn­ing event (Pul­li­ainen and Ko­rho­nen 1990). (Bai­ley, 1972; Bjorn, 1940; Cohen, et al., 1990; Kir­illov, 1988; Koli, 1990; Pul­li­ainen and Ko­rho­nen, 1990)

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

• Breeding interval

  Burbot spawn once yearly.

• Breeding season

  Burbot spawning occurs in the winter between December and March (varies geographically) but lasts no longer than one month for any one population.

• Range number of offspring

  100000 to 3000000

• Average number of offspring

  700000-800000

• Range time to hatching

  2 to 4 months

• Range age at sexual or reproductive maturity (female)

  1 to 8 years

• Average age at sexual or reproductive maturity (female)

  6 years

• Range age at sexual or reproductive maturity (male)

  1 to 8 years

• Average age at sexual or reproductive maturity (male)

  3 years

Bur­bot are broad­cast spawn­ers and pro­vide no parental care. Parental in­vest­ment in bur­bot is char­ac­ter­ized by an in­creased meta­bolic ac­tiv­ity level and food con­sump­tion rates in the fall in order to con­tribute to the growth and mat­u­ra­tion of go­nads in both male and fe­males over a four month pe­riod pre­ceed­ing spawn­ing events (Pul­li­ainen and Ko­ho­nen 1990; Kir­rilov 1988). It has been sug­gested that bur­bot may re­quire one to two years to re­plen­ish their nur­tri­tional re­serves after each spawn­ing event, but no fur­ther in­for­ma­tion on this topic was avail­able (Pul­li­ainen and Ko­ho­nen 1990). (Kir­illov, 1988; Pul­li­ainen and Ko­rho­nen, 1990)

• Parental Investment
• pre-fertilization
  • provisioning

Lifes­pan/Longevity

The lifes­pan of bur­bot has been known to be as high as 20 years, though stud­ies of nat­ural pop­u­la­tions rarely see in­di­vid­u­als ex­ceed­ing 10 to 12 years of age (Cohen 1990; Kir­illov 1988; Bai­ley 1972). In­ci­dence of older and larger in­di­vid­u­als in nearc­tic re­gions may ex­ceed that of older in­di­vid­u­als in palearc­tic re­gions due to the ab­sence of an es­tab­lished fish­ery, sport or oth­er­wise, in North Amer­ica where one thrives in Eura­sia (Kir­illov 1988). (Bai­ley, 1972; Cohen, et al., 1990; Kir­illov, 1988)

• Range lifespan
  Status: wild

  20 (high) years

• Typical lifespan
  Status: wild

  1 to 12 years

Be­hav­ior

Bur­bot are op­por­tunis­tic pis­ci­vores with a di­verse diet. They hide amongst avail­able refu­gia in their epiben­thic habi­tat such as rocks and fallen logs, and use am­bush tac­tics to cap­ture prey (Kahi­lainen and Lehto­nen 2003). They are cre­pus­cu­lar or noc­tur­nal and seek shal­low water to feed. Dur­ing times of low ac­tiv­ity, they con­gre­gate in deep holes (Riede 2004; Mor­row 1980; Scott and Cross­man 1973). In the win­ter, these fish mi­grate up­stream and form spawn­ing ag­gre­ga­tions (Cohen 1990). (Cohen, et al., 1990; Kahi­lainen and Lehto­nen, 2003; Mor­row, 1980; Riede, 2004; Scott and Cross­man, 1973)

• Key Behaviors
• natatorial
• nocturnal
• crepuscular
• motile
• migratory
• social

Com­mu­ni­ca­tion and Per­cep­tion

Bur­bot per­ceive chem­i­cal, tac­tile, vi­sual, and acoustic stim­uli, as do most fish. Though bur­bot and north­ern pike ex­hibit sim­i­lar hunt­ing strate­gies, bur­bot ap­pear to rely less on sight than pike (Kahi­lainen and Lehto­nen 2003). (Kahi­lainen and Lehto­nen, 2003; von der Emde, 2004)

• Perception Channels
• visual
• tactile
• acoustic
• vibrations
• chemical

Food Habits

Newly hatched bur­bot are com­pletely plank­tiv­o­rous, and re­main so even when they are no longer gape lim­ited (Ghan and Sprules 1993). Diet of lar­val bur­bot is dom­i­nated by ro­tifer species for the first two weeks. Diet then shifts to slightly larger nau­plii, chang­ing fur­ther dur­ing week four to cy­cloid cope­pods, daph­nia, and calanoid cope­pods (Ghan and Sprules 1993). Ju­ve­niles have a diet of mol­luscs and in­sect lar­vae (Tola­nen et al. 1999). Adult bur­bot are pis­civ­o­rous and con­sume over 99% fish by mass in Lake Su­pe­rior (Bai­ley 1972). Though bur­bot are al­ways a pri­mar­ily pis­civ­o­rous fish, their diet changes sea­son­ally and in re­sponse to com­pe­ti­tion. After the win­ter months, Tola­nen et al. (1999) found that bur­bot ate a much higher pro­por­tion of aquatic in­ver­te­brates, namely crus­taceans in the early sum­mer and op­pos­sum shrimp in the fall. In the Vi­lyusk re­sevoir, diet over­lap with pike forces bur­bot to broaden their diet breadth to in­clude more ben­thic in­ver­te­brates (Kir­illov 1988). In ad­di­tion to fish and in­ver­te­brates, Bai­ley (1972) also found rocks, wood chips, plas­tic, and other inert ma­te­ri­als in bur­bot stom­achs, in­di­cat­ing that bur­bot feed­ing habits were some­what in­dis­crim­i­nate. (Bai­ley, 1972; Ghan and Sprules, 1993; Kir­illov, 1988; Tola­nen, et al., 1999)

• Primary Diet
• carnivore
  • piscivore

• Animal Foods
• fish
• insects
• mollusks
• aquatic or marine worms
• aquatic crustaceans
• zooplankton

Pre­da­tion

North­ern pike are known to prey on bur­bot where the two species co­ex­ist (Schwalme 1992). Smelt and yel­low perch prey on lar­val and ju­ve­nile in­di­vid­u­als (Scott and Cross­man 1973). Hu­mans also exert pre­da­tion pres­sure on bur­bot through com­mer­cial and sport fish­eries (Cohen 1990; Kir­illov 1988). In the Great Lakes, the sea lam­prey, Petromy­zon mar­i­nus, is also known to prey on bur­bot (Smith 1971). Bur­bot rely on their cryp­tic habits and col­oration to avoid preda­tors. (Cohen, et al., 1990; Kir­illov, 1988; Schwalme, 1992; Scott and Cross­man, 1973; Smith, 1971)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • northern pike (Esox lucius)
  • yellow perch (Perca flavescens)
  • smelt (Osmerus eperlanus)
  • sea lamprey (Petromyzon marinus)
  • humans (Homo sapiens)

Ecosys­tem Roles

Bur­bot are top preda­tors in their ecosys­tem, some­times over­lap­ping with sim­i­lar top preda­tors such as pike or large salmonids (Kir­illov 1988). (Kir­illov, 1988)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Bur­bot are an im­por­tant com­mer­cial fish­ery in parts Eura­sia where they are used as a source of oil, the flesh is eaten, and liver is sold smoked or canned (Kir­illov 1988; Scott and Cross­man 1973). Bur­bot are also processed into fish meal (Scott and Cross­man 1973). Be­cause of slow move­ments and noc­tur­nal habits, lit­tle or no sport fish­ery ex­ists in North Amer­ica (Cohen 1990). (Cohen, et al., 1990; Kir­illov, 1988; Scott and Cross­man, 1973)

• Positive Impacts
• food
• body parts are source of valuable material

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known neg­a­tive ef­fects of bur­bot on hu­mans.

Con­ser­va­tion Sta­tus

Bur­bot are near ex­tinc­tion in the Koot­nai river in Idaho and British Co­lum­bia due to con­struc­tion of the Libby dam in Idaho. Ef­forts to bring back the pop­u­la­tion are on­go­ing (Koot­nai River Fish­eries In­ves­ti­ga­tion 2000). Bur­bot are stocked where com­mer­cial fish­eries exist in Eu­rope (Kir­illov 1988). ("Koote­nai River Fish­eries In­ves­ti­ga­tion: Stock Sta­tus of Bur­bot", 2000; Kir­illov, 1988)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Al­li­son Poor (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Greg Ja­cobs (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Kevin Wehrly (ed­i­tor, in­struc­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Idaho De­part­ment of Fish and Game. Koote­nai River Fish­eries In­ves­ti­ga­tion: Stock Sta­tus of Bur­bot. 85-65. Boise, Idaho: Idaho De­part­ment of Fish and Game. 2000.

Bai­ley, M. 1972. Age, Growth, Re­pro­duc­tion and Food of the Bur­bot, Lota lota (Lin­neaus), in South­west­ern Lake Su­pe­rior. Trans. Amer. Fish. Soc., 4: 667-674.

Bil­lard, R. 1997. Les pois­sons d'eau douce des rivières de France. Iden­ti­fi­ca­tion, in­ven­taire et répar­ti­tion des 83 espèces. Lau­sanne: Delachaux & Ni­estlé.

Bjorn, E. 1940. Pre­lim­i­nary Ob­ser­va­tions and Ex­per­i­men­tal Study of the ling, Lota lota (LeSueur), in Wyoming. Trans. Am. Fish. Soc., 69: 192-196.

Cahn, A. 1936. Ob­ser­va­tions on the Breed­ing of Lawyer, Lota lota . Copeia, 3: 163-165.

Cohen, D., T. Inada, T. Iwamoto, N. Scial­abba. 1990. Gad­i­form fishes of the world : Order Gad­i­formes, an an­no­tated and il­lus­trated cat­a­logue. Rome: Food and Agri­cul­ture Or­ga­ni­za­tion of the United Na­tions.

Ghan, D., W. Sprules. 1993. Diet and Prey Se­lec­tion in Young Bur­bot. Jour­nal of Fish Bi­ol­ogy, 42: 47-64.

Kahi­lainen, K., H. Lehto­nen. 2003. Pis­civory and prey se­lec­tion of four preda­tor species in a white­fish dom­i­nated sub­arc­tic lake. Jour­nal of Fish Bi­ol­ogy, 63:3: 659-672.

Kir­illov, A. 1988. Bur­bot of Vi­lyusk Re­sevoir. Jour­nal of Ichthy­ol­ogy, 28(2): 49-55.

Koli, L. 1990. Fishes of Fin­land. Helsinki: Werner Söder­ström Os­akey­htiö.

Mac­Crim­mon, H. 1959. Ob­ser­va­tions on Spawn­ing of Bur­bot in Lake Sim­coe, On­tario. Jour­nal of Wildlife Man­age­ment, 23(4): 447-449.

Mor­row, J. 1980. The Fresh­wa­ter Fishes of Alaska. Uni­ver­sity of British Co­lum­bia Re­source Ecol­ogy Li­brary: Uni­ver­sity of British Co­lum­bia.

Nel­son, J. 1994. Fishes of the World. New York: John Wiley and Sons.

Paragamian, V., V. Whit­man, J. Ham­mond, H. An­drusak. 2000. Col­lapse of bur­bot fish­eries in the Koote­nai River, Idaho, USA, and Koot­nay Lake, British Co­lum­bia, Canada. Pp. 155-164 in L Vaughn, V Paragamian, D Willis, eds. Bur­bot: Bi­ol­ogy, Ecol­ogy, and Man­age­ment, Vol. Pub­li­ca­tion No. 1. Spakane, Wash­ing­ton: Fish­eries Man­age­ment Sec­tion of the Amer­i­can Fish­eries So­ci­ety.

Pul­li­ainen, E., K. Ko­rho­nen. 1990. Sea­sonal Changes in Con­di­tion In­dices in Adult Ma­ture and Non-ma­tur­ing Bur­bot, Lota lota (L.), in the north-east­ern Both­n­ian Bay, North­ern Fin­land. Jour­nal of Fish Bi­ol­ogy, 36(2): 251-259.

Riede, K. 2004. Global reg­is­ter of mi­gra­tory species - from global to re­gional scales. Final re­port of the R&D Pro­jekt 808 05 081. Bonn, Ger­many: Fed­eral Agency for Na­ture Con­ser­va­tion.

Schwalme, K. 1992. A Quan­ti­ta­tive Com­par­i­son Be­twen Diet and Body Fatty Acid Com­po­si­tion in Wild North­ern Pike (Esox lu­cius L.). Fish Phys­iol. Biochem., 10(2): 91-98.

Scott, W., E. Cross­man. 1973. Fresh­wa­ter fishes of Canada. Bull. Fish. Res. Board Can., 184: 1-966.

Smith, B. 1971. Sea Lam­preys in the Great Lakes of North Amer­ica. Pp. 207-248 in M Hardisty, ed. The Bi­ol­ogy of Lam­preys. Lon­don: Aca­d­e­mic Press.

Tola­nen, A., J. Kjell­mann, J. Lap­palainen. 1999. Diet Over­lap be­tween Bur­bot and White­fish in a Sub­arc­tic Lake. Ann. Zool. Fen­nici, 36: 205-214.

Win­berg, G. 1960. Rate Me­tab­o­lism and Food Re­quire­ments for Fishes. F Fry, W Ricker, eds. Trans­la­tion Se­ries No. 194. Bi­o­log­i­cal Sta­tion, Na­ni­amo, B.C.: Fish­eries Re­search Board of Canada.

von der Emde, G. 2004. The Senses of Fish: Adap­ta­tions for the Re­cep­tion of Nat­ural Stim­uli. Boston: Kluwer.