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'{{pp-move-indef}} {{short description|Large species of baleen whale}} {{Use dmy dates|date=June 2014}} {{featured article}} {{Use British English|date=June 2014}} {{speciesbox | name = Sei whale<ref name=MSW3>{{MSW3 Cetacea|id=14300014}}</ref> | image = File:Sei whale mother and calf Christin Khan NOAA.jpg | image_caption = Sei whale mother and calf | image2 = Sei whale size.svg | image2_caption = Size compared to an average human | status = EN | status_system = IUCN3.1 | status_ref = <ref name="iucn">{{Cite journal | author = Reilly, S.B. | author2 = Bannister, J.L. | author3 = Best, P.B. | author4 = Brown, M. | author5 = Brownell Jr., R.L. | author6 = Butterworth, D.S. | author7 = Clapham, P.J. | author8 = Cooke, J. | author9 = Donovan, G.P. | author10 = Urbán, J. | display-authors = etal | title = ''Balaenoptera borealis'' | journal = [[The IUCN Red List of Threatened Species]] | volume = 2008 | page = e.T2475A9445100 | date = 2008 | url = http://oldredlist.iucnredlist.org/details/2475/0 | doi = 10.2305/IUCN.UK.2008.RLTS.T2475A9445100.en | access-date = 16 January 2018}}</ref> | genus = Balaenoptera | species = borealis | authority = [[René Primevère Lesson|Lesson]], 1828 | range_map = Cypron-Range Balaenoptera borealis.svg | range_map_caption = Sei whale range | subdivision_ranks = Subspecies | subdivision = *''B.b.borealis'' *''B.b.schlegellli'' | synonyms = *''Balaena rostrata'' <small>Rudolphi, 1822</small> *''Balaenoptera laticeps'' <small>[[John Edward Gray|Gray]], 1846</small> *''Sibbaldius laticeps'' <small>[[William Henry Flower|Flower]], 1864</small> *''Physalus laticeps'' <small>Flower, 1864</small> *''Rudolphius laticeps'' <small>Gray, 1868</small> }} The '''sei whale''' ({{IPAc-en|ˈ|s|eɪ}} or {{IPAc-en|ˈ|s|aɪ}}) (''Balaenoptera borealis'') is a [[baleen whale]], the third-largest [[rorqual]] after the [[blue whale]] and the [[fin whale]].<ref name="av">{{cite journal | author = S.L. Perry | author2 = D.P. DeMaster | author3 = G.K. Silber | year = 1999 | title = Special Issue: The Great Whales: History and Status of Six Species Listed as Endangered Under the U.S. Endangered Species Act of 1973 | journal = Marine Fisheries Review | volume = 61 | issue = 1 | url = http://spo.nwr.noaa.gov/mfr611/mfr611.htm | pages = 52–58 | access-date = 26 April 2011 | archive-url = https://web.archive.org/web/20110721055959/http://spo.nwr.noaa.gov/mfr611/mfr611.htm | archive-date = 21 July 2011 | dead-url = yes | df = dmy-all }}</ref> It inhabits most oceans and adjoining seas, and prefers deep offshore waters.<ref name="Gambell85a">{{cite book | author = Gambell, R. | year = 1985 | chapter = Sei Whale ''Balaenoptera borealis'' Lesson, 1828 | title = Handbook of Marine Mammals, Vol. 3 | editor = S.H. Ridgway | editor2 = R. Harrison | publisher = Academic Press | location = London | pages = 155–170 }}</ref> It avoids [[Polar region|polar]] and [[tropics|tropical]] waters and semienclosed bodies of water. The sei whale migrates annually from cool, subpolar waters in summer to [[temperateness|temperate]], [[subtropics|subtropical]] waters in winter with a lifespan of 70 years.<ref name="nmfs" /> Reaching {{convert|19.5|m|ft|abbr=on}} long and weighing as much as {{convert|28|t|abbr=on}},<ref name="nmfs">{{cite book | author = Reeves, R. |author2 = G. Silber|author3 = M. Payne | title = Draft Recovery Plan for the Fin Whale ''Balaenoptera physalus'' and Sei Whale ''Balaenoptera borealis'' | publisher = National Marine Fisheries Service|date=July 1998 | location = Silver Spring, Maryland | url = http://www.cresli.org/cresli/pdf%20documents/finwhale.pdf }}</ref> the sei whale consumes an average of {{convert|900|kg|lb|abbr=on}} of food every day; its diet consists primarily of [[copepod]]s, [[krill]], and other [[zooplankton]].<ref name="adw">{{cite web | author = Shefferly, N. | year = 1999 | title = Balaenoptera borealis | publisher = Animal Diversity Web | url = http://animaldiversity.ummz.umich.edu/site/accounts/information/Balaenoptera_borealis.html | accessdate = 4 November 2006}}</ref> It is among the fastest of all [[cetacea]]ns, and can reach speeds of up to {{convert|50|km/h|mph|abbr=on}} (27&nbsp;[[knot (unit)|knots]]) over short distances.<ref name="adw" /> The whale's name comes from the [[Norwegian language|Norwegian]] word for [[Pollachius virens|pollock]], a fish that appears off the coast of Norway at the same time of the year as the sei whale.<ref name="acs">{{cite web | url = http://www.acsonline.org/factpack/SeiBrydesWhales.htm | title = Sei Whale & Bryde's Whale ''Balaenoptera borealis'' & ''Balaenoptera edeni'' | publisher = American Cetacean Society |date=March 2004 | accessdate = 8 November 2006 | archiveurl = https://web.archive.org/web/20060927212353/http://www.acsonline.org/factpack/SeiBrydesWhales.htm <!--Added by H3llBot--> | archivedate = 27 September 2006 }}</ref> Following large-scale [[whaling|commercial whaling]] during the late 19th and 20th centuries, when over 255,000 whales were killed,<ref name="horwood87">{{cite book |author=Horwood, J. |year=1987 |title=The sei whale: population biology, ecology, and management |publisher=Croom Helm Ltd. |location=Kent, England |isbn=978-0-7099-4786-8}}</ref><ref>Berzin, A. 2008. ''The Truth About Soviet Whaling'' (Marine Fisheries Review), pp. 57–8.</ref> the sei whale is now internationally protected,<ref name="iucn" /> although limited hunting occurs under a controversial research program conducted by Japan.<ref name="wwf05">{{cite press release |publisher=WWF-International |title=Japanese Scientific Whaling: Irresponsible Science, Irresponsible Whaling |date=1 June 2005 |url=http://www.panda.org/about_wwf/what_we_do/species/publications/index.cfm?uNewsID=13793 |accessdate=10 November 2006 |deadurl=yes |archiveurl=https://web.archive.org/web/20060825094925/http://www.panda.org/about_wwf/what_we_do/species/publications/index.cfm?uNewsID=13793 |archivedate=25 August 2006 |df=dmy-all }}</ref> {{As of|2008}}, its worldwide population was about 80,000, less than a third of its prewhaling population.<ref name=Jefferon2008>{{cite book | author1 = Thomas A. Jefferson | author2 = Marc A. Webber | author3 = Robert L. Pitman | last-author-amp = yes | title = Marine Mammals of the World: A Comprehensive Guide to their Identification | publisher = Academic | year = 2008 | location = London | url =http://www.sciencedirect.com/science/book/9780123838537 |accessdate=9 November 2016}}</ref><ref>{{cite web |url=https://www.fisheries.noaa.gov/species/sei-whale |publisher=[[National Marine Fisheries Service]] |title=Sei whale |accessdate=2018-09-26}}</ref> == Etymology == ''Sei'' is the Norwegian word for [[pollock]], also referred to as coalfish, a close relative of codfish. Sei whales appeared off the coast of Norway at the same time as the pollock, both coming to feed on the abundant [[plankton]].<ref name="acs" /> The specific name is the Latin word ''borealis'', meaning northern. In the Pacific, the whale has been called the Japan finner; "finner" was a common term used to refer to rorquals. In Japanese, the whale was called ''iwashi kujira'', or sardine whale, a name originally applied to [[Bryde's whale]]s by early Japanese whalers. Later, as modern whaling shifted to [[Sanriku]] — where both species occur — it was confused for the sei whale. Now the term only applies to the latter species.<ref>Omura, Hidero. "Review of the Occurrence of the Bryde's Whale in the Northwest Pacific". ''Rep. Int. Commn.'' (Special Issue 1), 1977, pp. 88–91.</ref><ref name="natlgeo1911">{{cite journal | url = http://www.edwardtbabinski.us/whales/shore_whaling_industry.html | archive-url = https://web.archive.org/web/20061004121048/http://www.edwardtbabinski.us/whales/shore_whaling_industry.html | dead-url = yes | archive-date = 2006-10-04 | journal = National Geographic Magazine |date=May 1911 | title = Shore Whaling: A World Industry | author = Andrews, R.C. }}</ref> It has also been referred to as the '''fuck ur mom with my dick lesser fin whale''' because it somewhat resembles the fin whale.<ref name=allen>{{cite book| url=https://books.google.com/?id=30YZAAAAYAAJ&pg=PA234&dq=Balaenoptera+borealis | title=Whalebone Whales of New England | author = Glover Morrill Allen | year = 1916 | page = 234 | volume = 8 | accessdate=24 June 2009 }}</ref> The American [[naturalist]] [[Roy Chapman Andrews]] compared the sei whale to the [[cheetah]], because it can swim at great speeds "for a few hundred yards", but it "soon tires if the chase is long" and "does not have the strength and staying power of its larger relatives".<ref>Andrews, Roy Chapman. 1916. ''Whale hunting with gun and camera; a naturalist's account of the modern shore-whaling industry, of whales and their habits, and of hunting experiences in various parts of the world''. New York: D. Appleton and Co., p. 128.</ref> == Taxonomy == On 21 February 1819, a 32-ft whale stranded near [[Grömitz]], in [[Schleswig-Holstein]]. The Swedish-born German naturalist Karl Rudolphi initially identified it as ''Balaena rostrata'' (=''Balaenoptera acutorostrata''). In 1823, the French naturalist [[Georges Cuvier]] described and figured Rudolphi's specimen under the name "rorqual du Nord". In 1828, Rene Lesson translated this term into ''Balaenoptera borealis'', basing his designation partly on Cuvier's description of Rudolphi's specimen and partly on a 54-ft female that had stranded on the coast of France the previous year (this was later identified as a juvenile fin whale, ''Balaenoptera physalus''). In 1846, the English zoologist [[John Edward Gray]], ignoring Lesson's designation, named Rudolphi's specimen ''Balaenoptera laticeps'', which others followed.<ref>Gray, J. E. 1846. On the cetaceous animals. pp. 1–53 in ''The zoology of the voyage of H.M.S. Erebus and Terror''. Vol. 1. Mammalia, birds (J. Richardson and J. E. Gray, eds.). E. W. Jansen, London.</ref> In 1865, the British zoologist [[William Henry Flower]] named a 45-ft specimen that had been obtained from [[Pekalongan]], on the north coast of [[Java]], ''Sibbaldius'' (=''Balaenoptera'') ''schlegelii'' — in 1946 the Russian scientist A.G. Tomilin synonymized ''S. schlegelii'' and ''B. borealis'', creating the subspecies ''B. b. schlegelii'' and ''B. b. borealis''.<ref>{{cite journal | last1 = Flower | first1 = W. H. | year = 1865 | title = Notes on the skeletons of whales in the principal museums of Holland and Belgium, with descriptions of two species apparently new to science | url = | journal = Proceedings of the Zoological Society | volume = 1864 | issue = 25| pages = 384–420 }}</ref><ref name="Perrin2009">Perrin, William F., James G. Mead, and Robert L. Brownell, Jr. "Review of the evidence used in the description of currently recognized cetacean subspecies". ''NOAA Technical Memorandum NMFS'' (December 2009), pp. 1–35.</ref> In 1884–85, the Norwegian scientist G. A. Guldberg first identified the "sejhval" of [[Finnmark]] with ''B. borealis''.<ref>{{cite journal | last1 = Guldberg | first1 = G.A. | year = 1885 | title = On the existence of a fourth species of the genus Balaenoptera | url = | journal = Journ. Anat. And Phys. | volume = 19 | issue = | pages = 293–302 }}</ref> Sei whales are [[rorqual]]s (family Balaenopteridae), baleen whales that include the [[humpback whale]], the [[blue whale]], [[Bryde's whale]], the [[fin whale]], and the [[minke whale]]. Rorquals take their name from the [[Norwegian language|Norwegian]] word ''røyrkval'', meaning "furrow whale",<ref>{{cite web|url=http://www.iberianature.com/trivia/etymology_mammals.htm | title = Etymology of mammal names | publisher = IberiaNature – Natural history facts and trivia | accessdate = 7 December 2006}}</ref> because family members have a series of longitudinal pleats or grooves on the anterior half of their ventral surface. Balaenopterids diverged from the other families of suborder [[baleen whale|Mysticeti]], also called the whalebone whales or great whales, as long ago as the middle [[Miocene]].<ref name="evolution">{{cite book | chapter-url = http://www-personal.umich.edu/~gingeric/PDFfiles/PDG413_Whaleevol.pdf | title = McGraw-Hill Yearbook of Science & Technology | year = 2004 | publisher = The McGraw Hill Companies | chapter = Whale Evolution | author = Gingerich, P.}}</ref> Little is known about when members of the various families in the Mysticeti, including the Balaenopteridae, diverged from each other. Two [[subspecies]] have been identified—the '''northern sei whale''' (''B. b. borealis'') and '''southern sei whale''' (''B. b. schlegelii'').<ref name="ITIS">{{ITIS | id = 180526 | taxon = Balaenoptera borealis | accessdate = 10 November 2006 }}</ref> Their ranges do not overlap. == Description == [[File:Balaenoptera borealis.jpg|thumb|left|Painting of a sei whale.]] The sei whale is the fourth-largest balaenopterid, after the blue whale (up to 180 tonnes, 200 tons) and the fin whale (up to 70 tonnes, 77 tons) and the humpback whale (up to 40 tonnes, 44.5 tons).<ref name="av" /> In the North Pacific, adult males average {{convert|13.7|m|ft|abbr=on}} and adult females {{convert|15|m|ft|abbr=on}}, weighing 15 and 18.5 tonnes (16.5 and 20.5 tons),<ref name="Lockyer1976">{{cite journal|last1=Lockyer|first1=C.|title=Body weights of some species of large whales|journal=ICES Journal of Marine Science|volume=36|issue=3|date=February 1976 |pages=259–273|doi=10.1093/icesjms/36.3.259}}</ref> while in the North Atlantic adult males average {{convert|14|m|ft|abbr=on}} and adult females {{convert|14.5|m|ft|abbr=on}}, weighing 15.5 and 17 tonnes (17 and 18.5 tons)<ref name="Lockyer1976" /> In the Southern Hemisphere, they average 14.5 (47.5&nbsp;ft) and {{convert|15|m|ft|abbr=on}}, respectively, weighing 17 and 18.5 tonnes (18.5 and 20.5 tons).<ref name="Lockyer1976" /> (<ref name="evans1987">Evans, Peter G. H. (1987). ''The Natural History of Whales and Dolphins''. Facts on File.</ref> In the Northern Hemisphere, males reach up to {{convert|17.1|m|ft|abbr=on}} and females up to {{convert|18.6|m|ft|abbr=on}},<ref name=Klinowska>{{cite book | last = Klinowska| first = M.| title = Dolphins, Porpoises and Whales of the World: The IUCN Red Data Book| publisher = IUCN| year = 1991| location = Cambridge, U.K.| url =}}</ref> while in the Southern Hemisphere males reach {{convert|18.6|m|ft|abbr=on}} and females {{convert|19.5|m|ft|abbr=on}} — the authenticity of an alleged {{convert|22|m|adj=on|ft|abbr=on}} female caught 50 miles northwest of [[St Kilda, Scotland|St. Kilda]] in July 1911 is doubted.<ref name="Skinner2006">Skinner, J.D. and Christian T. Chimimba. (2006). ''The Mammals of the Southern African Sub-region''. Cambridge University Press, Third Edition.</ref><ref name=WentworthThompson1919>Thompson, D’Arcy Wentworth. "On whales landed at the Scottish whaling stations, especially during the years 1908–1914 — Part VII. The sei-whale". ''The Scottish Naturalist'', nos. 85-96 (1919), pp. 37–46.</ref><ref name="martin83" /> The largest specimens taken off [[Iceland]] were a {{convert|16.15|m|adj=on|ft|abbr=on}} female and a {{convert|14.6|m|adj=on|ft|abbr=on}} male, while the longest off Nova Scotia were two {{convert|15.8|m|adj=on|ft|abbr=on}} females and a {{convert|15.2|m|adj=on|ft|abbr=on}} male.<ref name="martin83">{{cite journal | author = Martin, A.R. | year = 1983 | title = The sei whale off western Iceland. I. Size, distribution and abundance | journal = Rep. Int. Whal. Comm. | volume = 33 | pages = 457–463 }}</ref><ref name="Mitchell1975">{{cite journal | last1 = Mitchell | first1 = E.D. | year = 1975 | title = Preliminary report on Nova Scotia fishery for sei whales (''Balaenoptera borealis'')". | url = | journal = Reports of the International Whaling Commission | volume = 25 | issue = | pages = 218–225 }}</ref> The longest measured during JARPN II cruises in the North Pacific were a {{convert|16.32|m|ft|abbr=on}} female and a {{convert|15|m|ft|abbr=on}} male.<ref name="JARPNII2005">{{cite journal| last1 = Tamura | display-authors = etal | year = 2005 | title = Cruise report of the second phase of the Japanese Research Program under Special Permit in the Western North Pacific (JAPRN II) in 2005 – Offshore component | url = | journal = Rep. Int. Whal. Comm. | volume = 58 | issue = | pages = 1–52}}</ref><ref name="JAPRNII2006">{{cite journal | last1 = Tamura | display-authors = etal | year = 2006 | title = Cruise report of the second phase of the Japanese Research Program under Special Permit in the Western North Pacific (JAPRN II) in 2006 (part I) – Offshore component | url = | journal = Rep. Int. Whal. Comm. | volume = 59 | issue = | pages = 1–26 }}</ref> The longest measured by Discovery Committee staff were an adult male of {{convert|16.15|m|ft|abbr=on}} and an adult female of {{convert|17.1|m|ft|abbr=on}}, both caught off South Georgia.<ref name="Mac1943">{{cite journal| last1 = Mackintosh | first1 = N. A. | year = 1943 | title = The southern stocks of whalebone whales | url = | journal = Discovery Reports | volume = XXII | issue = | pages = 199–300}}</ref> Adults usually weigh between 15 and 20 metric tons — a {{convert|16.4|m|ft|abbr=on}} pregnant female caught off Natal in 1966 weighed 37.75 tonnes (41.6 tons), not including 6% for loss of fluids during flensing.<ref name="Lockyer1976" /> Females are considerably larger than males.<ref name="nmfs" /> At birth, a calf typically measures {{convert|4.4|-|4.5|m|ft|abbr=on}} in length. == Anatomy == {{See also|Whale anatomy}} [[File:Balaenoptera-borealis.jpg|thumb|right|A sei whale showing distinctive upright dorsal fin]] The whale's body is typically a dark steel grey with irregular light grey to white markings on the [[Anatomical terms of location#Dorsal and ventral|ventral]] surface, or towards the front of the lower body. The whale has a relatively short series of 32–60 [[pleat]]s or grooves along its ventral surface that extend halfway between the pectoral fins and umbilicus (in other species it usually extends to or past the umbilicus), restricting the expansion of the buccal cavity during feeding compared to other species.<ref>{{cite journal | last1 = Brodie | first1 = P. | last2 = Víkingsson | first2 = G. | year = 2009 | title = On the feeding mechanism of the sei whale (''Balaenoptera borealis'')". | url = | journal = Journal of Northwest Atlantic Fishery Science | volume = 42 | issue = | pages = 49–54 | doi=10.2960/j.v42.m646}}</ref> The [[Rostrum (anatomy)|rostrum]] is pointed and the [[Fish anatomy#Types of fin|pectoral fins]] are relatively short, only 9%–10% of body length, and pointed at the tips.<ref name="acs" /> It has a single ridge extending from the tip of the rostrum to the paired [[Blowhole (biology)|blowholes]] that are a distinctive characteristic of baleen whales. The whale's skin is often marked by pits or wounds, which after healing become white scars. These are now known to be caused by [[Cookiecutter shark|"cookie-cutter" sharks]] (''Isistius brasiliensis'').<ref name="shevchenko">{{cite journal | author = Shevchenko, V.I. | year = 1977 | title = Application of white scars to the study of the location and migrations of sei whale populations in Area III of the Antarctic | journal = Rep. Int. Whal. Comm. | volume = Spec. Iss. 1 | pages = 130–134}}</ref> It has a tall, [[sickle]]-shaped [[dorsal fin]] that ranges in height from {{convert|38|-|90|cm|in|abbr=on}} and averages {{convert|53|-|56|cm|in|abbr=on}}, about two-thirds of the way back from the tip of the rostrum.<ref name=Matthews1938>{{cite journal| last1 = Matthews | first1 = L.H. | year = 1938 | title = The sei whale ''Balaenoptera borealis''". | url = | journal = Discovery Reports | volume = 17 | issue = | pages = 183–290}}</ref> Dorsal fin shape, [[pigment]]ation pattern, and scarring have been used to a limited extent in [[Wildlife photo-identification|photo-identification]] studies.<ref name="schilling">{{cite journal | author = Schilling, M.R. | author2 = I. Seipt | author3 = M.T. Weinrich | author4 = S.E. Frohock | author5 = A.E. Kuhlberg | author6 = P.J. Clapham | year = 1992 | title = Behavior of individually identified sei whales ''Balaenoptera borealis'' during an episodic influx into the southern Gulf of Maine in 1986 | journal = Fish. Bull. | volume = 90 | pages = 749–755 | url = https://secure2.nni.com/whalecenter/pdfs/Sei_whales_FishBull92.pdf | deadurl = yes | archiveurl = https://www.webcitation.org/5hcFfBPZK?url=https://secure2.nni.com/whalecenter/pdfs/Sei_whales_FishBull92.pdf | archivedate = 18 June 2009 | df = dmy-all }}</ref> The tail is thick and the [[Whale#Appendages|fluke]], or lobe, is relatively small in relation to the size of the whale's body.<ref name="acs" /> [[File:Baleen.jpg|thumb|left|Close-up view of baleen plates, used to strain food from the water|alt=Photo displaying dozens of baleen plates: The plates face each other, and are evenly spaced at approximately {{convert|0.25|in|cm|0|abbr=on}} intervals. The plates are attached to the jaw at the top, and have hairs at the bottom end.]] Adults have 300–380 ashy-black baleen plates on each side of the mouth, up to {{convert|80|cm|in|abbr=on}} long. Each plate is made of [[nail (anatomy)|fingernail]]-like [[keratin]], which is bordered by a fringe of very fine, short, curly, wool-like white bristles.<ref name="adw" /> The sei's very fine baleen bristles, about {{convert|0.1|mm|in|3|abbr=on}} are the most reliable characteristic that distinguishes it from other rorquals.<ref name="mead">{{cite journal | author = Mead, J.G. | year = 1977 | title = Records of sei and Bryde's whales from the Atlantic coast of the United States, the Gulf of Mexico, and the Caribbean | journal = Rep. Int. Whal. Comm. | volume = Spec. Iss. 1 | pages = 113–116}}</ref> The sei whale looks similar to other large baleen whales. The best way to distinguish between it and Bryde's whale, apart from differences in baleen plates, is by the presence of lateral ridges on the dorsal surface of the Bryde's whale's rostrum. Large individuals can be confused with fin whales, unless the fin whale's asymmetrical head coloration is clearly seen. The fin whale's lower jaw's right side is white, and the left side is grey. When viewed from the side, the rostrum appears slightly arched (accentuated at the tip), while fin and Bryde's whales have relatively flat rostrums.<ref name="nmfs" /> == Life history == === Surface behaviors === Sei whales usually travel alone<ref name="edds84">{{cite journal | author = Edds, P.L. |author2 = T.J. MacIntyre|author3 = R. Naveen | year = 1984 | title = Notes on a sei whale (''Balaenoptera borealis'' Lesson) sighted off Maryland | journal = Cetus | volume = 5 | issue = 2 | pages = 4–5 }}</ref> or in pods of up to six individuals.<ref name="schilling" /> Larger groups may assemble at particularly abundant feeding grounds. Very little is known about their [[social structure]]. During the southern Gulf of Maine influx in mid-1986, groups of at least three sei whales were observed "milling" on four occasions – i.e. moving in random directions, rolling, and remaining at the surface for over 10 minutes. One whale would always leave the group during or immediately after such socializing bouts.<ref name="schilling" /> The sei whale is among the fastest [[cetacea]]ns. It can reach speeds of up to {{convert|50|km/h|kn|abbr=on}} over short distances.<ref name="adw" /> However, it is not a remarkable diver, reaching relatively shallow depths for 5 to 15&nbsp;minutes. Between dives, the whale surfaces for a few minutes, remaining visible in clear, calm waters, with blows occurring at intervals of about 60 seconds (range: 45–90&nbsp;sec.). Unlike the fin whale, the sei whale tends not to rise high out of the water as it dives, usually just sinking below the surface. The [[Blowhole (biology)|blowholes]] and dorsal fin are often exposed above the water surface almost simultaneously. The whale almost never lifts its flukes above the surface, and are generally less [[Whale surfacing behaviour|active on water surfaces]] than closely related Bryde's whales; it rarely [[Whale#Behavior|breaches]].<ref name="nmfs" /> === Feeding === [[File:Balaenoptera borealis 3.jpg|thumb|right|Feeding at the surface|alt=]] [[File:Krill swarm.jpg|thumb|right|[[Krill]], shrimp-like marine invertebrate animals, are one of the sei whale's primary foods.|alt=Photo of krill in water]] This rorqual is a [[filter feeder]], using its [[baleen]] plates to obtain its food by opening its mouth, engulfing or skimming large amounts of the water containing the food, then straining the water out through the baleen, trapping any food items inside its mouth. The sei whale feeds near the surface of the ocean, swimming on its side through swarms of [[predation|prey]] to obtain its average of about {{convert|900|kg|lb|abbr=on}} of food each day.<ref name="adw" /> For an animal of its size, for the most part, its preferred foods lie unusually relatively low in the [[food chain]], including [[zooplankton]] and small fish. The whale's diet preferences has been determined from stomach analyses, direct observation of feeding behavior,<ref name="watkins">{{cite journal | author = Watkins, W.A.|author2=W.E. Schevill |year = 1979 |title= Aerial observations of feeding behavior in four baleen whales: ''Eubalaena glacialis'', ''Balaenoptera borealis'', ''Megaptera novaeangliae'', and ''Balaenoptera physalus'' |journal= J. Mammal.|volume= 60 |pages=155–163| doi = 10.2307/1379766 |issue= 1 |jstor=1379766}}</ref><ref name="weinrich">{{cite journal | author = Weinrich, M.T.|author2 = C.R. Belt|author3 = M.R. Schilling|author4 = M. Marcy| year = 1986 |title= Behavior of sei whales in the southern Gulf of Maine, summer 1986 |journal = Whalewatcher |volume = 20|issue = 4|pages = 4–7 }}</ref> and analyzing [[feces|fecal matter]] collected near them, which appears as a dilute brown cloud. The feces are collected in nets and DNA is separated, individually identified, and matched with known species.<ref name="NatGeo">{{cite web|url=http://news.nationalgeographic.com/news/2002/02/0206_020206_wirewhales.html | title = New Research Method May Ease Whale Killing | publisher = National Geographic News | accessdate = 19 December 2006 | date = 6 February 2002 | author = Darby, A.}}</ref> The whale competes for food against [[clupeidae|clupeid]] fish ([[herring]] and its relatives), [[basking shark]]s, and [[right whale]]s. In the [[Atlantic Ocean|North Atlantic]], it feeds primarily on [[Calanoida|calanoid copepods]], specifically ''[[Calanus finmarchicus]]'', with a secondary preference for [[krill|euphausiids]], in particular ''[[Meganyctiphanes norvegica]]'' and ''[[Thysanoessa inermis]]''.<ref name="mizroch84">{{cite journal | author = Mizroch, S.A. |author2 = D.W. Rice|author3 = J.M. Breiwick | year = 1984 | title = The Sei Whale, ''Balaenoptera borealis'' | journal = Mar Fish. Rev. | volume = 46 | issue = 4 | pages = 25–29 }}</ref><ref name="christensen92">{{cite journal |author = Christensen, I. |author2=T. Haug |author3=N. Øien |year= 1992 |title= A review of feeding and reproduction in large baleen whales (Mysticeti) and sperm whales Physeter macrocephalus in Norwegian and adjacent waters| journal= Fauna Norvegica Series A |volume = 13 | pages=39–48}}</ref> In the [[Pacific Ocean|North Pacific]], it feeds on similar zooplankton, including the copepod species ''Neocalanus cristatus'', ''N. plumchrus'', and ''Calanus pacificus'', and euphausiid species ''Euphausia pacifica'', ''E. similis'', ''Thysanoessa inermis'', ''T. longipes'', ''T. gregaria'' and ''T. spinifera''. In addition, it eats larger organisms, such as the [[Japanese flying squid]], ''Todarodes pacificus pacificus'',<ref name="tamura01">{{cite journal | author = Tamura, T. | title = Competition for food in the Ocean: Man and other apical predators | publisher = Reykjavik Conference on Responsible Fisheries in the Marine Ecosystem, Reykjavik, Iceland, 1–4 October 2001 | date = October 2001 | url = http://www.fao.org/tempref/FI/DOCUMENT/reykjavik/pdf/09Tamura.pdf | accessdate = 21 December 2011}}</ref> and small fish, including [[anchovy|anchovies]] (''Engraulis japonicus'' and ''E. mordax''), [[South American pilchard|sardines]] (''Sardinops sagax''), [[Pacific saury]] (''Cololabis saira''), [[Scomber|mackerel]] (''Scomber japonicus'' and ''S. australasicus''), [[Trachurus|jack mackerel]] (''Trachurus symmetricus'') and juvenile [[Sebastes|rockfish]] (''Sebastes jordani'').<ref name="mizroch84" /><ref name="nemoto">{{cite journal | author = Nemoto, T. |author2=A. Kawamura |year = 1977 |title = Characteristics of food habits and distribution of baleen whales with special reference to the abundance of North Pacific sei and Bryde's whales | journal = Rep. Int. Whal. Comm. |volume = Spec. Iss. 1 |pages =80–87}}</ref> Some of these fish are commercially important. Off central California, they mainly feed on anchovies between June and August, and on krill (''Euphausia pacifica'') during September and October.<ref name="rice77">{{cite journal | author = Rice, D.W. | year = 1977 | title = Synopsis of biological data on the sei whale and Bryde's whale in the eastern North Pacific | journal = Rep. Int. Whal. Comm. | volume = Spec. Iss. 1 | pages = 92–97}}</ref> In the Southern Hemisphere, prey species include the copepods ''Neocalanus tonsus'', ''Calanus simillimus'', and ''Drepanopus pectinatus'', as well as the euphausiids ''Euphausia superba'' and ''Euphausia vallentini''<ref name="mizroch84" /> and the pelagic [[amphipod]] ''[[Themisto gaudichaudii]]''. === Reproduction === {{See also|Whale reproduction}} [[Mating]] occurs in [[temperateness|temperate]], subtropical seas during the winter. [[Gestation]] is estimated to vary around 10{{frac|3|4}} months,<ref name="lockyer and martin">{{cite journal | author = Lockyer, C. |author2=A.R. Martin | year = 1983 | title= The sei whale off western Iceland. II. Age, growth and reproduction | journal= Rep. Int. Whal. Comm. |volume = 33 | pages= 465–476}}</ref> 11{{frac|1|4}} months,<ref name="lockyer77">{{cite journal | author = Lockyer, C. | year = 1977 |title= Some estimates of growth in the sei whale, ''Balaenoptera borealis'' | journal = Rep. Int. Whal. Comm. |volume = Spec. Iss. 1 | pages = 58–62}}</ref> or one year,<ref name="risting">{{cite journal | author = Risting, S | year = 1928 |title = Whales and whale foetuses | journal = Rapp. Cons. Explor. Mer | volume = 50| pages = 1–122}}</ref> depending which model of [[fetus|foetal]] growth is used. The different estimates result from scientists' inability to observe an entire pregnancy; most reproductive data for baleen whales were obtained from animals caught by commercial whalers, which offer only single snapshots of fetal growth. Researchers attempt to extrapolate conception dates by comparing fetus size and characteristics with newborns. A newborn is [[weaning|weaned]] from its mother at 6–9 months of age, when it is {{convert|8|-|9|m|ft|abbr=on}} long,<ref name=Klinowska /> so weaning takes place at the summer or autumn feeding grounds. Females reproduce every 2–3 years,<ref name="lockyer and martin" /> usually to a single calf.<ref name="adw" /> In the Northern Hemisphere, males are usually {{convert|12.8|-|12.9|m|ft|abbr=on}} and females {{convert|13.3|-|13.5|m|ft|abbr=on}} at sexual maturity, while in the Southern Hemisphere, males average {{convert|13.6|m|ft|abbr=on}} and females {{convert|14|m|ft|abbr=on}}.<ref name="evans1987" /> The average age of [[sexual maturity]] of both [[sex]]es is 8–10 years.<ref name="lockyer and martin" /> The whales can reach ages up to 65&nbsp;years.<ref name="wwf.com">{{cite web| url = http://www.panda.org/what_we_do/endangered_species/cetaceans/about/sei_whale/seiwhale_ecology_habitat/| date = 18 June 2007 | title = Sei whale – Ecology & Habitat | author = WWF | publisher = WWF Global Species Programme | accessdate = 19 January 2010}}</ref> === Vocalizations === {{See also|Whale sound}} The sei whale makes long, loud, low-frequency sounds. Relatively little is known about specific calls, but in 2003, observers noted sei whale calls in addition to sounds that could be described as "growls" or "whooshes" off the coast of the [[Antarctic Peninsula]].<ref name="mcdonald05">{{cite journal | author = McDonald, M. |author2=Hildebrand, J. |author3=Wiggins, S. |author4=Thiele, D. |author5=Glasgow, D. |author6=Moore, S. | title = Sei whale sounds recorded in the Antarctic | journal = The Journal of the Acoustical Society of America |date=December 2005 | volume = 118 | issue = 6 | pmid = 16419837 | pages = 3941–3945 | url = http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JASMAN000118000006003941000001&idtype=cvips&gifs=yes | doi = 10.1121/1.2130944}}</ref> Many calls consisted of multiple parts at different frequencies. This combination distinguishes their calls from those of other whales. Most calls lasted about a half second, and occurred in the 240–625&nbsp;[[hertz]] range, well within the range of human hearing. The maximum volume of the vocal sequences is reported as 156 [[decibel]]s relative to 1&nbsp;[[Pascal (unit)|micropascal (μPa)]] at a reference distance of one metre.<ref name="mcdonald05" /> An observer situated one metre from a vocalizing whale would perceive a volume roughly equivalent to the volume of a jackhammer operating two metres away.<ref>Direct comparisons of sounds in water to sounds in air can be complicated, see [http://www.surtass-lfa-eis.com/Terms/index.htm this description] {{webarchive|url=https://web.archive.org/web/20090725234254/http://www.surtass-lfa-eis.com/Terms/index.htm |date=25 July 2009 }} for more information.</ref> In November 2002, scientists recorded calls in the presence of sei whales off [[Maui]]. All the calls were downswept tonal calls, all but two ranging from a mean high frequency of 39.1&nbsp;Hz down to 21&nbsp;Hz of 1.3 second duration – the two higher frequency downswept calls ranged from an average of 100.3&nbsp;Hz to 44.6&nbsp;Hz over 1 second of duration. These calls closely resembled and coincided with a peak in "20- to 35-Hz irregular repetition interval" downswept pulses described from seafloor recordings off [[Oahu]], which had previously been attributed to fin whales.<ref>{{cite journal | last1 = Rankin | first1 = S. | last2 = Barlow | first2 = J. | year = 2007 | title = Vocalizations of the sei whale ''Balaenoptera borealis'' off the Hawaiian Islands | url = | journal = Bioacoustics | volume = 16 | issue = 2| pages = 137–145 | doi=10.1080/09524622.2007.9753572}}</ref> Between 2005 and 2007, low frequency downswept vocalizations were recorded in the Great South Channel, east of [[Cape Cod]], [[Massachusetts]], which were only significantly associated with the presence of sei whales. These calls averaged 82.3&nbsp;Hz down to 34&nbsp;Hz over about 1.4 seconds in duration. This call has also been reported from recordings in the Gulf of Maine, [[New England]] shelf waters, the mid-Atlantic Bight, and in [[Davis Strait]]. It likely functions as a contact call.<ref>{{cite journal | last1 = Baumgartner | first1 = M.F. | last2 = Van Parijs | first2 = S.M. | last3 = Wenzel | first3 = F.W. | last4 = Tremblay | first4 = C.J. | last5 = Esch | first5 = H.C. | last6 = Ward | first6 = A.A. | year = 2008 | title = Low frequency vocalizations attributed to sei whales (''Balaenoptera borealis'')". | url = | journal = Journal of the Acoustical Society of America | volume = 124 | issue = 2| pages = 1339–1349 | doi=10.1121/1.2945155| pmid = 18681619 }}</ref> BBC News quoted Roddy Morrison, a former whaler active in South Georgia, as saying, "When we killed the sei whales, they used to make a noise, like a crying noise. They seemed so friendly, and they'd come round and they'd make a noise, and when you hit them, they cried really. I didn't think it was really nice to do that. Everybody talked about it at the time I suppose, but it was money. At the end of the day that's what counted at the time. That's what we were there for."<ref>{{cite web|url=https://www.bbc.com/news/magazine-27734930|title=South Georgia: The lost whaling station at the end of the world|work=BBC News}}</ref> == Range and migration == [[File:Faroe stamp 403 sei whale (Balaenoptera borealis).jpg|thumb|right|upright|Drawing of a sei whale on a [[Faroe Islands|Faroese]] stamp, issued 17 September 2001]] Sei whales live in all oceans, although rarely in polar or tropical waters.<ref name="nmfs" /> The difficulty of distinguishing them at sea from their close relatives, Bryde's whales and in some cases from fin whales, creates confusion about their range and population, especially in warmer waters where Bryde's whales are most common. In the North Atlantic, its range extends from [[southern Europe]] or [[Northwest Africa|northwestern Africa]] to Norway, and from the [[southern United States]] to [[Greenland]].<ref name="Gambell85a" /> The southernmost confirmed records are strandings along the northern [[Gulf of Mexico]] and in the [[Greater Antilles]].<ref name="mead" /> Throughout its range, the whale tends not to frequent semienclosed bodies of water, such as the Gulf of Mexico, the [[Gulf of Saint Lawrence]], [[Hudson Bay]], the [[North Sea]], and the [[Mediterranean Sea]].<ref name="nmfs" /> It occurs predominantly in deep water, occurring most commonly over the [[continental shelf|continental slope]],<ref name="CETAP">{{cite journal | author = CETAP | year = 1982 | title = Final Report of the Cetacean and Turtle Assessment Program, University of Rhode Island, to Bureau of Land Management | publisher = U.S. Department of the Interior. Ref. No. AA551-CT8–48}}</ref> in basins situated between banks,<ref name="sutcliffe">{{cite book | author1= Sutcliffe, W.H. Jr. |author2=P.F. Brodie | year = 1977 | chapter = Whale distributions in Nova Scotia waters | title = Fisheries & Marine Service Technical Report No. 722 }}</ref> or [[submarine canyon]] areas.<ref name="kenney87">{{cite journal | author1= Kenney, R.D. |author2=H.E. Winn | year = 1987 | title = Cetacean biomass densities near submarine canyons compared to adjacent shelf/slope areas | journal = Cont. Shelf Res. | volume = 7 | pages = 107–114 | doi = 10.1016/0278-4343(87)90073-2 | issue=2}}</ref> In the North Pacific, it ranges from [[20th parallel north|20°N]] to [[23rd parallel north|23°N]] [[latitude]] in the winter, and from [[35th parallel north|35°N]] to [[50th parallel north|50°N]] latitude in the summer.<ref name="masaki76">{{cite journal | author = Masaki, Y. | year = 1976 | title = Biological studies on the North Pacific sei whale | journal = Bull. Far Seas Fish. Res. Lab. | volume = 14 | pages = 1–104 }}</ref> Approximately 75% of the North Pacific population lives east of the [[International Date Line]],<ref name="horwood87" /> but there is little information regarding the North Pacific distribution. {{As of|2017|February}}, the U.S. [[National Marine Fisheries Service]] estimated that the eastern North Pacific population stood at 374 whales.<ref>{{cite web |url=https://www.fisheries.noaa.gov/webdam/download/70095913 |title=SEI WHALE (Balaenoptera borealis borealis): Eastern North Pacific Stock |work=[[National Marine Fisheries Service]] Marine Mammal Stock Assessment Reports |date=2017-02-08 |accessdate=2019-05-23}}</ref> Two whales tagged in deep waters off California were later recaptured off [[Washington (state)|Washington]] and [[British Columbia]], revealing a possible link between these areas,<ref name="rice74">{{cite book | author = Rice, D.W. | year = 1974 | chapter = Whales and whale research in the North Pacific | editor = Schervill, W.E. | title = The Whale Problem: a status report | pages = 170–195 | publisher = Harvard University Press | location = Cambridge, Massachusetts| isbn= 978-0-674-95075-7}}</ref> but the lack of other tag recovery data makes these two cases inconclusive. Occurrences within the [[Gulf of California]] have been fewer.<ref>Gendron D.. Rosales C. S.. 1996. [http://www.aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/1996/AquaticMammals_22-02/22-02_Gendron.pdf Recent sei whale (Balaenoptera borealis) sightings in the Gulf of California, Mexico]. Aquatic Mammals 1996, 22.2, pp.127-130 (pdf). Retrieved on February 24, 2017</ref> In [[Sea of Japan]] and [[Sea of Okhotsk]], whales are not common, although whales were more commonly seen than today in southern part of Sea of Japan from Korean Peninsula to the southern [[Primorsky Krai]] in the past, and there had been a sighting in [[Golden Horn Bay]],<ref>{{cite web|url=http://www.zoosite.com.ua/animal-sei-whale-642.html|title=Сейвал / Balaenoptera borealis|website=www.zoosite.com.ua}}</ref> and whales were much more abundant in the triangle area around [[Kunashir Island]] in whaling days, making the area well known as sei – ground,<ref>Uni Y.,2006 [http://www.cho.co.jp/natural-h/download/archive/shiretoko/2703s_UNI.pdf Whales, Dolphins and Porpoises off Shiretoko]. Bulletin of the Shiretoko Museum 27: pp.37-46. Retrieved on 16 December 2015</ref> and there had been a sighting of a cow calf pair off the [[Sea of Japan]] coast of mid-[[Honshu]] during cetacean survey. Sei whales have been recorded from northern Indian Ocean as well such as around [[Sri Lanka]] and [[India]]n coasts.<ref>Sathasivam K.. 2015. [https://www.cbd.int/doc/meetings/mar/ebsaws-2015-01/other/ebsaws-2015-01-gobi-submission5-en.pdf A CATALOGUE OF INDIAN MARINE MAMMAL RECORDS] (pdf)</ref> In the Southern Hemisphere, summer distribution based upon historic catch data is between [[40th parallel south|40°S]] and [[50th parallel south|50°S]] latitude in the South Atlantic and southern Indian Oceans and [[45th parallel south|45°S]] and [[60th parallel south|60°S]] in the South Pacific, while winter distribution is poorly known, with former winter whaling grounds being located off northeastern Brazil ([[7th parallel south|7°S]]) and Peru ([[6th parallel south|6°S]]).<ref name="iucn" /> The majority of the "sei" whales caught off Angola and Congo, as well as other nearby areas in equatorial West Africa, are thought to have been predominantly misidentified [[Bryde's whale]]s. For example, Ruud (1952) found that 42 of the "sei whale" catch off [[Gabon]] in 1952 were actually Bryde's whales, based on examination of their baleen plates. The only confirmed historical record is the capture of a {{convert|14|m|ft|abbr=on}} female, which was brought to the Cap Lopez whaling station in Gabon in September 1950. During cetacean sighting surveys off Angola between 2003 and 2006, only a single confirmed sighting of two individuals was made in August 2004, compared to 19 sightings of Bryde's whales.<ref>{{cite journal| last1 = Weir | first1 = C.R. | year = 2010 | title = A review of cetacean occurrence in West African waters from the Gulf of Guinea to Angola | url = | journal = Mammal Review | volume = 40 | issue = | pages = 2–39 | doi=10.1111/j.1365-2907.2009.00153.x}}</ref> Sei whales are commonly distributed along west to southern Latin America including along entire Chilean coasts, within [[Beagle Channel]]<ref>Daniel.Bisson – [https://www.panoramio.com/photo/71888436 SEI Whale at Beagle canal, Ushuaia, Argentina] {{webarchive|url=https://web.archive.org/web/20160413175552/http://www.panoramio.com/photo/71888436 |date=13 April 2016 }}</ref> to [[Isla Grande de Tierra del Fuego]],<ref>Glenn Seplak – [https://www.flickr.com/photos/gauchocat/6529053177/in/photostream/ Minke Whale (Sei Whale?)]</ref> and possibly feed in the [[Aysén Region|Aysen]] region.<ref>OceanSounds e.V. - [http://ocean-sounds.org/en_US/whales-in-patagonia/marine-mammals-in-patagonia/sei-whale/ Sei whale]</ref> === Migration === In general, the sei whale migrates annually from cool and subpolar waters in summer to temperate and subtropical waters for winter, where food is more abundant.<ref name="nmfs" /> In the northwest Atlantic, sightings and catch records suggest the whales move north along the shelf edge to arrive in the areas of [[Georges Bank]], [[Gulf of Maine|Northeast Channel]], and [[Gulf of Maine|Browns Bank]] by mid- to late June. They are present off the south coast of [[Newfoundland (island)|Newfoundland]] in August and September, and a southbound migration begins moving west and south along the [[Nova Scotia]]n shelf from mid-September to mid-November. Whales in the [[Labrador Sea]] as early as the first week of June may move farther northward to waters southwest of [[Greenland]] later in the summer.<ref name="mitchell and chapman">{{cite journal | author = Mitchell, E. |author2=D.G. Chapman | year = 1977 | title = Preliminary assessment of stocks of northwest Atlantic sei whales (''Balaenoptera borealis'') | journal = Rep. Int. Whal. Comm. | volume = Spec. Iss. 1 | pages = 117–120 }}</ref> In the northeast Atlantic, the sei whale winters as far south as [[West Africa]] such as off [[Banc d'Arguin National Park|Bay of Arguin]], off [[Cintra Bay|coastal Western Sahara]] and follows the continental slope northward in spring. Large females lead the northward migration and reach the [[Denmark Strait]] earlier and more reliably than other sexes and classes, arriving in mid-July and remaining through mid-September. In some years, males and younger females remain at lower latitudes during the summer.<ref name="martin83" /> Despite knowing some general migration patterns, exact routes are incompletely known<ref name="martin83" /> and scientists cannot readily predict exactly where groups will appear from one year to the next.<ref name="jonsgard and darling">{{cite journal | author = Jonsgård, Å. |author2=K. Darling | year = 1977 | title = On the biology of the eastern North Atlantic sei whale, ''Balaenoptera borealis'' Lesson | journal = Rep. Int. Whal. Comm. | volume = Spec. Iss. 1 | pages = 124–129 }}</ref> F.O. Kapel noted a correlation between appearances west of Greenland and the incursion of relatively warm waters from the [[North Atlantic Current|Irminger Current]] into that area.<ref name="kapel85">{{cite journal | author = Kapel, F.O. | year =1985 | title = On the occurrence of sei whales (''Balenoptera borealis'') in West Greenland waters | journal = Rep. Int. Whal. Comm. | volume = 35 | pages = 349–352}}</ref> Some evidence from tagging data indicates individuals return off the coast of [[Iceland]] on an annual basis.<ref name="sigurjonsson83">{{cite journal | author = Sigurjónsson, J. | year = 1983 | title = The cruise of the ''Ljósfari'' in the Denmark Strait (June–July 1981) and recent marking and sightings off Iceland | journal = Rep. Int. Whal. Comm. | volume = 33 | pages =667–682}}</ref> An individual satellite-tagged off [[Faial Island|Faial]], in the [[Azores]], traveled more than {{convert|4,000|km|mi|abbr=on}} to the Labrador Sea via the [[Charlie-Gibbs Fracture Zone]] (CGFZ) between April and June 2005. It appeared to "hitch a ride" on prevailing currents, with erratic movements indicative of feeding behavior in five areas, in particular the CGFZ, an area of known high sei whale abundance as well as high copepod concentrations.<ref>{{cite journal| last1 = Olsen | first1 = E. | last2 = Budgell | first2 = P. | last3 = Head | first3 = E. | last4 = Kleivane | first4 = L. | last5 = Nøttestad | first5 = L. | last6 = Prieto | first6 = R. | display-authors = etal | year = 2009 | title = First satellite-tracked long-distance movement of a sei whale (''Balaenoptera borealis'') in the North Atlantic | url = | journal = Aquatic Mammals | volume = 35 | issue = 3| pages = 313–318 | doi=10.1578/am.35.3.2009.313}}</ref> Seven whales tagged off Faial and [[Pico Island|Pico]] from May to June in 2008 and 2009 made their way to the Labrador Sea, while an eighth individual tagged in September 2009 headed southeast – its signal was lost between [[Madeira]] and the [[Canary Islands]].<ref>Prieto, Rui, Monica A. Silva, Martine Berube, Per J. Palsbøll (2012). "Migratory destinations and sex composition of sei whales (''Balaenoptera borealis'') transiting through the Azores". ''SC/64/RMP6'', pp. 1-7.</ref> == Whaling == {{Main|Whaling|History of whaling}} The development of explosive [[harpoon]]s and steam-powered whaling ships in the late nineteenth century brought previously unobtainable large whales within reach of commercial [[Whaling|whalers]]. Initially their speed and elusiveness,<ref name="sigurjónsson88">{{cite journal | author = Sigurjónsson, J.|year = 1988 |title= Operational factors of the Icelandic large whale fishery | journal = Rep. Int. Whal. Comm. |volume = 38 |pages = 327–333}}</ref> and later the comparatively small yield of [[Whale oil|oil]] and [[whale meat|meat]] partially protected them. Once stocks of more profitable [[right whale]]s, blue whales, fin whales, and humpback whales became depleted, sei whales were hunted in earnest, particularly from 1950 to 1980.<ref name="av" /> === North Atlantic === [[File:Av hvalfangstens historie (1922) (20165115029).jpg|thumb|left|A sei whale (foreground) caught off Finnmark.]] In the North Atlantic between 1885 and 1984, 14,295 sei whales were taken.<ref name="horwood87" /> They were hunted in large numbers off the coasts of Norway and Scotland beginning in the late 19th and early 20th centuries,<ref name="jonsgard and darling" /> and in 1885 alone, more than 700 were caught off [[Finnmark]].<ref name="andrews16">{{cite journal | author = Andrews, R.C.| year= 1916 | title= The sei whale (''Balaenoptera borealis'' Lesson)| journal = Mem. Am. Mus. Nat. Hist. New Ser. | volume = 1 | issue = 6 | pages = 291–388}}</ref> Their meat was a popular Norwegian food. The meat's value made the hunting of this difficult-to-catch species profitable in the early twentieth century.<ref>{{cite book | author = Ingebrigtsen, A.| year = 1929 | chapter = Whales caught in the North Atlantic and other seas | title = Rapports et Procès-verbaux des réunions, Cons. Perm. Int. L'Explor. Mer, Vol. LVI| publisher = Høst & Fils | location = Copenhagen }}</ref> In Iceland, a total of 2,574 whales were taken from the [[Hvalfjörður]] whaling station between 1948 and 1985. Since the late 1960s to early 1970s, the sei whale has been second only to the fin whale as the preferred target of Icelandic whalers, with meat in greater demand than [[whale oil]], the prior target.<ref name="sigurjónsson88" /> Small numbers were taken off the [[Iberian Peninsula]], beginning in the 1920s by Spanish whalers,<ref name="aguilar and lens">{{cite journal | author = Aguilar, A. |author2=S. Lens | year = 1981 | title = Preliminary report on Spanish whaling operations | journal = Rep. Int. Whal. Comm. |volume = 31 | pages = 639–643}}</ref> off the [[Nova Scotia]]n shelf in the late 1960s and early 1970s by Canadian whalers,<ref name="mitchell and chapman" /> and off the coast of West Greenland from the 1920s to the 1950s by Norwegian and Danish whalers.<ref name="kapel85" /> === North Pacific === [[File:The American Museum journal (c1900-(1918)) (17974297289).jpg|thumb|right|A sei whale being harpooned off Japan.]] In the North Pacific, the total reported catch by commercial whalers was 72,215 between 1910 and 1975;<ref name="horwood87" /> the majority were taken after 1947.<ref name="barlow97">{{cite journal | author = Barlow, J. | author2 = K. A. Forney | author3 = P.S. Hill | author4 = R.L. Brownell Jr. | author5 = J.V. Carretta | author6 = D.P. DeMaster | author7 = F. Julian | author8 = M.S. Lowry | author9 = T. Ragen | author10 = R.R. Reeves | last-author-amp = yes | year = 1997 | title = U.S. Pacific marine mammal stock assessments: 1996 | publisher = NOAA Tech. Mem. NMFS-SWFSC-248 | url=http://swfsc.noaa.gov/publications/TM/SWFSC/NOAA-TM-NMFS-SWFSC-248.PDF }}</ref> Shore stations in [[Japan]] and [[Korea]] processed 300–600 each year between 1911 and 1955. In 1959, the Japanese catch peaked at 1,340. Heavy exploitation in the North Pacific began in the early 1960s, with catches averaging 3,643 per year from 1963 to 1974 (total 43,719; annual range 1,280–6,053).<ref name="tillman77">{{cite journal | author = Tillman, M.F.| year = 1977 | title = Estimates of population size for the North Pacific sei whale | journal = Rep. Int. Whal. Comm. | volume = Spec. Iss. 1 | pages = 98–106}}</ref> In 1971, after a decade of high catches, it became scarce in Japanese waters, ending commercial whaling in 1975.<ref name="mizroch84" /><ref name="CFWS42">{{cite book | author = Committee for Whaling Statistics | year = 1942 | title =International whaling statistics | publisher = Committee for Whaling Statistics | location = Oslo}}</ref> Off the coast of North America, sei whales were hunted off British Columbia from the late 1950s to the mid-1960s, when the number of whales captured dropped to around 14 per year.<ref name="av" /> More than 2,000 were caught in British Columbian waters between 1962 and 1967.<ref name="pike69">{{cite journal | author = Pike, G.C|author2=I.B. MacAskie | year = 1969| title = Marine mammals of British Columbia| journal = Fish. Res. Bd. Canada Bull. | volume = 171}}</ref> Between 1957 and 1971, [[California]] shore stations processed 386 whales.<ref name="rice77" /> Commercial Sei whaling ended in the eastern North Pacific in 1971. === Southern Hemisphere === A total of 152,233 were taken in the Southern Hemisphere between 1910 and 1979.<ref name="horwood87" /> Whaling in [[Southern Ocean|southern oceans]] originally targeted humpback whales. By 1913, this species became rare, and the catch of fin and blue whales began to increase. As these species likewise became scarce, sei whale catches increased rapidly in the late 1950s and early 1960s.<ref name="mizroch84" /> The catch peaked in 1964–65 at over 20,000 sei whales, but by 1976, this number had dropped to below 2,000 and commercial whaling for the species ended in 1977.<ref name="av" /> === Post-protection whaling === Since the moratorium on commercial whaling, some sei whales have been taken by Icelandic and Japanese whalers under the IWC's scientific research programme. Iceland carried out four years of scientific whaling between 1986 and 1989, killing up to 40 sei whales a year.<ref name="wwf-Iceland">{{cite press release | publisher = WWF-International | title = WWF condemns Iceland's announcement to resume whaling | date = 7 August 2003 | url = http://www.panda.org/about_wwf/where_we_work/arctic/news/index.cfm?uNewsID=8221 | accessdate = 10 November 2006 }}{{dead link|date=September 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Japanese scientists catch about 50 sei whales each year for this purpose. The research is conducted by the [[Institute of Cetacean Research]] (ICR) in [[Tokyo]], a privately funded, nonprofit institution. The main focus of the research is to examine what they eat and to assess the competition between whales and fisheries. Dr. Seiji Ohsumi, Director General of the ICR, said, :"It is estimated that whales consume 3 to 5 times the amount of marine resources as are caught for human consumption, so our whale research is providing valuable information required for improving the management of all our marine resources."<ref name="icr02a">{{cite press release | publisher = The Institute of Cetacean Research, Tokyo, Japan | title = Japan not catching endangered whales | date = 1 March 2002 | url = http://www.icrwhale.org/eng/SEI.pdf | format = PDF | accessdate = 10 November 2006 | deadurl = yes | archiveurl = https://web.archive.org/web/20061028211938/http://www.icrwhale.org/eng/SEI.pdf | archivedate = 28 October 2006 | df = dmy-all }}</ref> He later added, :"Sei whales are the second-most abundant species of whale in the western North Pacific, with an estimated population of over 28,000 animals. [It is] clearly not endangered."<ref name="icr02b">{{cite press release | publisher = The Institute of Cetacean Research, Tokyo, Japan | title = Japan's senior whale scientist responds to New York Times advertisement | date = 20 May 2002 | accessdate = 10 November 2006 | url = http://www.icrwhale.org/eng/NYTimes.pdf | format = PDF | deadurl = yes | archiveurl = https://web.archive.org/web/20061209053202/http://www.icrwhale.org/eng/NYTimes.pdf | archivedate = 9 December 2006 | df = dmy-all }}</ref> Conservation groups, such as the [[World Wide Fund for Nature|World Wildlife Fund]], dispute the value of this research, claiming that sei whales feed primarily on [[squid]] and [[plankton]] which are not hunted by humans, and only rarely on [[fish]]. They say that the program is :"nothing more than a plan designed to keep the whaling fleet in business, and the need to use whales as the scapegoat for overfishing by humans."<ref name="wwf05" /> At the 2001 meeting of the IWC Scientific Committee, 32 scientists submitted a document expressing their belief that the Japanese program lacked scientific rigor and would not meet minimum standards of [[peer review|academic review]].<ref name="clapham02">{{cite journal | author = Clapham, P.| year = 2002 | title = Relevance of JARPN II to management, and a note on scientific standards. Report of the IWC Scientific Committee, Annex Q1 | journal = Journal of Cetacean Research and Management | issue = supplement | pages = 395–396 | volume = 4|display-authors=etal}}</ref> In 2010, a Los Angeles restaurant confirmed to be serving sei [[whale meat]] was closed by its owners after prosecution by authorities for handling a protected species. <ref>{{cite news| url=https://www.reuters.com/article/idUSTRE62J1A420100320 | work=Reuters | title=L.A. eatery charged with serving whale meat closes | date=20 March 2010}}</ref> == Conservation status == [[File:International Whaling Commission members.svg|thumb|Member states of the International Whaling Commission (in blue)|alt=World map showing that the U.S., China, India, Japan, Australia, Mexico, Russia, South Africa, and most European and Latin American states are members, among others.]] The sei whale did not have meaningful international protection until 1970, when the [[International Whaling Commission]] <!-- (IWC) --> first set catch quotas for the [[North Pacific]] for individual species. Before quotas, there were no legal limits.<ref name="allen80">{{cite book | author = Allen, K.R. | year = 1980 | title = Conservation and Management of Whales | publisher = Univ. of Washington Press | location = Seattle, WA | isbn = 978-0-295-95706-7 }}</ref> Complete protection from commercial whaling in the North Pacific came in 1976. Quotas on sei whales in the North Atlantic began in 1977. Southern Hemisphere stocks were protected in 1979. Facing mounting evidence that several whale species were threatened with extinction, the IWC established a complete moratorium on commercial whaling beginning in 1986.<ref name="nmfs" /> In the late 1970s, some "pirate" whaling took place in the eastern North Atlantic.<ref name="best92">{{cite journal | author = Best, P.B. | year = 1992 | title = Catches of fin whales in the North Atlantic by the M.V. ''Sierra'' (and associated vessels) | journal = Rep. Int. Whal. Comm. | volume = 42 | pages = 697–700 }}</ref> There is no direct evidence of illegal whaling in the North Pacific, although the acknowledged misreporting of whaling data by the [[Soviet Union]]<ref name="yablokov94">{{cite journal | author = Yablokov, A.V. | year = 1994 | title = Validity of whaling data | doi=10.1038/367108a0 | journal = Nature | volume = 367 | page = 108 | issue=6459}}</ref> means that catch data are not entirely reliable. The species remained listed on the [[International Union for Conservation of Nature|IUCN]] [[IUCN Red List|Red List of Threatened Species]] in 2000, categorized as "endangered".<ref name="iucn" /> Northern Hemisphere populations are listed as [[CITES]] Appendix II, indicating they are not immediately threatened with extinction, but may become so if they are not listed. Populations in the Southern Hemisphere are listed as [[CITES]] Appendix I, indicating they are threatened with extinction if trade is not halted.<ref name="adw" /> The sei whale is listed on both Appendix I<ref name="Appendices">"[http://www.cms.int/documents/appendix/Appendices_COP9_E.pdf Appendix I and Appendix II] {{webarchive|url=https://web.archive.org/web/20110611112003/http://www.cms.int/documents/appendix/Appendices_COP9_E.pdf |date=11 June 2011 }}" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009.</ref> and Appendix II<ref name="Appendices" /> of the Convention on the Conservation of Migratory Species of Wild Animals ([[Bonn Convention|CMS]]). It is listed on Appendix I<ref name="Appendices" /> as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them and also on Appendix II<ref name="Appendices" /> as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. Sei whale is covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region ([[Pacific Islands Cetaceans Memorandum of Understanding|Pacific Cetaceans MOU]]) and the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas ([[ACCOBAMS]]). The species is listed as endangered by the U.S. government [[National Marine Fisheries Service]] under the U.S. [[Endangered Species Act]].<ref name="av" /> == Population estimates == The current population is estimated at 80,000, nearly a third of the prewhaling population.<ref name="acs" /><ref name=Jefferon2008 /> A 1991 study in the North Atlantic estimated only 4,000.<ref name="braham92">{{cite journal | author = Braham, H. | year = 1992 | title = Endangered whales: Status update | publisher = Alaska Fisheries Science Center, Seattle, WA}}</ref><ref name="blaylock95">{{cite journal | author = Blaylock, R.A. | author2 = J.W. Haim | author3 = L.J. Hansen | author4 = D.L. Palka | author5 = G.T. Waring | last-author-amp = yes | year = 1995 | title = U.S. Atlantic and Gulf of Mexico stock assessments | publisher = U.S. Dept. of Commerce, NOAA Tech. Memo NMFS-SEFSC-363}}</ref> Sei whales were said to have been scarce in the 1960s and early 1970s off northern Norway.<ref name="jonsgard74">{{cite book| author= Jonsgård, Å. |year = 1974 |chapter = On whale exploitation in the eastern part of the North Atlantic Ocean | pages = 97–107 | editor = W.E. Schevill|title= The whale problem |publisher = Harvard University Press | location= Cambridge, MA}}</ref> One possible explanation for this disappearance is that the whales were [[Overexploitation|overexploited]].<ref name="jonsgard74" /> The drastic reduction in northeastern Atlantic [[copepod]] stocks during the late 1960s may be another culprit.<ref name="cattanach">{{cite journal | author = Cattanach, K.L. |author2 = J. Sigurjonsson|author3 = S.T. Buckland|author4 = Th. Gunnlaugsson | year = 1993 | title = Sei whale abundance in the North Atlantic, estimated from NASS-87 and NASS-89 data | journal = Rep. Int. Whal. Comm. | volume = 43 | pages = 315–321 }}</ref> Surveys in the [[Denmark Strait]] found 1,290 whales in 1987, and 1,590 whales in 1989.<ref name="cattanach" /> [[Nova Scotia]]'s population estimates are between 1,393 and 2,248, with a minimum of 870.<ref name="mitchell and chapman" /> A 1977 study estimated Pacific Ocean totals of 9,110, based upon catch and [[catch per unit effort|CPUE]] data.<ref name="tillman77" /> Japanese interests claim this figure is outdated, and in 2002 claimed the western North Pacific population was over 28,000,<ref name="icr02b" /> a figure not accepted by the scientific community.<ref name="wwf05" /> In western Canadian waters, researchers with [[Fisheries and Oceans Canada]] observed five Seis together in the summer of 2017, the first such sighting in over 50 years.<ref>{{cite news |url=https://www.ctvnews.ca/mobile/sci-tech/scientists-stumble-across-endangered-whale-not-seen-in-canada-in-years-1.4110411 |title=Scientists stumble across endangered whale not seen in Canada in years |first=Mia |last= Rabson |work=[[The Canadian Press]] |publisher=[[CTV News]] |date=2018-09-26 |accessdate=2018-09-26}}</ref> In California waters, there was only one confirmed and five possible sightings by 1991 to 1993 aerial and ship surveys,<ref name="hill92">{{cite journal |author1=Hill, P.S. |author2=J. Barlow |lastauthoramp=yes | year = 1992 | title = Report of a marine mammal survey of the California coast aboard the research vessel "MacArthur" July 28 – 5 November 1991. | publisher = U.S. Dept. Commerce, NOAA Technical Memo NMFS-SWFSC-169 |url=http://swfsc.noaa.gov/publications/TM/SWFSC/NOAA-TM-NMFS-SWFSC-169.PDF }}</ref><ref name="carretta93">{{cite journal |author1=Carretta, J.V. |author2=K.A. Forney |lastauthoramp=yes | year = 1993 | title = Report of two aerial surveys for marine mammals in California coastal waters utilizing a NOAA DeHavilland Twin Otter aircraft: March 9 – 7 April 1991, and February 8 – 6 April 1992 | publisher = U.S. Dept. Commerce, NOAA Technical Memo NMFS-SWFSC-185 | url=http://swfsc.noaa.gov/publications/TM/SWFSC/NOAA-TM-NMFS-SWFSC-185.PDF }}</ref><ref name="carretta93" /><ref name="mangels94">{{cite journal |author1=Mangels, K.F. |author2=T. Gerrodette |lastauthoramp=yes | year = 1994 | title = Report of cetacean sightings during a marine mammal survey in the eastern Pacific Ocean and the Gulf of California aboard the NOAA ships "MacArthur" and "David Starr Jordan" July 28 – 6 November 1993 | publisher = U.S. Dept. Commerce, NOAA Technical Memo NMFS-SWFSC-211 | url= http://swfsc.noaa.gov/publications/TM/SWFSC/NOAA-TM-NMFS-SWFSC-211.PDF }}</ref> and there were no confirmed sightings off Oregon coasts such as [[Maumee Bay]] and Washington. Prior to commercial whaling, the North Pacific hosted an estimated 42,000.<ref name="tillman77" /> By the end of whaling, the population was down to between 7,260 and 12,620.<ref name="tillman77" /> In the Southern Hemisphere, population estimates range between 9,800 and 12,000, based upon catch history and CPUE.<ref name="braham92" /> The IWC estimated 9,718 whales based upon survey data between 1978 and 1988.<ref name="IWC96">{{cite journal | author = IWC | year = 1996 | title = Report of the sub-committee on Southern Hemisphere baleen whales, Annex E | journal = Rep. Int. Whal. Comm. | volume = 46 | pages = 117–131 }}</ref> Prior to commercial whaling, there were an estimated 65,000.<ref name="braham92" /> == Mass deaths == Mass death events for sei whales have been recorded for many years and evidence suggests endemic poisoning ([[red tide]]) causes may have caused mass deaths in prehistoric times. In June 2015, scientists flying over southern Chile counted 337 dead sei whales, in what is regarded as the largest mass beaching ever documented.<ref>{{cite news|last1=Howard|first1=Brian Clark|title=337 Whales Beached in Largest Stranding Ever|url=http://news.nationalgeographic.com/2015/11/151120-worlds-largest-whale-stranding-sei-chile-animals/|accessdate=December 11, 2015|agency=National Geographic|date=November 20, 2015}}</ref> The cause is not yet known; however, toxic algae blooms caused by unprecedented warming in the Pacific Ocean, known as [[The Blob (Pacific Ocean)|the Blob]], may be implicated.<ref>{{cite news|author=On the Coast|title=Dead whales in Pacific could be fault of the Blob|url=http://www.cbc.ca/news/canada/british-columbia/dead-whales-pacific-blob-1.3228268|accessdate=December 11, 2015|agency=CBC|date=September 14, 2015}}</ref> == See also == {{Portal|Cetaceans|Mammals|Marine life}} *[[List of cetacean species]] *[[Marine biology]] *[[Pacific Islands Cetaceans Memorandum of Understanding]] *[[HMS Daedalus (1826)]] == Footnotes == {{notelist}} == References == {{Reflist|30em}} == Further reading == {{refbegin}} *''National Audubon Society Guide to Marine Mammals of the World'', Reeves, Stewart, Clapham and Powell, 2002, {{ISBN|0-375-41141-0}} * Eds. C. Michael Hogan and C.J.Cleveland. [http://www.eoearth.org/article/Sei_Whale?topic=49540 ''Sei whale''. Enclyclopedia of Earth, National Council for Science and Environment; content partner Encyclopedia of Life] *''Whales & Dolphins Guide to the Biology and Behaviour of Cetaceans'', Maurizio Wurtz and Nadia Repetto. {{ISBN|1-84037-043-2}} *''Encyclopedia of Marine Mammals'', editors Perrin, Wursig and Thewissen, {{ISBN|0-12-551340-2}} *''Whales, Dolphins and Porpoises'', Carwardine (1995, reprinted 2000), {{ISBN|978-0-7513-2781-6}} *{{cite journal | last1 = Oudejans | first1 = M. G. | last2 = Visser | first2 = F. | year = 2010 | title = First confirmed record of a living sei whale (''Balaenoptera borealis'' (Lesson, 1828)) in Irish coastal waters | url = | journal = Ir. Nat. J. | volume = 31 | issue = | pages = 46–48 }} {{refend}} == External links == {{Commons category|Balaenoptera borealis}} {{Wikispecies|Balaenoptera borealis}} *[http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/seiwhale.htm US National Marine Fisheries Service Sei Whale web page] *ARKive – [https://web.archive.org/web/20060503161943/http://www.arkive.org/species/GES/mammals/Balaenoptera_borealis/ images and movies of the sei whale ''(Balaenoptera borealis)''] *[http://oldredlist.iucnredlist.org/details/2475/all IUCN Redlist entry] *[http://www.panda.org/what_we_do/endangered_species/endangered_species_list/cetaceans/about/sei_whale/ World Wide Fund for Nature (WWF) – species profile for the Sei Whale] *[http://www.accobams.org/ Official website of the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area] *[http://cetus.ucsd.edu/voicesinthesea_org/species/baleenWhales/sei.html Voices in the Sea – Sounds of the Sei Whale] <!-- Meta-data goes here ---> {{Cetacea|M.}} {{Taxonbar|from=Q185097}} {{Authority control}} [[Category:Cetaceans of the Arctic Ocean]] [[Category:Baleen whales]] [[Category:Mammals of Japan]] [[Category:Cetaceans of the Indian Ocean]] [[Category:Cetaceans of the Atlantic Ocean]] [[Category:Cetaceans of the Pacific Ocean]] [[Category:Mammals described in 1828]] [[Category:ESA endangered species]]'