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Home , Blue whale, Pygmy blue whale

A Pygmy Blue (: Balaenopteridae) in the Inshore Waters ofNew Caledonia1

Philippe Borsa2,3 and Galice Hoarau 4

Abstract: The occurrence of a is reported for the first time for the New Caledonian archipelago. The whale, a juvenile male in poor condition, entered the shallow inshore waters of the coral reef lagoon (22 0 19-24' S, 1660 46-52' E) where it spent at least 1 month until it was killed by whaler sharks on 27 January 2002. Live observations, examination of photographic documents, and skull osteology indicated that this was a , musculus brevicauda. Nucleotide sequences of PCR-amplified fragments of its mitochondrial DNA were determined and compared with the few published homologous sequences of North Atlantic blue , B. m. musculus, but no obvious differences were apparent.

ALTHOUGH BLUE WHALES are among the with body length measured on sexually ma­ most cosmopolitan marine , sight­ ture individuals (from data analyzed ings of blue whales in the Southwest Pacific by Kato et al. [2000]) indicates two geo­ are reportedly scarce, and all of these but a graphically separated populations, now rec­ single sighting at the equator at about 1700 E ognized to belong to the pygmy (Balaenoptera occurred south of 300 S in the austral summer musculus brevicauda) and the (B. m. (Kato et al. 1995, Reeves et al. 1999). Groups intermedia) blue whale , respec­ of blue whales were observed in the vicinity tively (Rice 1998). One of the current of the Solomon Islands in August 1957, but objectives of the International Whaling no blue whale has been reported from the Commission (IWC) Scientific Committee is Southwest Pacific since then (Reeves et al. to discriminate the two types. Recent devel­ 1999). Historical catch records show the opments have led Kato et al. (2002) to pro­ geographic segregation of two major con­ pose the utility of morphology and centrations of blue whales in the Southern relative body shape to distinguish them at sea. Hemisphere during the austral summer: one Here we document the first recorded occur­ north of the Antarctic convergence mainly rence of a blue whale in the tropical South­ between 25 0 E and 800 E, the other south west Pacific in the summer. A preliminary, of the Antarctic convergence mainly be­ unpublished report on the same occurrence tween 55 0 E and 90 0 W (Ichihara 1966). The (Garrigue et al. 2003) used the criteria of strong correlation of geographical location Kato et al. (2002) to propose that the New Caledonian blue whale was a pygmy blue whale. Here we present a detailed chrono­ I Manuscript accepted 21 October 2003. 2 Institut de Recherche pour Ie Developpement, De­ logical account of the observations made on partement des Ressources Vivantes, BP A5, 98848 Nou­ this individual, we add morphological and mea cedex, Nouvelle-Caledonie (phone: +687 260741; osteological clues that confirm its identifi­ fax: +687 264326; e-mail: [email protected] cation as the brevicauda subspecies, and we .nc). 3 Corresponding author. provide partial nucleotide sequences of its 4 Department of Marine Biology, Centre for Ecolog­ mitochondrial DNA as a contribution to ge­ ical and Evolutionary Studies, Royal University of Gro­ netic databases on blue whales. ningen, P.O. Box 14, 9750 AA, Haren, The Netherlands. MATERIALS AND METHODS Pacific Science (2004), vol. 58, no. 4:579-584 © 2004 by University of Hawai'i Press The observations reported here were made All rights reserved in Baie-du-Prony, New Caledonia, by one of

579 580 PACIFIC SCIENCE· October 2004 us (P.B.) from RV Alcyan (Universite de ucts were obtained in both forward and re­ Nouvelle-Caledonie, Noumea) on 14 and 15 verse directions using the BigDye Terminator January 2002 and from RV Alis [Institut de Cycle sequencing kit (Applied Biosystems, Recherche pour Ie Developpement (IRD)] on Foster City, ) and the foregoing 25 January 2002. Other field data were gath­ PCR primers as sequencing primers. The ered on an opportunistic basis by observers products of the sequencing reaction were run interviewed by P.B. in an ABI PRISM 377 automatic sequencer From the numerous pictures of this whale (Applied Biosystems). that were taken between 9 January and 29 We compared the partial mitochondrial January, we selected those with key mor­ DNA sequences of the New Caledonian phological features that reportedly allow ce­ blue whale with published, homologous se­ tologists to distinguish B. m. brevicauda, the quences. At the time of writing, the total or pygmy blue whale, from B. m. internzedia, the partial mitochondrial DNA sequences of only other form present in the Southern Hemi­ five blue whales were publicly accessible. A sphere (Ichihara 1966, Omura et al. 1970, search of the nucleotide-sequence database Kato et al. 2000, 2002). Some of the photo­ of GenBank (http://www.ncbi.nlm.nih.gov/) graphs examined by us have been published returned one total mitochondrial DNA se­ (Anonymous 2002, Clua 2002, David et al. quence for blue whale (GenBank accession 2002), including some subsequently commu­ no. NC_001601), actually a North Atlantic nicated to the IWC Scientific Committee f~male blue whale x male whale (Garrigue et al. 2003). Additional pictures (Arnason and Gullberg 1993), and the partial were provided by P. Larue (pers. comm.), or sequence of the 12S rDNA of a blue whale taken from public television video footages, of unknown origin (GenBank AF320513 or were our own. The latter have been filed [Tebbutt et al. 2000]). Browsing the scientific at the library ofIRD in Noumea and can be literature through lSI Web of Science (Insti­ obtained through the corresponding author. tute for Scientific Information, Philadelphia), The whale's body length was estimated by we found the partial cytochrome b gene se­ measuring with a rope the distance from tip quences (120 bp at the 3' end of the gene) of of snout to end of tail on the floating dead three more individuals (Kimura et al. 1997) (on 29 January). Measurements on and the sequence of a 298-bp fragment of the plates were made to the nearest centi­ 5' end of the control region of another North meter using a ruler. Those on tympanic bul­ Atlantic female blue whale x male lae were made to the nearest millimeter using hybrid ("Caneliiias hybrid" [Berube and a Vernier caliper. Aguilar 1998]). For genetic analyses, a ca. l-cm2 piece of sloughed skin (now preserved in alcohol at RESULTS IRD, Noumea) was recovered in Rade-Nord (22° 20' S, 166° 52' E) on 14January 2002 by The first confirmed sighting of a blue whale snorkeling in the trail of the whale. Approxi­ in New Caledonia was on 29 December 2001 mately 2 mg of skin tissue was subjected to as it was swimming in circles at the northern total genomic DNA extraction according to extremity of Canal-Woodin in the southern Hoarau et al. (2002). DNA extracts were lagoon ofNew Caledonia (22° 24' S, 166° 46' subjected to polymerase chain reaction (PCR) E; depth 25-30 m). Subsequently (from 31 amplification of both a fragment of the December onward), the individual was sighted replication-control region of the mitochon­ in the nearshore, shallow (ca. 5-30 m) waters drial DNA and a fragment of the cytochrome of either Grande-Rade (22° 19-21' S, 166° b gene. For this, we used primer-pairs Dlpl.SI 49-50' E) or Rade-Nord (22° 19-20' S, 166° DipS of Baker et al. (1998) and CBl-LlCB2-H 51-52' E), two sheltered coves located in of Palumbi et al. (1991) and set the annealing Baie-du-Prony in the southwestern part of temperatures at 54 and 52°C, respectively. New Caledonia's Grande Terre. Invariably, Nucleotide sequences of the two PCR prod- the whale was seen circling randomly within a Pygmy Blue Whale in New Caledonia . Borsa and Hoarau 581

FIGURE 1. Underwater photograph of the head and neck of the New Caledonian blue whale, Baie-du-Prony, 14 January 2002. (Photograph courtesy of P. Larue.)

radius of a few hundred meters. The whale slices of flesh), confirmed nutritional stress. carried many , Echeneis naucrates, on No external injury was apparent. Early on its head, flippers, flanks, and fluke. There was 27 January in Grande-Rade, the whale was no evidence that the whale was feeding, and repeatedly bitten by two whaler sharks (iden­ the quantities of potential prey (, small tified by us from video footage as either pelagic , squids) captured using light Carcharhinus amboinensis or C. leucas), which traps set on 14 January according to standard were first seen swimming in its vicinity 2 days protocols (D. Ponton and P.B., unpubl. data) earlier. Harassment by sharks resumed in the were almost nil in Baie-du-Prony. The whale evening, leading to the death of the animal in was emaciated, with prominent jaws, orbital the night. Surfacing again ca. 36 hr after it bones, and vertebrae, and a depression in the sank, the carcass was pulled offshore and left occipital region, giving it a reptilelike ap­ adrift, attracting scavengers including several pearance (Figure 1). Stretch marks were visi­ large tiger sharks, Galeocerdo cuvieri. ble all along the flanks and tail. All this was The whale's body length was estimated to suggestive of nutritional stress. The physio­ be 16.5 m. Blue whale calves are weaned at logical condition of the animal appeared to the age of 6-8 months, at which time their deteriorate slowly throughout the period it size is 16-17 m (Bannister 2002, Sears 2002). was observed: the average ± standard devia­ Pygmy blue whales reach sexual maturity at a tion dive duration decreased steadily from length ofca. 18 m or more and Antarctic blue 138 ± 44 sec (n = 13 dives, excluding inter­ whales at a minimum of 22.3 m (Ichihara vals between blows during a surfacing se­ 1966). The New Caledonian individual was quence) on 14 January to 38 ± 19 sec (n = 8 therefore a juvenile, possibly a newly weaned dives) on 25 January. Based on a different set young-of-the-year. Subsequent examination of observations, a similar trend was reported of the genital area showed that this was a by Garrigue et al. (2003). The thin , young male. about 5 cm thick (later measured on both the The live photographs examined by us, in­ ventral and dorsal sides from freshly exposed cluding some of those subsequently presented 582 PACIFIC SCIENCE· October 2004 in Garrigue et al. (2003), showed the follow­ tinguishing pygmy from ordinary blue whales ing: (1) anterior tip of the median groove in both juvenile and older. The largest length the blowhole extended beyond the anterior and width of the tympanic bullae (measures limit ofthe two nostrils (also visible on Figure no. 1 and 13 of Omura et al. [1970], respec­ 1); (2) proportion of tail length to total length tively) in the New Caledonian blue whale was ca. 0.25; (3) the anterior part of the trunk were 12.4 cm and 7.4 cm, respectively. Ac­ was bulky and the posterior part was thin and cording to Omura et al. (1970), these values elongated. The three foregoing features are tentatively point to the pygmy type (12.7 ± more characteristic of pygmy blue whales 1.0 cm and 6.9 ± 0.6 cm, respectively) rather than of other blue whale subspecies (Ichihara than to B. m. musculus (13.5 ± 1.0 cm and 1966, Kato et al. 2002). The position and 7.6 ± 0.5 cm, respectively) but are excluded relative size of the median groove of the from the confidence intervals given for B. m. blowhole presumably reflects the shape of the intermedia (13.7-15.7 cm and 9.8-11.2 cm, nasal bones, which differs between pygmy respectively). blue whales and ordinary blue whales (Omura Having reached the conclusion that the et al. 1970, Kato et al. 2002). The difference New Caledonian blue whale specimen was in general body shape is presumably related of the pygmy form, we decided to character­ to the fact that ribs in the anterior portion ize it genetically and add data to the current of the thorax are proportionally longer in sequence database of blue whales. The se­ pygmy blue whales than in northern blue quence of the control-region fragment of the whales, B. m. musculus (Omura et al. 1970; no mitochondrial DNA (now deposited in Gen­ data for B. m. intermedia). However, one can Bank under accession no. AY235201) was in­ question whether the shape of the blowhole cluded between nucleotide sites 15872 and and the general body shape of the animal are 16375 of the homologous fragment in North affected by its physiological condition. Atlantic blue whale (GenBank NC_001601). The calvarium of the whale, now pre­ The two sequences differed by seven tran­ served at Musee de I'Histoire Maritime, sitions, at sites 15975, 15976, 16036, 16105, Noumea (MHM), was retrieved from the sea 16174, 16217, and 16258. Comparing the se­ bottom in pieces because several bones were quence data with those for the Caneliiias hy­ broken and scavengers had chopped out some brid (298 bp included between sites 15888 other chunks. The condition of the skull and 16185 [Berube and Aguilar 1998]) re­ was characteristic of porotic hyperostosis, in vealed four transitions, at sites 15975, 15976, which the outer, dense layer of the bone has 16036, and 16174. Four of the five mutated disappeared and the porous bone is exposed. sites encountered on the 298-bp fragment Such a pathology is indicative of nutritional between NC_001601 and AY235201 were stress in humans (van der Merwe 1992). also variable between AY235201 and the Measurements made on the skull and the Caneliiias hybrid, but the difference between baleen plates yielded additional evidence the Caneliiias hybrid and NC_001601 was that the New Caledonian blue whale be­ three transitions (at sites 16083, 16105, and longed to B. m. brevicauda as detailed in the 16152), one of which (at site 16105) was following. The ratio of length to breadth for common with AY235201. The eytochrome-b the six baleen plates preserved at MHM is gene fragment (GenBank AY235202) was in­ 1.41 ± 0.09 (average ± SD), a value closer to cluded between nucleotide sites 14705 and 1.48, the average found for B. m. brevicauda, 15011 of the homologous fragment in North than 1.79, which is the reported average for Atlantic blue whale (GenBank NC_001601). B. m. intermedia (Ichihara 1966). The size The two sequences differed by one transition, of tympanic bullae also differs between blue at site 14954. No comparison was possible whale subspecies (Omura et al. 1970). Be­ with the sequence data ofKimura et al. (1997) cause this bone ceases to grow early in life because their and our fragments were chosen (Omura et al. 1970), it can be used in­ at opposite extremities of the cytochrome b dependently of body size as a clue for dis- gene, with no overlap. Therefore, no obvious Pygmy Blue Whale in New Caledonia . Borsa and Hoarau 583 genetic differences were apparent between putative intermedia blue whale, thus explain­ the New Caledonian pygmy blue whale (bre­ ing the lack of obvious genetic differences vicauda type) and two North Atlantic blue from the sequence data currently available whales (musculus type), but to be of some (this report). Nevertheless, the results an­ substance such comparisons may have to in­ nounced by Kato et al. (2002) and LeDuc et volve tens if not hundreds of specimens, in­ al. (2003) provide some genetic substantiation cluding some of the intermedia type, and the to the geographic segregation of pygmy mitochondrial DNA fragments under com­ versus intermedia blue whales because those parison probably should be much longer. authors reported significant allele differences between them. Thus, it is likely that increasing the number of loci in future DISCUSSION genetic tests will increase the ability to sepa­ Despite decades of intensive hunting that rate the two forms. These results, still pre­ led blue whales to the verge of , liminary, offer exciting perspectives on the knowledge of their geographical structure, evolutionary mechanisms that have led to population genetics, and migration routes is the presence of two forms of blue whales in still fragmentary. Such information is espe­ the . cially desirable in the southern Pacific be­ cause it is currently lacking (Reeves et al. 1999) and could be of value in setting up ACKNOWLEDGMENTS protection policies for this still-endangered We thank C. Chauvet (Universite de species. The fact that before the current ob­ Nouvelle-Caledonie, Noumea), E. Clua servation no blue whale had ever been sighted (Ministere de l'Agriculture, France), and R. in the vicinity of the New Caledonian archi­ Proner (IRD, Noumea) for arranging field pelago likely reflects the rarity of this species trips to Baie-du-Prony; E. Clua, J-Y. Halo, in the region. The New Caledonian individ­ S. Jacquet (IRD, Noumea), and D. Rames for ual was an immature, perhaps a young-of­ sharing their observations; L. Frigo (Museum the-year. We speculate that it was unable Victoria, Melbourne), C. Garrigue (IRD, to migrate to its summer feeding ground. A Noumea, then at University of Auckland), small population of blue whales, perhaps and R. G. LeDuc (Southwest Fisheries pygmy blue whales, was recently discovered Science Center, La Jolla [SWFSC]) for e­ summer-feeding on the upwelling off the mail correspondence; and L. T. Ballance southwestern coast of Victoria (Gill 2002). (SWFSC) and H. Kato (National Research Photoidentification and satellite tracking of Institute of Far Seas Fisheries, Shizuoka) for those whales may help trace their annual mi­ helpful comments. gration route and tell whether it crosses the tropical Southwest Pacific. Given the rarity of blue whale sightings in the Southwest Pacific, Literature Cited a more straightforward test would be to look for the eventual genetic relatedness of the Anonymous. 2002. Un geant des mers a New Caledonian whale with individuals of , Prony. I)Jouv. Caledoniennes 9212:1,10. the southern Australian population (and other Arnason, U., and A. Gullberg. 1993. Com- populations of the southern Pacific) by com­ parison between the complete mtDNA paring their DNA fingerprints. sequences of the blue and the fin whale, Recent tests using genetic markers (mi­ two species that can hybridize in nature. J tochondrial DNA and microsatellites [Kato et Mol. Evol. 37:312-322. al. (2002), LeDuc et al. (2003); raw data not Baker, C. S., L. Florez-Gonzalez, B. Aberne­ available though]) on blue whale samples of thy, H. C. Rosenbaum, R. W. Slade, J several tens of individuals from various geo­ Capella, and J L. Bannister. 1998. Mi­ graphical origins failed to find diagnostic tochondrial DNA variation and maternal markers of putative pygmy blue whale versus among humpback whales of the 584 PACIFIC SCIENCE· October 2004

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