Sei Whales Research Articles

Sei whale sounds recorded in the Antarctic

Sei whales are the least well known acoustically of all the rorquals, with only two brief descriptions of their calls previously reported. Recordings of low-frequency tonal and frequency swept calls were made near a group of four or five sei whales in waters west of the Antarctic Peninsula on 19 February 2003. These whales also produced broadband sounds which can be described as growls or whooshes. Many of the tonal and frequency swept calls (30 out of 68) consist of multiple parts with a frequency step between the two parts, this being the most unique characteristic of the calls, allowing them to be distinguished from the calls of other whale species. The average duration of the tonal calls is 0.45 +/- 0.3 s and the average frequency is 433 +/- 192 Hz. Using a calibrated seafloor recorder to determine the absolute calibration of a sonobuoy system, the maximum source level of the tonal calls was 156 +/- 3.6 dB re 1 microPa at 1 m. Each call had different character and there was no temporal pattern in the calling.

Whales and Dolphins of the World

Review: Whales and Dolphins of the World By Mark Simmonds Reviewed by Alan L. Chan Chinese Lutheran Church, San Francisco, USA Mark Simmonds. Whales and Dolphins of the World. Cambridge, MA: MIT Press. 2005. 160pp. ISBN 0-262-19519-4. U.S. $29.95 (cloth) The purpose of this book is described by the author himself, who is the director of science at the Whale and Dolphin Conservation Society: “This book is intended as both a celebration of the whales and dolphins of the world and as an introduction to their diversity, biology and conservation” (p.8). In chapter one, “Who Are The Whales and Dolphins”, Simmonds categorizes the various species of whales and dolphins (cetaceans) living in the oceans and rivers of our planet. For instance, it is fascinating to learn that there are many different kinds of ‘great whales’: the minke whale reaches 35 feet (10.7 meters), the Bryde’s whale reaches 51 feet (15.5 meters), the humpback whale reaches 53 feet (16 meters), the Sei whale reaches 61 feet (20 meters), the fin whale reaches 89 feet (27 meters), and the blue whale reaches 112 feet (34 meters). After a detailed introduction to the families of whales and dolphins, Simmonds discusses their intelligence and the adaptations that help them with their survival. Having recorded aspects of cetacean physiology, hunting techniques, reproduction, echolocation, language, communication, social structure and culture, Simmonds humbly comes to the conclusion that we actually know very little about them. In the third chapter, Simmonds begins with a short history of interactions between humankind and these animals, and then presents our evolving attitudes towards them, as first they were hunted as a food resource, then caught to provide products to maintain our industrial revolution, and, now as whale-watching has become the focus of marine eco-tourism. After that, Simmonds insightfully argues that the major threats posed to cetaceans right now are incidental capture in fishing operation and habitat degradation, not intentional commercial hunting which is prohibited by the International Whale Commission (IWC). In conclusion, Simmonds hopes that the conservation of cetaceans will become an integral part of our civilization and that co-existence between humans and cetaceans (for our sake as much as for theirs) can be supported and sustained. Without doubt, he has added a significant contribution to our knowledge and appreciation of whales and dolphins in this beautiful book

Plasma and Urine Levels of Electrolytes, Urea and Steroid Hormones Involved in Osmoregulation of Cetaceans

Cetaceans are well adapted to their hyperosmotic environment by properly developed osmoregulatory ability. A question here is how they regulate water and mineral balances in marine habitats. In the present study, we determined blood and urine levels of various chemicals involved in osmoregulation, compared them with those in artiodactyls, and characterized the values in the whales. Blood and urine samples obtained from baleen whales of common minke (Balaenoptera acutorostrata), sei (B. borealis), and Bryde's whales (B. brydei), and toothed whales of sperm whales (Physeter macrocephalus) were analyzed for osmolality, major electrolytes, urea, steroid hormones and glucose. The urine osmolality and Na(+) concentrations in the cetaceans were much higher than those in the cattle. Furthermore, the cetaceans had 5 to 11-fold urea in plasma than the cattle, and 2 to 4-fold urea in urine. There were no significant difference in the plasma concentrations of corticosteroids between the cetaceans and the cattle. The present results indicate that the osmoregulatory parameters seem to be not affected by the reproductive stage and sex steroid hormones. The concentrations of urea in plasma and urine of the baleen whales were higher than those of the sperm whales, indicating a possibility that their osmoregulatory mechanisms may be correlated to their feeding habits. The present results suggest that cetaceans have unique osmoregulatory mechanisms by which they excrete strongly hypertonic urine to maintain fluid homeostasis in marine habitats.

Whale mortality from ship strikes in Ecuador and West Africa

We document two unusual cases of a Bryde's and a sei whale struck by container cargo vessels and draped over the bow bulb, respectively in the Southeast Pacific and the Eastern Tropical Atlantic. The 207m-length P&O Nedlloyd Pantanal collided with an adult Bryde's whale Balaenoptera edeni in the southern Gulf of Guayaquil, Ecuador, on 10 December 2004. The whale showed massive dermal hematoma indicating that it was alive when struck. Similarly, the container ship OSNA Bruck arrived at Dakar port, Senegal, on 19 March 1998 with the fresh carcass of a juvenile sei whale B. borealis on its bow bulb. The collision occurred between Las Palmas, Gran Canaria and Dakar, Senegal. Freshly dead balaenopterids can hardly be picked up by ships since they sink at death and do not float until decomposition and bloating sets in. A review of previous cases show that ship strikes are rarely recorded in these regions, partly due to the lack of regulations, including no reporting obligation. However, the case studies reveal that another factor may severely augment under-reporting of ship strike mortality. In both instances the crew became aware of the collision only upon arrival at port, suggesting that whales which are hit and killed or wounded, but do not become draped over the bow bulb (if the vessel has one), go unnoticed. The probability of bow draping may be low, and modelling should be attempted. National authorities are encouraged to improve data collection and introduce regulations such as mandatory reporting. These are the first fully documented, fatal whale collisions in Ecuador and West Africa (south of the Canary Islands), and the first struck and killed Bryde's whale in the Southeast Pacific.

Mitochondrial Phylogenetics and Evolution of Mysticete Whales

The phylogenetic relationships among baleen whales (Order: Cetacea) remain uncertain despite extensive research in cetacean molecular phylogenetics and a potential morphological sample size of over 2 million animals harvested. Questions remain regarding the number of species and the monophyly of genera, as well as higher order relationships. Here, we approach mysticete phylogeny with complete mitochondrial genome sequence analysis. We determined complete mtDNA sequences of 10 extant Mysticeti species, inferred their phylogenetic relationships, and estimated node divergence times. The mtDNA sequence analysis concurs with previous molecular studies in the ordering of the principal branches, with Balaenidae (right whales) as sister to all other mysticetes base, followed by Neobalaenidae (pygmy right whale), Eschrichtiidae (gray whale), and finally Balaenopteridae (rorquals + humpback whale). The mtDNA analysis further suggests that four lineages exist within the clade of Eschrichtiidae + Balaenopteridae, including a sister relationship between the humpback and fin whales, and a monophyletic group formed by the blue, sei, and Bryde's whales, each of which represents a newly recognized phylogenetic relationship in Mysticeti. We also estimated the divergence times of all extant mysticete species, accounting for evolutionary rate heterogeneity among lineages. When the mtDNA divergence estimates are compared with the mysticete fossil record, several lineages have molecular divergence estimates strikingly older than indicated by paleontological data. We suggest this discrepancy reflects both a large amount of ancestral polymorphism and long generation times of ancestral baleen whale populations.

Summer distribution and relative abundance of cetacean populations off north-west Scotland

A line transect survey was conducted in July/August 1998 to investigate the distribution and abundance of cetaceans off north-west Scotland. Over 2156.5 km of survey effort, 304 sightings were recorded of which 184 were identified to species. Nine species were identified: Atlantic white-sided dolphin Lagenorhynchus acutus, fin whale Balaenoptera physalus, sei whale Balaenoptera borealis, long-finned pilot whale Globicephala melas, sperm whale Physeter macrocephalus, common dolphin Delphinus delphis, harbour porpoise Phocoena phocoena, white beaked dolphin Lagenorhynchus albirostris and Risso's dolphin Grampus griseus. The Atlantic white-sided dolphin was the most relatively abundant species. The relative abundance of large whales and dolphins was greatest in the Faroe–Shetland Channel. The continental slopes of this area are undergoing development by oil industries and concerns have been raised about the potential impacts of these activities on cetaceans. These waters are used year-round by cetaceans and provide feeding and breeding grounds and are a migration route for large whales.

Salt and water balance of modern baleen whales: rate of urine production and food intake

Whales, as pelagic marine mammals, are thought to have evolved from fresh-water-dependent terrestrial mammals. Baleen whales feed primarily on salty euphausiids (krill) and have no access to fresh water. How have these mammals adapted to lifelong habitation in a hyperosmotic medium? A new approach is proposed for studying this by using allometry (scaling) of endogenous creatinine clearance in mammals together with determinations of creatinine concentration in fresh postmortem blood and urine of fin whales (Balaenoptera physalus) and sei whales (Balaenoptera borealis). From the predicted mean creatinine-clearance values and the measured mean creatinine concentrations, a urine-production rates of 974 and 627 L/day for the fin and sei whales, respectively, were computed. Average daily krill ingestion of about 1300 and 835 L is predicted for the fin and sei whales, respectively. The whales seem to ingest about 30% more than earlier reported of a prey, which has about 50% of the salt concentration of seawater, thus maintaining the salt and water balance with a minimum of 1–2% seawater ingestion. The method used to estimate the above volumes could be a valuable tool in further studies of the water and salt balance of the large baleen whales, which may not have the same osmoregulatory control mechanisms as the smaller Odontoceti.

DIETS OF FIN, SEI, AND SPERM WHALES IN BRITISH COLUMBIA: AN ANALYSIS OF COMMERCIAL WHALING RECORDS, 1963–1967

AbstractDiets of fin (Balaenoptera physalus), sei (Balaenoptera borealis), and sperm whales (Physeter macrocephalus) were estimated from the stomach contents of individuals killed along the British Columbia coast from 1963 to 1967. The dominant prey types of fin whales were euphausiids, with minor contributions from copepods and fish. Sei whale stomachs contained primarily copepods in three years, whereas euphausiids or a variety of fish dominated the diet in the other two years. Sperm whales consumed primarily North Pacific giant squid (Moroteuthis robusta), but secondary prey differed between males and females. Female sperm whales frequently consumed ragfish (Icosteus spp.) and other fish, whereas the male diet also contained rockfish (Sebastes spp.). The high abundance of euphausiids along the British Columbia coast likely contributed to the presence of a summer resident population of fin whales. The high abundance of large copepods farther north probably influenced the migration of sei whales through the offshore waters of British Columbia. Sperm whale stomach contents differed by sex reflecting location and possibly breeding behaviors.

Reproduction, growth and migrations of sei whales Balaenoptera borealis off the west coast of South Africa

Results of the examination of 1 062 sei whales Balaenoptera borealis landed at the whaling station at Donkergat, Saldanha Bay, South Africa, in the 1962 and 1963 whaling seasons are presented. Sei whales were usually encountered off the edge of the continental shelf, with males being caught closer inshore than females and mature females furthest of all from the station. Females reached puberty at an average length of 46.1 ft (14.1 m) and an age of 8.2 (95% CI = 7.3, 9.0) years (assuming one growth layer group is formed in the ear plug per year). Males reached sexual maturity at an average length of 45.3 ft (13.8 m) and an age of 8.6 (95% CI = 7.8, 9.4) years. Mean lengths at which growth ceased were 52 ft (15.8 m) in females and 48.6 ft (14.8 m) in males. Most (~90%) conceptions occurred over a 70-day period with a peak in June, and primigravid females conceived six days later than multigravid females. Observed pregnancy rates were as high as 86.1%, but with ovulation rates averaging only 0.47 a year, the catch could not have been fully representative of the population. There was no significant decline in the observed pregnancy rate with age. During the northward migration (May–July), fewer whales were taken in water shallower than 2 000 m than in the southern migration, and the catch was largely composed of immatures. The few adult males taken at that time of year had significantly heavier testes than males of an equivalent size on the southern migration. The southward migration (August–October) was markedly structured, such that pregnant females and immatures of both sexes were in the vanguard, followed by mature males and lastly lactating females and calves. The availability of sei whales off Donkergat declined rapidly from 1965 to 1967, following an episode of massive catching by pelagic whalers in higher latitudes. Keywords: growth, migration, reproduction, sei whales, South Africa African Journal of Marine Science 2002, 24: 111–133

Predictions of critical habitat for five whale species in the waters of coastal British Columbia

Whaling records from British Columbia coastal whaling stations reliably report the positions of 9592 whales killed between 1948 and 1967. We used this positional information and oceanographic data (bathymetry, temperature, and salinity) to predict critical habitat off the coast of British Columbia for sperm (Physeter macrocephalus), sei (Balaenoptera borealis), fin (Balaenoptera physalus), humpback (Megaptera novaeangliae), and blue (Balaenoptera musculus) whales. We used generalized linear models at annual and monthly time scales to relate whale occurrence to six predictor variables (month, depth, slope, depth class, and sea surface temperature and salinity). The models showed critical habitat for sei, fin, and male sperm whales along the continental slope and over a large area off the northwest coast of Vancouver Island. Habitat models for blue, humpback, and female sperm whales were relatively insensitive to the predictor variables, owing partially to the smaller sample sizes for these groups. The habitat predictions lend support to recent hypotheses about sperm whale breeding off British Columbia and identify humpback whale habitat in sheltered bays and straits throughout the coast. The habitat models also provide insights about the nature of the linkages between the environment and the distribution of whales in the North Pacific Ocean.

Cetaceans of the Atlantic Frontier, north and west of Scotland

Surveys carried out to the north and west of Scotland have recorded 15 species of cetacean between 1979 and 1998. These were fin whale ( Balaenoptera physalus) , sei whale ( B. borealis) , minke whale ( B. acutorostrata) , humpback whale ( Megaptera novaeangliae) , sperm whale ( Physeter macrocephalus) , northern bottlenose whale ( Hyperoodon ampullatus) , Sowerby's beaked whale ( Mesoplodon bidens) , killer whale ( Orcinus orca) , long-finned pilot whale ( Globicephala melas) , Atlantic white-sided dolphin ( Lagenorhynchus acutus) , white-beaked dolphin ( L. albirostris) , Risso's dolphin ( Grampus griseus) , bottlenose dolphin ( Tursiops truncatus) , common dolphin ( Delphinus delphis) and harbour porpoise ( Phocoena phocoena) . Atlantic white-sided dolphin was the most abundant species in the region with a total of 6317 animals recorded. Harbour porpoise was the most frequently sighted cetacean species. The geographical distribution of sightings indicate that cetacean species have varying ecological requirements, with species such as sperm whale, pilot whale and white-sided dolphin favouring deep water off the continental shelf edge, while minke whale, white-beaked dolphin and harbour porpoise were apparently limited to the continental shelf. The diversity of species recorded in the region suggests that the Atlantic Frontier is an important habitat for cetaceans.

The implications of developments on the Atlantic Frontier for marine mammals

We review the available information on the distribution and abundance of marine mammals in the Atlantic Frontier area, and the literature on the potential effects of oil exploration and extraction on these species. Reliable estimates of seal abundance are only available for two species (grey and harbour seals). For grey seals and hooded seals there is also information from telemetry studies on their distribution at sea. Data on cetaceans comes from a variety of sources including whaling statistics, dedicated surveys, observers placed on vessels of opportunity, and from bottom-mounted hydrophone arrays. These indicate that the Atlantic Frontier region is of national, and possibly international, importance for a number of cetacean species. The most abundant small cetacean is likely to be the white-sided dolphin; however, smaller numbers of large whales, including endangered blue, right, fin and sei whales, and vulnerable humpback and sperm whales are also likely to be present in summer. There is growing evidence that a number of marine mammal species respond to the acoustic and physical disturbance associated with exploration for oil and gas resources, although the ecological impact of these responses is unclear. We describe how risk assessment frameworks, initially developed for evaluating the environmental impacts of hazardous chemicals, can be used to address this problem.

Records of Cetacean Strandings in the Northern Territory of Australia

Fifty-seven cetacean strandings are here documented for the Northern Territory (NT) coastline. This total includes events discovered in the course of Parks and Wildlife surveys, chance encounters reported by a variety of observers, and records held by various other government agencies and institutions. A total of 35 of these records are identified to species, seven to genus (Globicephala, Balaenoptera), and the remainder can be listed only as 'dolphin' (3), 'beaked whale ' (1) or 'not known' (11). Of 26 species known to occur in Australia's tropical waters only 12 had previously been confirmed for the NT, and two others were provisionally listed on the basis of specimen material requiring further analysis. Strandings reported here include 10 of those 12 species and verify the two previously listed as uncertain (Globicephala macrorhynchus, Kogia simus). The total confirmed list for NT waters (within three nautical miles of the coast) is further expanded to 16 species, now including the melon-headed whale Peponocephala electra (2 strandings) and killer whale Orcitws orca (sighting). A further species, the sei whale Balaenoptera borealis (trawled carcass), can also be added to the Commonwealth waters (within two hundred nautical miles) off the NT coast.

MIGRATION AND POPULATION STRUCTURE OF NORTHEASTERN PACIFIC WHALES OFF COASTAL BRITISH COLUMBIA: AN ANALYSIS OF COMMERCIAL WHALING RECORDS FROM 1908‐1967

AbstractData recorded from 24,862 whales killed by British Columbia coastal whaling stations between 1908 and 1967 revealed trends in the abundance, sex ratios, age structure, and distribution of sperm (Physeter macrocephalus), fin (Balaenoptera physalus), sei (Balaenoptera borealis), humpback (Megaptera novaeangliae), and blue (Balaenoptera musculus) whales. The catch data were analyzed using annual and monthly mean values. Monthly and annual variation in whaling effort was deduced from accounts of the history of British Columbia coastal whaling, and biases arising from changes in effort were considered in the interpretation of the results. During the later years of whaling (1948‐1967), the mean lengths of captured whales declined significantly and pregnancy rates dropped to near zero in fin, sei, and blue whales. Monthly patterns in numbers killed revealed a summer migration of sei and blue whales past Vancouver Island, and confirms anecdotal suggestions that local populations of fin and humpback whales once spent extended periods in the coastal waters of British Columbia. Furthermore, the data strongly suggest that sperm whales mated (April‐May) and calved (July‐August) in British Columbia's offshore waters. The historic whaling records reveal much about the migratory behavior and distribution of the large whales species as they once were, and may continue to be, in the northeastern Pacific. Verifying the persistence of these trends in the remnant populations is a necessary and logical next step.

An initial examination of relationships between the distribution of whales and Antarctic krill Euphausia superba at South Georgia

The distribution of whales and krill in two survey boxes north of South Georgia was examined by comparing sightings and underway acoustic data collected as part of a multi-disciplinary research cruise carried out during January/February 1998. A total of 222 cetaceans of 10 species was recorded with the southern right whale (Eubalaena glacialis) and humpback whale (Megaptera novaeangliae) the two most frequent. The largest aggregation of cetaceans (21 southern right whales, 16 fin whales (Balaenoptera physalus), 4 sei whales (B. borealis), 1 humpback whale and 8 hourglass dolphins (Lagenorhynchus cruciger) occurred close to the largest single aggregation of krill. The level of association between baleen whales and krill was examined at a number of spatial scales. There was a positive relationship between whale abundance and mean krill density at the largest spatial scale examined (803100km). At progressively smaller scales the relationship weakened, due mainly to the increased frequency of areas of high krill density where whales were not recorded. In particular, whales were absent from inshore areas (up to 300m depth) that had higher mean krill densities compared with areas where whales were recorded. To thoroughly compare krill and whale distribution, particularly at smaller scales, will require information on krill swarm structure and density, as well as more information on the behaviour and feeding requirements of whales. Such information may also be crucial to understanding the role of scale-dependence in potential interspecies competition among krill-feeding marine predators.

Identification of marine mammal species in food products

Reference samples and processed products (frozen, smoked, salted, dried and gravad meat and blubber) from harp seal and minke, sei and fin whales were tested for species-diagnostic molecular markers by random amplification of polymorphic DNA (RAPD) and single-strand conformational polymorphism (SSCP) analysis of amplicons obtained using consensus primers for mitochondrial cytochrome b (mt cytb). RAPD analysis produced clear fingerprints of the products analysed from which the species could be easily identified. The interpretation of the SSCP analysis was less clear, probably owing to the use of consensus primers and, in fin whales, to intraspecific polymorphism. Except for one, all the commercial products were correctly labelled, and it was possible to identify the species in all the products labelled simply as 'whale': three of them contained minke whale and two fin whale.

Evidence of Brucella infection in marine mammals in the North Atlantic Ocean

Between 1983 and 1996 a total of 1386 samples of serum were taken from four species of seal and three species of whale in the waters west of Iceland, the...

Helminths parasites of whales in Brazil

Three species of whale Balaenoptera borealis Lesson, 1828, B. physalus (Linnaeus, 1758) and Physeter catodon Linnaeus, 1758 captured in the Brazilian coast were necropsied for helminths. Balaenoptera borealis and B. physalus were infected by Crassicauda crassicauda (Nematoda, Tetrameridae) and Ogmogaster antarcticus (Digenea: Notocotylidae), which are referred for the first time in Brazil. Balaenoptera borealis was also infected by Lecithodesmus goliath (Digenea, Campulidae) and Bolbosoma turbinella (Acanthocephala, Polymorphidae). Physeter catodon was infected by Anisakis physeteris (Nematoda, Anisakidae), which is a new record to this host in Brazilian waters.

Estimates of Prey Consumption and Trophic Impacts of Cetaceans in the USA Northeast Continental Shelf Ecosystem

Whales, dolphins and porpoises are significant consumers of prey resources in the USA Northeast Shelf marine ecosystem to a far greater extent than was realized two decades ago. Seasonal estimates of the consumption of finfish, squid and zooplankton by cetaceans were calculated for four regions of the Northeast Shelf system defined as Gulf of Maine, Georges Bank, Southern New England and Mid-Atlantic Bight. Estimates were based on seasonal cetacean abundance using standard mammalian metabolic models scaled as appropriate for assimilation, activity and migratory fasting. Estimates were made of mean body mass and proportion of the diet comprised of each of the three main prey types. Cetaceans of the Northeast Shelf were found to consume nearly 1.9 million tons annually, including about 1.3 million tons of fish, 337 000 tons of squid and 244 000 tons of zooplankton. Their predation on fish and squid exceeded tonnages harvested in the commercial fishing industry. Consumption estimates of fish dominated in most regions and seasons, primarily because of the widespread distribution and high relative abundance of large piscivorous fin whales, and secondarily due to the presence of humpback and minke whales and some of the smaller odontocetes. Zooplankton consumption, principally by right and sei whales and secondarily by other mysticetes, was significant in some seasons in the Gulf of Maine and Georges Bank regions. An assemblage which included a variety of teuthivorous odontocete species inhabiting the shelf break vicinity consumed substantial quantities of squid in all regions except the Gulf of Maine. Using a simple five-level trophic model and 10% estimated trophic transfer efficiency, the estimates implied that a significant fraction of the total net primary production, ranging from 11.7% in the Mid-Atlantic Bight to 20.4% in the Gulf of Maine, was required to the support cetacean apex predation.

CATCHES OF HUMPBACK AND OTHER WHALES FROM SHORE STATIONS AT MOSS LANDING AND TRINIDAD, CALIFORNIA, 1919–1926

AbstractLogbook data from California shore whaling stations at Moss Landing (1919–1922 and 1924) and Trinidad (1920 and 1922–1926) are analyzed. The logs for the two stations record the taking of 2,111 whales, including 1,871 humpbacks, 177 fin whales, 26 sei whales, 3 blue whales, 12 sperm whales, 7 gray whales, 1 right whale, 1 Baird's beaked whale, and 13 whales of unspecified type (probably humpbacks). Most whales were taken from spring to autumn, but catches were made in all months of some years. The sex ratios of humpback, fin, and sei whales (the three species with sufficient sample sizes to test) did not differ from parity. Primary prey, determined from stomach contents, included sardines and euphausiids for both humpback and fin whales, and ‘plankton’ (probably euphausiids) for sei whales. The prevalence of pregnancy was 0.46 among mature female humpbacks and 0.43 among mature female fin whales, although these values are reported with caution. Information on length distribution for all species is summarized. Analysis of the catch data for this and other areas supports the current view that humpback whales along the west coast of the continental United States comprise a single feeding stock and also suggests that the present population is well below pre‐exploitation levels.