Sei Whales Research Articles

Diverse baleen whale acoustic occurrence around two sub-Antarctic islands: A tale of residents and visitors

Knowledge on the occurrence and behaviour of baleen whales around sub-Antarctic regions is limited, and usually based on short, seasonal sighting research from shore or research vessels and whaling records, neither of which provide accurate and comprehensive year-round perspectives of these animals’ ecology. We investigated the seasonal acoustic occurrence and diel vocalizing pattern of baleen whales around the sub-Antarctic Prince Edward Islands (PEIs) using passive acoustic monitoring data from mid-2021 to mid-2023, detecting six distinct baleen whale songs from Antarctic blue whales, Madagascan pygmy blue whales, fin whales, Antarctic minke whales, humpback whales, and sei whales. Antarctic blue and fin whales were detected year-round whereas the other species’ songs were detected seasonally, including a new Antarctic minke whale bio-duck song sub-type described here for the first time. Antarctic minke and sei whales were more vocally active at night-time whereas the other species had no clear diel vocalizing patterns. Random forest models identified month and/or sea surface temperature as the most important predictors of all baleen whale acoustic occurrence. These novel results highlight the PEIs as a useful habitat for baleen whales given the number of species that inhabit or transit through this region.

Observations of Attacks on Sei and Fin Whales by Killer Whales in Magellanic Sub-Antarctic Waters, Chile

Observations of Attacks on Sei and Fin Whales by Killer Whales in Magellanic Sub-Antarctic Waters, Chile

Distribution models of baleen whale species in the Irish Exclusive Economic Zone to inform management and conservation

Irish waters are under increasing pressure from anthropogenic sources including the development of offshore renewable energy, vessel traffic and fishing activity. Spatial planning requires robust datasets on species distribution and the identification of important habitats to inform the planning process. Despite limited survey effort, long-term citizen science data on whale presence are available and provide an opportunity to fill information gaps. Using presence-only data as well as a variety of environmental variables, we constructed seasonal ensemble species distribution models based on five different algorithms for minke whales, fin whales, humpback whales, sei whales, and blue whales. The models predicted that the coastal waters off the south and west of Ireland are particularly suitable for minke, fin and humpback whales. Offshore waters in the Porcupine Seabight area were identified as a relevant habitat for fin whales, sei whales and blue whales. We combined model outputs with data on maritime traffic, fishing activity and offshore wind farms to measure the exposure of all the species to these pressures, identifying areas of concern. This study serves as a baseline for the species presence in Irish waters over the last two decades to help develop appropriate marine spatial plans in the future.

Annual phenology and migration routes to breeding grounds in western-central North Pacific sei whales

The sei whale (Balaenoptera borealis) is an important species among baleen whales in the North Pacific and plays a significant role in the ecosystem. Despite the importance of this species, information regarding its migration patterns and breeding locations remains limited. To enhance the understanding of the phenology of North Pacific sei whales, we deployed satellite-monitored tags on these whales in the western and central North Pacific from 2017 to 2023. We fitted 55 sei whale tracks to a state-space model to describe the whales’ seasonal movements at feeding grounds and their migratory behavior. The whales typically leave their feeding grounds between November and December, with migration pathways extending from off Japan to the west of the Hawaiian Islands. These southward transits converge in the waters of the Marshall Islands and north of Micronesia between 20° N and 7° N, which appear to be breeding grounds. After a brief stay at these breeding grounds, the whales migrate northward from January to February, reaching their feeding grounds around 30°N by March. To the best of our knowledge, this is the first study to present the phenology of feeding and breeding seasons and the migration pattern of North Pacific sei whales.

Cetacean presence and ambient sound level analysis in Bermuda: A comparison to historical records

Marine Protected Areas (MPAs) are established to conserve nature while also preserving ecosystem services and cultural values. Many ongoing MPA discussions are centered on offshore islands, including Bermuda, a British Overseas Territory in the North Atlantic Ocean, which is currently assessing a management plan to protect 20% of its EEZ. Marine mammals are essential targets to monitor as part of effective MPA management because they are keystone species. In addition, as human activities raise ocean noise levels worldwide, monitoring ambient sound levels is essential to evaluating impacts on marine ecosystems. We collected nine months of passive acoustic data (at 250 kHz sampling rate and with 24-bit resolution) between December 2021 and September 2022, approximately 24 nm south of Bermuda, close to a location where previous studies were conducted in 1966 and 2013–2014. The cetacean presence and ambient sound levels derived from our dataset will be compared to these historical datasets. Our comparative analysis focused on humpback whales (Megaptera novaeangliae), fin whales (Balaenoptera physalus), minke whales (Balaenoptera acutorostrata), blue whales (Balaenoptera musculus), sei whales (Balaenoptera borealis), and beaked whales (family Ziphiidae). Results will illustrate how Bermuda’s offshore underwater soundscape has changed over nearly six decades.

Contribution to the Knowledge of Cetacean Strandings in Chile between 2015 and 2020

Strandings caused by anthropogenic factors are one of the most worrying threats in relation to the conservation of cetacean species, and in the case of Chile, due to its geography and large extension of the coastline, monitoring and access to these events is difficult, making their study more complex. Chile has a shortage of specialized scientific forensic research facilities for cetaceans; however, for this study, it was able to collect data recorded from official institutions and sporadic scientific biological sampling oriented to investigate the causes of death or stranding. According to the Chilean government official database, we described that the main causes of unusual mortality events (UME) and mass strandings from 2015 and 2016 were acute poisoning by biotoxins and strandings by multiple possible causes, respectively, while individual strandings would have their causes in anthropogenic activities, such as entanglements in fishing and aquaculture gears and collisions with vessels. The predominant species in mass strandings was the sei whale (Balaenoptera borealis). The geographical area of greatest prominence in mass strandings was the Aysén Region in the Central Patagonia of Chile, while the species mostly involved in individual strandings along the south-central, central, and northern coasts of Chile was the small porpoise (Phocoena spinipinnis). The most common gross pathological findings were advance decay of the carcasses and non-specific wounds of different natures.

Characteristics and spatiotemporal variation of sei whale (Balaenoptera borealis) downsweeps recorded in Atlantic Canada.

The call characteristics and vocal behaviour of sei whales (Balaenoptera borealis) off eastern Canada, including potential spatiotemporal variation, is poorly understood. Such information can improve the performance of automated detector-classifiers, enhancing the accuracy and efficiency of identifying sei whales in large acoustic datasets. Ultimately, these data can be used to understand the occurrence, distribution, and population structure of sei whales in Atlantic Canada. We measured sei whale downsweep characteristics recorded from six locations off Nova Scotia (NS) and Newfoundland and Labrador (NFLD), Canada over a two-year period (2015-2017), and examined variation between call subtypes (singlets, doublets, triplets+), and seasons (Spring, Summer, Fall, Winter). We found that downsweeps had a mean duration of 1.58 s, sweeping from 75.66 to 34.22 Hz, with a peak frequency of 43.89 Hz and an intra-call interval of 2.22 s. Most call characteristics did not vary between location, subtype, or season; however, significantly longer downsweeps occurred off NS, within doublet calls, and in fall months. We also found that NFLD had a higher proportion of doublets (70%) than NS (52%). This variation may be evidence of acoustically diverging sei whale populations, as well as useful for improving detector-classifiers of sei whales in the region.

Seasonal acoustic presence of sei whales off the Juan Fernandez Archipelago, Chile

Seasonal acoustic presence of sei whales off the Juan Fernandez Archipelago, Chile

Acoustic recording tags provide insight into the springtime acoustic behavior of sei whales in Massachusetts Bay.

The acoustic ecology of sei whales (Balaenoptera borealis) is poorly understood due to limited direct observation of the behavioral context of sound production and individual behavior. Suction cup-attached acoustic recording tags were deployed on sei whales to unambiguously assign call types and explore the acoustic behavior of this endangered species. Twelve tag deployments resulted in ∼173 h of acoustic data and 1030 calls. Sound types included downsweeps and three previously undescribed call types. Knocks were short duration (<1 s), with an average peak frequency of 330 Hz. Pulse type 1 and pulse type 2 calls, typically produced in sequences, were short in duration (0.08 and 0.28 s) and low in average peak frequency (50 and 26 Hz), with relatively high received levels. Average call rates for all call types combined were three calls per hour, but increased during twilight. Sex differences in call type usage included a higher use of pulses by females and knocks by males. Calls were almost exclusively produced at depths <10 m, although whales rarely dove deeper in this study. These data provide a more comprehensive picture of the acoustic and behavioral ecology of sei whales than previously possible, which can inform future conservation efforts for this endangered species.

Establishing baselines for predicting change in ambient sound metrics, marine mammal, and vessel occurrence within a US offshore wind energy area

Abstract Evaluating potential impacts on marine animals or increased sound levels resulting from offshore wind energy construction requires the establishment of baseline data records from which to draw inference. This study provides 2 years of baseline data on cetacean species’ presence, vessel activity, and ambient sound levels in the southern New England wind energy area. With eight species/families present in the area for at least 9 months of the year, this area represents an important habitat for cetaceans. Most species showed seasonality, with peak daily presence in winter (harbour porpoise, North Atlantic right, fin, and humpback whales), summer (sperm whales), spring (sei whales), or spring and fall/autumn (minke whales). Delphinids were continuously present and blue whales present only in January. The endangered North Atlantic right whales were present year round with high presence in October through April. Daily vessel presence showed an increase from summer through fall/autumn. On average, ambient sound levels were lowest in summer and increased late 2021 through 2022 with most temporal variability occurring across lower frequencies. The area showed a complex soundscape with several species sharing time–frequency space as well as overlap of vessel noise with the communication range of all baleen whale species.

Mysticete whale abundance and observations of prey associations on the central Bering Sea shelf

Visual surveys for cetaceans were conducted along transect lines in the central Bering Sea in association with a groundfish stock assessment survey from 5 July to 5 August 1999. There were 125 sightings of single or groups of mysticete whales during 6,043km of survey effort. Fin whales were most common (60% of all sightings), with distribution clustered along the outer continental shelf break near the 200m isobath. In addition, there were 27 sightings of minke whales and 17 sightings of humpback whales. Minke whales were primarily found along the upper slope in water 100-200m deep, while humpbacks clustered along the eastern Aleutian Islands and near the USA/Russian Convention Line southwest of St. Lawrence Island. Abundance estimates for fin, humpback and minke whales were: 4,951 (95% CI = 2,833-8,653); 1,175 (95% CI = 197-7,009) and 936 (95% CI = 473-1,852), respectively. These three species were the only ones for which sufficient on-effort sightings were available to estimate abundance. Sei whales, a gray whale and a pair of northern right whales were also seen. Although right whales have been seen in this area before, some behavioural details are provided here because observations of these whales remain rare.

Estimates of abundance south of 60°S for cetacean species sighted frequently on the 1978/79 to 1997/98 IWC/IDCR-SOWER sighting surveys

Estimates of abundance are calculated for six cetacean species in the Southern Ocean south of 60° in the austral summer, using the IWC database estimation package (DESS). The sightings data in DESS were collected during the 1978/79 to 1997/98 IWC/IDCR and SOWER circumpolar surveys. Abundance estimates are developed for the first (1978/79–1983/84), second (1985/86–1990/91) and currently incomplete third (1991/92–1997/98) circumpolar sets of surveys. The strata surveyed in these three sets cover about 65%, 81% and 68% respectively of the open ocean area south of 60°S. The surveys were designed for Antarctic minke whales and may not be optimal for all these species. Furthermore, the estimates presented below (CVs in brackets) should not necessarily be considered as estimates for the whole Southern Hemisphere. Some results are also presented for hourglass dolphins and sei whales, but estimates of abundance are not considered reliable for those two species. Effective search half-width and mean school size were estimated by pooling across strata and years. Pooling is effected separately for each circumpolar set of surveys. Additional pooling across closing and passing modes did not introduce substantial bias. The most frequently sighted species were minke, southern bottlenose, sperm, humpback and killer whales; the effective search half-widths for all five increase over time. The sensitivity of the abundance estimates to a number of factors is investigated, none of which appears to impact the results substantially, except that the incorporation of ‘like species’ would increase the estimate for blue whales from the third circumpolar set of surveys by 25% and for fin whales by 61%. In general, the assumption that 100% of schools on the trackline are sighted introduces variable negative bias to estimates for all species. Only two significant trends in abundance over time (for comparable areas) were detected, but both may be artefacts of changes in survey design.

Sex hormone concentrations in the blood of sei whales (Balaenoptera borealis) off Iceland

Blood samples were collected postmortem at sea, from 195 sei whales (127 females and 68 males) caught southwest of Iceland between 1983 and 1988. The reproductive status of the whales was determined by anatomical/histological methods. The blood samples were measured by radioimmunoassays for progesterone (P), testosterone (T) and oestradiol concentrations, which were then related to the reproductive status, the length of the whales and the days of the hunting season. Serum P concentrations in females were found to be clustered mainly into two groups, one with values at or below the detection limit (0.1nmol/L) of the assay (Group I) and the other with values about two orders of magnitude higher (Group III) with intermediate values (Group II) in between. Anatomical results showed that Group I (n = 73) was largely a mixture of immature and anoestrous mature females. Group III (n = 39), with a significantly (p &lt; 0.01) greater mean body length than Group I, had a distinct frequency distribution of serum P values with a mean (SD) concentration of 10.3nmol/L (4.1) and consisted predominantly of pregnant females. Many foetuses were lost at sea due to a slit in the abdomen for cooling purposes, but all 13 foetuses (1.5-3.7m in length) recovered belonged to females of Group III. Group II (n = 15) consisted mainly of anoestrous mature animals. When pregnancy was estimated by serum P values and sexual maturity by the anatomical findings, the apparent pregnancy rate of mature females was 0.37, agreeing reasonably with earlier reports. Male sei whales were classified into immature, pubertal and mature groups by anatomical/histological methods and had mean T concentrations (nmol/L, ranges) of 0.85, 0.1-4.5; 3.3, 0.1-14.7 and 4.8, 0.1-14.8, respectively. Serum T concentrations did not correlate significantly with body length in the groups but pubertal and mature males had significantly higher geometric mean T values than immature males. Mean serum T concentrations in males, classified as sexually mature by anatomical/histological methods, rose approximately 3.2-fold every 30 days during July-September indicating a seasonal breeding cycle. It is concluded that measurements of sex hormone concentrations in sei whales make a powerful addition to the earlier anatomical/histological methods for determination of reproductive status, not only corroborating them but apparently surpassing them in sensitivity of detecting pregnancy and cyclical changes in serum T values during the male reproductive cycle.

Abundance of fin (Balaenoptera physalus) and sei whales (B. borealis) amid oil exploration and development off northwest Scotland

A ship-based line transect survey was conducted during July-August 1998 to assess the distribution and abundance of cetaceans off northwest Scotland. Limited information from dedicated surveys exists for this area and the lack of baseline data is cause for concern given the expanding oil industry in these waters. Historical whaling records show that large numbers of baleen whales, particularly fin and sei whales, were captured in these waters during summer. The waters surveyed included former whaling grounds and currently licensed oil blocks to the west of the Outer Hebrides and the Faroe-Shetland Channel and both fin and sei whales were encountered. Neither species was recorded to the west of the Outer Hebrides whereas relatively high densities of both were recorded further north in the Faroe-Shetland Channel. The density of fin and sei whales was 0.021km–2 and 0.022km–2, respectively. Abundance was estimated as 933 (CV=0.38) fin whales, 1,011 (CV=0.35) sei whales and 1,923 (CV=0.33) ‘large whales’. The high density of whales recorded in the Faroe-Shetland Channel supports the idea that it is an important summer feeding ground for both species and the potential for acoustic disturbance associated with increasing industrialisation of this area is a concern. Factors affecting the distribution and abundance of these whales are discussed.

Assessing the viability of estimating baleen whale abundance from tourist vessels

Many populations of southern hemisphere baleen whales are recovering and are again becoming dominant consumers in the Southern Ocean. Key to understanding the present and future role of baleen whales in Southern Ocean ecosystems is determining their abundance on foraging grounds. Distance sampling is the standard method for estimating baleen whale abundance but requires specific logistic requirements which are rarely achieved in the remote Southern Ocean. We explore the potential use of tourist vessel-based sampling as a cost-effective solution for conducting distance sampling surveys for baleen whales in the Southern Ocean. We used a dataset of tourist vessel locations from the southwest Atlantic sector of the Southern Ocean and published knowledge from Southern Ocean sighting surveys to determine the number of tourist vessel voyages required for robust abundance estimates. Second, we simulated the abundance and distributions of four baleen whale species for the study area and sampled them with both standardized line transect surveys and non-standardized tourist vessel-based surveys, then compared modeled abundance and distributions from each survey to the original simulation. For the southwest Atlantic, we show that 12-22 tourist vessel voyages are likely required to estimate abundance for humpback and fin whales, with relative estimates for blue, sei, Antarctic minke, and southern right whales. Second, we show tourist vessel-based surveys outperformed standardized line transect surveys at reproducing simulated baleen whale abundances and distribution. These analyses suggest tourist vessel-based surveys are a viable method for estimating baleen whale abundance in remote regions. For the southwest Atlantic, the relatively cost-effective nature of tourist vessel-based survey and regularity of tourist vessel voyages could allow for annual and intra-annual estimates of abundance, a fundamental improvement on current methods, which may capture spatiotemporal trends in baleen whale movements on forging grounds. Comparative modeling of sampling methods provided insights into the behavior of general additive model-based abundance modeling, contributing to the development of detailed guidelines of best practices for these approaches. Through successful engagement with tourist company partners, this method has the potential to characterize abundance across a variety of marine species and spaces globally, and deliver high-quality scientific outcomes relevant to management organizations.

Estimates of large whale abundance in Greenlandic waters from a ship-based survey in 2005

A ship-based line transect survey of large whales in East and West Greenland was conducted in September 2005. The survey platform primarily targeted capelin, Mallotus villosus, using acoustic methods and systematically covered the east and west coasts of Greenland from the coast to the shelf break (approximately 200m). The surveyed area comprised 81,000km2 in East Greenland and 225,000km2 in West Greenland. A total of 194 sightings of 13 cetacean species were obtained and standard line transect methods were used to derive abundance estimates of the four most commonly encountered large cetaceans. Fin whales, Balaenoptera physalus, were most abundant in East Greenland (3,214, 95% CI=980-10,547) with lower abundances estimated for West Greenland (1,980, 95% CI=913-4,296). Sei whales, B. borealis, were frequently encountered in the same areas as fin whales, but the estimated abundance in East Greenland (763, 95% CI=236- 2,465) was lower than in West Greenland (1,599, 95% CI=690-3,705). Humpback whales, Megaptera novaeangliae, were found both in offshore and coastal areas of West Greenland (1,306, 95% CI=570-2,989) and in low numbers in East Greenland (347, 95% CI=48-2,515). Finally, common minke whale, B. acutorostrata, abundance was estimated at 1,848 (95% CI=197-17,348) for East Greenland and 4,479 (95% CI=1,760-11,394) for West Greenland. Inclusion of sightings of unidentified large baleen whales in West Greenland distributed in proportion to species and strata increased abundance estimates for fin, sei, and humpback whales to 2,824 (95% CI=1,346-5,925), 2,009 (95% CI=948-4,260), and 1,514 (95% CI=560-4,089), respectively. Despite good conditions and considerable effort, few cetaceans were observed in the northernmost strata in West Greenland. This suggests that the southbound fall migration of large whales from North West Greenland had already started by the time the survey was initiated. The abundance estimates presented in this study are negatively biased. No corrections were applied for whales missed by observers or for whales submerged during the passage of the survey platform, which should cause a particularly large negative bias, for the estimates of common minke whale abundance.

Occurrence and distribution of cetaceans off northern Angola, 2004/05

The occurrence and distribution of cetacean species off northern Angola was examined using dedicated survey data and incidental sighting records. Dedicated surveys for cetaceans were carried out during two geophysical seismic surveys off northern Angola between August 2004 and September 2005. A total of 3,268hr of survey effort data were collected, resulting in 779 on-effort cetacean sightings. There were 263 sightings reported off-effort and incidentally from other platforms and sports fishermen. With 21 cetacean species confirmed, the cetacean community off northern Angola is diverse and primarily tropical in characteristic, comprising four species of baleen whale, two sperm whale species, at least two beaked whale species, and 13 species of delphinid. Humpback and sperm whales were the most frequently recorded cetaceans. The occurrence of humpback whales was significantly higher within neritic waters, and during the winter and spring months in association with seasonal occupancy of their West African breeding grounds. Sperm whales were recorded in water depths exceeding 1,000m and demonstrated significant seasonality, with peak occurrence during the summer and autumn. Atlantic spotted dolphins and common dolphins (Delphinus sp.) were the most numerous delphinids recorded, with spotted dolphins showing a significant seasonal peak during the spring and summer, and common dolphins in the winter. Other species recorded included fin whale, sei whale, Bryde’s whale, dwarf sperm whale, Cuvier’s and Mesoplodon beaked whales, killer whale, short-finned pilot whale, false killer whale, melon-headed whale, Atlantic humpback dolphin, rough-toothed dolphin, Risso’s dolphin, bottlenose dolphin, Pantropical spotted dolphin, spinner dolphin, Clymene dolphin and striped dolphin. Further research is required to document the cetacean community in Angola, particularly given the unknown threat from fishery bycatch and the increasing level of oil and gas exploration in the region.

A note on observations on cetaceans in the western Indian sector of the Southern Ocean (20-56°S and 45-57°30’E), January to March 2004

A multi-disciplinary and multi-institutional pilot expedition was organised by the National Centre for Antarctic and Ocean Research (NCAOR) to the ice-free areas of the Western Indian Ocean sector of the Southern Ocean onboard ORV Sagar Kanya during the austral summer of 2004 (January-March). This survey, conducted by the Central Marine Fisheries Research Institute (CMFRI), is the first Indian attempt to survey for cetacean diversity in the Southern Ocean. The ultimate objective is to determine distribution, relative abundance, migration patterns and critical habitat parameters. 68% of a total of 13 sightings (22 individuals) were positively identified and species observed included Antarctic minke whales (Balaenoptera bonaerensis), fin whales (B. physalus), sei whales (B. borealis) and blue whales (B. musculus). The blue whales were not identified to the sub-species level. The highest concentration of cetaceans was between 35° and 37°S (along 45°E) and between 48° and 53°S (along 45°E). Relatively small numbers of cetaceans were observed during the present cruise, possibly because most of the cetacean sighting effort was made during inclement sea conditions. Results on the sighting characteristics and occurrence patterns of the cetaceans in relation to the region and hydrographical parameters are discussed briefly vis a vis published information from the Southern Ocean.

Distribution and density estimates of cetaceans along the midAtlantic Ridge during summer 2004

During 4 June-2 July 2004, the Norwegian R/V G.O. Sars conducted a multi-disciplinary survey along the mid-Atlantic Ridge (MAR) from the Reykjanes Ridge to north of the Azores. This provided the first systematic survey information on MAR cetacean populations. Using naked eye or 7350 hand-held binoculars, observers searched in a 140° arc centred along the ships’ heading. Eleven cetacean species and 10 other taxonomic groups were identified along 2,321km of transect effort. The sei whale (Balaenoptera borealis) and sperm whale (Physeter macrocephalus) were the most commonly sighted species (53 and 48 sightings, respectively). There were 12 sightings of the fin whale (B. physalus). There were 26, 13 and 12 sightings, respectively of the common dolphin (Delphinus delphis), pilot whale (Globicephala sp.) and striped dolphin (Stenella coeruleoalba). Density estimates of species ranged from 0.018 to 0.238 animals km–2. The precision of the estimates (CV) was low, ranging from 40% to 61%. Species distribution varied north to south; the highest aggregations of baleen whales were sighted at the Charlie Gibbs Fracture Zone (CGFZ). Sperm whales were also observed at the CGFZ as well as north of this area. Pilot whales and Atlantic white-sided dolphins (Lagenorhynchus acutus) were sighted mainly in the cold (5-16°C) and less saline (34.6-35.8‰) water masses along the Reykjanes Ridge. Conversely, common dolphins and striped dolphins were most commonly sighted south of the CGFZ in areas with warmer (12-22°C) and more saline (34.8-36.7‰) surface water temperatures.

Soviet catches of whales in the North Pacific: revised totals

The USSR conducted a global campaign of illegal whaling beginning in 1948. Catch records for Soviet pelagic operations in the Southern Hemisphere (and the northern Indian Ocean) have been largely corrected, but major gaps have remained for the North Pacific. Here, using newly discovered whaling industry reports, corrected figures for Soviet catches in this ocean are provided. During the period 1948–79, a minimum of 190,183 whales were killed by the USSR in the North Pacific (195,783 if one includes an estimate for sperm whales taken in years for which there are no true data); of these, only 169,638 were reported to the IWC, a difference of 20,568 whales (26,168 including the sperm whale estimate). Figures were falsified for 8 of 12 hunted species, with some catches over-reported to camouflage takes of illegal species. Revised catch totals (caught vs. reported) are as follows: blue whale – 1,621 vs. 858; fin whale – 14,167 vs. 15,445; humpback whale – 7,334 vs. 4,680; sperm whale – 153,686 vs. 132,505; sei whale – 7,698 vs. 11,363; North Pacific right whale – 681 vs. 11; bowhead whale – 145 vs. 0; gray whale – 172 vs. 24. Bryde’s, minke, killer and Baird’s beaked whale catches were reported correctly. Of all the hunted species, sperm and North Pacific right whales were the most heavily impacted. Major falsifications for sperm whales involved figures for both total catch and sex ratio.