scholarly journals Stretching the truth: length data highlight falsification of Japanese sperm whale catch statistics in the Southern Hemisphere

2016 ◽  
Vol 3 (9) ◽  
pp. 160506 ◽  
Author(s):  
Phillip J. Clapham ◽  
Yulia V. Ivashchenko
Keyword(s):  
Southern Hemisphere ◽  
North Pacific ◽  
Length Distribution ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Catch Data ◽  
The Past ◽  
Length Data ◽  
Catch Statistics

Falsification of reports on Japanese catches of sperm whales ( Physeter macrocephalus ) is known to have occurred at both land whaling stations and in North Pacific factory fleets. Here, we conduct an analysis of pelagic sperm whale catches in the Southern Hemisphere: we compare true Soviet length data from the Yuri Dolgorukiy factory fleet during 1960–1975 to data for the same period reported to the International Whaling Commission (IWC) by Japan. Prior to implementation of the International Observer Scheme (IOS) in 1972, the Soviet fleet killed 5536 females, of which only 153 (2.8%) were at or above the minimum legal length of 11.6 m. During the same period, Japan killed 5799 females and reported that 5686 (98.5%) were of legal size, with 88.5% of the entire length distribution reported as being between 11.6 and 12.0 m. This unrealistic distribution, together with the fact that Japanese fleets were supposedly able to catch 37 times the number of legal-sized females as the Soviet fleet, indicates extensive falsification of catch data by Japan. Further evidence of misreporting is that females >11.5 m dropped to 9.1% of the Japanese catch after 1971, when the IOS made cheating much more difficult. That 99.6% of 10 433 males in the pre-IOS catch were also reported to be of legal size, indicates that illegal catches were not confined to females. We caution that the Japanese sperm whale data in the IWC Catch Database are unreliable and should not be used in population assessments. The ease with which illegal catches were apparently made underscores the past failures of the IWC to effectively regulate whaling.

scholarly journals What's the catch? Validity of whaling data for Japanese catches of sperm whales in the North Pacific

2015 ◽  
Vol 2 (7) ◽  
pp. 150177 ◽  
Author(s):  
Yulia V. Ivashchenko ◽  
Phillip J. Clapham
Keyword(s):  
World War Ii ◽  
North Pacific ◽  
Large Scale ◽  
Minimum Length ◽  
Sperm Whales ◽  
Catch Data ◽  
The North ◽  
Commercial Whaling ◽  
Catch Statistics ◽  
The North Pacific

The failure of international efforts to manage commercial whaling was exemplified by revelations of large-scale illegal whale catches by the USSR over a 30 year period following World War II. Falsifications of catch data have also been reported for Japanese coastal whaling, but to date there has been no investigation of the reliability of catch statistics for Japanese pelagic (factory fleet) whaling operations. Here, we use data of known reliability from Soviet whaling industry reports to show that body lengths reported to the International Whaling Commission (IWC) by Japanese factory fleets for female sperm whales caught in the North Pacific are not credible. In 1968/1969, Japanese whaling fleets in the North Pacific killed 1568 females, of which 1525 (97.3%) were reported as being at or above the IWC's minimum length of 11.6 m (legal-sized females, LSFs). By contrast, Soviet fleets operating during this period killed 12 578 females; only 824 (6.6%) were LSFs. Adjusting for effort, catches of LSFs were up to 9.1 times higher for Japan compared with the USSR, and even higher for very large females. Dramatic differences in body length statistics were evident when both nations operated in the same area. Significantly, the frequency of LSFs and very large females in the Japanese catch markedly declined after the IWC's International Observer Scheme in 1972 made illegal whaling more difficult. We conclude that the Japanese length data reflect systematic falsification of catch statistics submitted to the IWC, with serious implications for the reliability of data used in current population assessments. The apparent ease with which catch data were falsified in the past underscores the necessity of transparent and independent inspection procedures in any future commercial whaling.

Past and recent sperm whales sightings in the Azores based on catches and whale watching information

2009 ◽  
Vol 89 (5) ◽  
pp. 1067-1070 ◽  
Author(s):  
N. Vieira ◽  
C. Brito
Keyword(s):  
Sperm Whale ◽  
Main Question ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Whale Watching ◽  
Azores Archipelago ◽  
The Past

The sperm whale, Physeter macrocephalus, was the most captured great whale in the Azores Archipelago by land-based whaling and nowadays is the most appealing species for whale watching, one of the archipelago's principal sources of tourism. Our objective was to compare number of sightings during whaling and whale watching activities. Our main question to address the possible impact of past whaling in recent whale watching is: does a present-day eco-tourist sight more or fewer sperm whales than a whaler could sight in the past? For that, a compilation of data resulting both from past whaling records and recent whale watching records was conducted. We obtained a total of 727 independent sightings of sperm whales during a total of 280 different days of sperm whaling between 1947 and 1973. A total of 1767 sperm whale sightings were made during 1133 days of whale watching activities, between 1997 and 2008. The sperm whale sighting per unit of effort average was significantly higher in the past (35.68) than in the present (12.06). In the Azores, captures over the decades greatly decreased the number of sperm whales in the region and twenty years after the end of sperm whaling a reduced number of recent sightings were found.

scholarly journals Architecture of the sperm whale forehead facilitates ramming combat

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1895 ◽  
Author(s):  
Olga Panagiotopoulou ◽  
Panagiotis Spyridis ◽  
Hyab Mehari Abraha ◽  
David R. Carrier ◽  
Todd C. Pataky
Keyword(s):  
Connective Tissue ◽  
Structural Engineering ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Moby Dick ◽  
Unique Structure ◽  
Complex Structural ◽  
Von Mises ◽  
Von Mises Stresses

Herman Melville’s novelMoby Dickwas inspired by historical instances in which large sperm whales (Physeter macrocephalus L.) sank 19th century whaling ships by ramming them with their foreheads. The immense forehead of sperm whales is possibly the largest, and one of the strangest, anatomical structures in the animal kingdom. It contains two large oil-filled compartments, known as the “spermaceti organ” and “junk,” that constitute up to one-quarter of body mass and extend one-third of the total length of the whale. Recognized as playing an important role in echolocation, previous studies have also attributed the complex structural configuration of the spermaceti organ and junk to acoustic sexual selection, acoustic prey debilitation, buoyancy control, and aggressive ramming. Of these additional suggested functions, ramming remains the most controversial, and the potential mechanical roles of the structural components of the spermaceti organ and junk in ramming remain untested. Here we explore the aggressive ramming hypothesis using a novel combination of structural engineering principles and probabilistic simulation to determine if the unique structure of the junk significantly reduces stress in the skull during quasi-static impact. Our analyses indicate that the connective tissue partitions in the junk reduce von Mises stresses across the skull and that the load-redistribution functionality of the former is insensitive to moderate variation in tissue material parameters, the thickness of the partitions, and variations in the location and angle of the applied load. Absence of the connective tissue partitions increases skull stresses, particularly in the rostral aspect of the upper jaw, further hinting of the important role the architecture of the junk may play in ramming events. Our study also found that impact loads on the spermaceti organ generate lower skull stresses than an impact on the junk. Nevertheless, whilst an impact on the spermaceti organ would reduce skull stresses, it would also cause high compressive stresses on the anterior aspect of the organ and the connective tissue case, possibly making these structures more prone to failure. This outcome, coupled with the facts that the spermaceti organ houses sensitive and essential sonar producing structures and the rostral portion of junk, rather than the spermaceti organ, is frequently a site of significant scarring in mature males suggest that whales avoid impact with the spermaceti organ. Although the unique structure of the junk certainly serves multiple functions, our results are consistent with the hypothesis that the structure also evolved to function as a massive battering ram during male-male competition.

scholarly journals Socially segregated, sympatric sperm whale clans in the Atlantic Ocean

2016 ◽  
Vol 3 (6) ◽  
pp. 160061 ◽  
Author(s):  
Shane Gero ◽  
Anne Bøttcher ◽  
Hal Whitehead ◽  
Peter Teglberg Madsen
Keyword(s):  
Social Interactions ◽  
Sperm Whale ◽  
Mantel Test ◽  
Good Evidence ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Sympatric Populations ◽  
The Pacific ◽  
Matrix Correlation ◽  
Social Units

Sperm whales ( Physeter macrocephalus ) are unusual in that there is good evidence for sympatric populations with distinct culturally determined behaviour, including potential acoustic markers of the population division. In the Pacific, socially segregated, vocal clans with distinct dialects coexist; by contrast, geographical variation in vocal repertoire in the Atlantic has been attributed to drift. We examine networks of acoustic repertoire similarity and social interactions for 11 social units in the Eastern Caribbean. We find the presence of two socially segregated, sympatric vocal clans whose dialects differ significantly both in terms of categorical coda types produced by each clan (Mantel test between clans: matrix correlation = 0.256; p  ≤ 0.001) and when using classification-free similarity which ignores defined types (Mantel test between clans: matrix correlation = 0.180; p  ≤ 0.001). The more common of the two clans makes a characteristic 1 + 1 + 3 coda, while the other less often sighted clan makes predominantly regular codas. Units were only observed associating with other units within their vocal clan. This study demonstrates that sympatric vocal clans do exist in the Atlantic, that they define a higher order level of social organization as they do in the Pacific, and suggests that cultural identity at the clan level is probably important in this species worldwide.

scholarly journals Calves as social hubs: dynamics of the social network within sperm whale units

2013 ◽  
Vol 280 (1763) ◽  
pp. 20131113 ◽  
Author(s):  
Shane Gero ◽  
Jonathan Gordon ◽  
Hal Whitehead
Keyword(s):  
Social Relationships ◽  
Social Role ◽  
Group Formation ◽  
Time Lag ◽  
Group Living ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Social Unit ◽  
The Social

It is hypothesized that the primary function of permanent social relationships among female sperm whales ( Physeter macrocephalus ) is to provide allomothers for calves at the surface while mothers make foraging dives. In order to investigate how reciprocity of allocare within units of sperm whales facilitates group living, we constructed weighted social networks based on yearly matrices of associations (2005–2010) and correlated them across years, through changes in age and social role, to study changes in social relationships within seven sperm whale units. Pairs of association matrices from sequential years showed a greater positive correlation than expected by chance, but as the time lag increased, the correlation coefficients decreased. Over all units considered, calves had high values for all measured network statistics, while mothers had intermediate values for most of the measures, but high values for connectedness and affinity. Mothers showed sharp drops in strength and connectedness in the first year of their new calves' lives. These broad patterns appear to be consistent across units. Calves appeared to be significant nodes in the network of the social unit, and thus provide quantitative support for the theory in which communal care acts as the evolutionary force behind group formation in this species.

scholarly journals DNA preserved in jetsam whale ambergris

2020 ◽  
Vol 16 (2) ◽  
pp. 20190819 ◽  
Author(s):  
Ruairidh Macleod ◽  
Mikkel-Holger S. Sinding ◽  
Morten Tange Olsen ◽  
Matthew J. Collins ◽  
Steven J. Rowland
Keyword(s):  
Natural Product ◽  
Dna Sequences ◽  
Reference Data ◽  
Nuclear Genome ◽  
Indirect Evidence ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Ecological Mechanisms

Jetsam ambergris, found on beaches worldwide, has always been assumed to originate as a natural product of sperm whales (Physeteroidea). However, only indirect evidence has ever been produced for this, such as the presence of whale prey remains in ambergris. Here, we extracted and analysed DNA sequences from jetsam ambergris from beaches in New Zealand and Sri Lanka, and sequences from ambergris of a sperm whale beached in The Netherlands. The lipid-rich composition of ambergris facilitated high preservation-quality of endogenous DNA, upon which we performed shotgun Illumina sequencing. Alignment of mitochondrial and nuclear genome sequences with open-access reference data for multiple whale species confirms that all three jetsam samples derived originally from sperm whales ( Physeter macrocephalus ). Shotgun sequencing here also provides implications for metagenomic insights into ambergris-preserved DNA. These results demonstrate significant implications for elucidating the origins of jetsam ambergris as a prized natural product, and also for the understanding of sperm whale metabolism and diet, and the ecological mechanisms underlying these coproliths.

scholarly journals The nose of the sperm whale: overviews of functional design, structural homologies and evolution

2014 ◽  
Vol 96 (4) ◽  
pp. 783-806 ◽  
Author(s):  
Stefan Huggenberger ◽  
Michel André ◽  
Helmut H. A. Oelschläger
Keyword(s):  
Sperm Whale ◽  
Pulse Generation ◽  
Nasal Passage ◽  
Generation Process ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Acoustic Window ◽  
Deep Diving ◽  
Toothed Whale ◽  
Fat Bodies

The hypertrophic and much elongated epicranial (nasal) complex of sperm whales (Physeter macrocephalus) is a unique device to increase directionality and source levels of echolocation clicks in aquatic environments. The size and shape of the nasal fat bodies as well as the peculiar organization of the air sac system in the nasal sound generator of sperm whales are in favour of this proposed specialized acoustic function. The morphology of the sperm whale nose, including a ‘connecting acoustic window’ in the case and an anterior ‘terminal acoustic window’ at the rostroventral edge of the junk, supports the ‘bent horn hypothesis’ of sound emission. In contrast to the laryngeal mechanism described for dolphins and porpoises, sperm whales may drive the initial pulse generation process with air pressurized by nasal muscles associated with the right nasal passage (right nasal passage muscle, maxillonasolabialis muscle). This can be interpreted as an adaptation to deep-diving and high hydrostatic pressures constraining pneumatic phonation. Comparison of nasal structures in sperm whales and other toothed whales reveals that the existing air sac system as well as the fat bodies and the musculature have the same topographical relations and thus may be homologous in all toothed whales (Odontoceti). This implies that the nasal sound generating system evolved only once during toothed whale evolution and, more specifically, that the unique hypertrophied nasal complex was a main driving force in the evolution of the sperm whale taxon.

Coda communication by sperm whales (Physeter macrocephalus) off the Galápagos Islands

1993 ◽  
Vol 71 (4) ◽  
pp. 744-752 ◽  
Author(s):  
Linda Weilgart ◽  
Hal Whitehead
Keyword(s):  
Social Cohesion ◽  
Temporal Pattern ◽  
Sequential Analysis ◽  
Sperm Whale ◽  
Galapagos Islands ◽  
Physeter Macrocephalus ◽  
Galápagos Islands ◽  
Sperm Whales ◽  
Insight Into

To gain insight into the function of sperm whale vocalizations known as codas (short, patterned series of clicks), sperm whales (Physeter macrocephalus) were tracked continuously for periods of days totalling months off the Galápagos Islands, Ecuador, and vocalizations were tape recorded systematically. In total, 1333 codas were classified according to their temporal pattern and the number of clicks they contained. Codas were found to be temporally very clustered, and could be categorized into 23 fairly discrete types. Sequential analysis of codas revealed that they overlapped one another according to type in a nonrandom way, and that type 5 tended to initiate coda exchanges. "Regular" coda types (with evenly spaced clicks) tended to occur with other regular coda types and "irregular" coda types (with one or two delayed final clicks) were heard with other irregular coda types. Codas may function principally as a means of communication, to maintain social cohesion within stable groups of females following periods of dispersion during foraging.

Foraging on squid: the sperm whale mid-range sonar

2007 ◽  
Vol 87 (1) ◽  
pp. 59-67 ◽  
Author(s):  
M. André ◽  
T. Johansson ◽  
E. Delory ◽  
M. van der Schaar
Keyword(s):  
Stomach Contents ◽  
Sperm Whale ◽  
Target Strength ◽  
Directional Hearing ◽  
Experimental Measurements ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Long Time ◽  
Minimum Requirements ◽  
The Subject

The sonar capabilities of the sperm whale, Physeter macrocephalus, have been the subject of speculation for a long time. While the usual clicks of this species are considered to support mid-range echolocation, no physical characteristics of the signal have clearly confirmed this assumption nor have they explained how sperm whales forage on squid. The recent data on sperm whale on-axis recordings have allowed us to simulate the propagation of a 15 kHz pulse as well as its received echoes from different targets, taking into account the reflections from the bottom and the sea surface. The analysis was performed in a controlled environment where the oceanographic parameters and the acoustic background could be modified. We also conducted experimental measurements of cephalopod target strength (TS) (Loligo vulgaris and Sepia officinalis) to further investigate and confirm the TS predictions from the geometric scattering equations. Based on the results of the computer simulations and the TS experimental measurements (TS squid=−36.3±2.5 dB), we were able to determine the minimum requirements for sperm whale sonar, i.e. range and directional hearing, to locate a single 24.5 cm long squid, considered to be (from stomach contents) the major size component of the sperm whale diet. Here, we present the development of the analysis which confirms that sperm whale usual clicks are appropriate to serve a mid-range sonar function, allowing this species to forage on individual organisms with low sound-reflectivity at ranges of several hundreds of metres.

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