Sperm whale abundance estimates from acoustic surveys of the Ionian Sea and Straits of Sicily in 2003

2007 ◽  
Vol 87 (1) ◽  
pp. 353-357 ◽  
Author(s):  
T. Lewis ◽  
D. Gillespie ◽  
C. Lacey ◽  
J. Matthews ◽  
M. Danbolt ◽  
...  
Keyword(s):  
Sperm Whale ◽  
Western Mediterranean ◽  
Small Sample ◽  
Line Transect ◽  
Ionian Sea ◽  
Sperm Whales ◽  
Detection Function ◽  
Abundance Estimate ◽  
Abundance Estimates ◽  
Acoustic Surveys

Acoustic surveys for sperm whales, using line-transect methodology, were carried out in the Ionian Sea and Straits of Sicily, Mediterranean Sea, in 2003. A total of 17 whales were detected along 3846 km of designed survey track in the Ionian Sea, and no whales along 892 km in the Straits of Sicily. This total was insufficient to estimate a detection function, so further data were obtained from quasi-random passages made elsewhere in the western Mediterranean in the same year. The encounters included several tight aggregations with inter-animal spacing less than 1 km, primarily from the western Mediterranean. Including individuals from these aggregations distorted the detection function due to the small sample sizes. No such aggregations were found during formal survey of the two areas of interest, and the aggregations were therefore excluded from detection function estimation. The resultant effective strip half-width was 10.0 km (n=40). On the assumption that g(0)=1, the resulting abundance estimates for the Ionian Sea were 62 (with 95% lognormal confidence limits of [24,165]), and 0 for the Straits of Sicily. The low abundance estimate for the Ionian Sea indicates that careful monitoring of the population is needed in the future. During passages along the Hellenic Trench, that were not part of the designed survey, several sperm whales including two aggregations were detected, suggesting that this may be a higher density area and ought to be considered as a separate stratum when designing future surveys.

scholarly journals Foraging dives of sperm whales in the north-western Mediterranean Sea

2012 ◽  
Vol 92 (8) ◽  
pp. 1799-1808 ◽  
Author(s):  
Alexandre Gannier ◽  
Estelle Petiau ◽  
Violaine Dulau ◽  
Luke Rendell
Keyword(s):  
Prey Capture ◽  
Sperm Whale ◽  
Western Mediterranean ◽  
Sperm Whales ◽  
The North ◽  
Western Mediterranean Sea ◽  
Single Animal ◽  
Components Analysis ◽  
Passive Acoustic ◽  
North Western

Oceanic odontocetes rely on echolocation to forage on pelagic or benthic prey, but their feeding ecology is difficult to study. We studied sperm whale foraging dives during summer in the north-western Mediterranean, using visual and passive acoustic observations. Clicking and creaking activities were recorded during dives of focal whales, at distances <3000 m using a towed hydrophone and DAT recorder. A total of 52 sperm whales were recorded over at least one full dive cycle. Data were obtained for 156 complete dives in total, including sequences of up to nine consecutive dives. Various dive and environmental variables were entered in multiple linear regression and principal components analysis, as well as estimated mass of whales. Creak rate was 0.80 creak/minute on average, with moderate variance. Bigger whales tended to dive longer at greater depths (as suggested by ascent durations), and emitted more creaks during a dive: 20.2 creaks/dive on average for individuals <24 tons, compared to 25.6 creaks/dive for animals >24 tons of estimated mass. For individual whales, creak rates did not vary significantly with size (range 0.78–0.80 creak/minute), but decreased with time of the day, and increased for shorter foraging phases. For different dives, higher creak rates were also observed earlier in the day, and linked to shorter foraging phases and surface durations. Although the exact significance of creak emissions (i.e. foraging attempt or prey capture) is not precisely determined, creak rates may be reliably used to quantify sperm whale foraging when single animal dives can be followed acoustically.

SST fronts and the summer sperm whale distribution in the north-west Mediterranean Sea

2007 ◽  
Vol 87 (1) ◽  
pp. 187-193 ◽  
Author(s):  
Alexandre Gannier ◽  
Emilie Praca
Keyword(s):  
Mediterranean Sea ◽  
Feeding Strategy ◽  
Sperm Whale ◽  
Western Mediterranean ◽  
Relative Distribution ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
The North ◽  
North Western ◽  
Sst Fronts

The relative distribution of sperm whales (Physeter macrocephalus) and sea surface temperature (SST) fronts have been studied in summer in the north-western Mediterranean Sea. We used passive acoustic data (778 samples) obtained offshore during dedicated surveys between 1999 and 2004 and Pathfinder/Modis remote sensing data to compute front maps and to calculate mean distances from sperm whale detections (N=132) to SST-fronts. Mean distances from sperm whale acoustic detections to SST-fronts were significantly lower (10.4 km) than from other acoustic samples to those fronts (17.0 km). The same result was obtained when calculating distances from sperm whales to the North Balearic Front surface signature. If sperm whales are commonly observed along the continental slope, we showed that offshore individuals were located close to SST-fronts. This bimodal distribution in the north-western Mediterranean is linked to sperm whale feeding strategy, demonstrating ecological opportunistic behaviour in this high level predator.

scholarly journals Trumpet sounds emitted by male sperm whales in the Mediterranean Sea

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
D. S. Pace ◽  
C. Lanfredi ◽  
S. Airoldi ◽  
G. Giacomini ◽  
M. Silvestri ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sperm Whale ◽  
Western Mediterranean ◽  
Sperm Whales ◽  
Acoustic Parameters ◽  
Photo Identification ◽  
Western Mediterranean Sea ◽  
Observation Area ◽  
Before And After ◽  
Area North

AbstractSperm whale trumpets are sounds only occasionally documented, with a well recognisable and stereotyped acoustic arrangement. This study investigated the acoustic features of the trumpets and the context in which these sounds were recorded, using acoustic data collected over 22 years, in the Pelagos Sanctuary area (North-Western Mediterranean Sea). Analysed trumpets (n = 230), recorded at the beginning of a dive after the whale fluke-up, comprised a series of acoustic units organized in short sequences. Acoustic parameters were derived for the entire trumpet and for each distinguishable unit in a trumpet. Overall, trumpet durations and their initial frequencies were higher in recordings collected when multiple whales were visually or acoustically detected in the observation area. The identity of 68 whales was assessed through photo-identification, with 29 individuals producing trumpets within and between years. The variability of the acoustic parameters appeared to be higher within the same individuals rather than between different individuals, suggesting an individual plasticity in composing and arranging units in a trumpet. Different click patterns were observed before and after the trumpets, with more complex sequences when (1) other whales were visually/acoustically detected, and (2) individuals were in suitable foraging sites (i.e., canyon areas). Trumpets were commonly followed or preceded by click patterns suited for communication, such as codas and/or slow clicks. Significant relations between the trumpet emission and the male-only long-range communication click pattern (i.e. slow clicks) emerged, supporting the hypothesis that a trumpet is a sound emitted by maturing/mature males in feeding grounds. This study provides the first evidence that trumpets were conserved in the sperm whale acoustic repertoire at the decadal timescale, persisting across years and individuals in the same area. This persistence may be functionally specific to foraging activities performed by males in a well-established feeding area.

scholarly journals A first acoustic density estimate for sperm whales in Irish offshore waters

2020 ◽  
Vol 21 (1) ◽  
pp. 123-133
Author(s):  
Jonathan Gordon ◽  
Douglas Gillespie ◽  
Russell Leaper ◽  
Arthur Lee ◽  
Lindsay Porter ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Weather Conditions ◽  
Sperm Whale ◽  
Oil And Gas Industry ◽  
Line Transect ◽  
Commercial Fishing ◽  
Sperm Whales ◽  
Density Estimates ◽  
Deep Diving ◽  
Target Motion Analysis

Previous studies off western Ireland have suggested that substantial numbers of, mainly male, sperm whales may be found in these habitats. Whaling vessels operating from shore stations in Ireland in the early 20th century frequently caught sperm whales in oceanic waters. It is likely that this North Atlantic region contains important foraging habitats for this species, and that mature males must also migrate through this area moving between breeding grounds to the south and other feeding areas further north. Increasingly, these offshore waters are being utilised and potentially impacted by human industrial activities. For example, as inshore resources are depleted and technology improves, both the commercial fishing and the oil and gas industry are becoming more active in deeper waters beyond the continental margin. It is important therefore to better understand the biology and ecology of sperm whales in these more remote areas. However, their offshore location and deep diving habits, together with weather constraints in the exposed Atlantic, make research difficult. New sperm whale density estimates are reported using data from six seasonal passiveacoustic surveys carried out in two successive years (2015 and 2016). These covered a corridor approximately 110km wide which bounded a major portion of Ireland’s continental shelf break. Towed hydrophone line-transect methodologies were used, which have proven to be highly effective for surveying sperm whales in offshore waters and in poor weather conditions. Target motion analysis was applied to calculate the ranges of vocalising whales from the survey tracklines and the effective strip half-width calculated across all surveys was 7,958m. The study area was surveyedin three blocks and animal densities within these blocks varied between 1 and 4.6 individuals per 1,000km2 (CV 0.34 and 0.21 respectively) with an overall mean density in waters deeper than 300m of 3.2 individuals per 1,000km2(CV 0.04). These robust density estimates are the first of their kind for Irish waters and are similar to those reported in other Atlantic areas considered significant for this species. These results emphasise the significance of this region as sperm whale habitat. The results of this study should be used to inform the future sustainable development and management of Ireland’s offshore Atlantic.

scholarly journals Combined line-transect and cue-count estimate of sperm whale abundance in the North Atlantic, from Icelandic NASS-2001 shipboard survey

2009 ◽  
Vol 7 ◽  
pp. 73
Author(s):  
Thorvaldur Gunnlaugsson ◽  
Gisli A Víkingsson ◽  
Daniel G Pike
Keyword(s):  
North Atlantic ◽  
Sperm Whale ◽  
Line Transect ◽  
Physeter Macrocephalus ◽  
Preliminary Estimate ◽  
Sperm Whales ◽  
Deep Dive ◽  
The North ◽  
Surface Time ◽  
Track Line

Sperm whales (Physeter macrocephalus) pose a particular problem to shipboard surveys as they dive for extended periods and are therefore likely to be missed (not available) even if they are right under the track line. To address these problems the NAMMCO planning committee for the NASS 2001 survey drew up guidelines to be followed when sperm whales were sighted. This required every deep dive to be recorded and considered to be a cue, from which a cue-count estimate is calculated if the cue rate is known. For those whales that did not dive before coming abeam, a conventional line-transect estimate is calculated, which gives an instantaneous surface estimate from which a total estimate can be obtained if the proportion of the time spent at the surface is known. These estimates are compared and combined. Precise dive cycle information is missing for the mostly single all male sperm whales in this area but a preliminary estimate of 11,185 (cv 0.34) is obtained for the surveyed area with an assumed surface time of 20% and two deep dives per hour.

A robust baseline for bottlenose dolphin abundance in coastal Moreton Bay: a large carnivore living in a region of escalating anthropogenic impacts

2008 ◽  
Vol 35 (7) ◽  
pp. 593 ◽  
Author(s):  
Vimoksalehi Lukoschek ◽  
B. Louise Chilvers
Keyword(s):  
Bottlenose Dolphin ◽  
Anthropogenic Impacts ◽  
Bottlenose Dolphins ◽  
Estimation Methods ◽  
Line Transect ◽  
Mark Recapture ◽  
Abundance Estimate ◽  
Photo Identification ◽  
Moreton Bay ◽  
Abundance Estimates

Marine megafauna populations in coastal waters are increasingly threatened by anthropogenic impacts. Moreton Bay, a large embayment in south-east Queensland, lies adjacent to one of the fastest growing regions in Australia and has a resident population of bottlenose dolphins, Tursiops aduncus. Evaluation of the effectiveness of any proposed management strategy requires robust population abundance estimates. We estimated abundances of bottlenose dolphins in central eastern Moreton Bay (350 km2) using two commonly used abundance estimation methods for cetaceans: photo-identification mark–recapture and line-transect surveys. Mark–recapture data were analysed in CAPTURE using a model that allowed capture probabilities to vary between sampling events and between individuals. Based on an estimated 76% of the population identifiable photographically, total abundance estimates were 673 ± 130 s.e. (1997) and 818 ± 152 s.e. (1998). Line-transect data, analysed using DISTANCE, gave an abundance estimate of 407 ± 113.5 s.e. (2000). These abundance estimates are large compared with many other coastal bottlenose dolphin populations. The line-transect surveys comprised a pilot study, and the lower line-transect abundance estimate is probably best attributable to methodological issues. In particular, smaller mean group size was estimated for the line-transects surveys (2.85 ± 0.29 s.e.) than the mark–recapture surveys (4.87 ± 0.39 s.e., 1997; 5.78 ± 0.73 s.e., 1998), and line-transect group sizes were probably underestimated. In addition, the line-transect detection probability (g(o)) was assumed to be one but was almost certainly less than one. However, the possibility of an actual decline in population size cannot be ruled out. Coefficients of variation (CV) were lower for mark–recapture than for line-transect surveys, however, CVs of line-transect estimates could be lowered through improved survey design. We evaluated the power of these surveys to detect trends in potential population declines for bottlenose dolphins in Moreton Bay and make recommendations for ongoing monitoring strategies.

Stomach contents of a sperm whale (Physeter macrocephalus) stranded in Italy (Ligurian Sea, north-western Mediterranean)

2013 ◽  
Vol 94 (6) ◽  
pp. 1087-1091 ◽  
Author(s):  
Fulvio Garibaldi ◽  
Michela Podestà
Keyword(s):  
Stomach Contents ◽  
Sperm Whale ◽  
Western Mediterranean ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Western Basin ◽  
Ligurian Sea ◽  
Beak Size ◽  
Species Specific ◽  
Available Information

The stomach contents of a male sperm whale, Physeter macrocephalus, stranded on Forte dei Marmi beach (Italy, Ligurian Sea) were examined. Food items consisted exclusively of cephalopod hard parts: 233 upper and 291 lower beaks and one fish eye lens. The majority of the identified cephalopod beaks belonged to Histioteuthis bonnellii, but a few beaks of Galiteuthis armata and Octopoteuthis sp. were also found. A new beak size–cephalopod size regression was created for H. bonnellii with specimens caught in the study area. Reconstructed prey weight for the species was much higher when applying this new regression instead of Clarke's, highlighting the need for area- and species-specific regressions for dietary studies. Our analysis represents the second report on the stomach contents of sperm whales from the Mediterranean and the first available information for the Western basin.

Current status of Odontocetes in the Antarctic

1995 ◽  
Vol 7 (4) ◽  
pp. 365-379 ◽  
Author(s):  
Fujio Kasamatsu ◽  
Gerald G. Joyce
Keyword(s):  
Sperm Whale ◽  
Current Status ◽  
Line Transect ◽  
Sperm Whales ◽  
Killer Whales ◽  
Northern Regions ◽  
Beaked Whales ◽  
Pilot Whales ◽  
Using Data ◽  
The Antarctic

The current status of Antarctic Odontocetes – sperm whales Physeter catodon, killer whales Orcinus orca, long-finned pilot whales Globicephala melaena, hourglass dolphins Lagenorhynchus cruciger and poorly known species of beaked whales (family Ziphiidae)–were studied in Anatarctic waters using data gathered in sighting surveys conducted from 1976/77 to 1987/88. Temporal variation in density demonstrated the different migration patterns by species, especially between sperm whale and killer whale. Spatial distributions during mid-summer demonstrated different peaks of occurrence for each species by latitude that suggest possible segregation between the species. Killer whales occur mainly in the very southernmost areas, sperm whales in the southern half of the study area, beaked whales (mostly southern bottlenose whales Hyperoodon planifrons) ranged over a wide area, and long-finned pilot whales and hourglass dolphins were mainly in the northern regions of Antarctic waters. Several longitudinal peaks of occurrence and apparent distribution gaps were identified for sperm, beaked and killer whales. Abundance estimates for south of the Antarctic Convergence in January are based on line transect theory and were 28 100 animals (coefficient of variation CV 0.18) sperm whales, 599 300 (0.15) beaked whales (mostly southern bottlenose whales), 80 400 (0.15) killer whales, 200 000 (0.35) long-finned pilot whales, and 144 300 (0.17) hourglass dolphins. Based on this, biomass of these species were estimated as 0.77 (sperm whales), 2.70 (beaked whales), 0.32 (killer whales), 0.16 (long-finned pilot whales) and 0.01 (hourglass dolphins) million tonnes. Consumption of food (mostly squid) by the Odontocetes is estimated as 14.4 million tonnes with 67% of the total consumed by beaked whales. Indirect consumption of Antarctic krill through the predation of squid by beaked whales is estimated to be c. 24 million tonnes. This value is similar to the estimate of krill consumption by penguins in the Antarctic (33 million tonnes). Odontocetes, especially southern bottlenose whales, are suggested to have a much greater role in the Antarctic ecosystem than has previously been considered.

scholarly journals The long-range echo scene of the sperm whale biosonar

2020 ◽  
Vol 16 (8) ◽  
pp. 20200134
Author(s):  
Pernille Tønnesen ◽  
Cláudia Oliveira ◽  
Mark Johnson ◽  
Peter Teglberg Madsen
Keyword(s):  
Long Range ◽  
Prey Selection ◽  
Sperm Whale ◽  
Depth Interval ◽  
Encounter Rate ◽  
Sperm Whales ◽  
Detection Function ◽  
Prey Location ◽  
Large Predators ◽  
Selection Of

Sperm whales use their gigantic nose to produce the most powerful sounds in the animal kingdom, presumably to echolocate deep-sea prey at long ranges and possibly to debilitate prey. To test these hypotheses, we deployed sound recording tags (DTAG-4) on the tip of the nose of three sperm whales. One of these recordings yielded over 6000 echo streams from organisms detected up to 144 m ahead of the whale, supporting a long-range prey detection function of the sperm whale biosonar. The whale navigated this complex acoustic scene by maintaining a stable, long-range acoustic gaze suggesting continual resource evaluation. Less than 10% of the echoic organisms recorded by the tag were targeted for capture and only 18% of the buzzes were emitted within the 50 m depth interval of maximum organism encounter rate, demonstrating echo-guided prey selection. Buzzes were initiated more than 20 m from the prey, showing that sperm whales do not debilitate their prey with sound, but trade echo levels for reduced forward masking and rapid updates on prey location in keeping with the lower manoeuvrability of these large predators. We conclude that the powerful biosonar of sperm whales enables long-range echolocation and selection of prey, but not acoustic debilitation.

scholarly journals Sperm whale presence observed using passive acoustic monitoring from gliders of opportunity

2020 ◽  
Vol 42 ◽  
pp. 133-149 ◽  
Author(s):  
P Cauchy ◽  
KJ Heywood ◽  
D Risch ◽  
ND Merchant ◽  
BY Queste ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sperm Whale ◽  
Acoustic Monitoring ◽  
Western Mediterranean ◽  
Sperm Whales ◽  
Passive Acoustic Monitoring ◽  
The North ◽  
Western Mediterranean Sea ◽  
Passive Acoustic ◽  
North Western

Habitat use by the endangered Mediterranean sperm whale subpopulation remains poorly understood, especially in winter. The sustained presence of oceanographic autonomous underwater vehicles in the area presents an opportunity to improve observation effort, enabling collection of valuable sperm whale distribution data, which may be crucial to their conservation. Passive acoustic monitoring loggers were deployed on vertically profiling oceanographic gliders surveying the north-western Mediterranean Sea during winter 2012-2013 and June 2014. Sperm whale echolocation ‘usual click’ trains, characteristic of foraging activity, were detected and classified from the recordings, providing information about the presence of sperm whales along the glider tracks. Widespread presence of sperm whales in the north-western Mediterranean Sea was confirmed. Winter observations suggest different foraging strategies between the Ligurian Sea, where mobile and scattered individuals forage at all times of day, and the Gulf of Lion, where larger aggregations target intense oceanographic features in the open ocean such as fronts and mixing events, with reduced acoustic presence at dawn. This study demonstrates the ability to successfully observe sperm whale behaviour from passive acoustic monitoring gliders. We identified possible mission design changes to optimize data collected from passive acoustic monitoring glider surveys and significantly improve sperm whale population monitoring and habitat use.

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