Comparison of Two Computer-Assisted Photo-Identification Methods Applied to Sperm Whales (Physeter macrocephalus)

2005 ◽  
Vol 31 (2) ◽  
pp. 243-247 ◽  
Author(s):  
Bas W. P. M. Beekmans ◽  
Hal Whitehead ◽  
Ruben Huele ◽  
Lisa Steiner ◽  
Adri G. Steenbeek
PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244204
Author(s):  
Hayao Kobayashi ◽  
Hal Whitehead ◽  
Masao Amano

Little is known about the social structure of male sperm whales (Physeter macrocephalus) after they leave their natal units. While previous studies found no evidence for preferred associations among males, the observation of mass-strandings consisting exclusively of males, suggest that they have strong social bonds. To investigate the social associations among male sperm whales, we used half weight index of association, permutation tests and standardized lagged association rate models on a large photo-identification database collected between 2006 and 2017 in Nemuro Strait, Japan. Our results suggest that while male sperm whales are not as social as females, they do form long term associations, have preferred companionship, and forage in social proximity to each other. The best-fitting model to the standardized lagged association rate showed that associations among males last for at least 2.7 years and as most males leave the area after 2 years, associations may last for longer. Twenty dyads were observed associating over more than 2 years, for a maximum 5 years. One dyad was observed associating on 19 different days and clustered on 7 different days. Male associations may function to enhance foraging or to fend off predators. Such relationships seem to be adapted to a pelagic habitat with uncertain resource availability and predation pressure.


Author(s):  
Caroline R Weir ◽  
Tim Collins ◽  
Inês Carvalho ◽  
Howard C. Rosenbaum

Killer whales Orcinus orca are considered to be relatively uncommon in tropical waters. Few sightings have been reported from the west coast of Africa due to a paucity of survey coverage. We present data on 32 killer sightings from tropical waters off Angola (N = 18), Gabon (N = 7), São Tomé (N = 6) and Cameroon (N = 1), comprising a combination of dedicated survey sightings (N = 21) and reliable anecdotal records (n = 11). Killer whales were reported from coastal waters, the shelf edge and deep, oceanic areas. Sightings indicate a probable year-round occurrence of killer whales within the region. Mean group size was 5.6 animals. There was no difference in group size between sightings in waters >200 m deep and those on the continental shelf. No photo-identification matches were found between Angola, Gabon and São Tomé. Re-sightings of two individuals occurred annually in São Tomé during 2002–2004. Killer whales had external appearance consistent with the Type A nominate species form. Antagonistic encounters were recorded between killer whales and humpback whales Megaptera novaeangliae off Angola, Gabon and Cameroon, and with sperm whales Physeter macrocephalus off Angola. Predation on ocean sunfish Mola mola was recorded in São Tomé, and possible predation on sharks was recorded twice in Gabon.


Author(s):  
Lisa Steiner ◽  
Luca Lamoni ◽  
Marta Acosta Plata ◽  
Silje-Kristin Jensen ◽  
Erland Lettevall ◽  
...  

Little is known about the movements of male sperm whales, Physeter macrocephalus, in the North Atlantic. Recoveries of traditional harpoons and tags during commercial whaling indicated movements from Nova Scotia to Spain and from the Azores to Iceland and Spain. We compared collections of photo-identification images from different areas using the North Atlantic and Mediterranean Sperm Whale Catalogue and the Eurphlukes Phlex/Match programs. The largest collections of identified males (number of individuals, start and end date for data collection shown in parentheses) are for the Azores (297, 1987–2008), Andenes (375, 1988–1996 and 2008), Tromsø (84, 2005–2008). There were six matches between Andenes and Tromsø (~25 nm), with three of these re-sighted in multiple years and three photo-identification matches from the Azores to Norway (~2400 nm). In all cases individuals first photographed in the Azores (in 1993, 1999 and 2003) were matched to images collected later in Tromsø (in 2007 and 2008). In 1997 a photo-identification image from Andenes matched a male stranded on the west coast of Ireland. No matches were made to images in smaller collections from Iceland, Nova Scotia, Greenland, Dominica, Guadeloupe, Gulf of Mexico and the Mediterranean. These findings show the value of data collected from whale watching vessels and the importance of collaboration between groups to allow investigation on an ocean basin scale. It is hoped that with the coordinated collection of more images from around the Atlantic, further insight might be gained into the movements of these widely ranging animals.


2021 ◽  
Author(s):  
JASON Holmberg ◽  
Shane Gero ◽  
Andrew Blount ◽  
Jason Parham ◽  
jacob Levenson

Photo-identification of individual sperm whales (Physeter macrocephalus) is the primary technique for mark-recapture-based population analyses for the species The visual appearance of the fluke - with its distinct nicks and notches - often serves as the primary visual differentiator, allowing humans to make recorded sightings of specific individuals. However, the advent of digital photography and the significant increase in volume of images from multiple projects in combination with pre-existing historical catalogs has made applying the method more challenging.with the required human labor for de-duplication (reduction of Type II errors) and reconciliation of sightings between large datasets too cost- and time- prohibitive. To address this, we trained and evaluated the accuracy of PIE v2 (a triplet loss network) along with two existing fluke trailing edge-matching algorithms, CurvRank v2 and Dynamic Time Warping (DTW), as a mean to speed comparison among a high volume of photographs. Analyzed data were collected from a curated catalog of well-known sperm whales sighted across years (2005-2018) off the island of Dominica. The newly-trained PIE model outperformed the older CurvRank and DTW algorithms, and PIE provided the following top-k individual ID matching accuracy on a standard min-3/max-10 sighting training data set: Rank-1: 87.0%, Rank-5: 90.5%, and Rank-12: 92.5%. An essential aspect of PIE is that it can learn new individuals without network retraining, which can be immediately applied in the presence of (and for the resolution of) duplicate individuals in overlapping catalogs. Overall, our results recommend the use of PIE v2 and CurvRank v2 for ID reconciliation in combination due to their complementary performance.


2021 ◽  
Author(s):  
Usua Oyarbide ◽  
Laura Joan Feyrer ◽  
Jonathan Gordon

Interactions between various cetacean species and fisheries are geographically widespread and diverse. Foraging in association with fishing activities may increase prey encounter rates and possibly increase the quantity and the quality of the food consumed. This paper describes interactions between benthic trawlers, targeting mainly Greenland halibut, and two whale species: sperm whales and northern bottlenose whales, in the eastern Grand Banks of the northwest Atlantic. Whale behaviors were compared during four trawling-related activities: preparing/ shooting the net, towing, hauling and transiting between fishing sites. Sperm whales and bottlenose whales were more likely to be observed during hauling. We observed probable feeding behavior of both species close to the surface at the end of hauling which suggests they are taking fish escaping from the cod end of the net when it is close to the surface. It is not clear whether feeding attempts are made during other phases of the trawling cycle. Ten sperm whales were photo-identified and six of these individuals were resighted on different days. Resights of individuals indicated that sperm whales could follow trawlers through several sets over of distances up to 234 km. While some individuals were observed to move between fishing grounds others remained within one fishing area for some time. By contrast, even though twenty-three bottlenose whales were photo-identified, there were no resights of individual whales. While northern bottlenose whales have been studied quite extensively in some adjacent areas, particularly off Nova Scotia, their behaviour and distribution within the Grand Banks fishing areas has not been well described. No matches were found between northern bottlenose whales in this study and photo-identification catalogues for the Scotian Shelf or the Arctic. Whether and how northern bottlenose whales found in this area are connected to other subpopulations remains unclear.


2022 ◽  
Vol 48 (1) ◽  
pp. 3-8
Author(s):  
Keith D. Mullin ◽  
Lisa Steiner ◽  
Charlotte Dunn ◽  
Diane Claridge ◽  
Laura González García ◽  
...  

2021 ◽  
Author(s):  
Sarano Véronique ◽  
Sarano François ◽  
Girardet Justine ◽  
Preud’homme Axel ◽  
Vitry Hugues ◽  
...  

ABSTRACTThe long-term monitoring of long-lived animal populations often requires individual identification. For cetacean populations, this identification is mostly based on morphological characters observable from a boat such as shape, spots and cuts of the back, caudal and dorsal fins. This is well suited for species easily displaying their caudal fins, such as the humpback whales Megaptera novaeangliae, or those whose skin pigmentation patterns enable individual identification.However, for elusive or shier species such as the sperm whales Physeter macrocephalus, this approach may be more challenging as individuals display a rather uniform skin pigmentation. They also do not show very often their caudal fin that must be photographed perpendicularly to the water surface, vertically and fully emerged, uneasing the individual identification from a boat. Immature sperm whales that usually have a caudal fin without any distinctive marks may sometimes be excluded from photo-identification catalogues.Within the framework of the Maubydick project, focusing on the long-term monitoring of sperm whales in Mauritius, passive underwater observation and video recording were used to identify long-lasting body markers (e.g., sex, ventral white markings, cut outs of fins) to improve individual identification. A catalogue of individual identity cards was developed and 38 individuals were recorded (six adult males, 18 adult females and 14 immatures). This catalogue was used in the field and enabled observers to record some nearly-daily and yearly recaptures. Advantages and disadvantages of this method are presented here.Such catalogues represent a robust baseline for conducting behavioural, genetic and acoustic studies in marine megafauna social species. Benefits of such newly acquired knowledge are of first importance to implement relevant conservation plans in the marine realm.


2003 ◽  
Vol 29 (1) ◽  
pp. 117-123 ◽  
Author(s):  
G. R. Hillman ◽  
B. Würsig ◽  
G. A. Gailey ◽  
N. Kehtarnavaz ◽  
A. Drobyshevsky ◽  
...  

2021 ◽  
Vol 9 (4) ◽  
pp. 444
Author(s):  
Charlotte Curé ◽  
Saana Isojunno ◽  
Marije L. Siemensma ◽  
Paul J. Wensveen ◽  
Célia Buisson ◽  
...  

Controlled exposure experiments (CEEs) have demonstrated that naval pulsed active sonar (PAS) can induce costly behavioral responses in cetaceans similar to antipredator responses. New generation continuous active sonars (CAS) emit lower amplitude levels but more continuous signals. We conducted CEEs with PAS, CAS and no-sonar control on free-ranging sperm whales in Norway. Two panels blind to experimental conditions concurrently inspected acoustic-and-movement-tag data and visual observations of tagged whales and used an established severity scale (0–9) to assign scores to putative responses. Only half of the exposures elicited a response, indicating overall low responsiveness in sperm whales. Responding whales (10 of 12) showed more, and more severe responses to sonar compared to no-sonar. Moreover, the probability of response increased when whales were previously exposed to presence of predatory and/or competing killer or long-finned pilot whales. Various behavioral change types occurred over a broad range of severities (1–6) during CAS and PAS. When combining all behavioral types, the proportion of responses to CAS was significantly higher than no-sonar but not different from PAS. Responses potentially impacting vital rates i.e., with severity ≥4, were initiated at received cumulative sound exposure levels (dB re 1 μPa2 s) of 137–177 during CAS and 143–181 during PAS.


1988 ◽  
Vol 45 (10) ◽  
pp. 1736-1743 ◽  
Author(s):  
Julia Mullins ◽  
Hal Whitehead ◽  
Linda S. Weilgart

During June 1986, two male sperm whales, Physeter macrocephalus, on the Scotian Shelf were tracked by listening for their clicks with a directional hydrophone for periods of 12.5 and 7 h, respectively. Each whale travelled along the edge of the shelf at about 2 kn (3.6 km/h), and one whale, on two occasions at least, dived to the ocean floor. After about 30 min underwater, the whales spent approximately 9 min at the surface breathing. When the whales were visible at the surface, they were silent, except on one occasion when "slow clicking" (mean interclick interval of 4.6 s) was heard from Whale 2. While underwater, most of the sound production consisted of "usual clicks" (mean interclick interval 0.96 and 0.69 s for the two whales) interrupted by frequent short silences (mean durations 21.06 and 27.82 s) and occasional "creaks" (with interclick intervals less than 0.2 s) and "slow clicks." No "codas" (stereotyped patterns of clicks) were heard from these two single whales. These results are consistent with the hypotheses that "usual clicks" and "creaks" are used for echolocation and "codas" for communication.


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