Dorsal fin scars as indicators of age, sex, and social status in humpback whales (Megaptera novaeangliae)

We compared the number of linear marks and the shapes of dorsal fins of different classes of humpback whales during the breeding season. Male humpbacks tend to have more marks than females. Such marks are probably scars resulting from physical contact during intrasexual competition for mates. Not all males have marks; therefore, an unmarked adult humpback could be a male or a female. An adult with many marks is likely a male, however. Differences in the dorsal fins of principal and secondary escorts in large groups of competing males suggest that not all escorts have the same chance of attaining principal escort status. Therefore, male – male competitions in large groups should not necessarily be viewed as contests between equals. Principal escorts showed significantly more of some types of marks than did lone escorts of cows with calves, suggesting that not all lone escorts may retain their position if challenged.

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Possible Sexing Technique for Humpback Whales (Megaptera novaeangliae)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f80-284 ◽

1980 ◽

Vol 37 (12) ◽

pp. 2362-2364 ◽

Cited By ~ 2

Author(s):

V. P. Jurasz ◽

D. McSweeney ◽

C. M. Jurasz

Keyword(s):

Morphological Feature ◽

Megaptera Novaeangliae ◽

Pregnant Female ◽

Humpback Whales ◽

Reasonable Accuracy ◽

Southeast Alaska ◽

Dorsal Fin ◽

Breeding Grounds

By comparing photographs of humpback whales (Megaptera novaeangliae) photographed at the peak of their arch during a dive, we found some to be smooth and others to be scalloped middorsally caudal to the dorsal fin. Out of 410 photographs taken in southeast Alaska and Hawaii, 66% were found to be smooth and 34% scalloped. All females with calves were smooth. One pregnant female was smooth and only one female who was pregnant was slightly scalloped. One known male was scalloped and one "singer" on the Hawaiian breeding grounds was scalloped. We suggest that the smoothness or scalloping of this region is a morphological feature and can be used with reasonable accuracy to determine sex in humpback whales.Key words: humpback whales, morphology, sex

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Interspecific cetacean interactions during the breeding season of humpback whale (Megaptera novaeangliae) on the north coast of Bahia State, Brazil

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315409000897 ◽

2009 ◽

Vol 89 (5) ◽

pp. 961-966 ◽

Cited By ~ 6

Author(s):

Marcos R. Rossi-Santos ◽

Elitieri Santos-Neto ◽

Clarêncio G. Baracho

Keyword(s):

Breeding Season ◽

Megaptera Novaeangliae ◽

Humpback Whales ◽

North Coast ◽

Balaenoptera Acutorostrata ◽

Cetacean Species ◽

The North ◽

Eastern Brazil ◽

North Eastern ◽

Stenella Attenuata

The large majority of cetacean interspecific studies report only on dolphin interactions, while studies on interactions between odontocete and mysticete are less common. The present work aims to report on sightings of cetacean interactions, during the breeding season of humpback whales(Megaptera novaeangliae), along 370 km of the Bahia State, north-eastern Brazil, addressing aspects of cetacean distribution and behaviour. During 7 seasons (2000–2006), a total of 230 research cruises were performed, in which 38 events of interactions among humpback whales and other cetaceans(Tursiops truncatus, Steno bredanensis, Peponocephala electraandBalaenoptera acutorostrata)were observed, plus another 5 encounters without the whale's presence, includingT. truncatus, S. bredanensis, P. electra, Stenella clymeneandStenella attenuata. Our results confirm the occurrence of multiple cetacean species in the Bahia State, being the first study in the world to report on a large range of interactions involving another 4 cetacean species, grouped with up to 3 mixed species per sighting, with humpback whales in their annual breeding ground.

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Shark scavenging and predation on cetaceans at Abrolhos Bank, eastern Brazil

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315412001154 ◽

2012 ◽

Vol 92 (8) ◽

pp. 1767-1772 ◽

Cited By ~ 13

Author(s):

Hugo Bornatowski ◽

Leonardo L. Wedekin ◽

Michael R. Heithaus ◽

Milton César C. Marcondes ◽

Marcos R. Rossi-Santos

Keyword(s):

Predation Risk ◽

Breeding Season ◽

Megaptera Novaeangliae ◽

Humpback Whales ◽

Eastern Coast ◽

Shark Species ◽

Bite Marks ◽

Eastern Brazil ◽

Shark Attacks ◽

Cookiecutter Shark

Although it is largely assumed that shark predation and predation risk are unimportant to large cetaceans, whales can make up large portions of the diets of some shark species. We investigated interactions between sharks and cetaceans in the Abrolhos Bank (16°40′ to 19°40′S), off the eastern coast of Brazil, including scavenging and predation attempts on living humpback whales (Megaptera novaeangliae). In order to determine the frequency of shark bites on cetaceans, both living and postmortem, we used carcasses discovered along the coast of Abrolhos Bank between 2001 and 2010 and photographs of living cetaceans during systematic and opportunistic visual surveys from 2004 to 2009. We analysed a total of 221 cetacean carcasses, of which 150 (67.8%) were humpback whales. Large sharks had fed on 22.3% (35 of 150) of humpback whales carcasses, and 20.8% (10 of 48) of carcasses of other species. Only three living humpback whales (<1%) had bite scars from large sharks, suggesting that they at least occasionally target living humpbacks. Cookiecutter shark bite marks also were observed on both dead and living cetaceans, with numerous living humpbacks showing multiple bites. The abundance of humpback whale carcasses available over the Abrolhos Bank, mainly during the humpback breeding season, may be an important component of shark diets seasonally. Further work is needed to better understand the frequency of shark attacks on mysticetes, potential costs of sublethal injuries, and importance of whales to shark diets.

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Photo-identification of individual Southern Hemisphere humpback whales (Megaptera novaeangliae) using all available natural marks:

J. Cetacean Res. Manage. ◽

10.47536/jcrm.v21i1.186 ◽

2020 ◽

Vol 21 (1) ◽

pp. 71-83

Author(s):

Wally Franklin ◽

Trish Franklin ◽

Peter Harrison ◽

Lyndon Brooks

Keyword(s):

Poor Quality ◽

Megaptera Novaeangliae ◽

Humpback Whales ◽

Parameter Estimates ◽

Photo Identification ◽

Dorsal Fin ◽

Matching Process ◽

Lateral Body ◽

Logistic Mixed Effects Model ◽

Natural Marks

Misidentification errors in capture-mark recapture studies of humpback whales (Megaptera novaeangliae) related to poor quality of photographs as well as changes in natural marks can seriously affect population dynamics parameter estimates and derived estimates of population size when using sophisticated modelling techniques. In this study we used an innovative photo-identification matching system to investigate and examine the long-term stability and/or changes in natural marks on ventral-tail flukes, dorsal fin shapes and lateral body marks from a sample of 79 individual humpback whales, resighted in 2 to 11 years over timespans ranging from 2 to 21 years. A binary logistic mixed effects model, on a pair-matched sample of the 79 individual whales, found no significant differences in the proportions of ventral-tail fluke marks, dorsal fin shapes and lateral body marks, that displayed changes in primary and/or secondary characteristics over years (F=0.939, df=1/156, p =0.334). The results of this study substantiate the value and reliability of using primary and secondary natural marks on the ventral-tail flukes, in conjunction with dorsal fin shapes and secondary lateral body marks as double-tags. This provides a means of maximising observations of individual humpback whales over years, while minimising and managing misidentification errors in the photo-identification matching process, thus significantly improving modelling outcomes.

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Segregation by humpback whale (Megaptera novaeangliae) cows with a calf in coastal habitat near the island of Hawaii

Canadian Journal of Zoology ◽

10.1139/z94-109 ◽

1994 ◽

Vol 72 (5) ◽

pp. 805-811 ◽

Cited By ~ 58

Author(s):

Mari A. Smultea

Keyword(s):

Breeding Season ◽

Deep Sea ◽

Megaptera Novaeangliae ◽

Humpback Whales ◽

Sexually Active ◽

Breeding Behavior ◽

Coastal Habitat ◽

Use Patterns ◽

Related Development ◽

Temporal And Spatial

Humpback whales (Megaptera novaeangliae) were tracked from shore to determine habitat-use patterns in an area relatively undisturbed by human activity near the "Big Island" of Hawaii during the winter 1988 and 1989 calving seasons. The temporal and spatial distributions of whales differed with group size and composition. During afternoon hours, groups containing a calf occurred in water significantly shallower and nearer to shore than did groups without a calf. Late in the breeding season, the same segregation pattern occurred throughout the day. Between-groups distances were significantly greater for groups with a calf than distances between all other groups. The number of whales observed per hour peaked during mid-February, although the relative sighting rates for various group sizes and compositions varied across the breeding season. Adults without a calf may use deep water to facilitate breeding behavior, while maternal females may use shallower water to avoid harassment and injury to calves from sexually active males, turbulent offshore or deep sea conditions, or predators. The predominance of cows with a calf in coastal habitat increases their exposure to expanding human-related development and aquatic activities that could injure, disturb, or displace them.

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Temporal pattern of humpback whale (Megaptera novaeangliae) group structure around Abrolhos Archipelago breeding region, Bahia, Brazil

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315407054616 ◽

2007 ◽

Vol 87 (1) ◽

pp. 87-92 ◽

Cited By ~ 21

Author(s):

Maria E. Morete ◽

Tatiana L. Bisi ◽

Sergio Rosso

Keyword(s):

Social Status ◽

Temporal Pattern ◽

Group Composition ◽

Group Structure ◽

Temporal Patterns ◽

Humpback Whale ◽

Megaptera Novaeangliae ◽

Humpback Whales ◽

Migration Patterns ◽

The Social

To characterize temporal patterns of humpback group structure around Abrolhos Archipelago, Brazil, seven years (1998–2004) of data obtained from July through November were analysed. During one-hour scans, observers determined group composition within 9.3 km around a land-based station. A total of 930 scans, comprising 4288 groups were analysed. Seven group categories were identified and their frequencies were 14.6% of 1AD (lone whale), 25.2% of DYAD (two adult whales), 7.3% of TRIO (three adult whales), 5.2 of TRIO+ (more than three adults), 24.9% of MOC (mother and calf), 19.6% of MOCE (mother, calf and one escort), and 3.1% of MOCE+ (mother, calf and more than one escort). Proportions of whale-group categories did not change between morning and afternoon, nor among years. However, as the season progressed, groups with calves increased while groups without calves decreased. This progression may be explained by the segregated migration patterns of humpback whales and also by changes in the social status of individuals. The Abrolhos Reef provides protection from the prevailing winds, which may explain the higher proportion of groups with calves in the area.

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