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

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

Canadian Journal of Zoology ◽

10.1139/z88-059 ◽

1988 ◽

Vol 66 (2) ◽

pp. 416-420 ◽

Cited By ~ 11

Author(s):

Kevin Chu ◽

Sharon Nieukirk

Keyword(s):

Social Status ◽

Breeding Season ◽

Intrasexual Competition ◽

Megaptera Novaeangliae ◽

Physical Contact ◽

Humpback Whales ◽

Dorsal Fin ◽

Large Groups

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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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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A STOP FOR A SNACK: apparent humpback whale (Megaptera novaeangliae) feeding behavior and association with gillnets during migration off south-eastern Brazil

Boletim do Laboratório de Hidrobiologia ◽

10.18764/1981-6421e2019.6 ◽

2019 ◽

Vol 29 (1) ◽

Author(s):

Salvatore Siciliano ◽

Júlio Cardoso ◽

Arlaine Francisco ◽

Sérgio Carvalho Moreira

Keyword(s):

Humpback Whale ◽

Megaptera Novaeangliae ◽

Humpback Whales ◽

Southeastern Brazil ◽

Brazilian Coast ◽

Tropical Regions ◽

Eastern Brazil ◽

Breeding Grounds ◽

Migratory Period

Baleias-jubarte (Megaptera novaeangliae) migram anualmente desde as águas frias dos polos, onde alimentam-se de krill e pequenos peixes, em direção a regiões tropicais e subtropicais em busca de ambientes favoráveis para reprodução e cria de filhotes. Ainda pouco conhecidos são os casos de baleias-jubarte alimentando-se em áreas de reprodução. Nesse trabalho relatamos as primeiras observações em campo de uma baleia juvenil – yearling, em provável comportamento de forrageamento buscando por prováveis crustáceos ou cefalópodes em curtos mergulhos fundos. São relatadas outras observações semelhantes nas quais das baleias pareciam aproximar-se de redes de emalhe, provavelmente atraídas por peixes ali enredados e disponíveis. Considera-se que em alguns desses casos a aproximação das baleias em direção às redes tenha causado emalhamentos, que pelo menos em um caso o exemplar libertou-se das redes. Em outros casos as redes podem ter causados ferimentos e lesões nas baleias-jubarte. Recomenda-se um acompanhamento dessas interações pela costa brasileira a longo prazo para uma melhor avaliação dessas interações.Palavras-chave: Baleia-jubarte; Enredamento; Forrageamento; Brasil.ABSTRACTHumpback whales (Megaptera novaeangliae) migrate annually from the cold waters of the poles, where they feed on krill, towards subtropical and tropical regions in search of favorable environments for breeding and calving. Cases of humpback whales feeding on breeding grounds are still poorly known in the world. This study reports field observations of a juvenile whale - yearling, in Brazilian waters, with evidence of foraging behavior, in search of prey that seemed to be prawn or squid, during short dives. In addition, other similar observations are reported in southeastern Brazil in which the whales showed interest and approach gillnets, probably attracted by entangled fish. In some of these cases, it is considered that whale approaching towards the nets has caused entanglements, and in at least one case the specimen freed itself from nets. In other cases, nets may have caused humpback whale injuries. A follow-up of these interactions throughout the Brazilian coast is recommendedfor a better evaluation of these interactions with fishing nets, since they may represent a new form of behavior of these whales in their migratory period.

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Humpback whales, Megaptera novaeangliae (Cetaceaa : Balaenopteridae), in Hervey Bay, Queensland .

Wildlife Research ◽

10.1071/wr9940293 ◽

1994 ◽

Vol 21 (3) ◽

pp. 293 ◽

Cited By ~ 20

Author(s):

PJ Corkeron ◽

M Brown ◽

RW Slade ◽

MM Bryden

Keyword(s):

Megaptera Novaeangliae ◽

Humpback Whales ◽

Eastern Coast ◽

Western Coast ◽

Photo Identification ◽

Breeding Grounds ◽

Pass Through ◽

The Antarctic ◽

The Impact ◽

Final Cohort

Humpback whales, Megaptera novaeangliae, of the Antarctic Area V stock, pass through Hervey Bay, Queensland, during their southward migration. As part of an investigation of the impact of commercial whalewatching in the bay, aerial surveys were conducted during the 1988-90 whalewatching seasons, and a photo-identification project was run over the 1988 season. In 1988,60 pods containing 127 whales were observed. All pods were sighted on the transects in the eastern section of Hervey Bay, so surveys in 1989 and 1990 were confined to this area. In 1989, 223 whales in 121 pods were counted, and in 1990, 105 whales in 60 pods were observed. There was annual variation in the temporal pattern of the migration through Hervey Bay. Pods tended to occur in shallow water close to the western coast of Fraser Island and, on days when several whales were observed in the bay, pods were not distributed in a regular fashion. Mother-calf pods were the final cohort to migrate through the Bay. The recorded sizes of whale pods varied between observation platforms and averaged 1.75-2.81. In all, 100 whales were identified from photographs of natural marks. Most were photographed once only, although individual whales were sighted up to seven times. Of the 34 whales identified on more than one occasion, 24 were observed over a one- or two-day period. Pod sizes and residence times of whales in Hervey Bay resemble those of whales recorded at tropical breeding grounds. However, there are no data suggesting that Hervey Bay is of particular importance to any class of the humpback whale population migrating off the eastern coast of Australia.

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A Bayesian assessment of the conservation status of humpback whales (Megaptera novaeangliae) in the western South Atlantic Ocean

J. Cetacean Res. Manage. ◽

10.47536/jcrm.vi3.320 ◽

2020 ◽

pp. 131-144

Author(s):

Alexandre N. Zerbini ◽

Eric J. Ward ◽

Paul G. Kinas ◽

Marcia H. Engel ◽

Artur Andriolo

Keyword(s):

Population Size ◽

Probability Distributions ◽

Conservation Status ◽

South Atlantic ◽

Megaptera Novaeangliae ◽

Humpback Whales ◽

Eastern Coast ◽

Base Case ◽

Model Parameters ◽

Quantities Of Interest

The population of humpback whales (Megaptera novaeangliae) wintering off the eastern coast of South America is referred to by the International Whaling Commission as ‘Breeding Stock A’ (BSA). This population was heavily exploited in 20th century modern commercial whaling operations. After more than 30 years of protection, its present status remains unknown. A deterministic sex and age-aggregated population dynamics model was used to estimate the pre-exploitation population size (K), the maximum net recruitment rate (rmax), the maximum depletion level (Nmin/K), and other quantities of interest of BSA. Input data included modern whaling catch series, absolute estimates of abundance, observed growth rates and indices of relative abundance. A Bayesian statistical method was used to calculate probability distributions for the model parameters. Prior distributions were set on rmax – an uninformative (Uniform [0, 0.106]) and an informative (Normal [0.067, 0.042]) – and on the population size in 2005 – N2005 (Uniform [500, 22,000]). A total of 10,000 samples were used to compute the joint posterior distribution of the model parameters using the Sampling-Importance-Resampling algorithm. Sensitivity of model outputs to the priors on rmax, a genetic constraint, data inclusion and catch allocation scenarios was investigated. Medians of the posterior probability distributions of quantities of interest for the base case scenario were: rmax = 0.069 (95% probability intervals [PI] = 0.013–0.104), K = 24,558 (95% PI = 22,791–31,118), Nmin/K = 2% (PI = 0.31%–12.5%), N2006/ K = 27.4% (PI = 18.3%–39.5%), N2020/K = 61.8% (PI = 23.8%–88.6%), and N2040/K = 97.3% (PI = 31.6%–99.9%). Despite apparent recovery in the past three decades, the western South Atlantic humpback whale population is still low relative to its pre-exploitation size and requires continued conservation efforts.

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