Feeding ecology of franciscana dolphin, Pontoporia blainvillei (Cetacea:Pontoporiidae), and oceanographic processes on the Southern Brazilian coast

The feeding regime of the franciscana dolphin was investigated from stomach contents of incidentally caught animals in gillnets along the southern Brazilian coast, from 1994 to 2000. The analyses were based mainly on Linear and Generalised Linear Models (LM and GLM). There were some diet differences within the population, as juveniles had eaten more small teleosts and shrimps, and adults consumed larger fish prey and more cephalopods. Adult females had similar diet to juveniles, possibly related to parental guidance. Feeding regimes from northern and southern areas also revealed significant differences, where the most important fish prey from the northern area only occurred once in the diet of the southern animals. More detailed analysis dividing the region into 7 smaller latitudinal zones confirmed many differences, with higher occurrence of warm water species in the diet of northern zones, and cold water species in the southern zones. Additionally, the prey frequency and size do not change gradually along the coast, and different zones revealed a diverse diet composition between northern and southern. This raised the question whether variations in environmental conditions along the coast may affect the distribution of franciscana prey, and consequently its feeding regime.To investigate the spatial and temporal patterns of environmental conditions off the study area, Sea Surface Temperature (SST) images from Advanced Very High Resolution Radiometer , and chlorophyll-a (chl a) images from Sea-viewing Wide Field-of-view were extracted. The analysis (MANOVA, PCA, and time series) revealed a marked temporal influence of warm temperatures from the Brazil Current (BC) in the northern zones, and cold temperatures related to Malvinas/Falkland Current (MC) in the southern zones. The central zones showed a dynamic-edge region in terms of temperature behaviour probably caused by the mixing of BC and MC. Northern zones showed low values of chl a concentration and southern zones high values, whereas central zones revealed intermediate values and less clear seasonal variation. The characteristics of the franciscana habitat had shown potential factors affecting the distribution and abundance of its prey, thus the prey species and size were treated as a function of the variables SST, chl a, latitude, depth, and season, using GLM and LM.Models suggested that habitat parameters influence the franciscana prey species and size. As expected, warm water species are more likely to occur in the diet for longer periods at lower latitudes, and cold water prey at higher latitudes. The SST effect on prey specimens size shows that bigger cephalopods and fish were most frequent in warmer temperatures. The chl a only influenced Engraulidae species. The latitude was the most important spatial predictor for many species, and bigger cephalopods were consumed in large quantities in central latitudes. The depth had great influence in the abundance of some prey species, with smaller fish and cephalopods being in higher numbers in shallower. The influence of the predictors on the franciscana prey is very similar to that found in the habitat by research cruises. Because some structures analysed may remain longer in the stomachs, the findings not only suggest a fairly opportunistic behaviour but it is likely that franciscana may occupy, possibly for long periods, small spatial ranges. This behaviour might be a strategy of minimizing energetic costs, ensuring low maintenance and thermoregulatory costs, and these include limiting excursions to distant areas

Feeding habits of the atlantic spotted dolphin, Stenella frontalis, in southeastern Brazil

O presente estudo apresenta novas informações sobre os hábitos alimentares de golfinhos-pintados-do-Atlântico, Stenella frontalis, no Atlântico Sudoeste. Foram analisados nove conteúdos estomacais de S. frontalis acidentalmente capturados em operações de pesca entre 2005 e 2007 pela frota pesqueira do município de Cananéia (25°00'S; 47°55'W), sudeste do Brasil. Foram recuperados dos conteúdos estomacais 1 422 bicos de cefalópodes, 147 otólitos e três camarões. Dos itens analisados, foram reportados um mínimo de oito espécies de peixes pertencentes às famílias Trichiuridae, Carangidae, Sparidae, Merluccidae, Engraulidae, Sciaenidae, Congridae e Scombridae, cinco espécies de cefalópodes pertencentes às famílias Loliginidae, Sepiolidae, Tremoctopodidae e Thysanoteuthidae, e uma espécie de camarão da família Penaeidae. Com base no Índice de Importância Relativa (IRI), o peixe-espada, Trichiurus lepturus, correspondeu à espécie de peixe com maior importância. Entre os cefalópodes, a espécie que apresentou o maior valor de IRI foi Doryteuthis plei. Algumas espécies foram reportadas pela primeira vez como presa de S. frontalis em águas brasileiras: Xiphopenaeus kroyeri, Tremoctopus violaceus, Semirossia tenera, Merluccius hubbsi, Pagrus pagrus e Paralonchurus brasiliensis. S. frontalis apresentou hábitos alimentares teutófagos e ictiófagos, com aparente predomínio do primeiro, e predou principalmente sobre itens pelágicos e demersais.This study presents new information on the feeding habits of the Atlantic spotted dolphins, Stenella frontalis, in the Western South Atlantic. Nine stomach contents of S. frontalis incidentally caught in fishing operations conducted by the gillnet fleet based on main harbour of Cananéia (25°00'S; 47°55'W), southeastern Brazil, were analyzed. These specimens were captured between 2005 and 2007. A total of 1 422 cephalopod beaks, 147 otoliths and three crustaceans were recovered from the stomach contents. The dolphins assessed preyed on at least eight different fish species of the families Trichiuridae, Carangidae, Sparidae, Merluccidae, Engraulidae, Sciaenidae, Congridae and Scombridae, five cephalopod species of the families Loliginidae, Sepiolidae, Tremoctopodidae and Thysanoteuthidae, and one shrimp species of the Penaeidae family. Based on the analysis of the Index of Relative Importance (IRI), the Atlantic cutlassfish, Trichiurus lepturus, was the most important fish species represented. Of the cephalopods, the squid Doryteuthis plei was by far the most representative species. Several items were reported for the first time as prey of the S. frontalis: Xiphopenaeus kroyeri, Tremoctopus violaceus, Semirossia tenera, Merluccius hubbsi, Pagrus pagrus and Paralonchurus brasiliensis. S. frontalis presented teuthophagous and ichthyofagous feeding habits, with apparent predominance of the first, and preyed mainly on pelagic and demersal items

Cadmium concentrations in franciscana dolphin (Pontoporia blainvillei) from south brazilian coast

Franciscanas foram utilizadas como fonte de informação sobre a biodisponibilidade de cádmio em águas neríticas da Costa Sul do Brasil. Amostras de fígado, obtidas de 44 indivíduos capturados acidentalmente ao largo da costa do Rio Grande do Sul, foram analisadas através de EAA eletrotérmica. Concentrações de cádmio, idade, peso e comprimento totais dos golfinhos analisados variaram entre 39 e 4144 µg.kg-1 (peso úmido), um e cinco anos, 17,5 e 49,2 kg, e entre 105,3 e 156,8 cm, respectivamente. Em relação às concentrações hepáticas de cádmio em franciscanas, não houve diferença significativa entre os dados gerados pelo presente estudo e informação proveniente da literatura, referente ao Estado do Rio de Janeiro. As baixas concentrações de cádmio observadas podem ser atribuídas ao fato de as lulas da Família Loliginidae constituírem a principal presa para franciscanas, dentre os cefalópodes. Este estudo corrobora investigações sobre níveis de cádmio em lulas brasileiras e reforça a hipótese de que cefalópodes loliginídeos não constituem vetores importantes da transferência de cádmio para cetáceos.Franciscana dolphins were used as source of information on the bioavailability of cadmium in the neritic waters off South Brazilian Coast. Liver samples obtained from 44 individuals incidentally captured off Rio Grande do Sul State were analyzed by electrothermal AAS. Cadmium concentrations, age, total weight and length of the analyzed dolphins varied between 39 and 4144 µg.kg-1 (wet weight), one and five years, 17.5 and 49.2 kg, and between 105.3 and 156.8 cm, respectively. Concerning hepatic cadmium concentrations of franciscanas, there was no significant difference between data raised by the present study and information from literature, regarding Rio de Janeiro State. The low cadmium concentrations observed may be attributed to the fact that loliginid squids constitute the main cephalopod prey for franciscanas. This study corroborates investigations on cadmium levels in Brazilian squids and strengthened the hypothesis that cephalopods of Loliginidae Family do not constitute important vectors of the transfer of cadmium to cetaceans

Killer whale predation on an Antarctic minke whale in the northern Antarctic Peninsula

ADDITIONAL FILE : A video with the recording of the predation event described is made available at https://mega.nz/ folder/VjMhka6I#7KJGqj2xcguvIIbVQIXwdA.We describe the seldom observed event of a group of type A killer whale (Orcinus orca) predating on an Antarctic minke whale (Balaenoptera bonaerensis) in austral summer 2019. A pod of 11-13 individuals was observed – and documented by photographs and video – as they killed and fed on the minke whale in the Bransfield Strait, northern Antarctic Peninsula. The pod was being observed for about one hour, when some killer whale’s individuals were noticed to be performing hunting behaviour. This lasted about 10 minutes, at the end of which the minke whale was killed. Three different species of seabirds were observed feeding on the minke carcass. A video of the encounter is provided.CNPq (National Council for Research and Development) and CAPES (Coordination for the Improvement of Higher Education Personnel).https://www.scielo.br/j/aabc/hj2024Mammal Research InstituteZoology and EntomologySDG-14:Life below wate

PRESENCE OF THE LEOPARD SEAL, HYDRURGA LEPTONYX (DE BLAINVILLE, 1820), ON THE COAST OF CHILE: AN EXAMPLE OF THE ANTARCTICA - SOUTH AMERICA CONNECTION IN THE MARINE ENVIRONMENT

Sightings of 114 leopard seals, Hydrurga leptonyx, have been recorded along the Chilean coasts from 1944 to 2010. Mostly immature seals occurred in northern and central Chile (18°30´S-39°59´S), especially in winter, while immature and adult individuals of both sexes and in good condition were commonly sighted year-round in glacial areas of southern Chile, especially Tierra del Fuego (south of 53°43´S), suggesting that this Antarctic species can be consider as a regular member of the marine fauna of Chile, with occasionally hauling out on the northern coastline not as vagrants, but as seasonal transients. Keeping in mind data limitation, we discuss some ways of northern dispersion and the subsequent residence of some animals in the Southern region of South America. These include, respectively: the close proximity of the Fueguian channels with the Antarctic Peninsula facilitated by the northward extension of the Antarctic pack ice during winter and/or through the influence of the Malvinas current; and the suitable habitat of the Fuegian channels, with similar characteristics to the Antarctic environment and locally abundant food resources.PRESENCIA  DE  LA  FOCA  LEOPARDO,  HYDRURGA  LEPTONYX  (DE  BLAINVILLE,  1820)  EN  LA COSTA DE CHILE: UN EJEMLO DE CONEXIÓN DE AMBIENTE MARINO ENTRE ANTÁRTICA Y AMÉRICA DEL SUR.  Entre 1927 y 2010, 115 focas leopardos, Hydrurga leptonyx, han sido egistradas a  lo  largo  de  la  costa  chilena.  En  la  región  centro-norte  (18°20´S-39°59´S),  especialmente  en  invierno,  la mayoría de los registros corresponden a individuos inmaduros; mientras que ejemplares maduros e inmaduros de ambos sexos y en buenas condiciones físicas son avistados durante todo el año, en áreas de glaciares del sur de Chile, especialmente en Tierra del Fuego (sur de los 53°43´S), sugiriendo que esta especie antártica puede ser considerado como un miembro regular de la fauna marina de Chile, con presencia ocasional en las costas norteñas, como vagabundo estacional. Teniendo en cuenta la limitación de los datos, discutimos algunas vías de dispersión hacia el norte y la presencia durante todo el año de los animales en la región austral de América del Sur. Estas incluyen, respectivamente: la cercana proximidad de los canales fueguinos con la Península Antártica, facilitado por la extensión hacia el norte del hielo marino antártico durante el invierno y/o a través de la influencia de la corriente de las Malvinas; y el hábitat apropiado de los canales fueguinos, con características similares al ambiente Antártico y abundante recursos alimenticios locales. Palabras claves: Foca leopardo; Chile; América del Sur; Océano austral.PRESENÇA DA FOCA-LEOPARDO, HYDRURGA LEPTONYX (DE BLAINVILLE, 1820), NA COSTA DO CHILE: UM EXEMPLO DA CONEXÃO ENTRE ANTÁRTICA E AMÉRICA DO SUL NO AMBIENTE MARINHO.  Entre 1927 e 2010, 115 focas-leopardo, Hydrurga leptonyx, foram avistadas ao longo da costa Chilena. Na região centro-norte (18°20´S-39°59´S), especialmente no inverno, a maioria dos registros esteve representada por indivíduos imaturos. Indivíduos imaturos e adultos de ambos os sexos ocorreram ao longo do ano, em boas condições físicas, em áreas glaciais da região sul do Chile, especialmente na Terra do Fogo (ao sul de 53°43´S). Nesta revisão, há evidências robustas para sugerir que a espécie é uma visitante regular da fauna Antártica em território austral chileno, ocorrendo eventualmente como vadios sazonais na costa norte do país. Apesar das limitações inerentes aos dados, discutem-se sobre a dispersão da espécie em direção ao norte e subsequente presença de indivíduos na porção austral da América do Sul. Estas incluem respectivamente: a proximidade entre os canais Foguinos e a Península Antártica, favorecida pela expansão da capa de gelo em direção ao norte durante o inverno e/ou pela influência da corrente das Malvinas; o habitat adequado nos canais Foguinos, com características similares àquelas do ambiente Antártico, somado à presença de recursos alimentares localmente abundantes. Palavras-chave: Foca-leopardo; Chile; América do Sul; Oceano Austral

Prey of killer whales (Orcinus orca) in Iceland

Publisher's version (útgefin grein)Killer whales have a cosmopolitan distribution and as a species are generalists, feeding on a variety of prey. However, local populations tend to specialise on specific prey types. In Icelandic waters, killer whales are generally associated with herring and, thus, have been presumed to be herring specialists. However, recent studies suggest a more complex foraging ecology, possibly including a mosaic of strategies. With increased observational effort in recent years due to research and whale-watching activities, there have been several reports of interactions with different prey, including confirmed predation events. In this study we aimed to summarise the range of potential prey of killer whales observed in Icelandic waters. We report on 12 previously unpublished accounts and review 15 accounts published in the scientific literature or local newspapers, making a total of 27 events where killer whales were observed interacting with actual or potential prey. Thirteen different species, including birds (n = 1), cephalopods (n = 1), fish (n = 5) and marine mammals (n = 6), are reported, although herring is by far the species that killer whales are most often observed interacting with. This study provides the first summary of actual and suspected killer whale prey in Icelandic waters, and contributes towards our understanding of this population’s prey preferences. However, describing the diet of individuals/groups was not possible and this study points to a need for continued monitoring to understand the intricacies of killer whale foraging behaviour in this area.MB was employed by Elding Whale Watching, MOE was employed by Whales Hauganes ehf., MTM was employed by Láki Tours, JNR was employed by Special Tours and BT was employed by Iceland Pro Cruises. The funders provided support in the form of salaries for authors and in all cases (except Iceland Pro Cruises) provided platforms from where observations were made, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. Funding for dedicated research was provided by the Icelandic Research Fund. The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer Reviewe

Photo-identification and satellite telemetry connect southern right whales from South Georgia Island (Islas Georgias del Sur) with multiple feeding and calving grounds in the southwest Atlantic

The sub-Antarctic waters of South Georgia Island (Islas Georgias del Sur, SG/IG) are a regularly visited feeding ground for southern right whales (Eubalaena australis, SRW) in the southwest Atlantic. Satellite telemetry and photo-identification records were compared to better understand the role of SG/IG in the SRW migratory network. We present the first insights from SRW satellite-tracked from the SG/IG feeding ground, habitat use patterns in the Scotia Arc, and movements to Antarctic habitats. Photo-identification comparisons to calving and feeding areas across the South Atlantic and a review of sightings of cetaceans reported from Bird Island (west of SG/IG) since 1979 illuminate long-term habitat use patterns in SG/IG. We present the first recorded migratory movement between SG/IG and multiple countries: Argentina, Uruguay, and Brazil. Photo-identification (1) linked SG/IG to a female SRW with a long-term sighting history in Brazil, and (2) provided the first match between SG/IG and the western Antarctic Peninsula, suggesting the latter could extend the feeding area for southwest Atlantic SRW. Satellite tracking and opportunistic sightings suggest that shelf and coastal waters west of SG/IG represent an important multi-season SRW feeding habitat and add to our overall understanding of habitats and ranges occupied by recovering southwest Atlantic SRW.Funding from an EU BEST 2.0 Medium Grant 1594, with additional support provided by a DARWIN PLUS award DPLUS057 and additional funding from the World Wildlife Fund, South Georgia Heritage Trust, and Friends of South Georgia Island.http://wileyonlinelibrary.com/journal/mmshj2024Mammal Research InstituteZoology and EntomologySDG-14:Life below wate

Photo-identification and satellite telemetry connect southern right whales from South Georgia Island (Islas Georgias del Sur) with multiple feeding and calving grounds in the southwest Atlantic

The sub-Antarctic waters of South Georgia Island (Islas Georgias del Sur, SG/IG) are a regularly visited feeding ground for southern right whales (Eubalaena australis, SRW) in the southwest Atlantic. Satellite telemetry and photo-identification records were compared to better understand the role of SG/IG in the SRW migratory network. We present the first insights from SRW satellite-tracked from the SG/IG feeding ground, habitat use patterns in the Scotia Arc, and movements to Antarctic habitats. Photo-identification comparisons to calving and feeding areas across the South Atlantic and a review of sightings of cetaceans reported from Bird Island (west of SG/IG) since 1979 illuminate long-term habitat use patterns in SG/IG. We present the first recorded migratory movement between SG/IG and multiple countries: Argentina, Uruguay, and Brazil. Photo-identification (1) linked SG/IG to a female SRW with a long-term sighting history in Brazil, and (2) provided the first match between SG/IG and the western Antarctic Peninsula, suggesting the latter could extend the feeding area for southwest Atlantic SRW. Satellite tracking and opportunistic sightings suggest that shelf and coastal waters west of SG/IG represent an important multi-season SRW feeding habitat and add to our overall understanding of habitats and ranges occupied by recovering southwest Atlantic SRW

Opportunistic feeding experiment in a captive franciscana (Pontoporia blainvillei): assessing gastrointestinal transit time and gastric digestion.

The data consists of spreadsheets containing (i) otolith and cephalopod beak numbers and sizes, and the time of recovery for seven different prey species of different meals; (ii) conditions of prey structures for each meal and its time of recovery; and (iii) the times that the plastic colour markers were ingested and evacuated from a feeding experiment with a franciscana dolphin in captivity