Daniel Danilewicz

Grupo de Estudos de Mamíferos Aquáticos do RS e Instituto Aqualie

Understanding animals' movements is essential to assess habitat use, life‐history strategies, and population dynamics. Here, we investigate the movement and behavior patterns of 153 humpback whales in the Southwest Atlantic Ocean (SWA) using data obtained by satellite telemetry between 2003 and 2019 during the species' breeding season (August–Decem...

"Acesso ao artigo: https://link.springer.com/article/10.1007/s00300-023-03206-9 " This study presents the pattern of occurrence of sub-Antarctic fur seals (SAFS), Arctocephalus tropicalis, in the southern Brazilian coast and evaluate its association with climatic variability and anomalies in the concentration of chlorophytes and sea surface temper...

This work presents insights about the biological aspects of a solitary Bryde's whale individual (11.51 meters long), sighted on the northern coast of São Paulo, Brazil. The data collection was done through drone monitoring, which allowed us to monitor respiratory cycles (ten intervals), speed of movement, behavior, and extract morphometric measure...

The ecology and distribution of most baleen whales are poorly known in Brazilian waters, despite the history of whaling and the recent increase in the research effort. Although stranding data presents some caveats, it is useful to understand patterns of distribution and occurrence and to detect population trends. In this scenario, data from 25 year...

The franciscana Pontoporia blainvillei is the only extant member of the family Pontoporiidae, and its occurrence is restricted to coastal waters from Brazil to Argentina. The species is one of the most threatened cetaceans in the southwestern Atlantic Ocean, due to unsustainable bycatch levels. A total of 11 Franciscana Management Areas (FMAs) have...

We present the most recent data on the seasonal and spatial occupation of South American sea lions ( Otaria flavescens ) and fur seals ( Arctocephalus australis ) in the Wildlife Refuge of Ilha dos Lobos (WRIL) in southern Brazil throughout the year, based on aerial photographic counts. Thirty-one aerial photographic counts were conducted between J...

Line transect aerial surveys are widely used for estimating abundance of biological populations, including threatened species. However, estimates obtained with data collected from aircraft are often underestimated because of visibility bias and bias in estimating group sizes from a fast-moving platform. An assessment of multiple sources of bias in...

Humpback whales ( Megaptera novaeangliae ) perform seasonal migrations from high latitude feeding grounds to low latitude breeding and calving grounds. Feeding grounds at polar regions are currently experiencing major ecosystem modifications, therefore, quantitatively assessing species responses to habitat characteristics is crucial for understandi...

Marine protected areas (MPAs) have been considered one of the most effective instruments to protect marine biodiversity, including endangered species. However, the effectiveness of MPAs in conserving coastal, long-living, and mobile species, such as the franciscana, is quite challenging. In this chapter, we evaluate the existing MPAs’ potential to...

Conservation actions often rely on some knowledge of the status of a population and can be more effectively implemented if trends in population size are known. Therefore, estimation of abundance is key to contributing to the conservation of the franciscana (Pontoporia blainvillei), the most endangered small cetacean in the western South Atlantic. A...

The franciscana, Pontoporia blainvillei, is the only extant species of its family and the most threatened small cetacean in the Western South Atlantic. Understanding life traits that shape the population dynamics and variation in the demography of threatened species is critical for their conservation. In this chapter, we provide a comprehensive rev...

Despite being a very coastal species, knowledge about franciscana dolphins (Pontoporia blainvillei) behavior is very scarce. This chapter aims to summarize information available in the literature as well as unpublished data involving different aspects related to the behavior of the species. Franciscana is a social species, forming aggregations of u...

The relationships between cetaceans and remoras are still poorly known, especially those involving the species commonly referred to as the whalesucker (Remora australis), which attaches to cetaceans only. We report here on the association between resident common bottlenose dolphins (Tursiops truncatus) and whalesuckers at the remote São Pedro and S...

The franciscana is endemic to subtropical coastal waters of Brazil, Uruguay, and Argentina, and is the only living species of the family Pontoporiidae. It is regarded as the most endangered cetacean in the western South Atlantic. Five management units are recognized (Franciscana Management Areas, FMAs – sensu Secchi et al., 2003a), with abundance e...

The franciscana dolphin ( Pontoporia blainvillei ) is a coastal dolphin endemic to the western South Atlantic Ocean. The dolphin is listed as vulnerable in the IUCN Red List, with incidental catches in gillnet fisheries the greatest conservation concern for this species. Insights into the feeding habits of this dolphin are essential to understand i...

Stranded cetaceans (whales, dolphins, and porpoises) are frequently used to obtain data on species occurrence and demographic trends. Accurate species-level identification of these individuals is crucial, but often challenging or impossible when relying solely on morphological features (e.g., for highly decayed specimens). To aid in the development...

Understanding how organisms respond to environmental change is one of the most pressing grand challenges of organismal biology. In the vast oceans that cover 71% of Earth’s surface, remote sensing technologies have created unprecedented opportunities to create new knowledge and deliver integrated understandings of marine organism-environment intera...

The franciscana (Pontoporia blainvillei) is a coastal dolphin endemic to the south-western Atlantic Ocean. Incidental captures in fishing gillnets are the greatest conservation concern for this species. The present study examines the biophysical interactions between the franciscana prey composition and the marine environment. The feeding regime of...

The franciscana (Pontoporia blainvillei) is endemic to coastal waters from Brazil to Argentina. The species is regarded as one of the most threatened cetaceans in South America due to high bycatch levels. Four management units (FMAs) were defined throughout the species’ range. FMA II includes states along southeastern and southern Brazil, and repre...

We assessed the level of genetic variability and population structure of the common bottlenose dolphin (Tursiops truncatus) in the tropical and subtropical portions of the southwestern Atlantic Ocean and compared the results with previous morphological findings. We analyzed 109 samples of common bottlenose dolphins that were sequenced for control r...

Humpback whales follow well-defined long-distance migratory corridors - over prolonged periods (>15+ years) - despite environmental, oceanographic and geomagnetic change.

The population of humpback whales from breeding stock A is increasing, and little is known about the routes used by humpbacks that move north of the main calving area of Brazil, the Abrolhos Bank. The aim of this study was to describe the movements of humpback whales in a reoccupation wintering area (Serra Grande, Bahia state, Brazil) based on land...

In the last decades, an increasing fishing effort and a decreasing trend in fish catches have been observed in southern Brazil. Considering that marine mammals and fisheries usually compete for the same resources, it is reasonable to presume that the feeding ecology of these predators is affected by the current scenario. To evaluate this hypothesis...

The franciscana (Pontoporia blainvillei) is the most threatened small cetacean of South America. The species isendemic to coastal waters of the western South Atlantic Ocean, where it is distributed from Itaúnas (Brazil) toGolfo San Matias (Argentina). Its range was divided in four Franciscana Management Areas (FMAs) for con-servation purposes. Howe...

Estimation of visibility bias is critical to accurately compute abundance of wild populations. The franciscana, Pontoporia blainvillei, is considered the most threatened small cetacean in the southwestern Atlantic Ocean. Aerial surveys are considered the most effective method to estimate abundance of this species, but many existing estimates have b...

Synchronous breathing may be a useful proxy for studying other, and perhaps more complex, aspects of cetacean behavior. Here we describe a study conducted in Babitonga Bay, southern Brazil, where we investigated the synchrony of breathing in two small populations of franciscana (Pontoporia blainvillei) and Guiana dolphins (Sotalia guianensis). The...

The western South Atlantic humpback whale Megaptera novaeangliae population was severely depleted by commercial whaling in the late 19th and 20th centuries, and today inhabits a human-impacted environment in its wintering grounds off the Brazilian coast. We identified distribution patterns related to environmental features and provide new estimates...

Listas de espécies ameaçadas identificam taxa com real ou potencial risco de extinção em uma escala regional e global, embasando a tomada de decisões e a formulação de políticas públicas. A construção da primeira lista estadual de espécies ameaçadas de extinção na Bahia teve início em 2013. Este artigo descreve a avaliação do status de conservação...

The killer whale (Orcinus orca) has a worldwide distribution and its feeding habits varies greatly among populations. In the southern Atlantic Ocean, knowledge about the distribution and diet of the species is still scarce. Herein we report the first evidence of a killer whale’s attack on a southern right whale (Eubalaena australis) in Brazilian wa...

Age is one of the most important life history parameters required to understand the dynamics of mammalian populations. Growth Layers Groups (GLGs) are incremental units of calcified tissue in the teeth (dentine and cementum), which represent a pattern of cyclical deposition that can be counted. However, the estimation of absolute age in GLGs demand...

Hundreds of thousands of cetaceans die each year due to commercial fishing catches, which is the main threat to global populations of these animals. Mortality by fishing gets disastrous proportions mainly in developing countries, for which effective fisheries management programs, as well as monitoring, environmental education or analysis of the cat...

A little-studied common bottlenose dolphin (Tursiops truncatus) population inhabits the offshore waters surrounding Saint Paul's Rocks, a Brazilian marine protected area in the equatorial Atlantic Ocean. Five field expeditions (May 2011-May 2013) were conducted to characterize the habitat use, population size, and site fidelity of this population....

The stomach contents of 21 stranded bottlenose dolphins were collected by a marine mammal research team (Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul - GEMARS) during systematic beach surveys (mostly monthly) along the central-northern coast of Rio Grande do Sul, southern Brazil, between November 1991 and October 2008. The area surv...

The western South Atlantic (WSA) humpback whale population inhabits the coast of Brazil during the breeding and calving season in winter and spring. This population was depleted to near extinction by whaling in the mid-twentieth century. Despite recent signs of recovery, increasing coastal and offshore development pose potential threats to these an...

1. Historical catch records from whaling activity are crucial for assessments of whale populations. However, several gaps in the exploitation history for many populations from before the twentieth century create limitations that may lead to overestimates of the recovery of these populations. The history of modern whaling along the Brazilian coast i...

Accurate estimates of group sizes through line transect sampling methods are important to correctly ascertain the abundance of animals that occur in groups. Since the average observed group size is a component of the distance sampling formula, bias in these data leads to biased abundance estimates. This study aimed to evaluate the potential errors...

The southern right whale (SRW), Eubalaena aus-tralis, was heavily depleted by the whaling in the Southern Hemisphere. In the southwestern Atlantic, studies on SRWs have been concentrated in two main breeding grounds: Península Valdés, Argentina (~42°′S) and Santa Catarina (SC) State, Brazil (~28°′S). To better understand the ecology of SRWs in the...

This study describes operational interactions between coastal gillnet fishing and South American sea lions ( Otaria flavescens ) off the southern Brazilian coast. In total, 263 onboard surveys were carried out during three periods between 1992 and 2012 in fishing boats from two harbours on the northern coast of Rio Grande do Sul State: Passo de Tor...

Calculation of echolocation signals emission rate is necessary to estimate how many individuals are vocalizing, especially if passive acoustic density estimation methods are to be implemented. We calculated the individual emission rate of echolocation signals of franciscana dolphin. Fieldwork was between 22 and 31 January of 2014 at Babitonga Bay,...

The social structure of humpback whales in their tropical wintering grounds is very fluid. To date, no information has been published for cases in which two whales were both satellite-tagged while in association. Here, we report the movements of four humpback whale pairs tagged together off the coast of Brazil. Fieldwork and satellite tagging of hu...

Birth, lactation, and maternal investment have been described and measured in many species of terrestrial and marine mammals that nurse their young on land such as pinnipeds, aquatic mustelids, and polar bears (Siniff & Ralls, 1991; Derocher & Stirling, 1995; Trillmich & Weissing, 2006). Because of their fully aquatic life cycle, information about...

The Atlantic spotted dolphin, Stenella frontalis, presents two geographically isolated populations in the western South Atlantic. This note reports on a 350 km northward extension range of the southern population. The sighted group of 80 animals was in waters 66 m deep and 75 nautical miles distant from the coast. The record was observed during a d...

Age and length data of 291 franciscana dolphins (Pontoporia blainvillei) incidentally captured on the coast of Rio Grande do Sul State (RS), southern Brazil, were used to fit growth curves using Gompertz and Von Bertalanffy growth models. A small sample of franciscanas (N ¼ 35) from Buenos Aires Province (BA), Argentina, were used to see if there a...

The White-tipped Plantcutter Phytotoma rutila has only one documented record for Brazil, that occurred in 1974 in the extreme west of Rio Grande do Sul. We report herein a second record - one individual photographed in April 2009 at a dunefield in the municipality of Capão da Canoa, northern coast of Rio Grande do Sul, about 700 km from the previou...

The franciscana dolphin has been considered the most threatened small cetacean in the south-western Atlantic Ocean due to gillnet by-catch. The estimation of the species' abundance has been recommended as the highest research priority. A line transect aerial survey to estimate franciscana abundance in Rio Grande do Sul, southern Brazil, was carried...

The northeastern Brazilian coast was a major whaling ground off the eastern coast of South America (IWC manage-ment area II – DONOVAN 1991) in the 20 th century. One land sta-tion operated in Costinha, Paraíba State (PB) (6º57'S, 34º51'W, Fig. 1), during 1904-1914 and 1924-1985 (e.g. WILLIAMSON 1975, DA ROCHA 1983). Catch data for all of these year...

The patterns of habitat use by the franciscana dolphins (Pontoporia blainvillei) along its distribution are poorly known. This study investigates the patterns of habitat use with respect to depth for 181 individuals of different age, size, gender and reproductive condition off Rio Grande do Sul, southern Brazil. The results reveal that franciscanas...

The humpback whale, Megaptera novaeangliae, is a highly migratory species distributed in all oceans of the world. It has been indicated that humpbacks do not normally feed while in their tropical breeding grounds or during migration. Here we document the first evidence of recent feeding in southern Brazil, a mid-latitude area in the western South A...

RESUMO O presente trabalho apresenta uma descrição detalhada da pesca costeira de média escala no litoral norte do Rio Grande do Sul, enfocando aspectos técnicos, econômicos e sociais de duas comunidades pesqueiras (Imbé/Tramandaí e Passo de Torres/Torres). Um total de 22 embarcações foram monitoradas entre janeiro de 2002 e dezembro de 2004. Os re...

91501-970, Porto Alegre, Rio Grande do Sul, Brazil (CBF) Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul (GEMARS), Rua Felipe Neri, 382/203, CEP: 90440-150, Porto Alegre, Rio Grande do Sul, Brazil (DD) In cetaceans almost all the energy reserves in lipid form are allocated to blubber and are related to basal metabolism and thermal insu...

The distribution of dolphins of the genus Stenella is poorly known in the southwest Atlantic Ocean. A complete review of records (n = 311) of these dolphin species was performed to describe distribution and habitat. Atlantic spotted dolphins S. frontalis occur in both southern (21 to 33° S) and northern Brazil (north of 06° S), with a hiatus in its...

The reproductive biology of male franciscanas (Pontoporia blainvillei), based on 121 individuals collected in Rio Grande do Sul State, southern Brazil, was studied. Estimates on age, length, and weight at attainment of sexual maturity are presented. Data on the reproductive seasonality and on the relationship between some testicular characteristics...

In this paper, the reproductive biology of female franciscanas ( Pontoporia blainvillei) is described based on a sample of 97 individuals collected in Rio Grande do Sul, southern Brazil. Data were collected from dolphins incidentally by-caught by the commercial fleet of Rio Grande and Tramandaí or stranded in the northern coast of Rio Grande do Sul...

The Fraser’s dolphin, Lagenodelphis hosei Fraser, 1956, is distributed in tropical oceanic waters worldwide. There is little information on the biology and distribution of this species in the Southwestern Atlantic Ocean. From September to November 1997, 10 stranded Fraser’s dolphins were collected along the northern Rio Grande do Sul coast, souther...

High numbers of franciscanas (Pontoporia blainvillei) have been bycaught in gillnets for at least four decades. The impact is strong but not homogeneous along the species distribution range, and there is evidence that at least one local population is declining. Reliable stock determination is important to evaluate how bycatch affects stocks so that...

Age distribution of incidentally caught and stranded franciscanas Age distribution of franciscanas incidentally caught in northern Rio de Janeiro State, southeastern Brazil, was reported for 62 males and 57 females (Di Beneditto and Ramos, 2000). Males ranged from 0 to 5 years but were mostly of age 2. Females ranged from 0 to 9 years and were most...

Growth -The asymptotic lengths of individuals of the southern form of P. blainvillei (distributed south of 32ºS) vary between 129.8cm and 136.4cm for males, and between 146.4cm and 161.9cm for females (Kasuya and Brownell, 1979; Walter, 1997; Barreto et al., 2000). The northern form of the species (distributed north of 27ºS), has asymptotic lengths...