Knowing the number of individuals living in a given location and the trends of this population is essential for conservation. From this information, we can monitor the impacts and the effectiveness of conservation strategies.

One of the main methodologies used by the project is Distance Sampling, which is the sampling of distances in linear transects. It can be performed from vessels or aircraft. All sighted animals are counted and, through statistical methods, it is possible to estimate the density and abundance of a population. Due to the challenge of observing franciscanas in the sea, the project has also been investing efforts in the development of acoustic methods in order to obtain population density and abundance.

Photo-identification is a method that allows recognizing individuals in nature based on their physical characteristics. For most cetaceans, including franciscanas, we use marks acquired on the dorsal fin. In Babitonga Bay, photo-identification has been used in the study of franciscanas since 2011 and allowed the construction of a catalog with more than 30 resident individuals. The method makes it possible to study the life history of individuals, their residence patterns, and estimate the size of the population through statistical mark-recapture methods.

Genetics is also an important tool in the study of populations. Small pieces of skin or muscle from animals found dead are analyzed to verify the degree of kinship and connectivity between populations. Through genetics, Toninhas do Brasil, in partnership with MAQUA/UERJ, evidenced that the franciscanas of Babitonga Bay form a unique population, distinct from those that live on the adjacent coast.

Two researchers at Toninhas do Brasil holding cameras while monitoring the porpoises in Babitonga Bay.

Knowing where franciscanas are distributed and how they use the region where they live is essential. Toninhas do Brasil has already worked with the use of different methods, considered complementary, including satellite tracking, photo-identification, linear transects and, more recently, passive acoustic monitoring.

Understanding how environmental parameters influence franciscanas’ distribution and habitat use is still a challenge, and the project has been incorporating these analyses into its different approaches. Knowing which environments are a priority for conservation is essential.

Toninhas do Brasil was a pioneer in carrying out mark-recapture-release procedures for small cetaceans in the marine environment in Brazil for satellite tracking. The work, carried out in 2011 and 2013, was conducted in partnership with a highly qualified team from the USA and Argentina, led by researchers from the Chicago Zoological Society and Fundación Aquamarina.

Three Toninhas do Brasil researchers aboard a vessel during the visual monitoring of porpoises in Babitonga Bay.

The franciscana is an animal with discreet habits, being difficult to observe in nature. Therefore, much of its behavior is still a mystery to researchers. They don’t usually jump and follow boats, like other dolphin species. In general, franciscanas only show a small part of the head, back and dorsal fin when they rise briefly to the surface to breathe. Most of the time, it is the rostrum that is seen first. However, aerial images have shown that they are very agile in the water, with constant head movements.

Franciscanas are social animals that live in small family groups, with 2 to 5 individuals. It is common to find several groups in the same area while feeding. During the reproductive period, they form monogamous couples.

The sounds produced by franciscanas are very special: they emit ultrasonic clicks (high-frequency pulsed sounds) that are very different from other dolphins. These clicks cannot be heard by humans, but, once recorded, they allow researchers to recognize the species by sound alone due to its distinct pattern. In addition to clicks, franciscanas also have the ability to produce tonal sounds, or whistles, but they are rarely registered.

The sounds are produced by the movement of air in the air sacs and are emitted by the frontal region of the head, known as the melon. In the case of clicks, they bounce off obstacles in the environment and bounce back in the form of echoes, which are then captured by the animal’s jaw and transmitted to the inner ear. From this information, the franciscana is able to produce an acoustic image of the environment around it, similar to an ultrasound exam. Through this process, called echolocation, dolphins are able to find prey and navigate in the ocean.

Toninhas do Brasil has been working in partnership with several artisanal fishing communities on the coast of Santa Catarina, Paraná and São Paulo, as it understands that reducing the mortality of the species requires integrated actions with fishermen. One of the strategies already used in other countries to reduce bycatch in gillnets is the use of acoustic alarms in nets. These devices are intended to alert the franciscanas, reducing the chance of them becoming trapped and dying. The project is a pioneer in Brazil in the use of this technology, which is in the pilot phase, being applied on a small scale, in partnership with artisanal fishermen.

Along with this strategy, the project’s research assistants monitor fishing landings to assess fisheries productivity, fishing effort and the occurrence of bycatch. Through these efforts, the project intends to understand the operational and socioeconomic feasibility of implementing alarms in gillnet fisheries and cooperatively build measures to reduce impacts. Traditional knowledge is also a very important component in the search for solutions, which must encompass a set of strategies.

Porpoise researcher installing an acoustic alarm for porpoises in a research module.

The distribution of franciscanas is directly related to the availability of prey. The main method used to discover the diet of franciscanas is the analysis of stomach contents, taken from franciscana carcasses found dead on beaches.

The fish and squid species that franciscanas feed on are identified by means of structures resistant to digestion, which remain in the stomach, such as fish otoliths and squid beaks. Stable isotope analysis is a complementary approach, as it has contributed immensely to understanding the trophic level and identifying the habitats where franciscanas feed.

Another important aspect that has already been analyzed by the project in Babitonga Bay is the abundance and distribution of prey, through the collecting of fish using various fishing techniques, such as beach seines (or drag nets), gillnets and bottom trawling.

Pesquisadora do Toninhas do Brasil em um laboratório olhando através de um microscópio durante análises de conteúdo estomacal.

The analysis and collection of samples from carcasses of animals found dead on beaches is one of the main methods for obtaining a variety of information about cetaceans around the world. For more than twenty years, Toninhas do Brasil has been recording and collecting carcasses on the beaches of the north coast of Santa Catarina, contributing to generate information on diet, genetics, morphology, toxicology, age, growth and reproduction, among others.

Since 2015, this work has been carried out systematically by the Santos Basin Beach Monitoring Project (PMP-BS), of which UNIVILLE is part of. A large volume of data and samples has been stored through PMP-BS, enabling the advancement of studies on biological parameters. In this sense, the project has contributed significantly to knowledge on reproduction, genetics, age and sexual maturity, among other topics.

However, despite the advances obtained by analyzing carcasses, the intense monitoring activities of PMP-BS also brought to light a sad reality: the mortality of franciscanas has remained exceedingly high in the last seven years, with an average of 550 animals found dead per year. This number does not represent the total, as many carcasses do not end up on the beaches.

Toninhas do Brasil researcher aboard a vessel placing equipment in the water to assess biological parameters.

Information obtained through multiple research approaches is the basis for assessing the impacts that affect franciscanas in the project’s areas of operation.

The assessments are generated considering specific impacts, as well as at an ecosystem level. The goal is to support public entities and decision makers, contributing to establishing conservation strategies. The main lines of research directly involved in this approach include bioacoustics, carcass analysis, toxicology, and the monitoring of bycatch in fisheries.

In Babitonga Bay, for example, the project added data on the distribution of franciscanas to a broad characterization of the underwater acoustic landscape, concluding that franciscanas avoid the noisiest areas, closer to the ports, which end up causing a significant habitat loss for the species.

Toninhas do Brasil researcher on board a vessel with a clipboard and GPS equipment during a field trip.