Rocío Loizaga

National Research Council Argentina (CONICET) · Center for the Study of Marine Systems (CESIMAR-CONICET)

‘Rewilding’ is a nature conservation strategy gaining prominence worldwide. Established in the Northern Hemisphere, rewilding initiatives have increasingly been proposed in Argentina, but their relative merits, feasibility of implementation and accountability have lacked adequate analysis and discussion. Recently, 125 scientists and practitioners w...

Killer whales ( Orcinus orca ) are highly mobile, large marine apex predators that inhabit all oceans. Despite being the most conspicuous top predator, little is known about their ecology along Patagonia, Argentina. Here, we used carbon (δ ¹³ C) and nitrogen (δ ¹⁵ N) isotope analysis of bone and dentine collagen from killer whales ( n = 13) strande...

En los últimos años se han desarrollado en Argentina distintas intervenciones relacionadas con el rewilding (o re-asilvestramiento), abarcando una variedad de especies (e.g., grandes carnívoros, ungulados, psitácidos) y ecorregiones (e.g., Chaco Húmedo y Seco, Estepa Patagónica). El reasilvestramiento es definido como una estrategia aplicada en el...

Ecological information useful for conservation purposes have benefitted from recent and rapid advancements in genetic techniques, revealing unknown aspects of behavior, natural history, population structure and demography of several aquatic mammal species, many of them with conservation concerns. Molecular markers have been used to define managemen...

A key in species conservation is understanding the amount and distribution of genetic diversity and how environmental changes that occurred in the recent past may have influenced current patterns of population structure. Commerson’s dolphin, Cephalorhynchus commersonii, has two subspecies, one of which is endemic to South America (C. commersonii co...

RED LIST ASSESSMENT OF THE MAMMALS OF ARGENTINA 2019: SUMMARY AND ANALYSIS OF THREATS. Assessing the extinction risk of species has become an important decision tool for the implementation of species conservation policies. In this work we summarize the result of the latest oficial categorization of the mammals of Argentina with emphasis on the thre...

Commerson’s dolphins ( Cephalorhynchus commersonii ) are separated into the subspecies C. c. commersonii , found along southern South America (SA) and the Falkland Islands/Islas Malvinas (FI/IM), and C. c. kerguelenensis , restricted to the subantarctic Kerguelen Islands (KI). Following the dispersal model proposed for the genus, the latter is thou...

Diphyllobothriosis caused by the Pacific broad tapeworm Adenocephalus pacificus (syn. Diphyllobothrium pacificum) is an emerging parasitic disease reported also from non‐endemic areas, including Europe (Spain). The origin of these human cases is unknown but should be related to fresh marine fish imported from endemic areas. In this study, we molecu...

The poorly known Clymene dolphin (Stenella clymene) is a small oceanic cetacean distributed in tropical and subtropical waters of the Atlantic Ocean. In this study, we report, for the first time, a vagrant individual of Clymene dolphin in Argentina (Rada Tilly) that represents the current southern-most record for this cetacean species. We provide a...

Difference among colonies in the population structure of otariids can be driven by philopatry and/or by specializa-tions in the foraging ecology of females. In northern Patago-nia, the South American sea lion (SASL) shows some degree of spatial genetic structure among colonies from north and south zones. This study aims to explore the isotopic nich...

This study analyzed mtDNA sequences of two bottlenose dolphin subspecies found along the northern Patagonian coast, Argentina: the endangered Tursiops truncatus gephyreus and the data deficient Tursiops trun-catus truncatus. Three haplotypes were recovered from nine samples. The most frequent haplotype represented the coastal morph, also two haplot...

This study analyzed mtDNA sequences of two bottlenose dolphin subspecies found along the northern Patagonian coast, Argentina: the endangered Tursiops truncatus gephyreus and the data deficient Tursiops truncatus truncatus . Three haplotypes were recovered from nine samples. The most frequent haplotype represented the coastal morph, also two haplot...

Successful conservation strategies require an accurate estimation of population size, and this parameter is one of the most important factors that determine the rate of various evolutionary processes. In this study, we integrated information from genetic, photo-identification, and aerial surveys of dusky dolphins to determine the effective populati...

Natural or human-induced environmental changes can modify the structure of ecological communities and thus alter food web interactions. After the collapse of hake stocks (Merluccius hubbsi) provoked by fisheries over the Patagonian shelf in 1997 profound changes have taken place in the community, including long-term dietary shifts in some marine ve...

Commerson’s dolphin Cephalorhynchus commersonii and Peale’s dolphin Lagenorhynchus australis live in sympatry along the southwestern South Atlantic Ocean, suggesting the existence of some degree of habitat partitioning to reduce their competition for resources. Both species are usually associated with coastal environments, but information on their...

We report on the investigation of a mass stranding of 68 short-beaked common dolphins (Delphinus delphis) that occurred in Golfo Nuevo, Península Valdés, Argentina in March 2018. Twenty-one of the stranded dolphins were returned alive to the sea, while 47 animals died. Dead dolphins included all ages, with more males than females (29 males and 18 f...

D-loop sequences of Otaria flavescens from Northern Patagonia Argentina

Colony formation is related to dispersal, philopatry, conspecific attraction, available suitable habitat, proximity and availability of food resources, and reproductive success. In this study we analyzed if female South American sea lions, (SASL, Otaria flavescens), exhibit natal fidelity at a small geographic scale (between colonies of the same br...

The South American sea lion (Otaria flavescens) is widely distributed along the southern Atlantic and Pacific coasts of South America with a history of significant commercial exploitation. We aimed to evaluate the population genetic structure and the evolutionary history of South American sea lion along its distribution by analyses of mitochondrial...

List of individuals that bear each mitochondrial DNA control region haplotype, and the respective GenBank number. Absolute frequency in the sample and geographic distribution of haplotypes for South American sea lion. (DOCX)

List of individuals that bear each mitochondrial DNA cytochrome b haplotype. Absolute frequency in the sample and geographic distribution of haplotypes for South American sea lion. (DOCX)

Extended Bayesian skyline plot showing the effective population size fluctuation of South American sea lions populations throughout time based on the mtDNA control region. Internal dashed lines are median estimates and thin lines and coloured areas are the 95% Central Posterior Density (CPD) intervals. Nef, effective female population size (log sca...

Extended Bayesian skyline plot showing the effective population size fluctuation of South American sea lions populations throughout time based on the mtDNA control region. Internal black dashed lines are median estimates and thin lines are the 95% CPD intervals. Thin green lines are the individual population trajectories. Nef, effective female popu...

Species and access number of sequences downloaded from GenBank used to estimate the Bayesian phylogeny (Fig 3). (DOCX)

Genetic diversity of South American sea lions for each locus per clustered localities and for the species as whole. (A) Number of alleles, (E) = exclusive alleles, (Ho) observed heterozygosity, (He) expected heterozygosity.* Loci that deviated from HW equilibrium after Bonferroni correction. (DOCX)

Plots from STRUCTURE HARVESTER performed with Evanno’s method. (A) Highest value of (ΔK) = 79.20 on K = 2. (B) Mean of estimated Ln probability of data (± sd) averaging ten runs from K = 1 to K = 10. (TIF)

STRUCTURE bar plot from the test for migrants or hybrids between oceans using the sampling locations (in this case the ocean basin) and the USEPOPINFO model. Each bar is one individual and each colour represents the assignment probability of the individual to belong to that genetic cluster. (TIF)

As the feeding habits of marine mammals are particularly difficult to observe, stable isotope analysis has become an essential tool to investigate several aspects of dolphin's trophic ecology. Short-beaked common dolphins (Delphinus delphis) occur off Argentina coastline from 36°S to 42°S, but nothing is known about latitudinal changes in diet. A s...

The taxonomy of common dolphins (Delphinus sp.) has always been controversial, with over twenty described species since the original description of the type species of the genus (Delphinus delphis Linnaeus, 1758). Two species and four subspecies are currently accepted, but recent molecular data have challenged this view. In this study we investigat...

The taxonomy of common dolphins (Delphinus sp.) has always been controversial, with over twenty described species since the original description of the type species of the genus (Delphinus delphis Linnaeus, 1758). Two species and four subspecies are currently accepted, but recent molecular data have challenged this view. In this study we investigat...

The dusky dolphin Lagenorhynchus obscurus occurs in the Southern Hemisphere, where it is restricted to coastal temperate areas. This study aimed to characterize the feeding ecology of dusky dolphins inhabiting northern and central Patagonia by using δ¹³C and δ¹⁵N stable isotope ratios in skin samples. We searched for evidence of geographical and se...

The dusky dolphin ( Lagenorhynchus obscurus ) represents one of the most abundant species of small cetacean in Argentine waters. During the 1980s and 1990s, high levels of incidental mortality in purse and trawl fisheries were documented, and in recent decades tourism activities have been added as a potential source of disturbance. The study object...

The dusky dolphin, Lagenorhynchus obscurus, is a coastal small cetacean widespread in the southern hemisphere. Here, we present the first record of cestode parasites present in the blubber of dusky dolphin off Argentine coast. The host examined, corresponded to a 15 years old mature female and measured 171 cm long. Cysts of helminths belonging to C...

Commerson's dolphins, Cephalorhynchus commersonii, suffer bycatch in fisheries and are target of dolphin-watching activities along Patagonia. Here we described dolphins' habitat use and behavioural pattern at the estuary of Santa Cruz River. Behavioural observations were made from vantage points using a spotting scope. Boat surveys were conducted r...

Commerson’s dolphins, Cephalorhynchus commersonii, suffer bycatch in fisheries and are target of dolphin-watching activities along Patagonia. Here we described dolphins’ habitat use and behavioural pattern at the estuary of Santa Cruz River. Behavioural observations were made from vantage points using a spotting scope. Boat surveys were conducted r...

Interactions between killer whales and sea lions are widely known. This work describes the predator-prey behaviour of killer whales and South American sea lion associated with a trawling fishery. In Argentina the predatory behaviours of killer whales and anti-predatory behaviours of South American sea lions have been described from costal based obs...

In recent years, analysis of tissue samples has become a powerful tool in cetacean ecology since it provides information for effective conservation and management policies. Biopsy samples taken for such studies have been obtained by various means including crossbows, rifles, and pole systems. We investigated sampling success and the reaction of dus...

Interactions between killer whales and sea lions are widely known. This work describes the predator-prey behaviour of killer whales and South American sea lion associated with a trawling fishery. In Argentina the predatory behaviours of killer whales and anti-predatory behaviours of South American sea lions have been described from costal based obs...

We present a new record of sperm whale with notes on diet, age determination and a review of strandings along the continental Argentine coast. A complete necropsy was made in the field, and morphometric data were taken. The specimen stranded was a mature male of 64+ years old. This is the oldest specimen determined for a sperm whale in the Southwes...

Several major breeding areas have been defined for the South American sea lion (Otaria flavescens) along the Atlantic Ocean including the Uruguayan and Patagonian coasts. Together with a documented and severe reduction in population sizes caused by commercial hunting in the last century, these areas show opposite population trends. While Patagonian...

Most aquatic mammals have high dispersal potential, and there are often severe conservation concerns related to their legal or illegal harvesting. Therefore, economic, social and forensic factors often arise in decisions relating to their population management. Molecular markers are essential tools in modern conservation genetics, revealing previou...

The striped dolphin, Stenella coeruleoalba (Meyen, 1833), is a pelagic small cetacean with primary distribution in tropical and subtropical waters. Here, we present a record of a vagrant individual of striped dolphin in Patagonia, out of its distribution range. The animal was 1 year old, measured 148 cm. and weighted 35 Kg. The specimen was classif...