Intrapopulation variation in the diet of franciscana dolphin (Pontoporia blainvillei) off southern Brazil

2021 ◽  
pp. 1-17
Author(s):  
Manuela Bassoi ◽  
Eduardo R. Secchi ◽  
Daniel Danilewicz ◽  
Ignacio B. Moreno ◽  
Roberta A. Santos ◽  
...  
Keyword(s):  
Sexual Maturity ◽  
Linear Models ◽  
Prey Species ◽  
Prey Availability ◽  
Prey Selection ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Brazilian Coast ◽  
Pontoporia Blainvillei ◽  
Franciscana Dolphin

Abstract 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 its distribution, movements and use of habitat, which are fundamental for effective management of the species. The feeding habits of franciscana dolphins were investigated from analyses of stomach contents of animals incidentally caught by two fishing operations from southern and northern regions of the southern Brazilian coast. In this study we investigate the existence of intrapopulation (sexual maturity and sex-related) variation in the diet of the franciscana dolphin, evaluating the spatial (northern and southern geographic areas) and seasonal influences. The analyses were based on Linear and Generalized Linear Models (LM and GLM). The majority of identified prey species were bottom-dwelling teleosts and the squid Doryteuthis sanpaulensis. The most important prey differed spatially and seasonally between northern and southern regions of the study area, and our results revealed significant differences between sexes and sexual maturity stages, mainly related to prey species sizes. This variation might indicate differences in prey selection, availability or habitat use patterns among these groups. In any case, these dietary differences are likely to minimize intraspecific competition for food resources, and/or indicate spatio-temporal variation in prey availability.

scholarly journals Feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil

2020 ◽  
Vol 100 (2) ◽  
pp. 301-313
Author(s):  
Laura Busin Campos ◽  
Xênia Moreira Lopes ◽  
Ednilson da Silva ◽  
Marcos César de Oliveira Santos
Keyword(s):  
Feeding Habits ◽  
Stomach Contents ◽  
Small Fish ◽  
South Eastern ◽  
Important Prey ◽  
Fishing Vessels ◽  
Eastern Brazil ◽  
Significant Difference ◽  
Pontoporia Blainvillei ◽  
Franciscana Dolphin

AbstractThis study evaluated the feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil. Stomach contents were collected from a total of 145 dead specimens found incidentally caught by fishing vessels or stranded between 2005 and 2015. Fish otoliths, cephalopod beaks and whole non-digested prey were used for prey species identification. A total of 9337 prey items were identified, including 26 species of teleost fishes and three species of cephalopods. The most important prey families were Sciaenidae among fish and Loliginidae among cephalopods. Franciscana dolphins tended to feed on small fish (mean = 5.25 cm) and cephalopods (mean = 8.57 cm). The index of relative importance (IRI) showed that Pellona harroweri and Doryteuthis plei were the most important prey for both males and females. The PERMANOVA test confirmed that there is no significant difference between the feeding habits of different sexes, but detected a significant difference among seasons. Overall, our results show that franciscana dolphins are predominantly ichthyophagous and non-selective in relation to the type of prey, feeding on pelagic, demersal and pelagic-demersal prey.

Diet and prey selection dynamics of Cancer polyodon in three different habitat types in Tongoy Bay, Chile

2004 ◽  
Vol 84 (4) ◽  
pp. 751-756 ◽  
Author(s):  
Rafael I. León ◽  
Wolfgang B. Stotz
Keyword(s):  
Prey Species ◽  
Prey Availability ◽  
Prey Selection ◽  
Feeding Habits ◽  
Habitat Types ◽  
Important Prey ◽  
Selection Dynamics ◽  
Argopecten Purpuratus ◽  
Sea Grass ◽  
Main Factors

Feeding dynamics of Cancer polyodon was studied, by comparing the diets of three size-classes of the crab to environmental abundance of prey species in three habitats in Tongoy Bay, Chile (30°S). In the sea grass and sand–gravel habitats cannibalism was observed, the small C. polydon being actively selected as the main prey in spite of their lower abundance compared with other crustaceans. In the mud habitat the scallop Argopecten purpuratus was the most important prey, being actively selected although occurring at low relative abundance. Cancer polyodon showed plasticity in feeding habits, adapting to differential prey availability, but always selecting certain species independently of their abundance in each habitat. Accessibility, more than the abundance of the prey, seem to be the main factors influencing prey selection.

scholarly journals Prey consumed by Guiana dolphin Sotalia guianensis (Cetacea, Delphinidae) and franciscana dolphin Pontoporia blainvillei (Cetacea, Pontoporiidae) in an estuarine environment in southern Brazil

2012 ◽  
Vol 102 (2) ◽  
pp. 131-137 ◽  
Author(s):  
Marta J. Cremer ◽  
Pedro C. Pinheiro ◽  
Paulo C. Simões-Lopes
Keyword(s):  
Prey Species ◽  
Stomach Contents ◽  
Frequency Of Occurrence ◽  
Teleost Fishes ◽  
Southern Brazil ◽  
Sympatric Populations ◽  
Sotalia Guianensis ◽  
Important Prey ◽  
Pontoporia Blainvillei ◽  
Lolliguncula Brevis

The present study provides information about the diet of sympatric populations of small cetaceans in the Babitonga Bay estuary. This is the first study on the diet of these species in direct sympatry. The stomach contents of seven Guiana dolphins Sotalia guianensis and eight franciscanas Pontoporia blainvillei were analyzed. The prey of both cetaceans was mostly teleost fishes, followed by cephalopods. We identified 13 teleost fishes as part of the diet of the franciscanas, and 20 as part of the diet of Guiana dolphins. Lolliguncula brevis was the only cephalopod recorded, and was the most important prey for both cetaceans. Stellifer rastrifer and Gobionellus oceanicus were also important for franciscana, so as Mugil curema and Micropogonias furnieri were important for Guiana dolphins. Stellifer rastrifer and Cetengraulis edentulus were the fishes with the highest frequency of occurrence for franciscana (50%), while Achirus lineatus, C. edentulus, S. brasiliensis, Cynoscion leiarchus, M. furnieri, M. curema, Diapterus rhombeus, Eugerres brasilianus and G. oceanicus showed 28.6% of frequency of occurrence for Guiana dolphins. Franciscanas captured greater cephalopods than the Guiana dolphins in both total length (z= -3.38; n= 40; p< 0.05) and biomass (z = -2.46; n = 40; p<0.05). All of the prey species identified occur inside the estuary, which represents a safe habitat against predators and food availability, reinforcing the importance of the Babitonga Bay for these cetacean populations.

Comparison between the feeding habits of spotted eagle ray (Aetobatus narinari) and their potential prey in the southern Gulf of Mexico

2018 ◽  
Vol 99 (3) ◽  
pp. 661-672 ◽  
Author(s):  
F. Serrano-Flores ◽  
J.C. Pérez-Jiménez ◽  
I. Méndez-Loeza ◽  
K. Bassos-Hull ◽  
M.J. Ajemian
Keyword(s):  
Gulf Of Mexico ◽  
Prey Species ◽  
Prey Availability ◽  
Feeding Habits ◽  
Small Scale ◽  
Potential Prey ◽  
Important Prey ◽  
Ecological Aspects ◽  
Southern Gulf Of Mexico ◽  
Spotted Eagle Ray

In the southern Gulf of Mexico, the spotted eagle ray (Aetobatus narinari) is the second most frequently caught batoid in small-scale fisheries off Campeche. Ecological aspects of this ray are unknown in this region, hampering the understanding of the relationship between its distribution and prey availability in the fishing area. In order to study the feeding habits of this batoid and characterize its potential prey in the study area, stomachs and intestines of 154 specimens (68 females and 86 males) were analysed. The results indicated that A. narinari near Campeche is a specialist and selective predator that feeds mainly on gastropods (92.7% IRI), with no significant differences in the diet found between sexes, size groups, or between stomach and intestine contents. In addition, the results indicated that the most important prey species in the diet were among the most common benthic species in three of the four sampling transects positioned in or adjacent to fishing areas for rays. These most important prey species were Strombus pugilis (53.33% IRI) and Americoliva reticularis (25.6% IRI). Other prey species included Lobatus costatus (5.6% IRI) and Petrochirus diogenes (3.6% IRI). This study suggests that this widely distributed ray species feeds in Campeche's coastal waters and that the study of its potential prey increases the understanding of ecological aspects of the species, which emphasizes the added importance of monitoring fishery impacts on prey species (e.g. the conch fishery off Campeche) to help support integrated assessment and management of fisheries.

scholarly journals Finless porpoises (Neophocaena asiaeorientalis) in the East China Sea: insights into feeding habits using morphological, molecular, and stable isotopic techniques

2017 ◽  
Vol 74 (10) ◽  
pp. 1628-1645 ◽  
Author(s):  
Bingyao Chen ◽  
Lin Wang ◽  
Hui Wang ◽  
Shanshan Li ◽  
Thomas A. Jefferson ◽  
...  
Keyword(s):  
East China Sea ◽  
Prey Species ◽  
Trophic Position ◽  
Feeding Habits ◽  
Stomach Contents ◽  
East China ◽  
The East China Sea ◽  
Stable Isotopic ◽  
Short And Long Term

Describing feeding habits of cetaceans is crucial to understanding their feeding strategies and conservation status. Here, both morphological and molecular techniques were employed to identify the stomach contents of 122 finless porpoises (Neophocaena spp.) in the East China Sea for insight into their short-term feeding habits, and stable isotopes of δ13C and δ15N were used to analyze prey resource use and trophic position as a manifestation of their long-term feeding habits. In total, 33 prey species consisting of 19 teleosts, seven crustaceans, five cephalopods, and two gastropods were identified. In both short- and long-term analyses, teleosts represented primary prey, cephalopods and crustaceans were secondary prey, and gastropods were occasional prey; but the primary prey species composition differs between the short- and long-term diets. The composition of stomach contents showed sexual and age-related variation. This finding is supported by stable isotopic analyses, which indicated the separation of trophic position of adult males, adult females, and young males. In general, finless porpoises prey on species that are primarily caught by fisheries.

scholarly journals On the feeding habit of the Guiana Dolphin Sotalia guianensis (van Bénedèn, 1864) (Mammalia: Cetartiodactyla: Delphinidae) in southeastern Brazil (~220S): has there been any change in more than two decades?

2017 ◽  
Vol 9 (2) ◽  
pp. 9840 ◽  
Author(s):  
Ana Paula Madeira Di Beneditto ◽  
Clara Da Cruz Vidart Badia ◽  
Salvatore Siciliano
Keyword(s):  
Prey Species ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Southeastern Brazil ◽  
Feeding Preferences ◽  
Sotalia Guianensis ◽  
The North ◽  
Trichiurus Lepturus ◽  
Janeiro State ◽  
Guiana Dolphin

Along the north and central coast of Rio de Janeiro State (22025’S–23000’S), southeastern Brazil, the Guiana Dolphin Sotalia guianensis forages on neritic prey, mainly fish.  From the analysis of the dolphin’s stomach contents and the identification of partially digested prey, it was verified that the most frequent prey species were young specimens of Trichiurus lepturus.  Comparing our results with previous studies on the feeding habits of Guiana Dolphin in the same region, we noticed the maintenance of its feeding preferences during more than two decades, indicating little or no change in the use of prey by this top predator. 

Feeding habits of John Dory, Zeus faber, off the Portuguese continental coast

1999 ◽  
Vol 79 (2) ◽  
pp. 333-340 ◽  
Author(s):  
Alexandra Silva
Keyword(s):  
Prey Species ◽  
Feeding Habits ◽  
Parallel Evolution ◽  
Stomach Contents ◽  
Abundant Species ◽  
Temporal Variations ◽  
Food Composition ◽  
Diet Shift ◽  
Feeding Intensity ◽  
Zeus Faber

The feeding habits of John Dory (Zeus faber) were studied, based on the analysis of stomach contents from fish sampled in five groundfish surveys. These surveys were carried out off the Portuguese coast during different seasons between 1990 and 1992. The main aspects of feeding biology analysed in this paper are: ontogenetic diet changes, temporal variations in food composition and feeding intensity. Multivariate methods were used to investigate ontogenetic diet shifts. Two main length groups were identified: 8.0–24.9 cm fish, feeding mainly on dragonets and silvery pout, and 25.0–55.9 cm fish whose diet was mainly composed of blue whiting and snipefish. A transitional phase (24.0–30.9 cm fish) with a mixed food composition was observed. This ontogenetic diet shift does not seem to correspond to any important change in body morphology but it does coincide with the onset of sexual maturity in the species.John Dory switched from a diet of small prey species with more pronounced benthic behaviour to a diet of larger schooling pelagic species. This suggests parallel evolution to more pelagic foraging behaviour. However, John Dory feeding habits appear to be largely controlled by the availability and accessibility of prey species: (i) the diet of adult John Dory is dominated by very abundant species; (ii) shifts in the main prey items between different times of the year and between different areas seem to be related both with their absolute and relative abundance in the environment and with the overlap between the depth distribution of predator and prey.

Feeding ecology of the southern thorny skate,Amblyraja doellojuradoion the Argentine Continental Shelf

2013 ◽  
Vol 93 (8) ◽  
pp. 2207-2216 ◽  
Author(s):  
G.E. Delpiani ◽  
M.C. Spath ◽  
D.E. Figueroa
Keyword(s):  
Continental Shelf ◽  
Generalized Linear Models ◽  
Feeding Ecology ◽  
Sexual Maturity ◽  
Linear Models ◽  
Feeding Habits ◽  
Benthic Fauna ◽  
Relative Importance ◽  
The North ◽  
Index Of Relative Importance

The feeding ecology of the southern thorny skate,Amblyraja doellojuradoi, on the Argentine Continental Shelf was evaluated using generalized linear models.Amblyraja doellojuradoipreyed mainly on crabs (85.41% index of relative importance (IRI)) and to a lesser extent on polychaetes (4.98% IRI), teleosts (3.28% IRI), isopods (2.03% IRI), other crustaceans (1.52% IRI) and other invertebrates (2.78% IRI). As individuals increased in size, the consumption of crabs also increased and the consumption of polychaetes and other invertebrates decreased. The study area was divided into a northern (36°–43°S) and a southern (43°–50°S) region. Regarding the latitude of capture, it was observed thatA. doellojuradoimainly fed on crabs in the north and on fish, isopods and other crustaceans in the south. Females ofA. doellojuradoihad a stronger preference for fish and isopods than males. As to sexual maturity, immatures fed more on polychaetes and other crustaceans than did mature. The ontogenetic change in feeding habits could be attributed to body size and an increasing ability to capture larger prey, rather than to food availability. However, this point cannot be confirmed because little is known about the benthic fauna of this area.

scholarly journals Stranded dolphin stomach contents represent the free-ranging population's diet

2013 ◽  
Vol 9 (3) ◽  
pp. 20121036 ◽  
Author(s):  
Glenn Dunshea ◽  
Nélio B. Barros ◽  
Elizabeth J. Berens McCabe ◽  
Nicholas J. Gales ◽  
Mark A. Hindell ◽  
...  
Keyword(s):  
Bottlenose Dolphin ◽  
Prey Species ◽  
Prey Selection ◽  
Stomach Contents ◽  
Molecular Data ◽  
Habitat Associations ◽  
Fundamental Aspect ◽  
Dolphin Population ◽  
Free Ranging

Diet is a fundamental aspect of animal ecology. Cetacean prey species are generally identified by examining stomach contents of stranded individuals. Critical uncertainty in these studies is whether samples from stranded animals are representative of the diet of free-ranging animals. Over two summers, we collected faecal and gastric samples from healthy free-ranging individuals of an extensively studied bottlenose dolphin population. These samples were analysed by molecular prey detection and these data compared with stomach contents data derived from stranded dolphins from the same population collected over 22 years. There was a remarkable consistency in the prey species composition and relative amounts between the two datasets. The conclusions of past stomach contents studies regarding dolphin habitat associations, prey selection and proposed foraging mechanisms are supported by molecular data from live animals and the combined dataset. This is the first explicit test of the validity of stomach contents analysis for accurate population-scale diet determination of an inshore cetacean.

scholarly journals Integrating disparate datasets to model the functional response of a marine predator: a case study of harbour porpoises in the southern North Sea

2021 ◽  
Author(s):  
Janneke Ransijn ◽  
Phillip Hammond ◽  
Mardik Leopold ◽  
Signe Sveegaard ◽  
Sophie Smout
Keyword(s):  
Functional Response ◽  
North Sea ◽  
Prey Species ◽  
Prey Availability ◽  
Stomach Contents ◽  
Prey Consumption ◽  
Predator Species ◽  
Marine Predator ◽  
Southern North Sea ◽  
Foraging Range

1. Quantifying consumption and prey choice for marine predator species is key to understanding their interaction with prey species, fisheries, and the ecosystem as a whole. However, parameterising a functional response for large predators can be challenging because of the difficulty in obtaining the required datasets on predator diet and the availability of multiple prey species. 2. This study modelled a Multi-Species Functional Response (MSFR) to describe the relationship between consumption by harbour porpoises (Phocoena phocoena) and the availability of multiple prey species in the southern North Sea. Bayesian methodology was employed to estimate MSFR parameters and to incorporate uncertainties in diet and prey availability estimates. Prey consumption was estimated from stomach contents data of stranded harbour porpoises. Prey availability to harbour porpoises was estimated based on the spatial overlap between prey distributions, estimated from fish survey data, and porpoise foraging range in the days prior to stranding predicted from telemetry data. 3. Results indicated a strong preference for sandeel in the study area. Prey switching behaviour (change in preference dependent on prey abundance) was confirmed by the favoured Type III functional response model. Variation in the size of the foraging range (estimated area where harbour porpoises could have foraged prior to stranding) did not alter the overall pattern of the results or conclusions. 4. Integrating datasets on prey consumption from strandings, predator foraging distribution using telemetry and prey availability from fish surveys into the modelling approach provides a methodological framework that may be appropriate for fitting MSFRs for other predators.

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