Latin American Journal of Aquatic Mammals (LAJAM)
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Feeding ecology of the franciscana (Pontoporia blainvillei) in marine and estuarine waters of Argentina
No full textStomach contents of 110 franciscanas (Pontoporia blainvillei), from northern Argentina were analysed in order to improve our knowledge about the feeding habits of this species and to better characterise the lactation period. The samples included calves, juveniles and adults of both sexes. Evidence of predation by franciscanas is seen at a very young age (2.5-3 months), with a transition diet composed by both milk and solid food, mainly represented by crustaceans. Weaning seems to begin by April, when franciscanas are about 6-7 months old. Franciscanas inhabiting two different habitats were analysed in this study: a brackish water estuary and an adjacent marine coastal system. The diet of Pontoporia blainvillei in northern Argentina was composed by a total of 26 prey species: 20 teleosts, 4 crustaceans and 2 cephalopods. Based on the Index of Relative Importance (IRI) the main prey species were Cynoscion guatucupa, Micropogonias furnieri, Loligo sanpaulensis and Urophycis brasiliensis. Estuarine franciscanas preyed mainly on Micropogonias furnieri (dominant species), Cynoscion guatucupa, Odonthestes argentinensis and Macrodon ancylodon, while dolphins from marine areas preyed mainly on Cynoscion guatucupa (dominant species), Loligo sanpaulensis and Urophycis brasiliensis. Our results confirm that franciscanas prey mainly on juvenile fish (<8cm) and small loliginid squids, in close agreement with previous results obtained in southern Brazil and Uruguay. Qualitative and quantitative differences observed in the diet of dolphins from each habitat emphasise the need to discriminate between samples from different habitats and environmental parameters
Records of franciscana (Pontoporia blainvillei) from the coastal waters of São Paulo State, southeastern Brazil
No full textLittle is known about franciscana (Pontoporia blainvillei) in the coastal waters of São Paulo State (~23-25° S), Brazil. This is due to the lack of long-term research efforts directed towards this species. The data presented in this paper reflect the efforts of three research groups in collecting information from marine mammal stranding events along portions of São Paulo State coast. Data from 109 records, mostly of single stranding events (n=98), are presented. Ten individuals that were captured incidentally by gillnets were obtained from local fishermen. One calf was caught by a swimmer in shallow waters and released after four hours. The number of reported strandings was not evenly distributed throughout the year with more strandings being reported during summer, spring and winter months than in the autumn. Calves (n=28) were reported year-round with no significant seasonal differences. Six live strandings of calves were reported. Five of these calves died shortly after being held in small pools and one was released alive in coastal waters. Because of recent efforts in research and recovering of a relatively high number of dead animals, the easy accessibility to carcasses and local logistics, the central region of São Paulo State coast, known as 'Baixada Santista', offers the best potential to better develop P. blainvillei research
Report of the Fourth Workshop for the Coordinated Research and Conservation of the Franciscana Dolphin (Pontoporia blainvillei) in the Western South Altantic
No full textReport of the Fourth Workshop for the Coordinated Research and Conservation of the Franciscana Dolphin (Pontoporia blainvillei) in the Western South Altanti
Parasites of franciscana (Pontoporia blainvillei) from São Paulo and Paraná States, Brazil
No full textThe franciscana, Pontoporia blainvillei, is a threatened small cetacean of the western South Atlantic Ocean and is commonly caught incidentally in fishing nets along its distribution. Detailed studies regarding parasite loads of P. blainvillei have been recommended as a tool to evaluated ecological segregation and stock structure. We analyzed metazoan parasites from stomach, intestines and lungs of 41 franciscanas from three close geographical areas: Group 1, Guarujá and Praia Grande (São Paulo State), n=12 (24° 00'S, 46° 17'W); Group 2, Cananéia (São Paulo State), n=17 (25° 00'S, 47° 56'W); Group 3, Paraná State, n=12 (25° 30'S, 48° 23'W). The sample consists mainly of immature specimens, less than 3 years old. No parasites were found in the lungs analyzed. The acanthocephalan (Polymorphus sp.) found in two stomachs were considered occasional. The trematode Hadwenius pontoporiae (Digenea: Campulidae) was the only parasite found in the intestines with prevalence of 100%; for Group 1, 82.35%; for Group 2 and 58.33%; for Group 3. The mean intensity of H. pontoporiae for Groups 1, 2 and 3 was 39.5, 25.05 and 13.5 parasites per host, respectively. In this study there was a significant difference between the number of parasites among the three groups (Kruskal-Wallis test, p=0.012). Groups 2 and 3 are geographically close, and exhibited non-significant differences in the total number of parasites found (Mann-Whitney test, p=0.063). Groups 1 and 3, that are further apart geographically, differed significantly in the total number of parasites found (Mann-Whitney test, p=0.003). Through the analysis of data from the areas where H. pontoporiae was found [i.e. Areas 1, 2, 3 (this study), Rio Grande do Sul State and Argentina], it could be noticed that the prevalence and mean intensity increase as latitude increases. H. pontoporiae may continue to be useful as a biological tag for identifying franciscana's ecological stocks, together with information from genetic, morphometric and other biological studies. However, it is essential that standardized methodology be used in the collection of the parasite data
Size and shape variability in the skull of Pontoporia blainvillei (Cetacea: Pontoporiidae) from the Brazilian coast
No full textThe existence of sexual dimorphism in Pontoporia blainvillei has long been known, with females being larger than males. However, no study so far has explored this dimorphism separately in its size and shape components. Here we analyse sexual dimorphism present in eight linear measurements of the skulls of 56 specimens (30 females and 26 males) of P. blainvillei from several localities along the Brazilian coast. We also investigate the sexual dimorphism in size and shape using geometric morphometric techniques, employing a subsample of the specimens above consisting of 27 skulls (12 females and 15 males). The analysis was based on landmarks digitized in four views of the skull: dorsal, ventral, lateral and occipital. A PCA showed the existence of two distinct populations, thus requiring the separation of two samples for the analysis of the effects of sexual dimorphism. Results of traditional and geometric morphometrics analyses revealed no sexual dimorphism in shape. All differences observed between the sexes are size related, with females bigger than males. Shape, however, is an important factor in the differentiation of at least two populations of this species
Incidental catches of franciscana (Pontoporia blainvillei) on the southern coast of São Paulo State and the coast of Paraná State, Brazil
No full textA total of 40 individuals of P. blainvillei, incidentally caught on the southern coast of São Paulo State (region of Cananéia) (25°00'S, 47°54'W and 25°04'S, 47°56'W) and on the coast of Paraná State (25°18'S, 48°05'W and 25°58'S, 48°35'W), were recorded between 1997 and 1999. The average mortality of franciscanas incidentally caught by the only fishing boat sampled on the southern coast of São Paulo State, which operated up to 40 nautical miles (nm) from the coast, was 11 individuals/year, with a proportion of 2.3 males for every female. An average mortality of 10 franciscanas/year was estimated for several artisanal fishing communities sampled on the coast of Paraná State, where fishing activities usually are not further than 5nm from the coast. There was no significant difference (P>0.05) between the proportion of males and females incidentally caught by the artisanal fisheries on the Paraná coast. The proportion of sexually immature franciscanas reached 55%; in southern São Paulo State, compared with 76.2%; for the coast of Paraná. Bottom-set gillnets, with a stretched mesh size of 7.0 and 13.0cm, recorded the greatest number of individuals incidentally caught in the Cananéia region. However, on the Paraná coast, the greatest number of franciscanas was incidentally caught in driftnets with a stretched mesh size of 10.0cm. Comparing these mesh sizes with those presented in the literature for franciscanas incidentally caught in other places, it seems that other fishery characteristics (e.g. distance from the coast, depth, fishing effort, and season) are more important than the mesh size itself. The predominance of captured males in the fisheries further away from the coast, and the greatest proportion of sexually immature franciscanas incidentally caught in the fisheries closer to the coast, suggest spatial segregation between some age groups and sexes for this species in the study area. The results also suggest that the fisheries with industrial fishing characteristics, carried out by the boats in the Cananéia region, could be causing a strong impact on the populations of P. blainvillei. This means that a continuous surveillance of fishing activity is necessary for a greater period, including as many boats as possible, in order to certify the mortality estimates in that region
DNA extraction from formalin fixed franciscana tissues
No full textThe present paper reports the extraction of DNA from formalin-fixed Pontoporia blainvillei tissues. Following the Vachot and Monerot (1996) protocol, fragmented DNA (300-700bp) was extracted from more than 95% of liver and muscle samples. DNA yield in liver samples was significantly higher than in muscle samples (4.574 ± 1.169mg DNA/mg versus 0.808 ± 0.297mg DNA/mg). Similar results were obtained from nine other species of cetaceans and five species of pinnipeds. It is of special interest to have a method that allows the utilisation of museum specimens not originally preserved for genetic studies, which may include rarely available, declining or extinct species
Incidental mortality of franciscana (Pontoporia blainvillei) in the artisanal fishery of Praia Grande, São Paulo State, Brazil
No full textThe artisanal fishery in Praia Grande, São Paulo State, southeastern Brazil, was monitored between August 1998 and June 2001 through interviews with fishermen and onboard observations. The objective was to describe the fleet, the gear and the fishing activities, and to monitor the bycatch of small cetaceans. The Praia Grande fishing community has 20 fishermen who operate five aluminum and one wooden open boat. Seven types of gillnet and one beach seine net are used. Nets are made of nylon monofilament; net length and height range from 60-1800m and 1.5-10m, respectively. Mesh sizes vary from 7-30cm. Each type of net is set up according to target species and weather conditions. Fish of the families Sciaenidae, Carangidae, Carcharhinidae, Trichiuridae and Ariidae are the main species captured. The incidental mortality of 31 franciscanas was recorded. Thirteen specimens were collected: 8 males (106-122cm) and 5 females (71-134cm). Captures took place in depths of up to 20m and along 31km of the coast. Catch per unit of effort for the period July 1999-June 2001 indicated a higher mortality in autumn and in gillnets with 14cm stretched mesh size ('malha 14') Three franciscanas were captured and released alive from beach seine nets. Several fishing communities with similar operational methods along the southeastern coast of Brazil remain unmonitored. This suggests that franciscana mortality may be substantial on a regional basis and emphasizes the urgency of systematic monitoring