The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-... more The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-western Atlantic Ocean. Incidental captures in fishing gillnets is possibly the greatest conservation concern for this species, and occurs within most of its geographical distribution. The aim of this paper is to determine the biological parameters of franciscana dolphin by-caught from artisanal coastal fisheries of the southern Buenos Aires province, Argentina. Between 2003 and 2009, carcasses of 54 incidentally captured franciscanas were collected. The age, sexual and physical maturity and body condition of each specimen was determined. The sex-ratio of the by-caught dolphins did not differ from parity and, consistent with other areas, juveniles younger than 4 yr old were captured in higher proportion (69%). In addition, 74% of the entangled animals were sexually immature and 85% physically immature. Sexually immature dolphins were predominant in the spring, a period which coincides with the breeding season. An assessment of the body condition of captured franciscanas suggests that entanglements were not associated with a disease or physiological disorder. The results presented here are important to assess the impact of artisanal fisheries on the population of franciscana dolphins in the southernmost area of its distribution.
Mammalian Biology - Zeitschrift für Säugetierkunde, 2014
Please cite this article in press as: Giardino, G.V., et al., Travel for sex: Long-range breeding... more Please cite this article in press as: Giardino, G.V., et al., Travel for sex: Long-range breeding dispersal and winter haulout fidelity in southern sea lion males. Mammal. Biol. (2014), http://dx.a b s t r a c t Southern sea lions (Otaria flavescens; SSLs) have a polygynous mating system and a prolonged socialsexual maturation period for males. Male haulouts are common in this species, with some very distant from central breeding rookeries, although the functions of these aggregations are not clearly understood. To estimate the potential connectivity between northern Argentina male colonies and breeding rookeries in Patagonia and Uruguay, we monitored the summer breeding activities and winter presence of 559 individually identified SSL males from haulouts in Mar del Plata and Quequén harbors. Our results confirm that male groups are formed by sexually active sea lions that show a strong annual connection with distant (up to 700 km) breeding colonies. Circa 70% of the marked males made long-distance round-trips (72 ± 26.7 days; n = 325) from northern Argentina to Patagonia and Uruguay, indicating a high degree of winter site fidelity. Mating activity was confirmed for 53% of the sea lions re-sighted in breeding colonies, with approximately 80% of them having central positions on the beach and holding harems of up to nine females. The chronology of this cycle is finely tuned with the onset of the breeding season, which may result in comparative advantages such as anticipating female arrival or a prolonged participation in mating activities. Our results suggest a model of male haulouts spatially segregated from the central breeding areas, but with a summer recurrent flow of animals that contributes a significant proportion of the male population of northern Patagonia and Uruguay.
The present study provides information about the diet composition of franciscana dolphin, Pontopo... more The present study provides information about the diet composition of franciscana dolphin, Pontoporia blainvillei, from southern Buenos Aires coast, Argentina. From 2003 to 2011 we collected 66 franciscana dolphins that were incidentally entangled in artisanal fishing nets. We analyzed the stomach contents and estimated the prey size in order to evaluate the diet composition and the overlapping with fisheries. We identified 11 prey species in the stomach contents; only two of them were important in the diet, the striped weakfish, Cynoscion guatucupa, and the squid, Loligo sanpaulensis. Almost all the prey found in the diet of franciscana dolphins are of commercial interest. The overlapping of target species and prey that are subject to overfishing could enhance the vulnerability of franciscana by reducing food availability.
The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-... more The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-western Atlantic Ocean. Incidental captures in fishing gillnets is possibly the greatest conservation concern for this species, and occurs within most of its geographical distribution. The aim of this paper is to determine the biological parameters of franciscana dolphin by-caught from artisanal coastal fisheries of the southern Buenos Aires province, Argentina. Between 2003 and 2009, carcasses of 54 incidentally captured franciscanas were collected. The age, sexual and physical maturity and body condition of each specimen was determined. The sex-ratio of the by-caught dolphins did not differ from parity and, consistent with other areas, juveniles younger than 4 yr old were captured in higher proportion (69%). In addition, 74% of the entangled animals were sexually immature and 85% physically immature. Sexually immature dolphins were predominant in the spring, a period which coincides with the breeding season. An assessment of the body condition of captured franciscanas suggests that entanglements were not associated with a disease or physiological disorder. The results presented here are important to assess the impact of artisanal fisheries on the population of franciscana dolphins in the southernmost area of its distribution.
A partir del análisis de 73 cráneos de Arctocephalus australis se determinó el patrón y orden de ... more A partir del análisis de 73 cráneos de Arctocephalus australis se determinó el patrón y orden de cierre de 12 suturas craneanas utilizando cuatro estadios de cierre sutural (1: sutura abierta, 2: sutura menos del 50 % cerrada, 3: sutura más del 50 % cerrada y 4: sutura cerrada). Las suturas presentaron patrones de cierre diferentes según la región del cráneo considerada. Las suturas del neurocráneo (Región Neural) son las primeras en mostrar un cierre parcial caracterizado por un único patrón de cierre, proporcional al incremento en el largo del cráneo, y alcanzan el cierre completo en una etapa temprana del desarrollo. Las suturas de la Región Rostral (rostro y paladar) comienzan su maduración en forma tardía, con una gran variación en las diferentes etapas de desarrollo del cráneo, y presentan tres patrones principales de cierre. El avance de cierre de las suturas de A. australis, responde a un patrón postero-anterior y dorso-basal. Pese al conocido dimorfismo sexual en los pinnípedos, no se observaron diferencias en el patrón y orden de cierre de las suturas estudiadas en machos y hembras. Algunas de las suturas estudiadas pueden ser consideradas como claras indicadoras del estadio de desarrollo de la especie, como el caso de las suturas basioccipital-basisfenoides y la basisfenoides-presfenoides, cuyos cierres completos definen claramente la madurez física del cráneo.
Plastic debris (PD) ingestion was examined in 106 Franciscana dolphins (Pontoporia blainvillei) i... more Plastic debris (PD) ingestion was examined in 106 Franciscana dolphins (Pontoporia blainvillei) incidentally captured in artisanal fisheries of the northern coast of Argentina. Twenty-eight percent of the dolphins presented PD in their stomach, but no ulcerations or obstructions were recorded in the digestive tracts. PD ingestion was more frequent in estuarine (34.6%) than in marine (19.2%) environments, but the type of debris was similar. Packaging debris (cellophane, bags, and bands) was found in 64.3% of the dolphins, with a lesser proportion (35.7%) ingesting fishery gear fragments (monofilament lines, ropes, and nets) or of unknown sources (25.0%). PD ingestion correlated with ontogenetic changes in feeding regimes, reaching maximum values in recently weaned dolphins. Because a simultaneous increase in gillnet entanglement and the bioaccumulation of heavy metals take place at this stage, the first months after trophic independence should be considered as a key phase for the conservation of Franciscana dolphin stocks in northern Argentina.
Franciscana dolphin is an endemic cetacean in the southwestern Atlantic Ocean and is classified a... more Franciscana dolphin is an endemic cetacean in the southwestern Atlantic Ocean and is classified as Vulnerable A3d by the International Union for Conservation of Nature. Cadmium accumulation was assessed in two geographic groups from Argentina; one inhabits the La Plata River estuary, a high anthropogenic impacted environment, and the other is distributed in marine coastal, with negligible pollution. Despite the environment, marine dolphins showed an increase of renal Cd concentrations since trophic independence; while in estuarine dolphins was from 6 years. This is associated with dietary Argentine anchovy which was absent in the diet of estuarine dolphins, being a trophic vector of cadmium in shelf waters of Argentina. Cluster analysis also showed high levels of cd in association with the presence of anchovy in the stomach. The difference in the fine scale distribution of species influences dietary exposure to Cd and, along with other data, indicates two stocks in Argentina.
Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolp... more Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolphin is an endemic cetacean from the Southwestern Atlantic Ocean, classified as Vulnerable A3d by the IUCN. Metallothionein, copper and zinc in Franciscana were assessed in two geographic groups; one inhabits La Plata River estuary, anthropogenically impacted, and the other inhabits marine coastal ecosystems, with negligible pollution. Despite the environment, hepatic and renal MT concentrations were similar, but there was a declining trend from early to later developmental stages. Metallothionein K/L, Cu and Zn levels corresponded to normal reported ranges. MT was not related with Cd. Fetal concentrations were higher than its mother. These results and the health status of dolphins are suggesting that MT correspond to physiological ranges for the species, and they are closely to homeostasis of Zn and Cu, according to its ontogenetic changes. The information constitutes the first MT information on Franciscana dolphin and can be considered as baseline for the species conservation.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2014
Energetics Fur seals Heat increment of feeding Linear mixed effect models Resting metabolic rate ... more Energetics Fur seals Heat increment of feeding Linear mixed effect models Resting metabolic rate Bio-energetic models used to characterize an animal's energy budget require the accurate estimate of different variables such as the resting metabolic rate (RMR) and the heat increment of feeding (HIF). In this study, we estimated the in air RMR of wild juvenile South American fur seals (SAFS; Arctocephalus australis) temporarily held in captivity by measuring oxygen consumption while at rest in a postabsorptive condition. HIF, which is an increase in metabolic rate associated with digestion, assimilation and nutrient interconversion, was estimated as the difference in resting metabolic rate between the postabsorptive condition and the first 3.5 h postprandial. As data were hierarchically structured, linear mixed effect models were used to compare RMR measures under both physiological conditions. Results indicated a significant increase (61%) for the postprandial RMR compared to the postabsorptive condition, estimated at 17.93 ± 1.84 and 11.15 ± 1.91 mL O 2 min −1 kg −1 , respectively. These values constitute the first estimation of RMR and HIF in this species, and should be considered in the energy budgets for juvenile SAFS foraging at-sea.
The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-... more The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-western Atlantic Ocean. Incidental captures in fishing gillnets is possibly the greatest conservation concern for this species, and occurs within most of its geographical distribution. The aim of this paper is to determine the biological parameters of franciscana dolphin by-caught from artisanal coastal fisheries of the southern Buenos Aires province, Argentina. Between 2003 and 2009, carcasses of 54 incidentally captured franciscanas were collected. The age, sexual and physical maturity and body condition of each specimen was determined. The sex-ratio of the by-caught dolphins did not differ from parity and, consistent with other areas, juveniles younger than 4 yr old were captured in higher proportion (69%). In addition, 74% of the entangled animals were sexually immature and 85% physically immature. Sexually immature dolphins were predominant in the spring, a period which coincides with the breeding season. An assessment of the body condition of captured franciscanas suggests that entanglements were not associated with a disease or physiological disorder. The results presented here are important to assess the impact of artisanal fisheries on the population of franciscana dolphins in the southernmost area of its distribution.
Mammalian Biology - Zeitschrift für Säugetierkunde, 2014
Please cite this article in press as: Giardino, G.V., et al., Travel for sex: Long-range breeding... more Please cite this article in press as: Giardino, G.V., et al., Travel for sex: Long-range breeding dispersal and winter haulout fidelity in southern sea lion males. Mammal. Biol. (2014), http://dx.a b s t r a c t Southern sea lions (Otaria flavescens; SSLs) have a polygynous mating system and a prolonged socialsexual maturation period for males. Male haulouts are common in this species, with some very distant from central breeding rookeries, although the functions of these aggregations are not clearly understood. To estimate the potential connectivity between northern Argentina male colonies and breeding rookeries in Patagonia and Uruguay, we monitored the summer breeding activities and winter presence of 559 individually identified SSL males from haulouts in Mar del Plata and Quequén harbors. Our results confirm that male groups are formed by sexually active sea lions that show a strong annual connection with distant (up to 700 km) breeding colonies. Circa 70% of the marked males made long-distance round-trips (72 ± 26.7 days; n = 325) from northern Argentina to Patagonia and Uruguay, indicating a high degree of winter site fidelity. Mating activity was confirmed for 53% of the sea lions re-sighted in breeding colonies, with approximately 80% of them having central positions on the beach and holding harems of up to nine females. The chronology of this cycle is finely tuned with the onset of the breeding season, which may result in comparative advantages such as anticipating female arrival or a prolonged participation in mating activities. Our results suggest a model of male haulouts spatially segregated from the central breeding areas, but with a summer recurrent flow of animals that contributes a significant proportion of the male population of northern Patagonia and Uruguay.
The present study provides information about the diet composition of franciscana dolphin, Pontopo... more The present study provides information about the diet composition of franciscana dolphin, Pontoporia blainvillei, from southern Buenos Aires coast, Argentina. From 2003 to 2011 we collected 66 franciscana dolphins that were incidentally entangled in artisanal fishing nets. We analyzed the stomach contents and estimated the prey size in order to evaluate the diet composition and the overlapping with fisheries. We identified 11 prey species in the stomach contents; only two of them were important in the diet, the striped weakfish, Cynoscion guatucupa, and the squid, Loligo sanpaulensis. Almost all the prey found in the diet of franciscana dolphins are of commercial interest. The overlapping of target species and prey that are subject to overfishing could enhance the vulnerability of franciscana by reducing food availability.
The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-... more The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-western Atlantic Ocean. Incidental captures in fishing gillnets is possibly the greatest conservation concern for this species, and occurs within most of its geographical distribution. The aim of this paper is to determine the biological parameters of franciscana dolphin by-caught from artisanal coastal fisheries of the southern Buenos Aires province, Argentina. Between 2003 and 2009, carcasses of 54 incidentally captured franciscanas were collected. The age, sexual and physical maturity and body condition of each specimen was determined. The sex-ratio of the by-caught dolphins did not differ from parity and, consistent with other areas, juveniles younger than 4 yr old were captured in higher proportion (69%). In addition, 74% of the entangled animals were sexually immature and 85% physically immature. Sexually immature dolphins were predominant in the spring, a period which coincides with the breeding season. An assessment of the body condition of captured franciscanas suggests that entanglements were not associated with a disease or physiological disorder. The results presented here are important to assess the impact of artisanal fisheries on the population of franciscana dolphins in the southernmost area of its distribution.
A partir del análisis de 73 cráneos de Arctocephalus australis se determinó el patrón y orden de ... more A partir del análisis de 73 cráneos de Arctocephalus australis se determinó el patrón y orden de cierre de 12 suturas craneanas utilizando cuatro estadios de cierre sutural (1: sutura abierta, 2: sutura menos del 50 % cerrada, 3: sutura más del 50 % cerrada y 4: sutura cerrada). Las suturas presentaron patrones de cierre diferentes según la región del cráneo considerada. Las suturas del neurocráneo (Región Neural) son las primeras en mostrar un cierre parcial caracterizado por un único patrón de cierre, proporcional al incremento en el largo del cráneo, y alcanzan el cierre completo en una etapa temprana del desarrollo. Las suturas de la Región Rostral (rostro y paladar) comienzan su maduración en forma tardía, con una gran variación en las diferentes etapas de desarrollo del cráneo, y presentan tres patrones principales de cierre. El avance de cierre de las suturas de A. australis, responde a un patrón postero-anterior y dorso-basal. Pese al conocido dimorfismo sexual en los pinnípedos, no se observaron diferencias en el patrón y orden de cierre de las suturas estudiadas en machos y hembras. Algunas de las suturas estudiadas pueden ser consideradas como claras indicadoras del estadio de desarrollo de la especie, como el caso de las suturas basioccipital-basisfenoides y la basisfenoides-presfenoides, cuyos cierres completos definen claramente la madurez física del cráneo.
Plastic debris (PD) ingestion was examined in 106 Franciscana dolphins (Pontoporia blainvillei) i... more Plastic debris (PD) ingestion was examined in 106 Franciscana dolphins (Pontoporia blainvillei) incidentally captured in artisanal fisheries of the northern coast of Argentina. Twenty-eight percent of the dolphins presented PD in their stomach, but no ulcerations or obstructions were recorded in the digestive tracts. PD ingestion was more frequent in estuarine (34.6%) than in marine (19.2%) environments, but the type of debris was similar. Packaging debris (cellophane, bags, and bands) was found in 64.3% of the dolphins, with a lesser proportion (35.7%) ingesting fishery gear fragments (monofilament lines, ropes, and nets) or of unknown sources (25.0%). PD ingestion correlated with ontogenetic changes in feeding regimes, reaching maximum values in recently weaned dolphins. Because a simultaneous increase in gillnet entanglement and the bioaccumulation of heavy metals take place at this stage, the first months after trophic independence should be considered as a key phase for the conservation of Franciscana dolphin stocks in northern Argentina.
Franciscana dolphin is an endemic cetacean in the southwestern Atlantic Ocean and is classified a... more Franciscana dolphin is an endemic cetacean in the southwestern Atlantic Ocean and is classified as Vulnerable A3d by the International Union for Conservation of Nature. Cadmium accumulation was assessed in two geographic groups from Argentina; one inhabits the La Plata River estuary, a high anthropogenic impacted environment, and the other is distributed in marine coastal, with negligible pollution. Despite the environment, marine dolphins showed an increase of renal Cd concentrations since trophic independence; while in estuarine dolphins was from 6 years. This is associated with dietary Argentine anchovy which was absent in the diet of estuarine dolphins, being a trophic vector of cadmium in shelf waters of Argentina. Cluster analysis also showed high levels of cd in association with the presence of anchovy in the stomach. The difference in the fine scale distribution of species influences dietary exposure to Cd and, along with other data, indicates two stocks in Argentina.
Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolp... more Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolphin is an endemic cetacean from the Southwestern Atlantic Ocean, classified as Vulnerable A3d by the IUCN. Metallothionein, copper and zinc in Franciscana were assessed in two geographic groups; one inhabits La Plata River estuary, anthropogenically impacted, and the other inhabits marine coastal ecosystems, with negligible pollution. Despite the environment, hepatic and renal MT concentrations were similar, but there was a declining trend from early to later developmental stages. Metallothionein K/L, Cu and Zn levels corresponded to normal reported ranges. MT was not related with Cd. Fetal concentrations were higher than its mother. These results and the health status of dolphins are suggesting that MT correspond to physiological ranges for the species, and they are closely to homeostasis of Zn and Cu, according to its ontogenetic changes. The information constitutes the first MT information on Franciscana dolphin and can be considered as baseline for the species conservation.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2014
Energetics Fur seals Heat increment of feeding Linear mixed effect models Resting metabolic rate ... more Energetics Fur seals Heat increment of feeding Linear mixed effect models Resting metabolic rate Bio-energetic models used to characterize an animal's energy budget require the accurate estimate of different variables such as the resting metabolic rate (RMR) and the heat increment of feeding (HIF). In this study, we estimated the in air RMR of wild juvenile South American fur seals (SAFS; Arctocephalus australis) temporarily held in captivity by measuring oxygen consumption while at rest in a postabsorptive condition. HIF, which is an increase in metabolic rate associated with digestion, assimilation and nutrient interconversion, was estimated as the difference in resting metabolic rate between the postabsorptive condition and the first 3.5 h postprandial. As data were hierarchically structured, linear mixed effect models were used to compare RMR measures under both physiological conditions. Results indicated a significant increase (61%) for the postprandial RMR compared to the postabsorptive condition, estimated at 17.93 ± 1.84 and 11.15 ± 1.91 mL O 2 min −1 kg −1 , respectively. These values constitute the first estimation of RMR and HIF in this species, and should be considered in the energy budgets for juvenile SAFS foraging at-sea.
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Incidental captures in fishing gillnets is possibly the greatest conservation concern for this species, and occurs within most
of its geographical distribution. The aim of this paper is to determine the biological parameters of franciscana dolphin
by-caught from artisanal coastal fisheries of the southern Buenos Aires province, Argentina. Between 2003 and 2009, carcasses of 54 incidentally captured franciscanas were collected. The age, sexual and physical maturity and body condition of each specimen was determined. The sex-ratio of the by-caught dolphins did not differ from parity and, consistent with other areas, juveniles younger than 4 yr old were captured in higher proportion (69%). In addition, 74% of the entangled animals were sexually immature and 85% physically immature. Sexually immature dolphins were predominant in the spring, a period which coincides with the breeding season. An assessment of the body condition of captured franciscanas suggests that entanglements were not associated with a disease or physiological disorder. The results presented here are important to assess the impact of artisanal fisheries on the population of franciscana dolphins in the southernmost area of its distribution.
Incidental captures in fishing gillnets is possibly the greatest conservation concern for this species, and occurs within most
of its geographical distribution. The aim of this paper is to determine the biological parameters of franciscana dolphin
by-caught from artisanal coastal fisheries of the southern Buenos Aires province, Argentina. Between 2003 and 2009, carcasses of 54 incidentally captured franciscanas were collected. The age, sexual and physical maturity and body condition of each specimen was determined. The sex-ratio of the by-caught dolphins did not differ from parity and, consistent with other areas, juveniles younger than 4 yr old were captured in higher proportion (69%). In addition, 74% of the entangled animals were sexually immature and 85% physically immature. Sexually immature dolphins were predominant in the spring, a period which coincides with the breeding season. An assessment of the body condition of captured franciscanas suggests that entanglements were not associated with a disease or physiological disorder. The results presented here are important to assess the impact of artisanal fisheries on the population of franciscana dolphins in the southernmost area of its distribution.