Comparative analysis of the diet of Arctocephalus gazella (Pinnipedia), at two localities of the South Shetland Islands, with emphasis on the fish component / Análisis comparativo de la dieta de Arctocephalus gazella (Pinnipedia), en dos localidades de las Islas Shetland del Sur, con énfasis en su componente íctico

We studied the diet of non-breeding male Antarctic fur Seals Arctocephalus gazella (Peters, 1875) at two different localities of the South Shetland Islands: Stranger Point, King George Island/Isla 25 de Mayo and Duthoit Point, Nelson Island, by the analysis of 65 faecal samples collected in February 2012. Overall, Antarctic krill Euphausia superba (Dana, 1850) and fish were the main prey taxa followed by penguins and cephalopods. Myctophids were dominant among fish; Gymnoscopelus nicholsi (Gilbert, 1911) was the most important prey species at both sampling sites, followed by Electrona antarctica (Gunther, 1878) at Stranger Point and by the nototheniid Pleuragramma antarctica (Boulenger, 1902) at Duthoit Point. The relative similarity found in the dietary composition of fur seals from both locations suggest they might have been sharing common feeding areas. Our results were compared with those reported in the literature for different localities of the South Shetland Islands and the Scotia Sea region. The absence of formerly harvested demersal notothenioid species in the diet of fur seals may reflect the negative impact that commercial fisheries had on some fish populations and supports the importance of implementing long-term monitoring studies on the feeding habits of A. gazella in the area.

Se estudió la dieta de ejemplares macho no reproductivos de lobo fino antártico, Arctocephalus gazella (Peters, 1875) en dos localidades de las Islas Shetland del Sur: Cabo Funes/Punta Stranger, Isla 25 de Mayo / Isla Rey Jorge y Punta Duthoit, Isla Nelson; por medio del análisis de 65 muestras de materia fecal colectadas en Febrero de 2012. En general, el krill antártico Euphausia superba (Dana, 1850) y los peces fueron los taxa presa más consumidos, seguidos por pingüinos y cefalópodos. Entre los peces, los mictófidos fueron dominantes; Gymnoscopelus nicholsi (Gilbert, 1911) fue la especie más importante en ambos apostaderos, seguido por Electrona antarctica (Gunther, 1878) en Punta Stranger y por el nototénido Pleuragramma antarctica (Boulenger, 1902) en Punta Duthoit. La similitud hallada en la composición dietaria de los agrupamientos de lobo estudiados sugiere áreas de alimentación en común. Nuestros resultados fueron comparados con aquellos reportados en la literatura para diferentes localidades de las Islas Shetland del Sur y la región del Mar de Scotia. La ausencia de especies de nototenoideos demersales históricamente diezmadas en la dieta del lobo fino podría estar reflejando el impacto negativo que las pesquerías comerciales han tenido sobre algunas poblaciones de peces y enfatizar la necesidad de realizar un monitoreo a largo plazo de los hábitos alimentarios de A. gazella en el archipiélago de las Islas Shetland del Sur.

Comparative analysis of the diet of Arctocephalus gazella (Pinnipedia), at two localities of the South Shetland Islands, with emphasis on the fish component

RESUMEN Se estudió la dieta de ejemplares macho no reproductivos de lobo fino antártico, Arctocephalus gazella (Peters, 1875) en dos localidades de las Islas Shetland del Sur: Cabo Funes/Punta Stranger, Isla 25 de Mayo / Isla Rey Jorge y Punta Duthoit, Isla Nelson; por medio del análisis de 65 muestras de materia fecal colectadas en Febrero de 2012. En general, el krill antártico Euphausia superba (Dana, 1850) y los peces fueron los taxa presa más consumidos, seguidos por pingüinos y cefalópodos. Entre los peces, los mictófidos fueron dominantes; Gymnoscopelus nicholsi (Gilbert, 1911) fue la especie más importante en ambos apostaderos, seguido por Electrona antarctica (Gunther, 1878) en Punta Stranger y por el nototénido Pleuragramma antarctica (Boulenger, 1902) en Punta Duthoit. La similitud hallada en la composición dietaria de los agrupamientos de lobo estudiados sugiere áreas de alimentación en común. Nuestros resultados fueron comparados con aquellos reportados en la literatura para diferentes localidades de las Islas Shetland del Sur y la región del Mar de Scotia. La ausencia de especies de nototenoideos demersales históricamente diezmadas en la dieta del lobo fino podría estar reflejando el impacto negativo que las pesquerías comerciales han tenido sobre algunas poblaciones de peces y enfatizar la necesidad de realizar un monitoreo a largo plazo de los hábitos alimentarios de A. gazella en el archipiélago de las Islas Shetland del Sur.

ABSTRACT We studied the diet of non-breeding male Antarctic fur Seals Arctocephalus gazella (Peters, 1875) at two different localities of the South Shetland Islands: Stranger Point, King George Island/Isla 25 de Mayo and Duthoit Point, Nelson Island, by the analysis of 65 faecal samples collected in February 2012. Overall, Antarctic krill Euphausia superba (Dana, 1850) and fish were the main prey taxa followed by penguins and cephalopods. Myctophids were dominant among fish; Gymnoscopelus nicholsi (Gilbert, 1911) was the most important prey species at both sampling sites, followed by Electrona antarctica (Gunther, 1878) at Stranger Point and by the nototheniid Pleuragramma antarctica (Boulenger, 1902) at Duthoit Point. The relative similarity found in the dietary composition of fur seals from both locations suggest they might have been sharing common feeding areas. Our results were compared with those reported in the literature for different localities of the South Shetland Islands and the Scotia Sea region. The absence of formerly harvested demersal notothenioid species in the diet of fur seals may reflect the negative impact that commercial fisheries had on some fish populations and supports the importance of implementing long-term monitoring studies on the feeding habits of A. gazella in the area.

Comparative analysis of the diet of Arctocephalus gazella (Pinnipedia), at two localities of the South Shetland Islands, with emphasis on the fish component / Análisis comparativo de la dieta de Arctocephalus gazella (Pinnipedia), en dos localidades de las Islas Shetland del Sur, con énfasis en su componente íctico

We studied the diet of non-breeding male Antarctic fur Seals Arctocephalus gazella (Peters, 1875) at two different localities of the South Shetland Islands: Stranger Point, King George Island/Isla 25 de Mayo and Duthoit Point, Nelson Island, by the analysis of 65 faecal samples collected in February 2012. Overall, Antarctic krill Euphausia superba (Dana, 1850) and fish were the main prey taxa followed by penguins and cephalopods. Myctophids were dominant among fish; Gymnoscopelus nicholsi (Gilbert, 1911) was the most important prey species at both sampling sites, followed by Electrona antarctica (Gunther, 1878) at Stranger Point and by the nototheniid Pleuragramma antarctica (Boulenger, 1902) at Duthoit Point. The relative similarity found in the dietary composition of fur seals from both locations suggest they might have been sharing common feeding areas. Our results were compared with those reported in the literature for different localities of the South Shetland Islands and the Scotia Sea region. The absence of formerly harvested demersal notothenioid species in the diet of fur seals may reflect the negative impact that commercial fisheries had on some fish populations and supports the importance of implementing long-term monitoring studies on the feeding habits of A. gazella in the area.(AU)

Se estudió la dieta de ejemplares macho no reproductivos de lobo fino antártico, Arctocephalus gazella (Peters, 1875) en dos localidades de las Islas Shetland del Sur: Cabo Funes/Punta Stranger, Isla 25 de Mayo / Isla Rey Jorge y Punta Duthoit, Isla Nelson; por medio del análisis de 65 muestras de materia fecal colectadas en Febrero de 2012. En general, el krill antártico Euphausia superba (Dana, 1850) y los peces fueron los taxa presa más consumidos, seguidos por pingüinos y cefalópodos. Entre los peces, los mictófidos fueron dominantes; Gymnoscopelus nicholsi (Gilbert, 1911) fue la especie más importante en ambos apostaderos, seguido por Electrona antarctica (Gunther, 1878) en Punta Stranger y por el nototénido Pleuragramma antarctica (Boulenger, 1902) en Punta Duthoit. La similitud hallada en la composición dietaria de los agrupamientos de lobo estudiados sugiere áreas de alimentación en común. Nuestros resultados fueron comparados con aquellos reportados en la literatura para diferentes localidades de las Islas Shetland del Sur y la región del Mar de Scotia. La ausencia de especies de nototenoideos demersales históricamente diezmadas en la dieta del lobo fino podría estar reflejando el impacto negativo que las pesquerías comerciales han tenido sobre algunas poblaciones de peces y enfatizar la necesidad de realizar un monitoreo a largo plazo de los hábitos alimentarios de A. gazella en el archipiélago de las Islas Shetland del Sur.(AU)

The commercial fishing fleet using the middle stretch of the Madeira river, Brazil / A frota pesqueira comercial do médio rio Madeira, Brasil

Fishery resources in the Amazon region are exploited by both industrial and artisanal fishing fleets, that differ in their use of fishing gear and fishing grounds. Data on the physical characteristics of the vessels belonging to the fishing fleets using the Solimões/Amazonas river and estuaries are limited. This article presents an analysis of some physical characteristics of the commercial fishery fleet using the middle stretch of the Madeira river. Data were quantitative collected using interviews of the owners and/or skippers of fishery vessels between January 2003 and May 2004. The boats used for fishing in the region varied in size from 8 to 14 meters and had an average storage capacity ranging from 4.5 to 6.1 tons. Canoes were also used for fishing and ranged in length from 5 to 9 meters, with an average storage capacity of 0.2 tons. The results of this study demonstrate that boats in the Madeira river fleet had similar characteristics to the fishery fleet of the Solimões/Amazonas river with respect to length, use of gear, and fish storage.

Os recursos pesqueiros na região amazônica são explotados por duas frotas denominadas industrial e artesanal, classificadas de acordo com sua área de atuação e com os apetrechos que utilizam, entretanto, as informações disponíveis sobre as características físicas das mesmas estão concentradas na frota que pratica a atividade no rio Solimões/Amazonas e no estuário. Visando preencher esta lacuna, este trabalho apresenta uma análise das características da frota pesqueira artesanal do médio rio Madeira. Entrevistas foram efetuadas com os proprietários e/ou encarregados pelas embarcações de pesca no período de janeiro de 2003 a maio de 2004. Os barcos de pesca da região mediram entre 8 e 18 metros, com capacidade média de estocagem variando entre 4,5 e 6,1 toneladas. As canoas apresentaram amplitude de comprimento entre 5 e 9 metros, com capacidade média de estocagem de 0,2 tonelada. Ficou evidenciado que as embarcações da frota desta região possuem características similares às frotas que atuam no rio Solimões/Amazonas quanto ao comprimento, utilização de apetrechos e tipo de armazenamento de pescado.