There is some evidence that the presence of Tursiops truncatus in fishing areas represents a real economic threat to fishermen due the dolphin feeding on the entangled fish, damaging the nets and reducing the fish catch. We have carried out experiments to assess the efficiency of a pinger in decreasing the interaction between the dolphins and fishing nets, in a fishing area off the coast of southern Italy, where Tursiops truncatus is frequently observed to interact with bottom gill nets. Two identical monofilament bottom gill nets (900 m long), one equipped with pingers and the other without, were used to measure the effect of these pingers on the abundance of the catch and net damage. For each haul (58 in total), data on dolphin sightings near the nets, damage judged to have been done by dolphins, weight and species composition of the catch were collected. All damage to the nets were recorded at the end of each haul. Dolphins in the fishing area were sighted 11 times out of 29 fishing activities (38%). The net equipped with pingers contained 28% more fish (biomass) than the net without pingers (t test, P \ 0.04) and was less damaged (-31%, t test, P \ 0.01). To assess whether the efficacy of these pingers remain constant over long period, long-term experiments should be carried out.

Photo-identification and video-identification techniques were applied to study the residence of Sotalia guianensis in the Babitonga Bay, north coast of Santa Catarina State. From November 2000 to February 2003 a photo-identification effort was conducted trough 21 months, with additional video-identification conducted from August 2003 to August 2004, totalizing 34 months of identification effort. Fifty-one different animals were identified with residence rates varying from 2.9% (n = 1 sighting) to 67.6% (n = 23 sightings). During the four years it was founded that more than 30% (n = 16) of identified individuals were observed during three years, and 25% (n = 13) only were seen within one year. Considering previous studies, the longest period of residence reached eight years for one individual. Due to the high rates of resightings observed for most of the animals and the small percentage of animals only seen once, it is clear that S. guianensis is resident year-round in the studied area.RESUMO: Técnicas de foto e de vídeo-identificação foram aplicadas objetivando estudar a residência de Sotalia guianensis na Baía da Babitonga, litoral norte de Santa Catarina. De novembro de 2000 a fevereiro de 2003 um esforço de foto-identificação foi conduzido através de 21 meses, somado a um esforço adicional de vídeo-identificação, conduzido de agosto de 2003 a agosto de 2004, totalizando 34 meses de esforço total de identificação. Cinqüenta e um animais foram identificados com diferentes taxas de residência, variando de 2,9% (n = 1 observação) á 67,6% (n = 23 observações). Durante os quatro anos verificou-se que mais de 30% (n = 16) dos indivíduos identificados foram observados por um período de três anos, e 25% (n = 13) foram observados apenas no período de um ano. Considerando estudos anteriores, o mais longo período de residência atingiu oito anos para um indivíduo. As altas taxas de recapturas observadas para a maioria dos animais e a pequena porcentagem de animais observados em apenas uma ocasião evidenciam a residência anual de S. guianensis na área estudada.

of carbon and nitrogen stable isotopes to study the feeding ecology of small coastal cetacean populations in southern Brazil. Biota Neotrop. 13(4): http://www.biotaneotropica.org.br/v13n4/en/abstract?article+bn01413042013Abstract: Samples from individuals of the populations of Sotalia guianensis (Guiana) and Pontoporia blainvillei (Franciscana) dolphins living in the Babitonga Bay estuary (26° 28' S/48° 50' W), and samples from individuals of a second population of P. blainvillei from a nearshore area (26° 38' S/48° 41' W), were collected and analyzed along with their prey between 2000 and 2006, to determine the carbon and nitrogen stable isotope ratios and to verify differences in their feeding ecology. No differences were found in the median ð 15 N values of Guiana (15.2‰) and Franciscana (15.9‰) dolphins living in Babitonga Bay, nor of nearshore Franciscana (15.0‰) individuals, suggesting no variation in the trophic level of these populations. However, the lack of more information on the isotopic compositions of their putative prey in the nearshore areas prevents the ability to draw definitive conclusions on this issue. The estuarine Franciscana and Guiana dolphin populations presented mean ð 13 C values of approximately -15.7‰, which were not statistically different from nearshore Franciscana individuals (-14.8‰). Based on stomach content analyses of these species from a previous study, it was reported that there was little overlap in the diet of estuarine Franciscanas and Guiana dolphins. However, based on the similarity of the ð 13 C values between these two species and of their putative prey, it appears that in fact there is an overlap in the diet of these two species. Based solely on stable isotope analysis, it was not possible to differentiate between estuarine and nearshore Franciscana populations, making it difficult to conclude whether captured nearshore specimens were indeed yearlong residents of these areas. Finally, this study suggests that Franciscana and Guiana dolphin populations are sharing the same resources, mostly L. brevis, D. rhombeus, and S. rastrifer. Therefore, the combination of resource sharing and commercial exploitation of their prey makes these two cetacean species vulnerable. Keywords: Pontoporia blainvillei, Sotalia guianensis, Babitonga Bay, feeding ecology, trophic level.HARDT, F.A.S., CREMER, M.J., TONELLO JUNIOR, A.J., BELLANTE, A., BUFFA, G., BUSCAINO, G., MAZZOLA, S., BARRETO, A.S., MARTINELLI, L.A. & ZUPPI, G.M. O uso dos isótopos estáveis de carbono e nitrogênio para o estudo da ecologia de populações de pequenos cetáceos costeiros no sul do Brasil. Biota Neotrop. 13(4): http://www.biotaneotropica.org.br/v13n4/pt/abstract?article+bn01413042013Resumo: Amostras de tecido de indivíduos pertencentes às populações de Sotalia guianensis (boto-cinza) e Pontoporia blainvillei (toninha) que vivem no estuário da Baía da Babitonga (26° 28' S/48° 50' W) e de uma segunda população de P. blainvillei da área costeira (26° 38' S/48° 41' W) foram coletadas entre os anos 2000 e 2006 para ...

Ocorrência de cetáceos nas proximidades de uma plataforma de petróleo no Sul do Brasil. No Brasil são escassas as informações sobre cetáceos em ambiente oceânico e as plataformas de petróleo podem representar uma importante oportunidade para a obtenção de informações. O presente trabalho foi realizado na plataforma de petróleo P-XIV (Petrobrás) (26 o 46'02,2"S; 46 o 47'02,15"W), na área do talude continental, com profundidade de 200m. No período de julho de 2000 a agosto de 2002 foram registrados 75 avistamentos de cetáceos em 38 dias de esforço. Dentre as espécies identificadas, Tursiops truncatus foi a mais comum, com 53,3% dos registros. Dentre os misticetos, foi possível identificar com confiança apenas Balaenoptera acutorostrata, com quatro avistamentos (5,3%). Estas foram as únicas espécies que se aproximaram da plataforma, permanecendo próximo a estrutura. Grande parte dos registros destas espécies foi realizada no período da noite, na área iluminada pelo queimador de gás junto à plataforma. Foi registrado um episódio de interação agressiva entre T. truncatus e B. acutorostrata.