Dolphin interactions with the mullet artisanal fishing on Southern Brazil: a qualitative and quantitative approach

Simões‐Lopes, Paulo C.; Fabián, Marta Elena; Menegheti, João Oldair

doi:10.1590/s0101-81751998000300016

Cited by 93 publications

(114 citation statements)

References 15 publications

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“…In Imbé/Tramandaí, also in the northern region of RS, sporadic surveys from shore-based locations were made between 1982 and 1995, covering all seasons (Simões-Lopes and Fabian, 1999). Systematic observations were carried out between April and June 1994, totaling 144h of observation effort (Simões-Lopes et al, 1998). Both studies confirmed the annual presence of dolphins in the area.…”

Section: Southern Brazil and Uruguaymentioning

confidence: 85%

“…In Santo Antônio Lagoon, southern Santa Catarina State, sporadic observations from land-based locations were made from 1984 to 1994 and monthly observations were made from August 1989 to December 1991, totaling 880h of survey effort from shore station (Simões-Lopes et al, 1998;Simões-Lopes and Fabian, 1999). From April 1991 to March 1992, boat-based surveys were carried out and a total of 52 groups of dolphins were recorded all year-round; 16 Barreto, A.S., Henrique-Garcia, J., Moreira, P.P.…”

Section: Southern Brazil and Uruguaymentioning

confidence: 99%

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Report of the Working Group on the Distribution of Tursiops truncatus in the Southwest Atlantic Ocean

Lodi¹,

Domit

Laporta

et al. 2017

Lat. Am. J. Aquat. Mamm.

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Section: Southern Brazil and Uruguaymentioning

confidence: 85%

Section: Southern Brazil and Uruguaymentioning

confidence: 99%

Report of the Working Group on the Distribution of Tursiops truncatus in the Southwest Atlantic Ocean

Lodi¹,

Domit

Laporta

et al. 2017

Lat. Am. J. Aquat. Mamm.

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“…In this region, dolphins cooperate with fishermen during the mullet season (Mugil spp.) aiding in entrapping fish (Simões-Lopes et al, 1998). The mullet season commences in April, which coincides with the beginning of our study.…”

Section: Study Design and Field Effortmentioning

confidence: 56%

“…More recently, abundance was estimated between 50 to 60 dolphins (Daura-Jorge et al, 2013). In this local population, dolphins display a high degree of residency (Simões-Lopes et al, 1998) and it seems that temporary emigration rates are low (Daura-Jorge et al, 2013).…”

Section: Introductionmentioning

confidence: 97%

“…In this region, bottlenose dolphins are resident and are well-known for a unique fishing technique with humans. A subset of dolphins (45%) interact with local artisanal fishermen (see Simões-Lopes et al, 1998 for a detailed description). This interaction seems to be a mutualistic cooperation that occurs mostly during the mullet season in the austral autumn and it may present implications to the evaluation of spatial pattern and social structure .…”

Section: Introductionmentioning

confidence: 99%

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Mark-recapture vs. line-transect abundance estimates of a coastal dolphin population: a case study of Tursiops truncatus from Laguna, southern Brazil

Daura‐Jorge

Simões-Lopes

2017

Lat. Am. J. Aquat. Mamm.

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Abstract. Cetacean populations in coastal habitats are increasingly threatened by multiple anthropogenic impacts. Monitoring these populations to obtain robust estimates of abundance and detect trends over time is critical to achieve conservation goals. Here, we conducted a pilot study to evaluate the effectiveness of two commonly used abundance estimation methods: mark-recapture and distance sampling line-transect. Surveys were conducted to estimate the abundance of bottlenose dolphins in Laguna, southern Brazil. We implemented power-analysis models and compared both techniques in terms of cost, time and effectiveness to detect trends over a five-year period. Mark-recapture models were analyzed in MARK and resulted in an abundance of 50 individuals (CI = 39-64) with a coefficient of variation (CV) of 0.13. The line-transect models were implemented using the program DISTANCE and resulted in an estimate of 62 individuals (CI = 38-103), with a CV of 0.24. Comparing both approaches, mark-recapture resulted 1.30 time more expensive than line-transect for a single season of effort, but was twice as effective in terms of precision. As a consequence, the probability of detecting a 5% trend during a five-year period is 2.08 times higher with mark recapture. Conversely, the final cost to detect a trend with distance sampling is 1.19 time higher but considering six more years of effort. These results highlight the importance of selecting a-priori sampling design techniques that include developing pilot studies that evaluate the bias, precision and accuracy of estimates while considering costs involved. Considering the small population size estimated herein, the sensitivity of both approaches for detecting trends is not sufficient because the original population would be markedly reduced by the time a declining trend was detected. Thus, a precautionary approach is still imperative, even when robust estimates are obtained.Resumo. Populações costeiras de cetáceos estão expostas a múltiplos impactos antropogênicos, sendo o monitoramento destas populações essencial para questões conservacionistas. Para isto, estimativas robustas de abundância são necessárias, principalmente quando o objetivo é detectar tendências populacionais. Por um estudo piloto, foi avaliada a efetividade de dois métodos comumente utilizados, captura-recaptura e transecção linear, para estimar a abundância do boto-datainha Tursiops truncatus, em Laguna, sul do Brasil. Ambas as técnicas foram comparadas em termos de custos, tempo e poder em detectar tendências, considerando um programa hipotético de cinco anos de monitoramento. Os modelos de captura-recaptura, analisados no programa MARK, geraram uma abundância de 50 indivíduos (IC = 39-64) com um coeficiente de variação (CV) de 0,13. O método de transecção linear, utilizando o programa DISTANCE, estimou uma abundância de 62 indivíduos (IC = 38-103), com um CV de 0,24. Comparando as duas abordagens, quando considerado apenas um ano de esforço, o método de captura-recaptura foi 1,30 vez mais dispendioso que ...

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Challenges in monitoring mobile populations: Applying bayesian multi‐site mark–recapture abundance estimation to the monitoring of a highly mobile coastal population of bottlenose dolphins

Nykänen

Oudejans²,

Rogan

et al. 2020

Aquatic Conservation

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Dolphin interactions with the mullet artisanal fishing on Southern Brazil: a qualitative and quantitative approach

Cited by 93 publications

References 15 publications

Report of the Working Group on the Distribution of Tursiops truncatus in the Southwest Atlantic Ocean

Report of the Working Group on the Distribution of Tursiops truncatus in the Southwest Atlantic Ocean

Mark-recapture vs. line-transect abundance estimates of a coastal dolphin population: a case study of Tursiops truncatus from Laguna, southern Brazil

Challenges in monitoring mobile populations: Applying bayesian multi‐site mark–recapture abundance estimation to the monitoring of a highly mobile coastal population of bottlenose dolphins

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