Artisanal fishing, dolphins, and interactive pinger: A study from a passive acoustic perspective

Abstract

1. Dolphins interact with many types of fishing gear, causing damage to fishing activities and in some cases facing harm and becoming entangled as bycatch.2. In this study, the behaviour of bottlenose dolphins during their interaction with set nets, equipped with and without interactive pingers, was investigated.

Guarding net effects on landings and discards in Mediterranean trammel net fishery: Case analysis of Egadi Islands Marine Protected Area (Central Mediterranean Sea, Italy)

“…Importantly, the EU encourages the adoption of more selective fishing gears and better control about the record of catches (Catanese et al, 2018). As trammel nets are one of the most commonly used gears in coastal waters worldwide (Goncalves et al, 2008;Gökcȩ et al, 2016), there have been some studies on discards (Purbayanto et al, 2001;Coelho et al, 2005;Martıńez-Baños and Maynou, 2018), but as with discard studies for most gears, the emphasis was on vertebrates and commercially valuable or protected species (Catanese et al, 2018;Brownell et al, 2019;Geraci et al, 2019;Swimmer et al, 2020;Buscaino et al, 2021). Nevertheless, ecologically important species such as habitat-builder species and invertebrates, species at risk, or small-sized individuals are also affected by discards, and such concerns regarding the ecological impact of trammel net fisheries on benthic communities within the coastal zone (Goncalves et al, 2008;Metin et al, 2009;Aydin et al, 2013;Gökcȩ et al, 2016) and the unwanted by-catch (according to the ICES, 2020 classification) of benthic species with no commercial interest-for instance, crustaceans (crabs and hermit crabs), echinoderms (starfish, sea urchins and sea cucumbers), and gastropods (Gökcȩ et al, 2016).…”

Abundance of the bottlenose dolphin (Tursiops truncatus) and proposal for a priority area of conservation in the Southern Gulf of Mexico marine ecoregion

“…Despite being a merely descriptive characterization, this local pattern is similar to the regional pattern in central Veracruz, as recorded by Hernández‐Candelario et al (2015) and Argüelles‐Jiménez, Soriano & De la Cruz‐Francisco (2019). Fishing activities can directly impact dolphins, generating competition for trophic resources (Hernández‐Candelario et al, 2015; Buscaino et al, 2021). Gillnets expose dolphins to potential bycatch, which can cause mortality, as reported by Mintzer, Diniz & Frazer (2018) and Avila & Giraldo (2022), among others.…”

Acoustic detection of bottlenose dolphin depredation on nets and implications for conservation

“…Mitigation actions proposed to resolve dolphin–fishery conflict by both fishery managers and researchers have mainly focused on acoustic deterrent devices, often with failing results, especially in the long term (Brownell et al, 2019; Buscaino et al, 2021), while operational and spatial changes in the fishing strategies were rarer (Lauriano et al, 2009; Gasco et al, 2015; Notarbartolo di Sciara et al, 2016; Hanselman, Pyper & Peterson, 2018; Tixier et al, 2010, 2019) and usually applied by single fishers based on personal empirical knowledge and perceptions but were not tested (Jog et al, 2022). Our results provide the first useful indications that dolphin depredation is related to the fishing operation duration, probably because the longest fishing effort may provide dolphins with the greatest chance of finding entangled fish (Tixier et al, 2010).…”

“…Thus, while methods based on observations (from the surface) of dolphins near nets or measurements of catch damage and loss may provide indications of dolphin depredation, the detection of clicks indicating a close‐range target search and target capture can be a more realistic measure of depredation events on nets. Surprisingly, to our knowledge, no studies have been done that acoustically measure bottlenose dolphin depredation on commercial small‐scale coastal fisheries in the Mediterranean Sea, with only two exceptions that mainly focused on measuring the effectiveness of acoustic deterrent devices (Snape et al, 2018; Buscaino et al, 2021). Hence, the aim of this study was to measure the consistency between the detection of dolphins by passive acoustic monitoring devices placed on nets and two methods commonly used to measure dolphin depredation on coastal static net fisheries: the direct observation of dolphins and catch measurements.…”