Factors determining the interaction between common bottlenose dolphins and bottom trawlers off the Balearic Archipelago (western Mediterranean Sea)

Gonzalvo, Joan; Valls, María; Cardona, Luís; Aguilar, Àlex

doi:10.1016/j.jembe.2008.08.013

Cited by 40 publications

(39 citation statements)

References 27 publications

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“…The increased nautical traffic in summer that characterizes this area could prompt displacement of these animals to areas where there are fewer recreational boats, to avoid noise and the risk of collisions. Gonzalvo et al (2008) found a similar migration trend around Balearic Islands. In the Archipelago de La Maddalena, as in the Balearic Islands, tourism is the main industry, with around 8.5 million visitors each year and around 15,000 registered leisure boats (Rotta, 2009).…”

Section: Discussionsupporting

confidence: 60%

Interaction between bottlenose dolphin (Tursiops truncatus) and trammel nets in the Archipelago de La Maddalena, Italy

et al. 2014

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Interactions between bottlenose dolphins (Tursiops truncatus) and fisheries are an increasing problem in the Mediterranean and effective management measures are needed. In order to assess the impact of dolphin interactions on artisanal trammel nets, we examine 354 fishing operations performed in waters of the Archipelago de La Maddalena (Italy). We evaluate whether interactions were related to the species composition of the catch and, using the local commercial value of the target species, we assess whether there was a real economic loss for fishermen. Bayesian models and partial correspondence analysis were used to determine the extent to which dolphin interactions and habitat differences contributed to variation in the species composition of catches. CPUE for fishing operations with no dolphin interactions was significantly higher than that for operations with dolphin interactions, although clearly this does not confirm a direct causal link, and associated economic loss was estimated to be non-significant. Geographic location, season, depth of seabed, moon phase, and mesh size were all important factors affecting the amount and species composition of the catch. Our results suggest that it is likely that these differences in species composition are due to a mixture of habitat and dolphin-induced effects.

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Section: Discussionsupporting

confidence: 60%

Interaction between bottlenose dolphin (Tursiops truncatus) and trammel nets in the Archipelago de La Maddalena, Italy

et al. 2014

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“…Such a mechanism, particularly in oligo trophic ecosystems, is related not only to the direct consumption of feed pellets around the fish cages, but also, and principally, to the increase in primary production through released nutrients and a rapid transfer of these nutrients up the food web, with a strong influence on the coupling between pelagic and benthic compartments (Belias et al 2003, Machias et al 2006, Pitta et al 2009). Bottlenose dolphins are known to be opportunistic allowing them to adapt to changes in prey availability (Shane et al 1986, Bearzi et al 2008b and to take advantage of human activities by either following fishing boats to feed on discarded fish (Fertl & Leatherwood 1997, Bearzi et al 1999, by catching/ stealing fish during fishing operations (Diaz López 2006, Lauriano & Bruno 2007, Gonzalvo et al 2008, or by feeding near fish farm facilities (Díaz López & Bernal Shirai 2007, Bearzi et al 2009). This feeding strategy has most likely been adopted by bottlenose dolphins to increase their feeding rate, while decreasing the energy expenditure associated with foraging (Fertl & Leatherwood 1997), in order to compensate for the lack of fish prey in the surrounding waters.…”

Section: Discussionmentioning

confidence: 99%

Marine open cage aquaculture in the eastern Mediterranean Sea: a new trophic resource for bottlenose dolphins

Piroddi¹,

Bearzi²,

Christensen³

2011

Mar. Ecol. Prog. Ser.

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“…The natural diet of bottlenose dolphins is principally miscellaneous fish and to a lesser extent cephalopods (Barros and Odell, 1990;Cockcroft and Ross, 1990;Pauly et al, 1998;Blanco et al, 2001;Gonzalvo et al, 2008). Currently, its population around the Corsican coast is estimated to be 200-350 animals (GECEM, 2007).…”

Section: Study Area and Data Collectionmentioning

confidence: 99%

“…In this area, the species is reported as the most involved in fishing operation interactions and net depredation (Bearzi, 2002;Gonzalvo et al, 2008). We used a large dataset collected over 3 years in the Bonifacio Strait Natural Reserve (BSNR), Corsica (France).…”

Section: Introductionmentioning

confidence: 99%

Changes in the catch composition of artisanal fisheries attributable to dolphin depredation in a Mediterranean marine reserve

Rocklin

Santoni²,

Culioli³

et al. 2009

ICES Journal of Marine Science

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. Changes in the catch composition of artisanal fisheries attributable to dolphin depredation in a Mediterranean marine reserve. -ICES Journal of Marine Science, 66: 699-707.There is increasing evidence from previous studies, and from fishers' observations, that coastal dolphins use fishing nets as an easily accessible feeding source, damaging or depredating fish caught in the nets. This study investigates the impact of dolphin depredation on artisanal trammelnets by analysing the catch composition of 614 artisanal fishing operations in the Bonifacio Strait Natural Reserve (France). Common bottlenose dolphins (Tursiops truncatus) attacked, on average, 12.4% of the nets and damaged 8.3% of the catch. However, attacked nets were characterized by statistically significantly higher catch per unit effort than unattacked ones. Catch composition also differed significantly after dolphin attacks; bentho-pelagic fish were more represented and reef-associated fish less represented. Our results suggest that (i) dolphins are attracted by high fish densities in the fishing area and/or nets, and (ii) their attacks induce specific fish-avoidance behaviour, according to the fish position in the water column. Although dolphins depredate a small part of the catch, damage to nets, not yet assessed in this area, could weaken the benefits that reserves can provide to artisanal fisheries.

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Factors determining the interaction between common bottlenose dolphins and bottom trawlers off the Balearic Archipelago (western Mediterranean Sea)

Cited by 40 publications

References 27 publications

Interaction between bottlenose dolphin (Tursiops truncatus) and trammel nets in the Archipelago de La Maddalena, Italy

Interaction between bottlenose dolphin (Tursiops truncatus) and trammel nets in the Archipelago de La Maddalena, Italy

Marine open cage aquaculture in the eastern Mediterranean Sea: a new trophic resource for bottlenose dolphins

Changes in the catch composition of artisanal fisheries attributable to dolphin depredation in a Mediterranean marine reserve

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