Leisure boating noise as a trigger for the displacement of the bottlenose dolphins of the Cres–Lošinj archipelago (northern Adriatic Sea, Croatia)

Rako, Nikolina; Fortuna, Caterina Maria; Holcer, Draško; Mackelworth, Peter; Nimak-Wood, Maja; Pleslić, Grgur; Sebastianutto, Linda; Vilibić, Ivica; Wiemann, Annika; Picciulin, Marta

doi:10.1016/j.marpolbul.2012.12.019

Cited by 92 publications

(50 citation statements)

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“…Short-term impacts associated with boat interactions include group directional changes (Steckenreuter, Möller, & Harcourt, 2012;, changes in group dispersion (Arcangeli & Crosti, 2009;Steckenreuter et al, 2012), heightened breathing synchrony (Hastie, Wilson, Tufft, & Thompson, 2003), increased dive times (Lusseau, 2003b) and changes in vocalizations (Buckstaff, 2004;Scarpaci, Bigger, Corkeron, & Nugegoda, 2000). Such changes can have longer lasting impacts resulting in seasonal (Rako et al, 2013) Relative to observable changes in surface behaviour, the impacts of boats on the acoustic behaviour of cetaceans has received less attention. Changes in the production or parameters of vocalizations may be related to elevated levels of anthropogenic noise associated with vessel engines (Jensen et al, 2009;Parks, Johnson, Nowacek, & Tyack, 2011;Pirotta et al, 2012), the physical presence of boats (Pirotta, Merchant, Thompson, Barton, & Lusseau, 2015), boat type (La Manna, Manghi, Pavan, Lo Mascolo, & Sarà, 2013) or vessel behaviour 3 during encounters, and the interplay between these factors can be difficult to disentangle (see Ellison, Southall, Clarke, & Frankel, 2011).…”

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“…Although excessive noise can cause hearing damage, and even strandings in cetaceans (Weilgart, 2007), the more relevant impacts of boat noise generated through marine tourism activities are likely to be the masking of calls (Jensen et al, 2009) or biological cues (Clark et al, 2009), behavioural changes (Williams et al, 2006) or displacement (Rako et al, 2013), and stress (Rolland et al, 2012). Animals can adjust their acoustic signalling behaviour to respond to increases in noise in several different ways, which are not necessarily mutually exclusive.…”

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“…These are summarized by Radford, Kerridge, and Simpson (2014) as (1) avoidance of noise, by moving away from the noise source or adjusting the timing of acoustic signals to coincide with low noise periods, (2) adjustment of acoustic signal temporal parameters, such as increasing call duration or rate, (3) amplitude shifts, such as the 'Lombard effect' whereby animals produce higher amplitude acoustic signals in noise (Lombard, 1911), (4) frequency shifts in acoustic signals or the relative amplitude of signal components and (5) shifting emphasis to an alternative signal modality, for example by increasing the use of visual or chemical signals. Cetaceans are known to respond to boat noise sources in the first four ways (Ansmann, Goold, Evans, Simmonds, & Keith, 2007;Foote, Osborne, & Hoelzel, 2004;Holt, Noren, Veirs, Emmons, & Veirs, 2009;Parks, Clark, & Tyack, 2007;Parks et al, 2011;Rako et al, 2013) and may also increase their use of visual cues in elevated noise conditions (point 5 above, see Dunlop, Cato, & Noad, 2010).…”

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Changes in bottlenose dolphin whistle parameters related to vessel presence, surface behaviour and group composition

et al. 2016

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Cetacean watching from tour boats has increased in recent years and has been promoted as an ethically viable alternative to cetacean viewing in captive facilities or directed take. However, short-and long-term impacts of this industry on the behaviour and energetic expenditure of cetaceans have been documented. Although multiple studies have investigated the acoustic 1 response of dolphins to marine tourism, there are several covariates that could also explain some of these results and should be considered simultaneously. Here, we investigated whether common bottlenose dolphins, Tursiops truncatus, inhabiting Walvis Bay, Namibia vary their whistle parameters in relation to boat presence, surface behaviour and/or group composition. We detected an upward shift of up to 1.99 kHz in several whistle frequency parameters when dolphins were in the presence of one or more tour boats and the research vessel. No changes were demonstrated in the frequency range, number of inflection points or duration of whistles. A similar, although less pronounced difference was observed in response to engine noise generated by the research vessel when idling, suggesting that noise alone plays an important role in driving this shift in whistle frequency. Additionally, a strong effect of surface behaviour was observed, with the greatest difference in whistle parameters detected between resting and other behavioural states that are associated with higher degrees of emotional arousal. Group composition also contributed to the variation observed, with the impact of boats dependent on whether calves were present or not. Overall these results demonstrate high natural variation in the frequency parameters of whistles utilized by dolphins over varying behavioural states and group composition. Anthropogenic impact in the form of marine tour boats can influence the vocalization parameters of dolphins and such changes could have a long-term impact if they reduce the communication range of whistles or increase energy expenditure. Key wordsbottlenose dolphin, marine tourism, Namibia, Tursiops truncatus, vocal behaviour Wildlife tourism involving cetacean (whale, dolphin and porpoise) watching has experienced rapid growth since the 1990s (Hoyt, 2001;O'Connor, Campbell, Cortez, & Knowles, 2009). 2Globally, boat-based cetacean watching generates an estimated 2.2 billion US dollars annually (IWC, 2014). Revenue can provide a valuable subsidy to fishing communities and in some cases wild cetacean viewing has replaced direct hunting of whales and dolphins (Amir & Jiddawi, 2001;Berggren et al., 2007). Compared with captive facilities, responsible boatbased cetacean watching has been promoted as an ethically acceptable option for observing dolphins, providing a valuable forum for environmental education and promotion of conservation efforts (IFAW, 1997). However, a considerable body of work has shown that boats and boat-based cetacean watching can have multiple negative impacts on the behaviour of the focal individual, population or species (Parsons,...

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Changes in bottlenose dolphin whistle parameters related to vessel presence, surface behaviour and group composition

et al. 2016

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“…Nevertheless, the effects on Mediterranean habitat use and behaviour of T. truncatus have never been studied in detail and very little data has been published in peer-reviewed journals. Permanent or temporary displacement of bottlenose dolphins from specific areas of the Mediterranean, as a consequence of boat traffic, has only been reported in the coastal waters of Croatia (Rako et al, 2013) and the Lampedusa Islands (Italy) (La , though similar negative effects have been reported for other places around the world. Allen & Read (2000), for instance, provided evidence that Florida bottlenose dolphins reduced the use of some feeding sites in relation to the density of boats, while Lusseau (2005) observed that the seasonal residence index of dolphins and the time spent by animals in the area were negatively correlated with the number of boat trips.…”

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Monitoring the habitat use of common Bottlenose Dolphins (Tursiops truncatus) using passive acoustics in a Mediterranean marine protected area

Manna¹,

Manghi²,

Sarà³

2014

Medit. Mar. Sci.

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The Mediterranean Tursiops truncatus subpopulation has been classified as Vulnerable on the IUCN Red List because of its decline. This species in coastal areas is exposed to a wide variety of threats: directed kills, bycatch, reduced prey availability caused by environmental degradation and overfishing, habitat degradation including disturbances from boat traffic and noise. Despite the increase in boat traffic in the Mediterranean Sea, the effect on T. truncatus' habitat use has not been studied in detail and published data are limited. This study represents the first attempt to characterise spatial and temporal habitat use by T. truncatus and its relation to boat traffic in the Isole Pelagie Marine Protected Area (Italy) on the basis of an originally developed passive acoustic monitoring system (PAM). The devices were deployed in 2 areas in the southern waters of Lampedusa, during 2 separate years (2006 and 2009), each time for 3 months (from July to September) and in 6 time slots (3 diurnal and 3 nocturnal). Acoustic analysis showed that T. truncatus used the Southern coastal area of Lampedusa independently of the year, primarily during the early summer, a period coinciding with the peak of the calving season. Dolphin occurrences appeared independent of boat traffic, with the exception of the smallest temporal scale (time slots); dolphin occurrences were more prevalent during the night when the level of boat traffic was lower. This study provides evidence on T. truncatus habitat use in the Mediterranean Sea and reveals that boat traffic could be one of the factors influencing it, thus stressing the need for further detailed investigation regarding this topic.

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The abundance of common bottlenose dolphins (Tursiops truncatus) in the former special marine reserve of the Cres‐Lošinj Archipelago, Croatia

Pleslić¹,

Gospić²,

Mackelworth³

et al. 2013

Aquatic Conservation

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There is a resident common bottlenose dolphin population inhabiting the Kvarnerić area of the northern Adriatic Sea, Croatia. The observed decline in population size between 1995 and 2003 led to the declaration of a part of the Kvarnerić as the Cres‐Lošinj Special Marine Reserve (CLSMR) in 2006. Protection lasted 3 years, before lapsing. A boat based photo‐identification study was conducted between 2004 and 2011 with the aim to estimate the number of bottlenose dolphins inhabiting the CLSMR area, investigate the factors influencing their habitat use and explore the possibility that this area is representative of the population for the whole Kvarnerić. Standard mark–recapture methods and the Mth estimator of Chao for closed populations were applied. The lowest value was estimated in 2008 (N = 112; 95% CI = 94–150) and the highest in 2006 (N = 310; 95% CI = 265–392). The statistically significant inter‐annual variability is likely to reflect natural and anthropogenic driven shifts in habitat use rather than real changes in population size. The average monthly sighting rate was lower in the tourist season (Jun–Aug) than in the pre‐ and post tourist‐season, suggesting that developed nautical tourism may influence shifts in habitat use. Other potential causes are distribution of prey and fishing effort. Inclusion of data from the rest of the Kvarnerić for the years of 2005 and 2011 did not reveal a significant increase in estimated abundance (2005: z = −0.413, P = 0.3398; 2011: z = −1.749, P = 0.0401). This indicates that the CLSMR area is representative of the whole Kvarnerić. The number of bottlenose dolphins using the CLSMR area seems to have increased compared with the previous study (1995–2003). This could be due to a shift in habitat use or an increase in population size. However, yearly variations indicate processes causing displacements within the dolphin population home range. Conservation measures aiming at reducing the displacements are proposed. Copyright © 2013 John Wiley & Sons, Ltd.

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Leisure boating noise as a trigger for the displacement of the bottlenose dolphins of the Cres–Lošinj archipelago (northern Adriatic Sea, Croatia)

Cited by 92 publications

References 31 publications

Changes in bottlenose dolphin whistle parameters related to vessel presence, surface behaviour and group composition

Changes in bottlenose dolphin whistle parameters related to vessel presence, surface behaviour and group composition

Monitoring the habitat use of common Bottlenose Dolphins (Tursiops truncatus) using passive acoustics in a Mediterranean marine protected area

The abundance of common bottlenose dolphins (Tursiops truncatus) in the former special marine reserve of the Cres‐Lošinj Archipelago, Croatia

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