Yo-yo vertical movements suggest a foraging strategy for tiger sharks Galeocerdo cuvier

Abstract

Many pelagic fishes exhibit 'yo-yo' diving behavior, which may serve several possible functions, including energy conservation, prey searching and navigation. We deployed accelerometers and digital still cameras on 4 free-ranging tiger sharks Galeocerdo cuvier, to test whether their vertical movements are most consistent with energy conservation or prey searching. All sharks swam continuously, with frequent vertical movements through the water column at mean swimming speeds of 0.5 to 0.9 m s -1 . Tail-beating was continuous except for sporadic, powerless gliding during descents (from 0 to 18% of total descent time). At a given tailbeat frequency, swimming speeds were lower during ascent than descent (consistent with negative buoyancy). Burst swimming events, which might represent prey pursuits, were observed during all phases of vertical movements. Camera images showed a variety of potential prey and the possible capture of a unicornfish. Collectively, results suggest that yo-yo diving by tiger sharks is not primarily for energy conservation, but probably represents an effective search strategy for locating prey throughout the water column. 424: 237-246, 2011 shown by this species in pelagic environments (Holland et al. 1999). Furthermore, forward-facing video cameras do not permit a detailed analysis of swimming behavior. Fortunately, recently developed accelerometers allow very fine-scale measurement of animal body movements (Yoda et al. 2001). OPEN PEN ACCESS CCESSMar Ecol Prog SerVertical movements by pelagic fishes might also be primarily related to foraging. For example, Sims et al. (2008) showed that the frequency distribution of vertical movements by pelagic predators agrees with the theoretical optimum for locating patchily distributed prey. However, until recently, it has proven extremely difficult to empirically quantify foraging in pelagic fishes. Fortunately the development of animal-borne image recorders has provided useful new tools for obtaining visual information about foraging behaviors (Marshall 1998, Heithaus et al. 2001, 2002, Watanabe et al. 2003, 2004. The combination of animal-borne image recorders with accelerometers offers a promising new method for evaluating the possible relationship between vertical movements and foraging behavior.The tiger shark Galeocerdo cuvier is a large (up to 5.5 m total length), wide-ranging obligate swimmer with a broad diet (Lowe et al. 1996, Holland et al. 1999, Meyer et al. 2009, and previous studies have revealed that this species exhibits yo-yo diving behavior (Holland et al. 1999, Heithaus et al. 2002. In the present study, we deployed accelerometers and digital still cameras on tiger sharks to quantify their fine-scale swimming behavior and to determine whether foraging occurred during vertical movements. Our goal was to ascertain whether yo-yo diving in tiger sharks most closely resembled theoretical energy-saving or effective prey search strategies. MATERIALS AND METHODS Deployment of instruments.Tiger sharks were captured using dem...

Convergent Foraging Tactics of Marine Predators with Different Feeding Strategies across Heterogeneous Ocean Environments

“…Consequently, blue sharks may be able to feed on them while performing deep, fast movements through the water column. In fact, burst swimming and prey capture events were observed during consecutive V-shaped dives ("yo-yo") in tiger sharks (Nakamura et al, 2011).…”

“…Archival tags, in particular, can record data at high temporal resolutions (sub-second) and have been used to determine movements and environmental preferences, identify behavioral patterns such as seasonal migrations or diel changes (Schaefer et al, 2007;Walli et al, 2009;Humphries et al, 2010;Gleiss et al, 2011bGleiss et al, , 2013Nakamura et al, 2011;Queiroz et al, 2012;Afonso and Hazin, 2015;Campana et al, 2015) and also, understand the underlying observed spatial dynamics (Sims et al, 2006(Sims et al, , 2008 and interactions with fisheries (Queiroz et al, 2016). Linking movement patterns to habitat use remains, however, a challenging task.…”

“…Linking movement patterns to habitat use remains, however, a challenging task. Detailed records of prey abundance and distribution and accurate indices of feeding are difficult to obtain for the majority of species and although visual assessment of prey capture is possible for some species (Seminoff et al, 2006;Elliott et al, 2008), in most cases, indirect parameters have been used as a proxy (e.g., gastric or visceral temperature changes, mouth/beak opening or head/jaw movement, accelerometer signatures; Sepulveda et al, 2004;Gleiss et al, 2011aGleiss et al, , 2013Nakamura et al, 2011Nakamura et al, , 2015Carroll et al, 2014;Nakamura and Sato, 2014). For efficient foraging by predators, patterns of habitat use are assumed to reflect the distribution, density and quality of prey resources (Stephens and Krebs, 1986;Austin et al, 2006;Carroll et al, 2017).…”

Post release survival and movement patterns of roosterfish (Nematistius pectoralis) off the Central American coastline

“…The oscillatory behavior typically occurred within relatively confined areas (i.e., 100 to 200 m) of high prey density and proximal to complex topographical features (i.e., reefs and river mouths). Increased vertical activity has been shown to be associated with active foraging in several pelagic fishes (Sepulveda et al, 2004;Bestley et al, 2010;Nakamura et al, 2011), and crepuscular periods have been shown to be consistently important foraging times for many species (Holland et al, 1996). Although this work was not able to verify feeding activity, the observation of tagged roosterfish pursuing prey at the surface in as little as 9 h after release suggests that some of the behaviors recorded in this study are representative of foraging patterns.…”

“…Although this observation does not assure longer-term survival, postrelease feeding is a critical step that must occur in order to facilitate recovery (Aalbers et al, 2004;Cooke & Schramm, 2007;Meka & Margraf, 2007). We also observed repeated periods of increased vertical movements (oscillations) during the track sessions, behaviors that have been shown to be associated with foraging activity in several pelagic species (Carey & Lawson, 1973;Pepperell & Davis, 1999;Sepulveda et al, 2004;Cartamil et al, 2010;Nakamura et al, 2011). These behaviors also contrast the unidirectional movements commonly associated with moribund behavior (Moyes et al, 2006;Heberer et al, 2010).…”