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From 1997 to 2001 the occurrence of hawksbill turtles (Eretmochelys imbricata) was characterized at neritic foraging habitats along the Pacific coast of the Baja California Peninsula and in the Gulf of California, Mexico, through inwater capture of live turtles and searches for dead carcasses. We recorded a total of 27 hawksbill turtles: 14 (four live-captured and 10 strandings [dead turtles)) along the Pacific coast of Baja California and 13 (seven live-captured and six strandings) in the Gulf of California. The range of straight carapace lengths for hawksbill turtles from the Pacific and the Gulf of California was 35.4 to 52.5 cm (mean = 42.5 cm) and 34.4 to 74.2 cm (mean = 48.0 cm), respectively. Although hawksbills are uncommon in coastal neritic habitats near Baja California, their continued presence indicates that this region should be included as a focus area for future conservation efforts.THE HAWKSBILL TURTLE, Eretmochelys imbricata (Linnaeus, 1766), is a higWy endangered and inadequately understood marine turtle with circumtropical distribution (Witzell 1983). The species is best described by its elongated beak and imbricate scutes on the carapace and plastron, especially during juvenile and subadult life stages. Known as "tortoiseshell" or "bekko," these plates have caused the hawksbill turtle to be the target

We tracked East Pacific green turtles Chelonia mydas using GPS-VHF telemetry in Estero Banderitas, a tidally-influenced foraging area in Bahía Magdalena, Baja California Sur, México. Tidal currents were measured with a bottom-mounted Acoustic Doppler Profiler (ADP) and the data used to predict tidal current speed and direction at the location and time during which turtles were tracked. Twenty-nine turtles were tracked in the summers of 2000 to 2003. Vagility (mean ± SD; 18.6 ± 11.4 km d ) of turtles was the greatest so far reported for green turtles at foraging areas. Turtles displayed highly linear movements, and movement patterns were circatidal. Vector correlation was used to compare turtle speed and direction with tidal speed and direction. Correlation coefficients were significant for 11 out of 13 tracks, indicating significant linear interdependence between turtles and tides. Speed and direction contributed equally to the correlation. Results indicated a new paradigm for green turtles in feeding areas, where turtles are transported on continual tides that allow them to exploit a patchy and seasonal distribution of algae, their main diet component. This tidal transport is markedly different than Selective Tidal Stream Transport, in which animals use either the ebb or flood tide for transport. Tidal currents may be an accurate indicator of turtle movement in tidal areas, and this transport system has implications for foraging ecology, energetics, and growth. KEY WORDS: Green turtle · Tidal movements · East Pacific Ocean · Wildlife telemetry · Foraging · Acoustic Doppler Profiler Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 386: [263][264][265][266][267][268][269][270][271][272][273][274] 2009 and location of food affect activity and movement patterns of green turtles in feeding areas (Bjorndal 1980, Mendonça 1983, Ogden et al. 1983, Limpus & Limpus 2000, Seminoff et al. 2002b, Taquet et al. 2006. In general, green turtles exhibit a bimodal pattern of movement, feeding in the early morning and late afternoon, and resting in deeper waters during midday and at night (Bjorndal 1980, Mendonça 1983, Ogden et al. 1983, Seminoff et al. 2002b, Taquet et al. 2006. In nontidal foraging areas, food availability is the main determinant of green turtle activity (Bjorndal 1980, Ross 1985, Balazs et al. 1987 while in areas where tidal currents are a dominant environmental force, it is possible that tides become the most important determinant of activity and movements.Ocean currents affect the movements of turtles undergoing large-scale migrations (Luschi et al. 2003a, Girard et al. 2006, and tidally-oriented movements have been observed for green, loggerhead Caretta caretta and Kemp's ridley Lepidochelys kempii sea turtles in tidal feeding areas (Byles 1988, Limpus et al. 1994, Limpus & Limpus 2000, Schmid et al. 2002. However, rarely have tidal currents been considered an important environmental factor affecting green turtles at feeding areas.Use of Selective ...

Understanding and mitigating potential effects of tags on instrumented animals is a crucial consideration when developing new tracking techniques. Some populations of aquatic megafauna spend the majority of their lives occupying small home ranges, yet conventional finescale tracking methods generally provide a limited number of non-continuous locations, while new technology is cost prohibitive. We developed a low-cost tethered telemetry system (<185 USD tag −1 ) for short-term tracking of marine turtles in nearshore environments that incorporated standard GPS data loggers and VHF transmitters into buoyant tags of 3 different designs. We then estimated the drag of each tethered tag using an instrumented flow tunnel, deployed them on freeliving green turtles along Mexico's Baja California peninsula, and compared movement patterns of turtles equipped with high-and low-drag tags. All tags provided high-resolution tracks that ranged from 5.2 to 184.0 h (mean ± SD = 43.2 ± 37.8 h; n = 26 turtles) for a total of 1122 h. We found that the first 2 tag designs increased drag on large juveniles at typical swimming speeds by approximately 7 to 10%, which is comparable to predicted drag increases incurred by similarly sized green turtles from most commercially available electronic tags. By contrast, the third tag design increased drag by 1% or less. Turtles fitted with the high-drag tags made fewer course changes and exhibited straighter (less tortuous) movements than those fitted with the low-drag tags. Although it is unclear if the observed behavioral differences were due entirely to the tags, our results highlight the importance of evaluating potential ecological impacts of telemetry devices on host species, particularly when developing new technology.