Wallace J. Nichols

California Academy of Sciences · Department of Herpetology

Aim Understanding the spatial ecology of animal movements is a critical element in conserving long‐lived, highly mobile marine species. Analyzing networks developed from movements of six sea turtle species reveals marine connectivity and can help prioritize conservation efforts. Location Global. Methods We collated telemetry data from 1235 indivi...

Grupo Tortuguero de las Californias (GTC – the Sea Turtle Conservation Network of the Californias), a sea turtle conservation effort in Baja California, is an example of a “conservation mosaic” approach to address declining turtle populations, poaching and related corruption. GTC is an example of using “soft power” approaches as an alternative to “...

In 2010, an international group of 35 sea turtle researchers refined an initial list of more than 200 research questions into 20 metaquestions that were considered key for management and conservation of sea turtles. These were classified under 5 categories: reproductive biology , biogeography, population ecology, threats and conservation strategies...

Exposure to natural environments can have calming and stress-reducing effects on humans. Moreover, previous studies suggest that these benefits may be greater in areas with higher species richness. Our study took advantage of a “natural experiment” to examine people’s behavioral, physiological, and psychological reactions to increases in levels of...

To further describe movement patterns and distribution of East Pacific green turtles (Chelo-nia mydas agassizii) and to determine threat levels for this species within the Eastern Pacif-ic. In order to do this we combined published data from existing flipper tagging and early satellite tracking studies with data from an additional 12 satellite trac...

Marine wildlife faces a growing number of threats across the globe, and the survival of many species and populations will be dependent on conservation action. One threat in particular that has emerged over the last 4 decades is the pollution of oceanic and coastal habitats with plastic debris. The increased occurrence of plastics in marine ecosyste...

Marine wildlife faces a growing number of threats across the globe, and the survival of many species and populations will be dependent on conservation action. One threat in particular that has emerged over the last 4 decades is the pollution of oceanic and coastal habitats with plastic debris. The increased occurrence of plastics in marine ecosyste...

Significance Loss of megafauna, termed trophic downgrading, has been found to affect biotic interactions, disturbance regimes, species invasions, and nutrient cycling. One recognized cause in air-breathing marine megafauna is incidental capture or bycatch by fisheries. Characterizing megafauna bycatch patterns across large ocean regions is limited...

Elucidating spatio-temporal movements of animals is an integral component of wildlife conservation and protected species management. Between 2008 and 2010 we satellite tracked 15 adult female hawksbill turtles Eretmochelys imbricata in the eastern Pacific Ocean to evaluate their movement behavior and to guide management and conservation efforts of...

Sea turtles live on the edge of extinction, spend a lot of time at the edge of land and sea, and, in the case of the Los Cabos nesting turtles, occupy the northernmost edge of the nesting grounds for their species (Fritts et al. 1982). Climate change may directly affect sea turtles by changing sea surface temperatures, eroding beaches, and pushing...

Satellite transmitter information for 30 loggerhead sea turtles (Caretta caretta) tracked off the BCP, Mexico. (PDF)

Highly productive hotspots in the ocean often occur where complex physical forcing mechanisms lead to aggregation of primary and secondary producers. Understanding how hotspots persist, however, requires combining knowledge of the spatio-temporal linkages between geomorphology, physical forcing, and biological responses with the physiological requi...

Adult hawksbill turtles (Eretmochelys imbricata) are typically described as open-coast, coral reef and hard substrate dwellers. Here, we report new satellite tracking data on female hawksbills from several countries in the eastern Pacific that revealed previously undocumented behaviour for adults of the species. In contrast to patterns of habitat u...

To assess the potential demographic consequences of alternative juvenile foraging strategies in loggerhead sea turtles Caretta caretta, we compared habitat selection, movement, size frequency, and diet of juvenile loggerheads in neritic versus oceanic habitats of the North Pacific. Forty juveniles satellite-tracked from neritic habitat revealed uti...

Green turtles spend most of their lives in coastal foraging areas where they face multiple anthropogenic impacts. Therefore, understanding their spatial use in this environment is a priority for conservation efforts. We studied the fine scale daily movements and habitat use of East Pacific green turtles (Chelonia mydas) at Laguna San Ignacio, a sha...

Over the past 3 decades, the status of sea turtles and the need for their protection to aid population recovery have increasingly captured the interest of government agencies, non-govern- mental organisations (NGOs) and the general public worldwide. This interest has been matched by increased research attention, focusing on a wide variety of topics...

Monthly in-water monitoring was conducted at 5 foraging areas off the Baja California Peninsula, Mexico, from 2001 to 2006 to assess black turtle population status. Turtles were captured with entanglement nets, size (straight carapace length, SCL) and weight of each individual were recorded and turtles were tagged on both rear flippers. A total of...

Sea turtles have historically been an important food resource for many coastal inhabitants of Mexico. Today, the consumption of sea turtle meat and eggs continues in northwestern Mexico despite well-documented legal protection and market conditions providing easier access to other more reliable protein sources. Although there is growing evidence th...

Since 2001, Grupo Tortuguero has been conducting monthly inwater monitoring of East Pacific green turtles (Chelonia mydas), also known as black turtles, at four neritic foraging areas (Bahía Magdalena, Laguna San Ignacio, Punta Abreojos, Laguna Ojo de Liebre) along the Pacific coast of Baja California Sur, Mexico. Extensive tagging (883 turtles tag...

The oceans have become one giant refuse bin for all manner of plastics. Environmental and health concerns associated with plastic pollution are a long recognised international problem (Carpenter & Smith 1972). Whilst approximately 10% of all solid waste is plastic (Heap 2009), up to 80% of the waste that accumulates on land, shorelines, the ocean s...

We studied the diet of green sea turtles (Chelonia mydas) at Bahía de los Angeles in the Gulf of California, México. From 1995–1999, we collected esophageal lavage and fecal samples from live-captured turtles and analyzed stomach contents from stranded carcasses encountered in the study area. Foods ingested did not vary with carapace length. Turtle...

We tracked East Pacific green turtles Chelonia mydas using GPS-VHF telemetry in Estero Banderitas, a tidally-influenced foraging area in Bahia Magdalena, Baja California Sur, Mexico. 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 t...

La mayoría de las poblaciones de tortugas marinas tienen historias naturales que traspasan fronteras y las redes multinacionales han llegado a ser una parte importante de exitosas investigaciones y de estrategias de conservación. La importancia de las redes se incrementa considerablemente al tratar con poblaciones de tortugas marinas poco estudiada...

Assessing mortality of long-lived organisms is fundamental for understanding population trends nd for implementing conservation strategies, but doing so for marine megafauna is challenging. Here we assessed anthropogenic mortality of endangered North Pacific loggerhead turtles in the coastal waters of Baja California Sur, Mexico (BCS), through the...

Assessing mortality of long-lived organisms is fundamental for understanding population trends and for implementing conservation strategies, but doing so for marine megafauna is challenging. Here we assessed anthropogenic mortality of endangered North Pacific loggerhead turtles in the coastal waters of Baja California Sur, Mexico (BCS), through the...

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The mangrove channels of Bahía Magdalena, Mexico, are important developmental areas for juvenile green, or black turtles (Chelonia mydas), but incidental bycatch and illegal hunting threaten population persistence. We studied size distribution, condition index (CI), growth rates, and mortality of black turtles in Estero Banderitas, the largest mang...

Background: Although bycatch of industrial-scale fisheries can cause declines in migratory megafauna including seabirds, marine mammals, and sea turtles, the impacts of small-scale fisheries have been largely overlooked. Small-scale fisheries occur in coastal waters worldwide, employing over 99% of the world's 51 million fishers. New telemetry dat...

Loreto is a particularly challenging location for sea turtle conservation because of a long history of poaching, lack of adequate law enforcement, and political divisions within the community. However, with Mexican and international support, the community of Loreto has the grassroots initiative to overcome obstacles and become a model for other dev...

Sea turtle products (e.g., meat, adipose tissue, organs, blood, eggs) are common food items for many communities worldwide, despite national regulations in some countries prohibiting such consumption. However, there may be hazards associated with this consumption due to the presence of bacteria, parasites, biotoxins, and environmental contaminants....

Bahia Magdalena on the Pacific coast of Baja California Sur, Mexico, is an important feeding and nursery ground for black turtles Chelonia mydas, loggerhead turtles Caretta caretta, olive ridley turtles Lepidochelys olivacea, and hawksbill turtles Eretmochelys imbricata. Despite international and national protection, sea turtles continue to be caug...

Sea-surface temperature (SST) fronts are integral to pelagic ecology in the North Pacific Ocean, so it is necessary to understand their character and distribution, and the way these features influence the behavior of endangered and highly migratory species. Here, telemetry data from sixteen satellite-tagged blue whales (Balaenoptera musculus) and s...

The waters of northwestern Mexico (fig. 20.1) have been among the most important feeding and developmental grounds in the eastern Pacific for 5 of the world’s 7 species of sea turtles. These are, in order of abundance: the green turtle (Chelonia mydas), known locally as the “black turtle,” the loggerhead (Caretta caretta), the olive ridley (Lepido-...

Baja California represents the northernmost reproductive area for Lepidochelys olivacea. This region is characterized by its high temperature and low humidity. Thus, nest site selection plays an important role in reproductive success. To evaluate the factors affecting site selection for oviposition Las Barracas Beach, located in the south of the pe...

From June 1995 to August 2002 we assessed green turtle (Chelonia mydas) population structure and survival, and identified human impact, at Bahia de los Angeles, a large bay that was once the site of the greatest sea turtle harvest rates in the Gulf of California, Mexico. Turtles were captured live with entanglement nets and mortality was quantified...

Long-term records of nesting numbers, or proxies to nesting numbers, show a precipitous decline in the size of many sea turtle populations. Population declines are most frequently attributed to fisheries bycatch, although direct quantification of this level of mortality is rare. We used satellite-tracking records for turtles in the Mediterranean Se...

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 in-water capture of live turtles and searches for dead carcasses. We recorded a total of 27 hawksbill turtles: 14 (four...

The green turtle Chelonia mydas is a circumglobal species that is susceptible to overexploitation as a food resource and incidental mortality in fisheries. Efforts to recover regional green turtle populations have been hampered by a lack of information on their biology. In particular, turtle movements and home ranges in neritic foraging habitats ar...

Growth rates recorded between 1995 and 2001 for green turtles in the central Gulf of California were analyzed using nonparametric regression modeling. A mixed longitudinal sampling design provided 21 growth rate estimates from 19 turtles recaptured at intervals ≥ 11 months. Initial straight carapace length (SCL) of turtles ranged from 58.6–93.8 cm....

The movements and submergence behaviour of two male green turtles (Chelonia mydas) on their mating grounds at Ascension Island were investigated by satellite telemetry. During the mating season, males tended to conduct much shorter dives (typically <15 min) than those recorded previously for females during the internesting period at this rookery. T...

Sea turtles have historically been a primary resource for many of the coastal inhabitants of Bahia Magdalena, Baja California S ur, Mexico. Despite their endangered status and the implementation in 1990 of Mexican laws prohib iting the harvest of sea turtles, the demand for and the supply of these animals has persisted to some degree. To determine...

The oceanic movements of a captive-raised adult loggerhead turtle ( Caretta caretta) were monitored with satellite telemetry for 368 d from 10 August 1996 to 12 August 1997. During this time the turtle migrated across the Pacific Ocean, covering more than 11,500 km between Santa Rosaliita, Baja California, Mexico (28°40'N, 114°14'W), and Sendai Bay...

In July 1994 a loggerhead turtle (Caretta caretta) was released from the central Pacific coast of the Baja California peninsula. Four hundred and seventy-eight days later the turtle was found by a fisherman off the coast of Kyushu, Japan. This represents a one-way transpacific migration of more than 10,000 km. This report is a reminder of the impor...

Plastic flipper tags used to identify black turtles in the central Gulf of California apparently contribute to incidental capture of the tagged turtles in gill nets. This assertion is based on field observations, interviews with local fishermen, and a study on captive tagged and untagged turtles. We recommend discontinuing the use of plastic tags o...

The presence of loggerhead turtles, Caretta caretta, in the Gulf of California and eastern Pacific has been considered enigmatic. No nesting is known to occur, however genetic affinities have been established among eastern Pacific loggerheads and those nesting in Japan and Australia. In July of 1993, a flipper tagged loggerhead turtle was released...

The Internet can provide a powerful means for biologists to share and communicate their findings with teachers and students. Teachers find that when students have access to "real" data, the students' learning experience is enriched. In this collaborative effort we have made satellite tracking data from a loggerhead turtle available on the Internet...

The Gulf of California is an important area for development and feeding of black sea turtles originating from nesting beaches of more southern portions of the eastern Pacific Ocean (Cliffton et al., 1982; Alvarado and Figueroa, 1992). As these animals move into the Gulf, they enter an enclosed body of water that is considered a dynamic and producti...