Sea turtles are reptiles that spend most of their lives in the sea. Their hydrodynamic shape, large size, and powerful front flippers allow them to dive to great depths and swim long distances.
In the world, there are seven species of sea turtles, distributed among two families:


Dermochelys coriacea


Caretta caretta
Green sea turtle
Chelonia mydas
Eretmochelys imbricata
Olive Ridley
Lepidochelys olivacea
Kemp's Ridley
Lepidochelys kempii
Natator depressus
Sea turtles are descendants of some of the most ancient animal lineages on Earth, having undergone very few evolutionary changes in the last 100 million years.
Video by Lachlan Ross


The Eastern Pacific – the project area for MarES Comunidad - hosts five of the world's seven sea turtle species: leatherbacks, loggerheads, olive ridleys, hawksbills, and green turtles. All sea turtle species are officially classified as threatened or endangered under U.S. and Mexico laws.
The main focus of this project is on two of the most iconic sea turtle populations: the North Pacific loggerhead and the East Pacific leatherback turtle. In recent decades, both populations have suffered significant declines.
The greatest threat to these populations continues to be mortality from fisheries bycatch. Various artisanal and industrial fishing fleets operate in coastal and offshore waters, using surface and bottom-set nets, longlines, and trawls, all known to accidentally catch and kill turtles in the region.


Leatherback (Dermochelys coriacea)

Leatherbacks roaming the oceans today are virtually carbon copies of their ancestors from more than 100 million years ago; they lived among dinosaurs, even outlasting them.
By far the largest of all living sea turtles, leatherbacks can grow to a carapace length of nearly 2 m (7 ft) and a weight of up to 800 kg (1,760 lbs).
They are easily distinguished from other living sea turtle species by their massive size and lack of a completely fused, bony shell. They also have a teardrop-shaped body and a somewhat flexible, smooth-skinned shell with pronounced ridges on their backs (dorsal) and bellies (ventral). Together, these features give leatherbacks unparalleled hydrodynamics and swimming efficiency among turtles.
In addition to their unique body form, leatherbacks have a diet unlike any other sea turtle: they exclusively consume soft-bodied prey on the high seas, such as jellyfish, salps, and pyrosomes.
Regarding distribution, leatherback nesting occurs along the Pacific coast of the Americas from México to Ecuador, concentrating in México and Central America.
After nesting, most Eastern Pacific leatherbacks migrate to waters in the southeastern Pacific, south of the equator, offshore of countries like Ecuador, Peru, and Chile, and northward into the Gulf of California. The number of nesting female leatherbacks in the Eastern Pacific has declined by more than 90 percent over the past thirty years. However, leatherback nesting has stabilized, particularly in Mexico.
Ongoing bycatch in commercial and artisanal and driftnet and longline fisheries remains the biggest threat to the species, with leatherbacks most susceptible to fisheries interactions directly adjacent to their nesting beaches and in the foraging areas in the southeastern Pacific.

Loggerhead (Caretta caretta)

The loggerhead is an enigmatic species. For years, fishers and scientists had seen loggerheads in the waters of the Eastern Pacific, especially along the coast of Mexico, yet nesting beaches were unknown in the region. Nowadays, there is an awareness that all loggerheads found off Pacific Mexico originate from nesting beaches in Japan, nearly 10,000 km (6213.7 mi) away.
Hatchling loggerheads depart Japanese nesting beaches and move eastward to distant developmental and foraging habitats where they grow and mature. While in foraging areas, loggerheads are opportunistic omnivores, consuming a variety of benthic prey found in the mid-water and coastal regions.
Once individuals reach sexual maturity, they return to their natal nesting beaches in Japan for reproduction and remain in the Western Pacific for the remainder of their life cycle, never returning to the Eastern Pacific.
Relative to historical abundance, today's loggerhead nesting population in Japan is substantially low, although some encouragingly positive trends exist in increasing nesting abundance. The primary causes of these declines are loss of nesting habitat and, more so, bycatch in marine fisheries.
These loggerheads forage in the high seas of the Central Pacific, with an unknown proportion of the population moving to the eastern Pacific, off southern California U.S., and the coasts of Northwest Mexico, especially in the Gulf of Ulloa along the Pacific Coast of the Baja California Peninsula.
The Gulf Of Ulloa is of significant importance for the North Pacific loggerhead population, as it is one of the hotspots for fisheries bycatch in Mexico, where more than 1,000 dead loggerheads would wash ashore in any given year. Thankfully, conservation efforts prompted by the Mexican government and local community groups have reduced this mortality rate.
Reducing sea turtle bycatch mortality in Mexico will involve numerous government agencies, academic institutions, N.G.O.s in the U.S. and Mexico, and communities and fishers.
The ultimate goal of the MarEs Comunidad initiative is to develop approaches that foster sustainable fishing practices and livelihood opportunities that result in healthier sea turtle populations and marine resources to support coastal communities throughout Pacific Mexico.

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Artisanal or small-scale fishers and fisheries use smaller open-skiff boats and primarily operate within a day's boat drive from the coast. These fisheries employ different gear types that target species consumed locally and mainly distributed to domestic markets.



Bycatch refers to the incidental hooking or entanglement of non-target species such as sea turtles, marine mammals, and seabirds in commercial and artisanal fishing gear. These animals are usually discarded because they are often protected and rarely have food or commercial value.

Bycatch is one of the most severe threats to the recovery and conservation of sea turtle populations.



Explore the different approaches we are co-creating and implementing with fishing communities to reduce bycatch, promote healthy sea turtle populations, and foster long-lasting, sustainable fishing practices.