The Kemp's ridley (Lepidochelys kempii, Garman 1880) is considered one of the most vulnerable sea turtle species worldwide (Márquez 1994). This species is nearly restricted to the Gulf of Mexico, having its major nesting beaches in the state of Tamaulipas, Mexico (Márquez 1994). However, certain beaches in Veracruz and Campeche, Mexico, as well as in Texas, Florida, and Louisiana in the United States, report regular nesting by these turtles, although nesting is less abundant compared to the activity reported in Tamaulipas (Márquez 1994). The Kemp's ridley population was subjected to an intense fishery, which brought it almost to extinction, but in the mid-1960s, its protection began through Mexican government-sponsored nesting beach conservation on its main nesting beach, Rancho Nuevo, Tamaulipas (Ross et al. 1989; Márquez 1996). Thanks to the tremendous effort made by the Mexican and American governments, Kemp's ridleys are in a recovery phase.

In Campeche there have been sea turtle conservation efforts on the nesting beaches for more than 25 years. Nesting by this species has been documented on numerous occasions (Escanero 1987, 1989; Escanero et al. 1988, 1990; Castro et al. 1991; Guzmán et al. 1993, 1994, 1995; Márquez 1994; Guzmán 1996, 1997, 2000, 2001, 2002, 2004). In addition to nesting beach conservation efforts, there has been valuable assistance by local fishers in the region. Live turtles which have been accidentally captured during fishing activities are often reported to and/or turned in to researchers. Involvement of fishers is a widely used strategy for determining sea turtle distribution in the marine zones, and valuable by-products of this partnership is the feeling of mutual respect between fishers and biologists as well as an enhanced sea turtle conservation ethic in local communities. This paper describes the nesting and capture reports of Kemp's ridley turtles for 20 years along the entire coast of Campeche and the north coast of the Yucatan Peninsula.

Nesting Records

During the standardized patrolling and surveillance of sea turtle nesting beaches in Campeche, during 20 years (1984–2003), 15 Kemp's ridley nests have been recorded. These nests were registered in 3 different nesting beaches in Campeche: 10 on Isla Aguada, 3 on Isla del Carmen, and 2 in Sabancuy (Fig. 1). Ten of these 15 nests were relocated to a hatchery, 4 were kept in styrofoam boxes, and only 1 was maintained in situ; this nest management was necessary because of a high level of risk (predation, poaching, and floods) jeopardizing their final success. Fourteen of these nests were found in the upper high tide zone and only 1 in the sand dunes zone. Average clutch size recorded in the nests relocated to the hatchery was 111.8 eggs (SD = 25.9, n = 10, range = 65–153 eggs). Average clutch size of nests in styrofoam boxes was 106.7 eggs (SD = 28.6, n = 4, range = 81–144 eggs). The 1 nest left in situ had 147 eggs. Average hatching success for hatchery nests was higher (mean = 67.1%, SD = 26.7, n = 10, range = 17.54%–93.02%) than those incubated in styrofoam boxes (mean = 60.5%, SD = 28.3, n = 4, range = 28.07%–95.59%); however, there were no significant differences in hatching success between them (χ² = 1.4, p = 0.237). Hatching success of the in situ nest was 63.3%. The mean incubation time for the nests relocated to the hatchery was on average 51.6 days (SD = 3.7, n = 9, range = 47–56 days), whereas that for eggs kept in styrofoam boxes was 51.5 days (SD = 3.5, n = 4, range = 48–55 days); contrasting with those left in situ which had a mean incubation time of 54 days. These nests contributed 1109 hatchlings to the Kemp's ridley population in the Gulf, representing at least 14 different cohorts. This hatchling contribution is small compared to the over 500,000 hatchlings being released more recently in Rancho Nuevo (US–Mexico Program 2004). However, Campeche is considered an important historic nesting and feeding site for Kemp's ridley because it is one of the few beaches, besides its main nesting site at Tamaulipas, where the species regularly nests, albeit at low levels. Moreover, its marine area harbors postnesting females looking for abundant crustacea, which makes it one of the 3 most important feeding areas in the Gulf of Mexico for the species (Pritchard and Márquez 1973; Márquez 1978; Hildebrand 1981; Márquez 1994). The fact that this nesting activity has been ongoing for more than 10 years in this region, more than 1200 km from Rancho Nuevo at Tamaulipas, corroborates the persistence of this highly vulnerable species, and helps support the idea that Campeche was an important nesting site decades ago, prior to spread of overfishing and other human impacts (Márquez 1994).

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Kemp's Ridley Nesting Females

During this study, a total of 3 nesting females were tagged and measured. The first was tagged in 2000 after she failed to nest at Isla Aguada, (inconel tag FM360); the second was tagged in 2002 at Isla del Carmen during egg laying (HL200); the last was tagged in 2003 also at Isla del Carmen (FPF601). These females had a mean curved carapace length (CCL) of 67.2 cm (SD = 3.6, range = 63.0–69.0), a size that is consistent with sexually mature females in Rancho Nuevo, Tamaulipas (Márquez 1994). Making an estimation using the Chaloupka and Zug (1997) and Zug et al. (1997) polyphasic growth function, we estimate that these females were between 13 and 15 years old.

Incidental Capture

During the cooperative program with fishermen (2001–2004), we released 4 Kemp's ridleys that were incidentally captured. The first was a female captured in front of Punta Xen, Campeche; it was tagged then released in the same area. The second and third were captured in 2004 at Isla del Carmen. One was a female (63.5-cm CCL) found stranded in a Terminos lagoon branch, then tagged and released in the zone known as Bahamitas near Isla del Carmen; the second (no size data) was accidentally captured with an entangling net, then also released at Bahamitas. A fourth female (70.0-cm CCL) bearing tag scars in both foreflippers was captured in 2004. The presence of these tag scars suggests that it had been tagged before. It was retagged and released in the same site.

Records of Kemp's Ridleys in the Marine Environment

During an in-water study of juvenile hawksbill turtles (Eretmochelys imbricata), 3 Kemp's ridleys were captured between March and August, 2002, and released after being flipper-tagged. The first turtle (68-cm CCL; 35 kg) was captured near Isla Aguada on March, inside the Terminos Lagoon (Fig. 1) at 6-m depth on a muddy bottom; the second turtle (59-cm CCL; 25 kg) was captured in June near Palo Alto, 7 km from Isla Aguada; the third turtle (68.8-cm CCL) was accidentally captured in Sabancuy in August. Sabancuy, Isla Aguada, and Isla del Carmen are linked to the Terminos Lagoon by several channels; some researchers consider this lagoon as an important foraging area for this species (Márquez 1994). The capture effort made during 4 years for these 7 recorded Kemp's ridleys involved 243 fishing boats working the same number of days near the coast, representing only 0.4% of the annual effort made by these fishermen in Campeche. Although the program for release of incidentally captured sea turtle continues in Campeche from Isla del Carmen to Champoton (Fig. 1), and many recaptures of hawksbills and green turtles (Chelonia mydas) have been recorded, none of the above captured Kemp's ridleys has been recently recaptured. As complementary records of Kemp's ridleys on the Yucatan Peninsula, which support the importance of the area for this species, Cuevas and Maldonado (2002) reported the incidental capture of 2 female Kemp's ridleys in Las Coloradas along the northeast coast of the Peninsula, which is also considered a foraging site for this species. Its presence in this region had not been reported for nearly a decade (Márquez 1994). Both individuals were captured shortly after the nesting season of this species in Tamaulipas, so Cuevas and Maldonado (2002) suggested that the present occurrence in this marine zone may be the result of the Kemp's ridleys recovery process in the southern Gulf of Mexico. In April 2004, a female Kemp's ridley (76.5-cm CCL) was apparently injured by a net and drowned near Holbox Island, Quintana Roo (northeast corner of the Peninsula). This report indirectly adds a record of the Kemp's ridleys occurrence again in that eastern area of the Peninsula. The present information confirms the Campeche coast as a nesting zone for Kemp's ridley turtles, and the Yucatan Peninsula, as well as the Terminos Lagoon, as important developmental zones for juveniles in the Gulf of Mexico. These records also underscore the importance of the beaches and shallow waters of the western Yucatan Peninsula for Kemp's ridleys, because these beaches are regular nesting sites for the species (Campeche), and an important foraging zone and migrating route (Campeche and Yucatan) for the postnesting females coming from Tamaulipas.