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During the 2000 season, there were eight arribazones (Note: An arribazón is "a great influx of fish to coasts and ports at certain seasons", which should not be confused with an arribada which is "the arrival of a vessel in port"; Anonymous 1966). In each arribazón there were more than 100 nests laid (Table 3). The great majority of nests laid by the Kemp´s ridley turtles are relocated to corrals (i.e. fenced open air hatcheries) which is usually undertaken less than 6 hours after oviposition. This action is necessary because of the high rate of natural predation and egg poaching that would occur otherwise. If the number of nests laid each year continues to increase, an alternative solution will need to be developed for the protection of the nests (Márquez-M. et al. in press). Indeed, to reduce the time of transport and to maximize efficiency, the number of turtle camps has been increased over the years (Table 2), so that over 230 km of sandy beaches in two states; Tamaulipas and Veracruz are now covered (Table 1).

The number of clutches laid during the 2000 season was higher at all monitored sites than in the recent past. When monitoring began in 1966, over 2,000 female turtles were observed in one day (Pritchard & Márquez-M. 1973; Márquez-M. 1994). Casas-A. (1971) estimated that over 5,000 females were nesting in one season (1969) at the Rancho Nuevo beach. Unfortunately, the population continued to decline, to a minimum between 1985 and 1987, when only an average of 740 nests per year were laid at Rancho Nuevo (Figure 1). Nevertheless conservation efforts continued and soon after the number of nests laid per year slowly started to increase (TEWG 1998; TEWG in press), with a more dramatic rise in the last few years (Figure 1; Table 4).

Table 1. The beaches monitored as part of the Kemp´s ridley nesting surveys. Steps 1-5 show the evolution of the extension of the Rancho Nuevo study area. The most northern and southern limits of the study zone and the period during which this area was monitored are given. Distances include the distance monitored and the increase in beach covered during each increment of increased monitoring.

Table 2. Data regarding nesting and hatching of Kemp's ridley nests and eggs throughout the areas monitored in México, during the 2000 season

Figure 1. Kemp´s ridley turtle nesting at beaches in Rancho Nuevo (solid), Tepehuajes and Barra del Tordo (hash) beaches, in Tamaulipas, México.

The overall increase in clutches laid per year for the Rancho Nuevo beach is also seen at the other south and north sectors of this beach, such as Barra del Tordo (Playa Dos) and Tepehuajes (Figures 1 & 2). The numbers of nests, eggs and hatchlings recorded in the 2000 nesting season for the individual camps are given in Table 2. All nests laid were relocated to corrals for incubation, except for 204 that were left in situ , 135 nests that were incubated in polystyrene boxes, 61 nests that were lost to natural predators, and 35 nests that were poached. In addition other nests were laid and protected on secondary beaches: about 80 in Tecolutla and 107 in Lechuguillas, Veracruz (R. Bravo pers. comm.); 1 in Isla Aguada, Campeche (V. Guzmán pers. comm.); and 12 at Padre Island, Texas, USA. (Shaver 2000).

Assuming that the annual increase in number of nests laid corresponds to an increase in the number of adult females, we conclude that the Kemp´s ridley sea turtle population is slowly expanding and responding positively to the many years of conservation and management.

Figure 2. Kemp´s ridley nesting trend in the period 1966-2000. Fitting for number of nests at: A = Rancho Nuevo (1966-1987), B = Rancho Nuevo (1987-2000) and C = Tepehuajes+Barra del Tordo (1990-2000).

Table 3. Arribazones with >100 nests during the 2000 nesting season in Rancho Nuevo, Tamaulipas, Mexico.

Table 4. Fitting of the linear regression (y=ax+b) for Kemp´s ridley nesting data obtained for the three neighboring beaches and "Survival rates" (S) from A: Rancho Nuevo (1966 to 1987); (B) Ranch Nuevo (1987 to 2000); C: Barra del Tordo and Tepehuajes (1990-2000). In B and C the slopes were positive and survival rates (S=exp^-(z*t)) were greater than 1.0. This suggests high recruitment since 1987 and surpasses the rate of total mortality (z). All relationships are highly significant p<0.0001.

Acknowledgements: The results of this work would not have been possible without the assistance of many researchers, students and voluntary workers from Mexican and US institutions, including the following: US Fish & Wildlife Service, National Marine Fisheries Service, Gladys Porter Zoo, National Fisheries Institute, Texas Shrimp Assoc. and the many students from Mexican Universities, voluntary workers, State organizations, NGOs, Mexican Navy, Fisheries Inspectors, ProFePa, Rancho Nuevo community, Fisheries Industry Association and Port Administration (API).

ANONYMOUS. 1966. Cassells Spanish Dictionary. (Eds). E.A. Peers, J.V. Barragán, F.A. Vinyals & J.A. Mora. Funk & Wagnalls Co., N. York. 1477pp.

CASAS-A. G. 1971. National and regional reports: México. Proc. 2^nd Working Meeting of Marine Turtle Specialists. IUCN Publication 31:41-46.

MÁRQUEZ-M., R. 1994. Synopsis of biological data on the Kemp´s ridley turtle , Lepidochelys kempi (Garman, 1880). NOAA Technical Memorandum, NMFS-SEFSC-343, 91pp.

MÁRQUEZ-M., R., J. DÍAZ, M. SANCHEZ, P. BURCHFIELD, A. LEO, M. CARRASCO, J. PEÑA, C. JIMENEZ & R. BRAVO. 1999. Results of the Kemp's ridley nesting beach conservation efforts in México. Marine Turtle Newsletter 85:2-4.

MÁRQUEZ-M., R., M.C. JIMÉNEZ, M.A. CARRASCO, A. LEO, J. DÍAZ-F. & M. GARDUÑO. (in press). Diagnóstico de la situación actual de la tortuga lora, Lepidochelys kempi . In: "Sustentabilidad y Pesca Responsable en México: Evaluación y Manejo 1997-
1998. Inst. Nal. de la Pesca, México, 24pp.

PRITCHARD, P.C.H. & R. MÁRQUEZ-M. 1973. Kemp´s ridley or the Atlantic Ridley, Lepidochelys kempi . I.U.C.N., Monograph. (Marine Turtle Series) 2, 30pp

SHAVER, D.J. 2000. North Padre Island Kemp´s Ridley Project and Texas Sea Turtle Nesting and Stranding. Report for: Kemp´s Ridley Working Group Meeting. October 25-26, 2000. Brownsville, Texas, 7pp.

Turtle Expert Working Group. 1998. An assessment of the Kemp´s ridley turtle (Lepidochelys kempii) and loggerhead (Caretta caretta) sea turtle populations in the Western North Atlantic. NOAA Technical Memorandum, NMFS-SEFSC-409, 96pp

TEWG (in press). Assessment update for the Kemp´s Ridley and loggerhead sea turtle populations in the Western North Atlantic. NOAA Technical Mem., NMFS-SEFSC.