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Marine Turtle Newsletter 23:3-4, © 1982

Atlantic Ridley Project, 1982: Preliminary Account

René Márquez M.
C.I.P. Manzanillo, c/o Delegación Federal de Pesca, Manzanillo, Col. 28200 Mexico

This was the 16th year of the Mexican project for restoring this species and the 5th year of cooperation with the U.S. Marine Fisheries Service. Out of a total of 874 nests, 753 were translocated; around 12.2% were lost to predators, poachers and in other ways. 67,571 eggs were transplanted to corrals and 10,332 to styrofoam boxes. This year there were no serious storms (see Marquez, R. 1982. Marine Turtle Newsletter 21, p. 3). Preliminary data on hatching success are: 63.5% from the corrals and 76% from the boxes at Rancho Nuevo, with an overall hatch rate of 69.5%. more than 47,000 hatchlings were released on the beach.

Twenty boxes with 2020 eggs were sent to Padre Island, and from there 1524 hatchlings went to the Galveston Laboratory, Texas, for head-starting. The hatching rate was 75.5%. Head-started turtles are released at around the age of 9 months in the Gulf of Mexico. Up till now, over the past 4 years, 6694 turtles, less than a year old, have been released. About 190 have been kept as a potential breeding stock in several U.S. aquaria and at the Cayman Turtle Farm (Mexus-Gulf's Sea Turtle Working Group's Accomplishments and Plans for 1978-85, ms. Veracruz, Mexico, 1982).

This year between 2 April and 18 July there were 61 emergences of females for nesting, some grouped some solitary. An unusual thing in 1982 was that there was only one important arribazon with around 300 turtle tracks; 251 nests from these were located and reburied the same day. Monel tags were applied to 197 turtles and 15 of these were double tagged with blue plastic jumbo tags on the opposite front flipper; 44 of these turtles nested twice and 4 thrice. Also 44 turtles tagged in previous years laid eggs and 5 of these turtles nested twice. 66 turtles with what looked like tag scars were retagged.

Temperature was monitored in 6 corral and 7 box clutches for studies of effects on sex ratio.

The work in the turtle camp began in the 2nd week of April and lasted till the 2nd week in September. The first turtle was seen laying on 11th April and the last on 18th July. The U.S. team was on the beach from 10 May till 16 August. An airplane was invaluable for surveying nesting turtles. Also to support the goals of the Western Atlantic Turtle Symposium (scheduled for July 1983 in Costa Rica), aerial surveys of shoreline characteristics and nesting activity were made 28 June-2 July.

Again the incidental catch of turtles by shrimp trawlers is the most serious obstacle to increasing this population.