For the past two years, annual nestings by endangered Kemp’s ridley sea turtles have declined on western Gulf of Mexico nesting beaches of Tamaulipas and Veracruz, Mexico, and Texas.
Because nestings on Tamaulipas beaches dominate this species’ annual reproductive effort, most Kemp’s ridley hatchlings are produced and released from those beaches.
In 2009, prospects for recovery of the Kemp’s ridley population were optimistic because nestings on the Tamaulipas nester-abundance-index beach were increasing by 19 percent per year, according to the “Bi-National Recovery Plan for the Kemp’s Ridley Sea Turtle,” published in 2011.
The recovery plan predicted that this rapid rate of increase would continue, but Kemp’s ridley suffered a major nesting setback in 2010, from which it hasn’t recovered. Various hypotheses were offered to explain the nesting setback, but none have been confirmed with certainty.
Among the criteria, established by the bi-national recovery plan, for down-listing Kemp’s ridley from endangered to threatened status are 10,000 adult females nesting on the Tamaulipas nester-abundance-index beach in a season, which is equivalent to 25,000 nests; and 300,000 hatchlings released from the Tamaulipas nester-abundance-index beach in a season.
The first criterion has yet to be fulfilled, but the second criterion has been exceeded in all years 2000-2019, except for year 2001. In fact, more than 900,000 hatchlings were released from the Tamaulipas nester-abundance-index beach in each year 2007, 2009, and 2012, and the number released in 2017 was nearly 900,000.
Kemp’s ridleys in the neritic life stage occupy shallow coastal waters of the Gulf, and include immature turtles, as well as adults. Neritic immature Kemp’s ridleys are much more abundant than adults, which require energy for long distance migrations to nesting beaches and reproduction.
In addition, carrying capacity for Kemp’s ridleys appears to be declining as a result of long term degradation of the Gulf of Mexico and other factors.
Two recent studies suggest that four decades of highly successful conservation efforts by Mexico and the United States, on land and at sea, may have unintentionally led to excessive numbers of neritic immature Kemp’s ridleys, according to two studies:
“Did Declining Carrying Capacity for the Kemp’s Ridley Sea Turtle Population Within the Gulf of Mexico Contribute to the Nesting Setback in 2010−2017?” published in Chelonian Conservation and Biology journal in 2018; and
“Excessive Annual Numbers of Neritic Immature Kemp’s Ridleys May Prevent Population Recovery” published in Marine Turtle Newsletter in 2019.
An updated Kemp’s ridley stock assessment is needed to determine whether the population is likely to recover under current conservation strategies.