Nesting activity of Olive ridley and effect of artificial shade at Cascajilloso Beach, a new inhabited nesting site in Pacific Panama

Sea turtle nesting activity on newly monitored beaches yields important data to support future regional and global conservation assessments. Here we report on nesting activity of Olive Ridley (Lepidochelys olivacea) at Cascajilloso Beach in Pacific Panama based on data from a new hatchery during seasons 2019, 2020 and 2021. Besides, we conducted a field experiment analyzing the effects of artificial shading on hatchlings' biometric characteristics, hatching success and the incubation period. Nesting activity based on number of egg clutches transferred to the hatchery reached a peak between September (33%) and October (25%). Curved carapace length (CCL) of nesting females (64.3–66.2 cm) was similar to other populations of the Eastern Tropical Pacific (ETP). The number of egg clutches was 80 in 2019, 74 in 2020 and 108 in 2021, however, the clutch size was slightly smaller (91.5 to 94.5 eggs) compared with other populations of the ETP. This could be a phenotypic variation of nesting females at this beach. The ability to move egg clutches to the hatchery was affected during 2020 season due to COVID-19 restrictions. Heavy rainfall during the incubation period influenced the nest temperatures registered under artificial shade and unshaded treatments (maximum average 29.9 °C), potentially resulting in males. The warmer temperatures in our experimental nests produced heavier hatchlings contrary to general assumptions, but this was also related to straight carapace length only after a threshold value of 40 mm. Hatchlings under the artificial shade were able to grow to a certain size but potentially at the cost of storing less mass (trade-off). The ongoing beach patrolling and hatchery management techniques with long-term baseline data collection are needed to secure the nesting population of L. olivacea at this recently surveyed beach.