First data on the population of the European pond turtle Emys orbicularis at Lake Tonga, El Kala National Park, Algeria

The North African distribution of Emys orbicularis (L., 1758) is rather local and discontinuous, with no data on the ecology of the Algerian population so far. Such data are essential in improving conservation efforts. Altogether, 216 individuals were captured during 2013–2015, consisting of 212 adult specimens, 129 males and 83 females, giving a male-biased sex ratio of 1.6:1. The Jolly-Seber index, of mark-recapture method, for the single year of 2015 was 451 ± 646.4 turtles, giving a density of 82 turtles ha−1. Regarding size classes, 80% of males had a straight carapace length (SCL) of 115–145 mm, 83% of females had a SCL of 125–155 mm. Comparison revealed significant sexual size dimorphism, females being larger and heavier than males; mean SCL of males 128.8 mm, mean SCL of females 132.8 mm; mean body mass (BM) of males 336.9 g, mean BM of females 396.1 g. The largest specimen was a female with a SCL of 167.5 mm and BM 680 g.