Shrinking turtles may be a good sign that this threatened species is bouncing back

Embargoed until: Publicly released: 2022-06-08 09:01

Australia; VIC

Savvas Michaelides, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Aussie led research has found that loggerhead turtles on an island in Cape Verde off the west coast of Africa are shrinking, with the average size of the nesting turtles dropping by about 2.4 cm over the last 11 years. While that might sometimes signal a population in danger from overharvesting or trophy hunting, the authors say this time it could be a sign that turtle numbers are bouncing back. There has been a 70-fold increase in annual nest numbers between 2008-2020 (from 506 to 35,507 nests) and a big influx of first-time nesters, which they say could explain the drop in turtle size.

Media release

From: The Royal Society

Changes in mean body size in an expanding population of a threatened species
URL after publication: http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2022.0696

With some taxa, a reduction in the mean size of individuals may reflect over-harvesting and/or trophy hunting. However, we show that in sea turtles, a reduction in the mean size of breeding individuals may be part of the good news story of an expanding population. We describe a 70-fold increase in annual nest numbers on the island of Sal (Cape Verde, North Atlantic) between 2008-2020 (from 506 to 35,507 nests), making this now one of the largest loggerhead (Caretta caretta) nesting aggregations in the world. We use 20,128 measurements of the size of nesting turtles to show that their mean annual size has decreased by about 2.4 cm, from 83.2 to 80.8 cm.

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Research The Royal Society, Web page Please link to the article in online versions of your report (the URL will go live after the embargo ends).

Journal/
conference: Proceedings of the Royal Society B

Research:Paper

Organisation/s: Deakin University

Funder: The authors received no funding for this study.

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