The number of sea turtle nests along Israel’s coast rose sharply for the second year in a row in 2021, according to a government report published this week.
According to the Israel Nature and Parks Authority, 449 nests were identified last year, up from 374 in 2020, which itself was a large increase over the previous year. In both 2021 and 2020, the number of nesting sites was nearly double the average annual tally of the five years prior. According to official figures, 231 nests on average were found annually from 2016 to 2020; for 2015-2019, the number was 191.
Of the 449 nests found last year, containing nearly 30,000 eggs, 386 were dug by loggerhead turtles and 57 by green turtles. Six nests could not be identified by turtle type.
Researchers in other parts of the Mediterranean have reported rising numbers of sea turtles in recent years, and expanding nesting ranges for loggerheads, reaching as far west as France. In Greece’s Laganas Bay, on Zakynthos Island, considered among the most important breeding sites, over 1,800 nests were tallied in 2020, up from an average of 1,000 annually between 2003 and 2010.
Scientists have offered several explanations for the rising numbers, including knock-on effects from climate change or the COVID-19 pandemic.
The Israeli report suggested increased conservation efforts or monitoring of nesting sites could be behind the rise, along with environmental factors.
The move in recent years to restrict fishing from May to August, when fish and turtles are both breeding, was seen as one possible factor helping boost population numbers.
Data collected by the Israel Sea Turtle Rescue and Rehabilitation Center in central Israel shows commercial fishing to be the biggest threat to turtles, the report said.
Roughly 2,000 turtles are injured in fishing-related accidents each year. On Saturday, a victim was found and transferred to the center for care.
עוד דוגמה לנזק האדיר שגורם הדיג בישראל לטבע הימי שלנו ????מדווח עירני מצא ביום שישי צב ים ירוק מסובך בחוטי דיג, דיווח…
Given that efforts to protect turtle nests began in the 1990s and turtles reach sexual maturity at the age of 20 to 30, the report surmises that females from one of the early cohorts could be returning and building the nests.
As for how loggerheads find their way back to the same beaches after so long away, a 2015 study found evidence that the creatures use Earth’s magnetic field to return home for laying, tuning into the particular magnetic signature of the specific part of coastline they are looking for.
To nest, pregnant females drag themselves onto land and across the sand, dig burrows with their flippers, drop large numbers of eggs into the holes, cover them up, and then make their way back to the sea.
The INPA report noted that inspectors are patrolling more beaches looking for nests, which may account for the jump. And the authors hypothesized that heavy rains in late 2019 and early 2020 could have increased nutrients in the sea, helping females to become particularly fertile.
On average, around three-quarters of the eggs in all nests hatched, with most of the hatchlings making it to the sea. Turtles use the light of the moon to navigate their way back to the sea, making disorienting city lights particularly hazardous.
Counting nests is considered to be the best way to estimate turtle populations, though some have noted that the method fails to account for male turtles.
The numbers are gathered from an extensive network of volunteers and professionals who scan Israel’s beaches for signs of turtles or nesting sites.
After the nests have been identified, specially trained inspectors move them to nature reserves to protect them from light pollution and human or animal disturbance.
Last year, 343 nests were relocated, while 84 were found in nature reserves and therefore left where they were. A further 44 were raided by predators right after the eggs had been laid and an additional 10 were only identified when the hatchlings emerged.
While nests were found from Rosh Hanikra on the northern tip of Israel to Zikim Beach close to the Gaza border in the south, the most popular laying sites were between Tel Aviv and Haifa, a stretch of coastline that is under severe development pressure.
Green sea turtles are listed as endangered by the International Union for Conservation of Nature.
Globally, loggerheads are classified by IUCN as vulnerable. However, in the Mediterranean, they are considered a species of least concern.