With climate change turning up the heat, sea turtle gender balance is being thrown way out of whack.
“It’s scary,” said Jeannette Wyneken of Florida Atlantic University’s lab at Gumbo Limbo Nature Center in Boca Raton. “I’m seeing more and more all-female nests, and even when we have males, it’s a very small percentage.”
As is the case with some reptiles, the sex of sea turtles is determined by the temperature of the sand where the eggs incubate. Wyneken’s research over 20 years shows that the number of males is decreasing across the three species she monitors — leatherbacks, loggerheads and green turtles — even as eggs are laid at different times. Using the past decade as a reference, she said seven out of the 10 years produced 100% female hatchlings. The three years in which nests produced males, the ratios ranged from just 10 to 20%.
Pink salmon may put other species at risk
Biological oceanographer Sonia Batten experienced her light bulb moment on the perils of too many salmon three years ago as she prepared a talk on the most important North Pacific seafood you’ll never see on a plate — zooplankton.
Zooplanktons nourish everything from juvenile salmon to seabirds to giant whales. But as Batten examined 15 years of data collected by instruments on container ships near the Aleutian Islands, she noticed a trend: zooplankton was abundant in even-number years and less abundant in odd-number years. Something was stripping a basic building block in the food web every other year. And just one predator fit that profile: pink salmon,
More researchers say the voracious eaters are thriving at the expense of higher-value sockeye salmon, seabirds and species with whom their diet overlaps. In addition to wild populations, 1.8 billion pink salmon are released annually by Alaska hatcheries and 3 billion-plus come from Asian hatcheries. A 2018 study estimated 665 million adult salmon in the North Pacific. Pink salmon dominated at 67%.
Greg Ruggerone, president of Natural Resources Consultants in Seattle, began analyzing pink salmon interactions with sockeye salmon in 2009 and found sockeye returns fell when pink salmon were abundant. The results, he said, suggest “there is this link between sockeye salmon and pink salmon related to competition for food.”