Today is World Sea Turtle Day. We need to shellebrate. Or at least celebrate.
Sea Turtles are in trouble world-wide. They are over-hunted, killed by long-liners as by-catch, drowned in seine nets, suffering from loss of forage and losing nesting beaches to sea level rise attendant to climate change. The future looks pretty grim.
There are about seven species of sea turtles, too many to talk about in a single blog post. So we’ll focus on one, the Green Sea Turtle. For a turtle, it’s pretty cosmopolitan. Its range extends throughout tropical and subtropical waters around the world, with two distinct populations in the Atlantic and Pacific Oceans.
Young green sea turtles are omnivorous; adults are pretty much herbivores. We don’t compete for the same food sources. They don’t adversely impact other species we depend upon. Yet they are listed as endangered by the IUCN and CITES and are protected from exploitation in many countries. It is illegal to collect, harm or kill them. In addition, many countries have laws and ordinances to protect nesting areas. However, turtles are still in danger due to human activity.
In some countries, turtles and their eggs are still hunted for food. In some cases, it is indigenous subsistence hunting; in others it is demand for exotic foods.
Pollution indirectly harms turtles at both population and individual scales. Green Sea Turtles are generally a near-shore species. As mankind dumps sewage, industrial waste and plastics into the ocean, the pollution hits this species first and hardest.
Many turtles die after being caught in fishing nets. Green Sea Turtles are air breathers; they don’t have gills. If they can’t get to the surface, they drown. The fishing nets trap the turtles underwater and, like a human in similar situation, they drown.
Also, real estate development often causes habitat loss by eliminating nesting beaches. Sea Turtles come ashore to lay their eggs. They climb up the beach, dig into the dry sand above tide line, and lay their eggs. The photo above shows the nest at the top and the female’s return to the ocean. Extensive development of coastal shoreline, as has happened in Mexico, for example, makes it difficult to impossible for the females to build their nests. The lights associated with development further disorient newly hatched turtles.
Survival of newly hatched Green Sea Turtles isn’t high; hatching time is kind of a feeding frenzy for every baby turtle-eating predator in the region. Then it takes about 20 years for a survivor to reach sexual maturity. And the females only breed every 2-4 years. So you have a very slowly reproducing species, which nonetheless has managed to survive on the planet for 65 million years.
There’s another, more subtle threat to Green Sea Turtles. The temperature wt which the buried turtle eggs are incubated determines the sex of the young turtle. If the temperature is over 30° C, the turtles are born female. Anthropogenic climate change – global warming – carries therisk of decimating the male population.
So, yes, “shellbrate” World Sea Turtle Day. While we still can.