Natural Threats
Turtles of the size range found on the Bermuda Platform have only one natural enemy: sharks. Small post-hatchlings found out in the Sargasso Sea are threatened by a wider range of predators including fish and several species of birds. Eggs and hatchlings on nesting beaches face predation by many animals on land, such as ants, crabs, birds and dogs. Once the hatchlings reach the sea, they face a host of marine carnivores such as snappers, groupers, barracudas and sharks. Nests are also lost to erosion of the nesting beach.
Learning from sea turtle necropsies.
Threats to sea turtles in Bermuda are documented by a Stranding Network at BAMZ that receives stranded turtles from the public in Bermuda. Some of these turtles can be treated and returned to the wild (see section on Rehabilitation). However, information on the cause of death of some of the animals that don’t survive can be gained during necropsies. Each year, as part of the Bermuda Turtle Project’s annual course, sea turtles that have died from a variety of causes are necropsied under the direction of Dr. Gaelle Roth, the veterinarian and Co-Director of BTP. The examples discussed below have been observed during these necropsies.
Human-Caused Threats
Although sea turtles are strongly protected in Bermuda waters, they still experience many negative impacts from humans.
Boat Collisions
The sea turtles of Bermuda have for many years been exposed to ships and marine craft which abound along our shores. However, with increasing numbers of high-speed, high-powered watercraft, sea turtles have a much more difficult task to elude these vessels. A number of sea turtles are killed in collisions with boats and many more are injured or debilitated for life.
By-catch in commercial longlines
Loggerheads and leatherbacks are vulnerable to mortality from longline fishing gear. They swallow the baited hooks or become accidentally snagged by the dangling hooks. Loggerheads have been found stranded in Bermuda with the heavy long-line hooks and line still attached.
Entanglement in Commercial Fishing Gear
Unattended, lost or discarded fishing nets and ropes can be a deadly trap for sea turtles. On occasion sea turtles are washed ashore tangled in the rope and twine. Unable to free themselves from such debris, their struggle to reach the ocean surface for a breath of air fails and this results in drowning. In other cases, the turtle becomes so entangled that it is unable to feed and it slowly starves to death.
The practice of trap fishing in Bermuda and elsewhere has been identified as a threat to the ocean-going leatherback turtle which occasionally comes near shore. Through adaptations for speed and power in the open ocean, the leatherback has lost the ability to swim backward which would allow it to extract itself from entrapment.
The leatherback is apparently attracted to the buoys that mark fishing traps and regularly become entangled in the attached line. With forward speed and power the only means of escape, the turtle will swim in circles that can result in a fatal entanglement.
Entanglement in Recreational Fishing Gear
An increasing problem in Bermuda’s territorial waters is entanglement of marine turtles in monofilament. This line often appears to have been discarded by recreational fishermen. Each year several turtles are brought to the aquarium that have drowned or been badly injured by discarded line. This is a problem that everyone can help with: if you find discarded fishing line, please remove it and dispose of it appropriately in the trash. If your fishing line becomes entangled on the rocks or bottom, do everything you can to retrieve the hook and line. If you can’t free the hook, try to get the line to break at the hook or leader by pulling as hard as you can. Don’t cut the line at the reel and then let a long piece of line go underwater.
Ocean Debris
Another serious threat to sea turtles is pollution and debris in our oceans.
Young turtles in their pelagic phase are dependent on ocean driftlines for food. It is at these driftlines that ocean debris accumulates. Young turtles feeding there are known to ingest plastics, styrofoam, balloons and tar, mistaking these as food. Also, species that feed on jellyfish often mistake plastic bags for food. Ingestion of such trash can lead to blockage of the digestive tract and eventually death.
Decline of Seagrass
Seagrasses are flowering plants found in shallow coastal marine waters and are different than seaweed (algae). Seagrass beds are important feeding and breeding habitats for many marine species, including sea turtles. The preferred seagrass in the Green sea turtles’ diet is turtle grass (Thalassia testudinum). Unfortunately, seagrass beds have been on the decline since decades due to multiple parameters, and is having an effect on the green turtles in Bermuda.
☎️ Report a sick, injured or dead sea turtle – BAMZ hotline 293 2727 #999.
To find out more about the threats that sea turtles face visit Sea Turtle Conservancy.