Boat strikes on sea turtles on the rise
Meet Loggerhead sea turtle egg No. 87 out of 112, which were laid on Algiers Beach on Sanibel in 1991.
Sea turtle No. 87, like much of her other 111 siblings, hatched during a warm, late summer evening.
With a yolk-sack strapped to his underside with about three-days worth of energy, No. 87 billows out of the sandy-walled nest with the majority of her siblings. She starts toward the first light she sees, which fortunately for her, is the twinkling moonlight shimmering off the Gulf of Mexico water.
Unfortunately, for almost a quarter of her brothers and sisters, they instead see the yard light from a nearby house and start their trek away from the water and will soon dehydrate or starve after crawling around lost for up to three days.
Another 12 or so of No. 87’s siblings get plucked up by a bypassing raccoon, which is in search of a midnight snack. But No. 87 keeps her destination in front of her and will eventually beat the odds against her getting to water, as she bobs in the surf and taken out to sea by the tide.
Now only less than half of the 112 eggs which hatched are still alive. But the dangers of living in the ocean come roaring to reality, as predators feast on the helpless and small sea turtles. The odds are definitely stacked against No. 87, but she keeps surviving by overcoming obstacles, would-be predators and starvation.
In fact, No. 87 is the lone survivor out of her nest after months of survival, as she overcomes the one in 1,000 odds of reaching it to adulthood, which is considered 20 to 30 years of age.
Now it’s 2015 and No. 87 has enjoyed a fruitful life and reproducing every two to three years, laying up to 110 eggs in three to five nests per year. She has helped replenish the failing Loggerhead sea turtle population with her journeys up to the beaches of Southwest Florida – until this past March.
No. 87 is hit by a speeding boat, as it making another trek to the Sanibel beaches to lay her eggs. The propeller ravages her bone shell, shredding into her cavity, as she sustains fatal injuries.
Although she has overcome everything Mother Nature has thrown at her in over two decades of life, she can’t beat the odds of what man poses.
This is a purely fiction story of No. 87, but it’s starting to be a reality for sea turtles in the Gulf, with already eight boat strikes reported on Sanibel this year. Last year as of April 8, there were seven reported boat strikes on sea turtles.
The last two years are disturbing trends, as in each of 2012 and 2013 as of April 8, only one case was reported, two in 2011 and four in 2010.
“We’ve had a total eight boat strikes this year out of 15 total strandings, which are cases of washed up sea turtles alive or dead,” said Sanibel Captiva Conservation Foundation biologist and sea turtle coordinator Kelly Sloan. “It’s an increasing problem in our area. More boats have something to do with it and if you look at the numbers, adults are getting hit the most, which coincides with their mating and breeding time. And that’s also where the boat traffic is.”
Of the eight boat strikes this year, five have been adults, which is a detriment in itself because they are the ones which lay the eggs.
“It’s a shame the adults are the ones getting hit, because they have beaten all the odds to get to that age,” Sloan said. “Then they get hit by a boat, and we take a decrease on the reproductive animals which can be laying eggs.”
Last year, there were 411 sea turtle nests on Sanibel, but with more boat strikes on sea turtles being had, it will eventually takes its toll on the number of eggs being laid.
In a paper published in 2008 by the Florida Sea Turtle Stranding Network, the number of boat strike injuries on sea turtles in Florida tripled from 1980 to 2008.
With the sea turtle mating season currently underway, males and females are inhabiting shallow water. The time most boat strikes occur is between 8 a.m. and noon, when the sea turtles are in the shallower water, which is also being buzzed by boaters.
“The Florida Fish and Wildlife are asking people voluntarily to minimize boat usage one kilometer off the shore and if you do go in there, try and slow down to idle speeds,” Sloan said.
A study published in the Journal of Experimental Marine Biology and Ecology in 2010 entitled Influence of small vessel operation and propulsion system on Loggerhead sea turtle injuries, concluded the obvious that the water vehicles’ speed determines the “likelihood of catastrophic damage, whereas depth in the water column does not.”
Jet propulsion crafts such as jet skis actually did not impact any of the test models, which were artificial or real shells from sea turtle carcasses.
In the 2010 study in the Journal of Experimental Marine Biology and Ecology, faster means a higher mortality rate: “Hazel et al. (2007) concluded that green turtles are unlikely to take effective evasive action when approached by vessels at speeds exceeding 4 km/hr; this is less than idle speed for many marine vessels.
With the standard propulsion system (outboard motor with no guard over the propeller), decreasing the speed of the boat from planing to idle speed decreased the occurrence of catastrophic wounds from 100-percent to 40-percent. (For the field tests, 14 km/hr was defined as the sub-planing speed).”
But not all boat strikes lead to fatalities and that’s where the Clinic for the Rehabilitation of Wildlife (CROW) comes in.
CROW has treated two boat strike sea turtle patients this year, not including one which came in dead on arrival. In 2014, CROW treated two Loggerheads with boat strike injuries.
“Boat strikes are one of the most common injury we see come in here,” said CROW hospital director Dr. Heather Barron. “When they come in, we assess their injuries and see how severe they are. We received a nice grant from the Sea Turtle Conservancy, who are the license plate people, which allowed us to purchase new equipment.”
The equipment purchased by CROW enables the veterinarians to conduct minimal evasive procedures using a scope to go inside the turtle and assess how bad the damage is.
“If the shell is breeched, that is OK, but if the shell and the cavity are breeched, more serious damage has occurred,” Dr. Barron said. “We will still treat them, but it’s just a worse prognosis.”
The treatment over the years have also improved dramatically. CROW now uses what is called vacuum assisted closure. A foam is delivered over the wounds and a vacuum is hooked up, called negative wound pressure therapy.
“It encourages healing over 70-percent faster than the old way of doing it, which just used bandages,” Dr. Barron said. “If the shell is broken, we can treat it orthopedically, and go in with screws and wires and wire these shells back together.”
If a boater thinks they have hit a sea turtle, do not leave the area. In most cases, a sea turtle will dive after being struck, but after a few minutes, the shock and pain will reside and they will float back up to the surface.
“Get under them with a net, always pick them up by the shell and avoid grabbing a limb, which can break a (leg),” Dr. Barron said. “But do it anyway you have to get them into the boat, because that matters more than just leaving them in the water to die.”
If you see an injured or dead sea turtle, it must be reported. CROW can be called at (239) 472-3644 or the Florida Fish and Wildlife at (863) 648-3200 or the SCCF at (239) 472-2329.
Ultimately, it will be up to the boater and their desired speed and location, which can help sea turtles like No. 87 live a longer and more prosperous life.
“Hopefully people will care about the sea turtles and slow down,” Sloan concluded.