Listen to the Interview: How Might the Deepwater Horizon Disaster Impact Endangered Kemp's Ridley Sea Turtles?

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While the nesting season at Padre Island National Seashore has been successful for Kemp's ridley sea turtles, there are concerns that oil from the Deepwater Horizon disaster could greatly impact the species, which is highly endangered. NPS photo

Kurt Repanshek's picture

Against the backdrop of the Deepwater Horizon disaster, there’s a biological wonder under way at Padre Island National Seashore where the Texas coastline meets the Gulf of Mexico. Where 15 years ago biologists might have seen only a handful of Kemp’s Ridley sea turtles nest on the national seashore’s beaches, this spring there have been at least 69 nests laid by the turtles, which are the most endangered sea turtles in the world.

While seashore biologist Dr. Donna Shaver is pleased with the nesting numbers, she fears how the oil gushing out of the bed of the Gulf of Mexico could impact the survival of both adult and juvenile Kemp’s Ridley sea turtles.

Traveler Editor Kurt Repanshek recently talked with Dr. Shaver about this year’s nesting success and how the Deepwater Horizon catastrophe could affect the species’ fortunes.

Transcript

NPT:

“I’m curious, I was looking at the numbers on the web site yesterday and I saw where you were up to at least 69 nests. Is that high or low for this time of year?”

DR. SHAVER:

“Well, we’re actually a little bit low compared to the last two years, of course we’ve been seeing big increases over the last decade. Fifteen years ago we were lucky to find four , five or six nests. The numbers, we’re happy to have what we do, but it is a little bit low compared to the last couple of years. The nesting season is still continuing, it’s possible that we could make up some ground in the next month. That remains to be seen. We did have a late start to the nesting season, it was a very cold winter here.”

NPT:

“For reference, do you recall what the numbers were for the last couple of years?"

DR. SHAVER:

“For an entire year, 2009, at Padre Island National Seashore there were 117 nests found, and in 2008 there were 94. I think we’ll probably end up somewhere in that range.”

NPT:

“Any idea why you’re lagging a bit behind? Is it the cold winter, or predation?"

DR. SHAVER:

“We think that we are lagging behind 2008 and 2009 probably because of the very cold winter. I don’t know whether you followed the cold stunning event that happened in Texas and in Florida. In Florida they had 4,000 turtles that were found floating or washed ashore due to freezing air temperatures, and we found over 400 in Texas. Now these weren’t adult Kemp’s ridleys, but it shows that it was a very cold winter. The adult Kemp’s ridleys that were out in the Gulf of Mexico likely had to travel further off-shore to find warmer waters. And the further off-shore they get it’s harder for them to find foraging resources. So it may have been that not as many of the turtles were ready to reproduce. They don’t reproduce every year.”

NPT:

“Those numbers, the 400 that you mentioned, where they fatalities or just stunned by the cold?"

Dr. SHAVER:

“These were almost exclusively juvenile green sea turtles, and about two-thirds of them were located dead. and the others alive.”

NPT:

“I did see the story out of Florida, and even the manatees were affected, I hadn’t seen anything out of the Texas area and the Gulf."

DR. SHAVER:

“It was a very cold winter and these turtles, like I said, they nest on average every other year, but they certainly got the capability of skipping an additional year and going every three years if they have a year when their body resources aren’t ready to undergo reproduction that year."

NPT:

“Is there an average number of eggs you’ll find in the nests?"

DR. SHAVER:

“It’s about 100 eggs.”

NPT:

“And any idea what the survival rate is?"

DR. SHAVER:

“Well, we bring the eggs in for protected incubation, on the Texas coast, and we get an average of about 80 to 85 percent hatching success. Then the hatchlings are given a protected release, so all the hatchlings that survive after emergence get into the water, but after that point the turtles are on their own and we don’t know. We know that certainly only a fraction of them will make it to adulthood. There are a lot of perils out in the marine environment, predation when they’re hatchlings, birds, fish, and then as they grow sharks and, of course, all sorts of problems with cold stunning or incidental capture in the fisheries, boat propeller injuries, etc.”

NPT:

“Now, Kemp’s ridley, that’s an endangered species.

DR. SHAVER:

“Yes, it’s the most critically endangered sea turtle species in the world.”

NPT:

“Right, that’s what I thought. Are you seeing progress in the population numbers going up?"

DR. SHAVER:

“Yes, yes, the population is increasing, we’re very excited about that. The numbers of nets found both in Mexico and Texas are increasing. There is some concern about this oil spill and the possible impacts that might have on setting back the progress that we’ve made. Many people have worked so hard to try to recover the species."

NPT:

“That was my next question. Have you seen any impacts yet, or what concerns do you have about potential impacts."

DR. SHAVER:

“We haven’t seen any impacts here at the national seashore or down in Mexico yet. The beaches are not oiled, the trajectory for the oil spill is more in the eastern Gulf of Mexico, not the western Gulf. We haven’t seen problems with that, we haven’t seen any oil on any sea turtles here. Our nesters likely came to the area before the spill occurred, because mating is thought to take place about 30 days before the first nest is laid, and off-shore from the nesting beach. We hope that our females were here already before the spill occurred. AGain, we haven’t seen any traces of oil on any of them.

“But, we do have concerns because I’ve point out now 48 satellite transmitters on nesting females after they’ve laid their eggs, and a large percentage of those turtles travel northward after the nesting season is done and then the locations for them have been either in the waters off the upper Texas coast, Louisiana, Mississippi, Alabama or the west coast of Florida, so a large number of them have gone through those waters for migration or have set up residency in those waters for foraging. So, we are concerned about the females that are taking the year off from nesting, as well as our females after they’ve done nesting for the season.

“I’ve put satellite transmitters this year on five Kemp’s ridley turtles so far, the nesting season is continuing and I hope to put out a few more, but on five so far and those can be followed on the Internet and two of the turtles are done nesting for the season and are already heading for that region. We are concerned about that, and that region where the spill is is very important for foraging habitat for juveniles.

“Of course we also have concerns about hatchlings while they’re in the water, because they’re planktonic, float with the currents and become associated with the seaweed and convergence lines of debris and the oil could accumulate there as well. So, we haven’t seen impacts yet, but we are concerned what the impacts could be down the line. For Kemp’s ridley, more than any other of the sea turtles, their life cycle is so dependent upon the Gulf of Mexico. The other sea turtles are more far-ranging.”

NPT:

“With the transmitters that you’ve attached to the turtles, do they give a signal when there’s a fatality?"

DR. SHAVER:

“What you may see is if the animal is still, that it remains at the surface, and you have a lot of messages from the transmitter. If the turtle just all of a sudden dies and sinks to the bottom of the ocean, then you will not know. If she washes ashore and is found then of course you will know.

“So, it’s not definitive that we will know that she dies. The transmitters obviously don’t last forever. We’ve had them anywhere from just a few days all the way to almost two years. When the transmissions cease, you really don’t know why. It can be because the batteries’ expended or the salt water switch has become fouled with barnacles or the antenna has become sheared off or the transmitter has just fallen off. They’re designed to just fall off the turtles.”

NPT:

“So you would have no way of knowing six months down the road whether...”

DR. SHAVER:

“You probably won’t know. What we can tell though, is, we can overlay those locations with where the oil spill is, did the turtles go into this oiled area?”

NPT:

“And of course if you recover a turtle you can do a necropsy."

DR. SHAVER:

“Oh yes, there’s a lot of effort that’s going into the oil spill, it’s a Unified Command system and there’s very well-defined procedures, very elaborate and time-consuming, and all the carcasses that are being found within this spill area are being saved and will be necropsied by a specific veterinarian.”

NPT:

“Have they found any Kemp’s ridley?"

DR. SHAVER:

“Yes they have.”

NPT:

"Any idea how many?”

DR. SHAVER:

“I can’t tell you the number, it’s changing every day. But that source of information is the NOAA - National Oceanic and Atmospheric Administration, their website. They’ve got a daily posting of the number of turtles that have been found stranded, and I believe that they’re also posting the numbers that have been recovered from the oil itself.

“There are some search and rescue operations ongoing, but the numbers, it’s difficult because the numbers found washed ashore and stranded ... but when a sea turtle is found stranded, that means it’s been found washed ashore either alive or dead. They can strand for a variety of reasons. So they’ve got a tally that includes all animals that have been found within the shoreline of what they call the area of concern, which is from Louisiana through the panhandle of Florida, and so it’s an aggregation of turtles that have been found from all causes, so you can’t say that they’re all from the oil spill. A portion of them have been oiled. They’ll tease that out in that database. It’s going to take a while to get that information, because a lot of the animals have been stockpiled for necropsy. It’s going to take a while to get exact numbers. But yes indeed they have found Kemp’s ridleys. Not adults, juveniles."

NPT:

“The females obviously come ashore to lay their eggs, where do the males go?”

DR. SHAVER:

“The males, well, that’s not as well-known. I’ve put satellite transmitters on two adult males that were caught on hook and line here, or where found stranded, and we tracked their movements, and both of them left the area. Conversely, in Mexico, I’ve put transmitters on 25 adult males that were captured for study, and most of them remain resident off the nesting beach year-round, only a few were migratory.

“So, we don’t know as much for our Texas males. So some of the males from the population are likely vulnerable to the spill, but some are likely going to be spared because it appears that many of them remain resident off the nesting beaches in Mexico year-round.”

NPT:

“Is that 69 tally a good number?"

DR. SHAVER:

“That’s the latest number. I update the numbers just about every day. We had a big day on Wednesday. Kemp’s ridleys tend to nest in aggregations called ‘arribadas,’ and we had 14 on Wednesday. That tied our other nesting record, which was 14 here at the park on the 19th of May. So we’re in a little hiatus now and hopefully things will pick up again.”

NPT:

“Now, years ago weren’t the nestings in hundreds, and thousands in some areas?”

DR. SHAVER:

“In Mexico. We don’t know what the numbers were here at Padre Island national Seashore. We know that it is a native to the area. In fact the first published record of Kemp’s ridleys nesting anywhere in the world was here at Padre island National Seashore in 1948, before it became a national seashore. But we don’t know what the numbers were.

“What we do know is that in Mexico in 1947 there was a film that was made, and that film wasn’t discovered to scientists until the early 1960s, and that information was revealed to the scientific community in a publication in the 1960s, but that film showed an estimated 40,000 Kemp’s ridley females nesting on one day at Racho Nuevo, the primary nesting area in Mexico. Yeah, when you see it it just brings chills to you because it’s so amazing, that so many of them would come up at one time at one place.

“The numbers declined dramatically through the mid-1980s. They just kept dropping and dropping and dropping and dropping and got to a low of only 702 nests world-wide in 1985. "

NPT:

“And what are we up to now?"

DR. SHAVER:

“What are we up to now? This year, the last I heard, they’re up to about 9 or 10,000 nests.”

NPT:

“Well, let’s hope that they can survive this oil spill someway.”

DR. SHAVER:

“Let’s hope so.”

Comments

Hope the oil spill doesn't reach the Texas shores!