I was asked by NOAA to assist with sea turtle conservation efforts associated with the Gulf oil spill.   Specifically, I was part of a team of researchers assembled to assess the effects of the oil spill on oceanic phase sea turtles. I was involved in all aspects of the project including running small vessels, surveying and capturing sea turtles.  

On my first trip, the primary mission was to document the effects of   the oil spill on oceanic phase sea turtles. We were addressing several basic biological questions.   First, we wanted to learn whether sea turtles recognize oil as threat and leave the area or stay around and suffer from the effects of oil toxicity. The second question involved trying to estimate the total number of sea turtles being affected by the spill in the northern Gulf. Finally, we wanted to capture heavily oiled turtles in need of assistance, and transport them to rehabilitation facilities for later release.

 Our home base was Venice, Louisiana. We left each morning in small boats (33’ catamarans) in search of habitat used by oceanic phase turtles. The oceanic phase is the first phase of a sea turtle’s life history. During this period, the small turtles live in convergence zone habitat characterized by concentrations of brown algae called sargassum weed. Sea turtles spend most of their time at or near the surface during this period. The convergence zones generally occur near the edges of large current systems. 

Convergence zones are exciting places with a high concentration of bio mass; sargassum weed, lots of fish, invertebrates, birds and young sea turtles.   Loggerhead turtles spend the first 8-13 years of their lives in this habitat. One of the principal investigators of the project, Florida Fish and Wildlife Conservation Commission (FFWCC) biologist Blair Witherington, had previously conducted surveys in healthy convergence zone habitat.  Our goal was to estimate sea turtle densities in convergence zones affected by oil and then compare those densities with Dr. Witherington’s previous studies. Further, we hoped to work with NOAA oceanographers to estimate the total amount of convergence zone habitat affected by oil in the northern Gulf via satellite imagery and then estimate the total sea turtles that might be affected by the spill. 

We generally located convergence zones 8 to 50 miles offshore. Once the habitat was located, we surveyed at idle speed, maybe four to six knots in general and caught turtles at a rate of one turtle per 20-30 minutes. Half appear to be mired in oil, the other half were free swimming.  All were heavily coated in oil. Once captured, they were   transferred to a support vessel with a veterinarian, who cleaned and stabilized them for transport to the rehab facility.

The spill area was not what I expected. I thought I would see more large oil slicks. There were some big continuous slicks around the Deepwater Horizon well, but otherwise the distribution of oil was fairly patchy. We spent most of our time anywhere from 10-50 miles offshore and most of the oil we saw was in a dispersed form. That is probably the most amazing thing, the amount of dispersed oil on the water column. From a distance the water looks normal, but when you stop the boat and look down, you see small globs of oil as far down in the water column as the visibility allows. When you start thinking about trying to put all those small globs together in one place the total volume of oil is astounding…

The location of the sargassum weedlines and oil was really dynamic, changing every day.  We were fortunate to have a helicopter providing aerial support for at least some of the time to help find the sargassum weedlines.

When we first started the surveys, we were not sure what to expect. We didn’t know how much oil would be in the convergence zone areas and whether we could operate boats safely in and around the oil. We also didn’t know how easy it would be to locate and capture sea turtles in heavily oiled areas. Unfortunately, we found very quickly that oil was concentrating in the convergence zone and that sea turtles were still using that habitat. The preliminary results from the capture work show that sea turtle densities in heavily oiled convergence zones were similar to those in healthy habitat suggesting that sea turtles do not recognize the oil as a threat and move away from the area.

Near the end of the first trip, we located a heavily oiled weed line and captured 10 turtles in 4 hours. There were several surface burns going on in the vicinity all day. As we got closer to the spill site, we realized the surface burn team was collecting or booming the oil at the opposite end of the weedline and lighting surface fires. At that point, we became concerned that the burn team may have been inadvertently burning turtles during surface burning operations.

On my second trip I was asked to spend several days at sea with the burn task force coordinated by the U.S. Coast Guard to try and get an idea of how they operate and if there were opportunities to put observers on the boats and to survey the oiled weedlines for turtles prior to burning.

This is something you have to see to believe. I was on a boat working very close to the wreck site so there are lots of planes and helicopters flying around. The oil was fairly thick on the surface of the ocean and dark brown or black in color. When the conditions were favorable there were four or five large fires burning at the same time with thick black smoke and flames up to 100 feet tall. It was like nothing I have seen before.

I spent several days offshore with the burn team.  The actual burns are a fairly simple process. There are two shrimp trawlers that pull 500 feet of boom at approximately ½ a knot in order to concentrate oil for burning. They continue to move forward slowly as the fire burns. An ignition boat pulls alongside the boom and ignites the oil that is collected inside the boom and then moves back to monitor the fire.

After observing the surface burning procedures in the Gulf, I have less concern about large numbers of turtles being killed during surface burning operations. First, the fire is relatively slow to ignite (2 minutes). Also, the burn rate is very slow, allowing actively swimming turtles to get out of the way. Most importantly, an observer could be stationed with the ignition crew to survey and remove sea turtles stuck in the oil prior to the burn. It is still a concern and needs to be monitored, but I think they can safely continue the surface burning operations with several small modifications to their protocols.   Obviously, the Coast Guard and burn crews did not want to kill sea turtles or any other wildlife, but sea turtles in the convergence zones are small and difficult to see. Following my trip, sea turtle observers were deployed with the burn team to ensure sea turtles were not killed during burning operations.

This spill is having a huge impact on people whose lives depend on recreational fisheries. However, we were really grateful to the people who helped us out. We used chartered deep sea fishing boats piloted by fishing captains. They were invaluable for their knowledge since they use the same habitat when they go to find tuna, dolphin and other big game fish that we use to look for turtles. And once they developed the site image of the turtles they were great at helping us locate them. They really got into helping us and even created turtle flags putting them up on the outrigger to show how many we captured each day. They were proud to be able to help with the conservation efforts by surveying for turtles. There are a lot of people working really hard that should be recognized for their efforts.  

The researchers and support staff I worked with in Gulf were impressive and highly dedicated. They worked long hours under difficult field conditions to assess the effects of the spill on sea turtles. Unfortunately, we found that most of the convergence zone habitat we surveyed has been destroyed and it is unknown at this time how long it will take for things to return to a healthy state.

The prognosis for sea turtles using this habitat is not good. In addition, hatchlings emerging from Florida and Alabama beaches are not likely to survive as a result of the spill. Future efforts will focus on expanding the range of the surveys to determine the extent of the effects of oil on sea turtles in the northern Gulf.