Turning Off the Heat: Impacts of Power Plant Decomissioning on Green Turtle Research in San Diego Bay

A paper by myself and Dr. Seminoff discusses some of the collective work of NOAA scientists during my master's program at Scripps Institution of Oceanography's Center for Marine Biodiversity and Conservation and may now be accessed online in Coastal Management Journal.


Abstract:
Green turtles (Chelonia mydas) are among the most high profile species in San Diego Bay, California, and understanding impacts of coastal development and industry is essential to the management and conservation of this local population. Here we describe power plant changing energy production and its impact on turtle habitat use and our ability to research and manage this population. For over 20 years, green sea turtles have been captured, assessed, and tagged near the South Bay Power Plant (SBPP) in the San Diego Bay; from 2002–2011, 104 turtles were captured on 212 occasions. As the 50-year-old SBPP generates less energy, effluent patterns change and water temperatures decrease, presumably to more natural conditions. There has been a concurrent decrease in turtle-capture success, perhaps due to lesser visitation to the effluent site where nets are tended. Seasonal catch-per-unit-effort declined from a high of 4.14 turtles per monitoring day, to a nine-year low of 1.33 during the 2010–2011 season. It is already apparent that management decisions related to energy policy are affecting the habitat and behavior of this stock of endangered turtles. Green turtles are expected to remain in the San Diego Bay after the SBPP becomes inoperative and continuing research will monitor future impacts and distribution shifts resulting from the expected changes in thermal pattern within south San Diego Bay. Research efforts to study this population (i.e., capture methods and locations) will require modification in response to these changes. Lessons learned here are applicable to the immediate coastal development of San Diego, as well as at similar interactions between marine turtles and industrial thermal effluent discharge throughout Southern California, the United States, and beyond. 

Cooperative Efforts to Reduce Sea Turtle Bycatch

My research is made possible through many partnerships - as is typically the case when working with long-lived and migrating animals like sea turtles.  One group I partner with is Grupo Tortuguero, a community-based conservation and research program based in La Paz, Baja California Sur, Mexico.  While green sea turtles (Chelonia mydas) is one species common to the Pacific waters off of Baja's coast, another species of sea turtles is even more common to see - the loggerhead turtle (Caretta caretta).  The loggerhead turtles in the Pacific Ocean feed off the the Mexican coast, where they eat pelagic red crabs, and other benthic (bottom dwelling) invertebrates.  Yet these loggerheads do not nest along the Mexican coast, instead, most of them come all the way across the Pacific Ocean from their nesting grounds in Japan!

Grupo Tortuguero has collaborated with fishermen in Mexico, as well as fishermen in Japan, to help find creative ways to reduce the number of marine turtles captured in their fishing nets and lines.  Finding a solution to this problem not only protects the turtles, but it can help the fishermen make more money, by not loosing fishing gear to tangled turtles, and by not wasting time having to remove turtles from their nets and lines. So this cooperative is a win-win for all parties involved.

This short video shows a new turtle-release method being tested and demonstrated at a recent meeting in Japan.  (Note on the end - those surface lines appear to be in place for the sake of this test at the aquarium...)  Enjoy!

Injured San Diego Turtle is Being Released!

If you recall back in February, NOAA researchers captured an adult male green sea turtle during one of our regular monitoring days, and noticed the turtle was not in good condition.  That day the turtle was taken to receive medical attention at SeaWorld, where the turtle was dubbed "Bruce" as his recovery began.

Today, several news sources reported that Bruce will be returned to the San Diego Bay today!  He has apparently recovered from his multiple injuries and severe dehydration, and has bulked up to a respectable 300 pounds. 

Here are some of the brief articles sharing this great news!

With any luck, I'll get to see Bruce again this year, as NOAA's monitoring in the South Bay will begin in the coming weeks. I'll keep you posted!

(This one from the LA Times has a great picture of Bruce!)

Green sea turtle once near death will be returned to San Diego Bay Los Angeles Times Bruce, the Pacific green sea turtle found close to death with gunshot wounds to his neck in January, is set to be returned to San Diego Bay on Tuesday. ...

Bruce the turtle ready to return to San Diego Bay San Jose Mercury News AP SAN DIEGO—A Pacific green sea turtle that was found near-dead of gunshot ... that Bruce the turtle is ready to be returned to San Diego Bay on Tuesday. ...

Recuperated Sea Turtle Returns to Ocean NBC San Diego By Sarah Grieco A sea turtle named "Bruce" by SeaWorld staff was found in San Diego Bay shot four times in the neck in February 2011. ...

Bruce The Sea Turtle Released To San Diego Bay KPBS Bruce the green sea turtle will be released into San Diego Bay today after undergoing nine months of veterinary care at SeaWorld San Diego. ...

Bruce the Turtle Ready to Return to San Diego Bay KOLO The Los Angeles Times (http://lat.ms/vjdtlm) reports that Bruce the turtle is ready to be returned to San Diego Bay on Tuesday. At Sea World, Bruce has ...

Bruce the turtle ready to return to San Diego Bay Ventura County Star AP SAN DIEGO — SAN DIEGO (AP) - A Pacific green sea turtle that was found ... that Bruce the turtle is ready to be returned to San Diego Bay on Tuesday. ...

Let the research begin!

Well, two years after graduating from UCSD's Scripps Institution of Oceanography's Marine Biodiversity and Conservation masters program, I'm back in school.

Now it's a PhD program at UCSD, in the Biological Sciences' Ecology, Behavior and Evolution (EBE) department. Over the next five years, my research will still be focused on the incredible reptiles which come and visit us in San Diego - our green sea turtles! But now, I will be studying the population of green sea turtles (Chelonia mydas) which reside not only here in San Diego's Bay, but throughout their entire geographic range in the Eastern Pacific from Los Angeles to Central Mexico.

My research will aim to help answer some very important questions about these animals - seemingly simple things - like how old are the turtles when they are in the open ocean? how old are they when they settle closer to the coast? can we make a more refined connection between the age of a turtle and its size? do some turtles stay in the open ocean and never move in close to the coast? is there an impact over time on the turtles living near human communities? can we tell which turtles have been affected by pollution from our cities, like San Diego? how fast do the turtles grow???

Believe it or not, we do not know a lot of the very basic information about sea turtles! This is a very common challenge for scientists studying large, long-lived, and migratory animals in the ocean. Other animals like some whales, dolphins, seals and sharks are the same way - they are all familiar animals, like sea turtles, but very basic questions about them remain unanswered since there are some many difficulties in studying them.


All of these questions driving my research are important because they will help us to better know how many of these animals are in the different parts of the Pacific ocean, and how the entire population of East Pacific green sea turtles is doing over all.  Knowing the population size of this species is key, because they are an endangered animal, protected by the Endangered Species Act.  I will continue to partner with scientists at NOAA's Southwest Fisheries Science Center to do this research, as NOAA's branch, the National Marine Fisheries Service (NMFS) is responsible for assessing and managing endangered species found in the oceans.


My research will help manage this population, so we can better understand the impact of things like fishing and pollution on the overall size of the population of turtles.


Stay tuned, as I'll continue sharing this journey!


PS - A recent article in the Voice of San Diego discussed the wetlands in the South San Diego Bay, where I help monitor the sea turtles residing there. A couple of times in the article it was said that the sea turtles will no longer be in the bay, now that the power plant has been turned off... this is not the case! The turtles are still in the bay!  The water in the South San Diego Bay is still a good temperature for the turtles, and there is still plenty of eelgrass for the turtles to eat!  Not to fear, our turtles like their home in San Diego, and won't be going anywhere any time soon!


What we may see, as discussed in previous posts, is that the time of year when turtles are visiting the bay will shift a little bit.  The turtles used to be in the south bay especially in the winter, when the power plant kept the cooler water warmer, but then they wouldn't be in the south bay as much during the summer, when the power plant made the water too hot much of the time.  Now, we may start seeing a change in these patters - we may see the turtles more in the summer when the bay is warm, and we may see them less in the winter, when the water cools a bit.  Again, NOAA researchers are working hard to continually monitor this population, so they are in good hands!  Stay tuned as our South Bay monitoring season will start in just a few weeks!