Wednesday, May 27, 2009

Learn all about San Diego's Sea Turtles: This Thursday, May 28th, 6pm


Tomorrow evening, Thursday, May 28th, at 6:00pm, I will speak at Pro Peninsula's downtown location about San Diego's own sea turtles, their situation in the San Diego Bay, and what it means for the people of San Diego.

Once the South Bay Power Plant is removed, which it will be in the next few years, the south part of the San Diego Bay's ecosystem will change. How will this affect the endangered green sea turtles that are attracted to the warm, tropical-like water that is discharged by the power plant? Join me tomorrow to learn more! (Hint: we will still have sea turtles in the bay once the power plant is gone...)

And once the plant has been removed, the City of Chula Vista and all the residents of San Diego County will have a wonderful opportunity to develop this bayfront land as they see fit. A large range of development options are possible, and sustainable and thoughtful planning CAN make the South Bay setting one that hosts a healthy and diverse ecosystem and wildlife, and at the same time stimulates the local economy and benefits the community.

One great opportunity is increased education for our local youth. Pro Peninsula's education program, Ocean Connectors, is one great example. Frances Kinney, Education Coordinator, will share more about Ocean Connectors and the sea turtles of San Diego Bay.

Join us tomorrow, to learn more about these great ocean creatures, and how you can be involved in protecting these animals and deciding the future of the south bay.

To learn more, visit Pro Peninsula or UCSD's Scripps Institution of Oceanography's Center for Marine Biodiversity and Conservation (see Announcements), hope to see you there!

Wednesday, May 20, 2009

Part 3: Turtle "Catchability" Appears to be Declining - What Does This Mean?

Photo: NOAA SWFSC scientists search for sea turtles in San Diego Bay

First studied in the 1970's, the population of resident San Diego sea turtles has been closely monitored by scientists. Today, researchers from NOAA's Southwest Fisheries Science Center (SWFSC) and other local universities are supported, largely by the Unified Port of San Diego, and monitor the health, behavior, and well-being of this group of endangered green sea turtles.

In looking at the total number of turtles caught by researchers each year (refer to April 20th blog on how NOAA researchers "catch" the turtles), we noticed that in the past few years, the turtles seemed to be getting harder to catch. Meaning, it took a longer time in recent years, to catch the same number of turtles when compared to previous years.

For example, during the 2002-2003 monitoring season, which usually runs from late October to early May, SWFSC researchers would expect to catch around 4 turtles every day they went out to monitor the turtles. This is often referred to as the Catch-Per-Unit-Effort, or CPUE, and is a common way that fisheries are managed and assessed. So, for the 2002-2003, the CPUE was just over 4 turtles per day.

When you compare that to this year's CPUE, you notice that it was much harder to catch 4 turtles. In fact, the 2008-2009 CPUE was just over 1 turtle per day! I will discuss more about the over all "catchability trend" in a future post, but for now, I will wrap up with the three possible reasons why the "catchability" of the sea turtles in the San Diego Bay is declining.

1- the population of sea turtles is getting smaller
2- the turtles are learning how to avoid the nets that scientists use to catch the turtles
3- the turtles are more spread out in the bay than they used to be.

It turns out that neither #1 or #2 are correct, but that #3 could be part of the explanation.

Stay tuned to the nest post to learn more about these three reasons!

Saturday, May 16, 2009

Part 2: Green Sea Turtles in San Diego Bay


The Eastern Green Sea Turtle, Chelonia mydas, is an endangered species, and while normally found in tropical regions such as Hawaii and Mexico, a population of resident green turtles is found year-round in the San Diego Bay. These animals usually spend most of their time in the southern section of the San Diego Bay, especially near the warm-water effluent (discharge) of the large South Bay Power Plant (see map).

A large earth structure separates where the power plant's intake pipes are from the discharge pipes. This land is now the Chula Vista Wildlife Reserve, and is the primary reason why there have NEVER been any green sea turtles caught in or on the power plant's intake pipes. The turtles are frequently seen on the south side of the land structure, where the warm discharge water creates a warmer-than-normal habitat (see the red area on map). The South San Diego Bay National Wildlife Refuge includes the salt evaporation ponds at the far south end of the bay, and provides additional protection to the sea turtles by requiring slower boat speeds for example.

First studied in detail by graduate student Margie Stinson in the 1980s, the population of San Diego Bay turtles continues to be monitored (Stinson, 1984). Constant observations by NOAA’s NMFS Southwest Fisheries Science Center and other researchers have added to the body of knowledge on this particular population (Dutton, 1990) (NOAA, NMFS SWFSC, 2008).

The image above was created in Google Earth. The yellow, orange and green coloration show different habitats in the South Bay and was created by the Unified Port of San Diego. Other images added by me include the red coloration depicts, the estimated warm-water plume generated by the power plant, estimated to extend about 5000 ft, to the end of the barge extending from the most western end of the Chula Vista Wildlife Reserve, and the turtle icon show some of the areas that turtles frequently visit.

Explore more of the San Diego Bay with the Unified Port of San Diego's new Google Earth tour of the Bay's natural resources


Sources:

Dutton, P. ( 1990). Sea turtles present in San Diego Bay. In T. J. Richardson (Ed.), Proceedings of the Tenth Annual Workshop on Sea Turtle Biology and Conservation (pp. 139-141). Washington DC: NOAA Technical Memorandum NMFS-SEFC-278.

NOAA, NMFS SWFSC. (2008, May 7). Marine Turtle Program. Retrieved December 1, 2008, from NOAA, NMFS Southwest Fisheries Science Center: http://swfsc.noaa.gov/prd-turtles.aspx

Stinson, M. (1984). Biology of sea turtles in San Diego Bay, California, and in the north eastern Pacific Ocean. San Diego State University. San Diego: Master's Thesis.

More infomation: State of the Bay Report.

Wednesday, May 13, 2009

Part 1: Status of Green Sea Turtles in the Eastern Pacific


Of the six (or seven, depending on who you ask!) species of sea turtles alive today, the green sea turtle, known as Chelonia mydas, is the species found in the San Diego Bay. The population of green turtles found in these waters of the Eastern Pacific Ocean, are Endangered and therefore monitored and protected according to federal law. The group of green sea turtles found in this region of the ocean (from California through Mexico and even South America) have been impacted by harvest (of both turtles and eggs) fishery bycatch, entanglement and ingestion of debris, and even boat collisions. Over the last 30-40 years, this population of green sea turtles has significantly declined.

Common among all sea turtles species, the eastern pacific green sea turtles nest in one location, but eat, or forage, the rest of the year in another location. San Diego bay provides food for the sea turtles who migrate to the central coast of Mexico to nest. Slow growing and long lived, green sea turtles may live to be over 70 years old, and do not reproduce until they are 25-30 years old. Even then, females breed only once every two to three years.

All habitats utilized by the green sea turtles are important, but those habitat known to support either feeding or breeding are of particular significance to the protection and recovery of these endangered animals.

Next, Part 2: Green Sea Turtles in the San Diego Bay


Source:
National Marine Fisheries Service and U.S. Fish and Wildlife Service. 1998. Recovery Plan for U.S. Pacific Populations of the East Pacific Green Turtle (Chelonia mydas).
National Marine Fisheries Service, Silver Spring, MD.

Thursday, May 7, 2009

Birch Aquarium Staff Gets to Learn More About San Diego Sea Turtles


On May 6th, I was fortunate enough to chat with some of the staff and volunteers from the Birch Aquarium's education program and share with them what type of research I have been doing with the sea turtles in the San Diego Bay - and about the social, political, and even economic impacts of the research.

Given my background in marine education, it was a great chance to come full-circle and make that connection between why research is conducted, and what it means at the social and political levels - not just at the scientific level.

It was a great way for research and its social implications to be shared and discussed with a group of people who regularly interface with the public and share the wonders of our oceans with kids and adults everyday.

After 30 minutes of hearing about the following aspects from me:
  • What turtles we have in California waters,
  • How these endangered animals are regulated and protected,
  • What NOAA scientists do when monitoring the turtles in the San Diego Bay,
  • What potential changes are expected once the power plant in the south end of the bay shuts down and stops discharging warm water which, especially during the winter months, creates a warm water refuge for the Eastern Pacific Green Sea Turtles,
  • How the entire situation presents a potentially wonderful opportunity for citizens in San Diego - considering the expected changes that will occur in the South Bay once the large power plant is removed in the next few years, and
  • That future development CAN embrace the endangered sea turtles, and the entire ecosystem of the South Bay, as a BENEFIT, it does not have to be a burden planning around a protected species.
There were wonderful questions and discussions about:
  • General sea turtle biology and behaviors
  • How many sea turtles are in the San Diego Bay? (Answer: around 60)
  • Specifics on what shifts may be expected from the sea turtles once the power plant closes
  • Education and volunteer opportunities for SD students, residents and visitors
  • and much more!

The big question: will the sea turtles stay in San Diego?

Answer: The good news on all of the initial research is that we expect the turtles to still visit us in San Diego even once the warm water from the power plant is gone. The south end of the San Diego Bay will continue to provide a safe and warm place for the sea turtles to visit and the eelgrass which they enjoy eating will still be available - even if it means they just change the time of the year they are around, and where they spend most of their time.

Many thanks again for the chance to talk with the staff of this wonderful organization! And to those who would like to join me for my next talk - see below for details on the May 28th talk at Pro Peninsula!

Monday, May 4, 2009

Come learn about San Diego's Sea Turtles! May 28th, 6pm

Come join me, and Educator Coordinator Frances Kinney of Pro Peninsula's Ocean Connectors program, on Thursday evening, May 28th, to learn more about the endangered Eastern Pacific Green Sea Turtles!

Located at Pro Peninsula in downtown San Diego, we'll share the research being done to monitor these charismatic turtles, and how these findings help to inform policy decisions - especially in regards to the South Bay Power Plant and future development of the Chula Vista bayfront - and how the turtles and the research also serve as a tool to engage the local students!

Marine turtles, like these in San Diego Bay, provide an opportunity to increase the social benefits of local natural ecosystems and resources - come join us on May 28th to find out more!

Visit www.propeninsula.org for more details!


Video: Taken by author in the Caribbean. The behavior of this green sea turtle surfacing to breathe and then returning to the ocean floor to rest is very similar to the behavior we expect from the green sea turtles in San Diego Bay. Much of the day they are eating, resting, and breathing at the surface as needed.

video