Our Team

David McGuire

MPH, Executive Director and Founder of Shark Stewards

David McGuire

David is the Founder and Director of the shark and marine conservation nonprofit “Shark Stewards”. A marine biologist, David is a National Geographic Explorer and a research associate at the California Academy of Sciences where he conducts shark studies and media production in the San Francisco Bay and in SE Asia. Shark Stewards introduced the first North American shark fin trade ban in California and led several states and international movements limiting the overfishing of sharks and the shark fin trade. Shark Stewards actively partners with NOAA in our National Marine Sanctuaries and the Ocean Protection Council in our California marine protected areas, where he is  Co-chair of a California MPA collaborative committee. A documentary filmmaker, David received an Emmy for Field Production and Camera on the documentary “Reefs to Rainforests” and has written for National Geographic and other publications. He is a popular public speaker on sharks and the ocean and lecturer at the University of San Francisco.

David’s Full Bio

Advisory Board

Gautam Barua

Gautam Barua

Board Chair

Gautam’s passion for the oceans started in childhood, as he built sandcastles on the shore of the Long Island Sound, avidly read about sharks, and unfortunately saw “Jaws” on the big screen at the age of 3. Currently an executive at science-focused startup Noble.AI, Gautam previously worked for McKinsey & Company, as a cleantech and biotech investor and entrepreneur, and as California Deputy State Controller. He also served on the board of pioneering conservation group Save the Bay. Gautam holds a Harvard MBA and a BA from Yale, where he assisted a Nobel laureate with modeling impacts of climate change.

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Bill Brick

Bill Brick

Bill is a passionate advocate for nature – exploring the wild since adolescence and captivated with the ocean since his first open water dive nearly 30 years ago. He held leadership positions in the corporate finance, technology and startup sectors for 20 years before dedicating himself to the urgent needs of climate change. Today, working with investors and developers, he helps large organizations implement clean energy to meet their decarbonization goals. Bill received a BS in Managerial Economics from UC Davis, an MBA from UC Irvine and is a Certified California Naturalist. He also serves on the Advisory Council for Nature in the City and is a trained citizen scientist with NOAA’s Beach Watch program. He’s honored to serve with Shark Stewards in protecting these magnificent animals and the marine environment they (and we) depend on.

Vivian Trembley

Vivian Trembley

Vivian received her BA in Economics from Williams College, MBA from Harvard Business School and joint MPA/URP degree in International Development and Urban Planning from Princeton University. An avid traveler who has been to over 200 countries and every continent, Vivian and her husband Michael have dived around the world, share a passion for sharks and ocean conservation and met volunteering at the Marine Mammal Center. After transitioning from finance to the tech industry, Vivian relocated to San Francisco for a role at Google and currently works at facebook. She is excited to be involved in the critical work Shark Stewards is championing to save sharks and preserve our oceans.

Pamela Ordoñez Comstock

Pamela Ordoñez Comstock

Pamela received her BA in Art History from the University of California, San Diego. While in college, she worked at Scripps Institution of Oceanography Archives and worked on papers such as renown Ichthyologist, Carl Hubbs, and several marine geologists. For the ocean, Pamela has worked with Ocean Voyages based in Sausalito, helping to inform people about the proliferation of ocean plastic trash, and was Project Manager of All One Ocean. Currently she provides financial and marketing advice for ocean non-profit organizations.

Jeff Morrison

Jeff Morrison

Jeff has been diving with sharks across the globe since 1997. He recalls the first sight of a Caribbean Reef Shark on his first open water dive as one of the most beautiful and majestic animals on earth. “What stunned me was how peaceful and serene she was…cruising so effortlessly but with purpose, I had no fear but only admiration and respect…as I learned more about sharks through scientific research and my own experiences in the water with over a dozen different species, taking action to save them was something I had to do. Fulfilling Shark Stewards mission is a big part of my life and my identity as a human on this planet.” Jeff Morrison is a professional jazz musician and active in pitbull/bully breed canine rescue, education and advocacy throughout the United States.

Diane Walton, PhD

Diane Walton, PhD

Diane Walton lives in San Francisco and is a teacher of various things, a non-competitive rower, a nascent swimmer, and an avid reader. She’s proud to be the immediate past President and still on the Board of San Francisco’s Dolphin Club, to serve on the Board of Stewards for Baykeeper and the Eugene Relief Nursery, and to be both a Banana Slug (BA, UC Santa Cruz) and a Duck (PhD, University of Oregon). She wants to swim under the Golden Gate, make a movie, celebrate the individual, and work in the collective. Even more than any of that, she wants our kids to care and know even more about our Bay and the world of water than we do… and that’s why she’s part of Shark Stewards.

Medea Isphording Bern

Medea Isphording Bern

Medea Isphording Bern is a native Floridian who grew up exploring the pristine coral reefs around the Florida Keys. She’s a certified Rescue diver and has been diving in multiple tropical seas. Medea is licensed to practice law in both Florida and California and she holds a California Real Estate Broker’s license. She is also the author of two books, short stories and multiple essays. She’s been keenly interested in marine protection for decades. She was an original board member and board chair of the Coral Reef Alliance, as well as a two-term board chair of the Marine Science Institute, both based in the San Francisco Bay area. Medea is proud to be associated with Shark Stewards, and its efforts to protect for these majestic apex creatures, along with the ecosystem that is vital to their health and survival.

Nicholas Philip

Nicholas Philip

Nick’s fascination with sharks and rays started with a grade school science project on Tiger sharks. As an avid scuba diver for over 30 years, Nick is committed to helping protect our ocean environments and shark species. Nick recently moved San Francisco from New York and works in the finance industry. Nick has an MBA from the University of Michigan and a BA in History from the University of Colorado.

Gretchen Coffman, PhD

Gretchen Coffman, PhD

Scientific Advisor

Dr. Coffman is a restoration ecologist who teaches field classes at the University of San Francisco’s Environmental Science Department and Masters of Science in Environmental Management program. She has always loved the Ocean growing up along the Georgia coast and now spends her free time swimming or rowing in the San Francisco Bay. She shares her love for aquatic ecosystems and passion for protecting them by taking her California Ecosystems and Ecology classes on expeditions to the Farallon Islands to learning about marine ecosystems and kayaking on the San Francisco Bay to learn about our estuary. Gretchen has been volunteering with Shark Stewards since 2011 as a science advisor and helping at outreach events with her students. Gretchen is also an avid diver and recently helped restore coral reefs and reintroduce sharks with Shark Stewards on Pom Pom Island, off the coast of Malaysian Borneo.

Media Resources, Operations & International Team

Dan Vallentyne

Dan Vallentyne

Communications Director

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Vincent Yip PhD, Singapore

Vincent Yip PhD, Singapore

Cultural Advisor, Education

Sharon Kwok Pong, Hong Kong

Sharon Kwok Pong, Hong Kong

Actress, Diver and Conservationist

Simon Christopher, Malaysia, Timor Leste

Simon Christopher, Malaysia, Timor Leste

Media Production & Sustainability

Katerina Sonntagova, South Africa,

Katerina Sonntagova, South Africa,

Graphics Design

Science Team

Wallace “J.” Nichols, PhD

Wallace “J.” Nichols, PhD

Science and Outreach

Jack Dumbacher PhD

Jack Dumbacher PhD

California Academy of Sciences

Viktoria Kuehn MS,

Viktoria Kuehn MS,

Field Ecologist

Bianca Bahman

Bianca Bahman

Shark and Data Science

Natalie Coy

Natalie Coy

Volunteer Coordinator, Science Team

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Vicky Fong

Vicky Fong

Science Dive, Science Team

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Chapter Leads

Maria Korcemaros

Maria Korcemaros

Southern California Team Lead

Mikayla Logan

Mikayla Logan

Bay Area Education Lead

Amber Platowski

Amber Platowski

Southeast USA, Chapter Lead