One Tiny Fish’s Struggle for Survival

The most important fish in the sea is facing an uphill battle for survival.

The Atlantic menhaden—a type of herring—is highly sought after by both fish and fisherman. Menhaden, also known as “bunker” or “pogy” to many anglers, is being fished at unsustainable rates and its population has plunged down below 10 percent of historic levels.

RSMAS Marine Biology & Fisheries Professor Jerry Ault is worried about these little plankton-eating fish and the ripple effect their dwindling numbers could send through the entire U.S. Atlantic coast marine ecosystem.

The coastal migration of menhaden schools intersects with the movements—and stomachs—of many larger and more highly valued predators. In Florida, the “Silver King” (Atlantic tarpon), king mackerel, sharks, cobia, and birds like brown pelicans, bald eagles, and ospreys, as well as Royal and Sandwich terns all rely upon these tiny fish to fuel their migrations.

“Wherever they travel, Atlantic menhaden feed on plankton, converting it into fatty, high-nutrient tissue that larger fish then readily consume to fuel their own migrations,” Ault explains. “All of these larger fish need the rich menhaden flesh for sustenance and reproductive power.”

In Chesapeake Bay, they are the primary diet for striped bass, bluefish and weakfish. As they head south for the winter, they cross paths with Atlantic tarpon off the Florida coast. When they head north again in late spring and summer, as far as the waters off Cape Cod, they become prey to bluefin tuna as well as many other ocean giants.

“If allowed to continue unchecked, the unsustainable fishing of menhaden could create a domino effect that cascades throughout east coast fisheries, potentially forcing the collapse of not only this fishery, but also other economically critical fisheries,” says Ault.

More of these tiny fish are caught per ton than any other fish on the East Coast, all for their rich, nutritious meat. Hundreds of millions of menhaden are hauled in annually, ground up, and reduced to fish meal and oil for human dietary supplements, such as like omega-3 fatty acid pills or processed into pet foods, fertilizers, and feed for agricultural animals, as well as farm-raised fish.

During a critical meeting in November, Ault urged the Atlantic States Marine Fisheries Commission (ASMFC), the inter-governmental body that manages the fishery and sets fishing levels, to support the science to better protect the small but mighty fish that plays a vital role in keeping our oceans healthy.

In an overwhelming vote of 14 to 3, the commission took the first step by agreeing to reduce harvest of Atlantic menhaden by 37 percent compared to 2010 levels.

“The action by the commission sets limits on the fishery and with the new reference points they adopted over the next few years the amount of menhaden left in the ocean will quadruple,” said Ault.

Watch this video to learn more about Ault’s fisheries research in the Dry Tortugas.

Annie Reisewitz
Follow Annie on Twitter @annelore

Twitter Use Earns RSMAS Student Trip To Auckland, New Zealand


RSMAS Ph.D. student David Shiffman, who is an expert on the use of social media for conservation advocacy and science education, has been selected as the first-ever official “Tweeter” of Marine Section of the Society for Conservation Biology. He is presently at the International Congress for Conservation Biology in Auckland, New Zealand, where he is live-Tweeting marine conservation presentations and workshops so that interested people around the world can follow along. You can follow along with David and other conference Tweeters by following hashtag #ICCB on Twitter, or by following David directly @WhySharksMatter.

-Andrew DeChellis
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Coral Gardeners at RSMAS

Around the world, coral reefs have drastically declined due to coastal development, increased water temperatures and storm frequency, global climate change, disease, pollution, and overfishing. In particular, populations of the threatened staghorn coral (Acropora cervicornis) have declined by up to 95% in the Caribbean. To help combat the continuing decline of staghorn coral and assist in their recovery, the Benthic Ecology Lab at the Rosenstiel School is growing corals at an in-water coral nursery to use in restoration activities. The coral nursery is located just east of Boca Chita Key within Biscayne National Park, about a 45-minute boat ride south from the RSMAS dock.

Staghorn coral reproduces naturally through the process of fragmentation, so we collect small pieces of coral called fragments from wild colonies and place them in a coral nursery. The nursery is constructed of cinderblock platforms with 10 pedestals where coral fragments are secured with underwater epoxy. Once secured in the nursery, staghorn fragments can grow up to 15 cm per year. When the fragments have grown to about 30 cm, they can be fragmented again to create more fragments without needing to collect more from wild colonies.

Currently, there are 542 small staghorn coral colonies at the RSMAS coral nursery totaling over 250 meters of healthy coral tissue. The coral nursery attracts many fish and invertebrate species such as snapper, grunts, urchins, lobster, and squid. SCUBA divers regularly clean the nursery with wire brushes to prevent algae and other encrusting organisms like sponges from overgrowing the corals. This process, known as “coral gardening” produces a sustainable, healthy stock of corals which can be transplanted to local coral reefs to help replenish declining staghorn populations. Corals from the RSMAS coral nursery are planned to be outplanted in Spring 2012.

-Stephanie A. Schopmeyer
Senior Research Associate

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Can Corals Adapt to a Warming World?

In the Coral Reef Conservation Research Lab at RSMAS we are conducting experiments on coral bleaching and recovery. Coral bleaching is the breakdown of the relationship between corals and the symbiotic algae that live inside their tissues and provide them with energy through photosynthesis. As the corals lose the algae they also lose their color, hence the term, ‘bleaching.’

In our study, over 600 small coral ‘cores’ were drilled out of larger coral colonies and then experimentally ‘bleached’ by exposure to seawater at 32°C. The different coral cores were bleached to different levels of severity to simulate mild and severe bleaching events in nature.

The corals were then allowed to recover at two different cooler temperatures (24°C and 29°C) for several months, where they regained their algae and their color. As corals recovered, the photosynthetic performance and density of their symbiotic algae was monitored in order to see how both bleaching severity and recovery temperature might affect the speed of recovery, and the types of symbiotic algae they recover with. Some of the corals recovered after the first bleaching experiment with different kinds of symbiotic algae known to be more tolerant to high heat. Now they are being exposed to high heat again to observe how past bleaching history and changes in symbiont communities affect bleaching sensitivity.

Ross Cunning, RSMAS graduate student

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