Shellfish consumed by humans are, ironically, more resistant to extinction

A recent study from the Smithsonian Institution has revealed new details about the relationship between human consumption and the survival of shellfish. In a time where overfishing and exploitation of marine resources are urgent global concerns, this research provides both a note of optimism and a stern warning.

The study, led by Stewart Edie of the Smithsonian, Shan Huang of the University of Birmingham and their colleagues, greatly expands our understanding of human-harvested shellfish, particularly bivalves such as clams, oysters, mussels, and scallops.

Focus of the research 

Prior to this study, the United Nations’ Food and Agriculture Organization’s Production Database listed only 81 bivalve species known to be exploited by humans. The researchers have identified an additional 720 species to add to this list. 

The team also discovered specific traits that make these particular shellfish both desirable to humans and resilient to extinction.

“Many of the traits that make these bivalve species attractive to humans have also lowered their risk of extinction,” explained Edie, who also serves as the National Museum of Natural History’s curator of fossil bivalves. 

Sustainable management of shellfish 

According to the research, bivalve species have a propensity to live across a spectrum of climates, enabling them to adapt to a wide range of temperatures. This adaptability enhances their ability to withstand natural extinction pressures. 

But Edie also cautioned that human demand can put these species and their ecosystems in danger. “Humans can transform the environment in the geologic blink of an eye, and we have to sustainably manage these species so they are available for generations that will come after us.”

Integral to human diets

Bivalve mollusks have been integral to human diets for thousands of years. Historical examples include the indigenous Calusa tribe in Estero Bay, Florida, who harvested an estimated 18.6 billion oysters, even constructing an entire island out of their shells. 

However, there are also many instances of overexploitation, such as the collapses of oyster populations in Chesapeake Bay, San Francisco Bay, and Botany Bay near Sydney, Australia.

What the researchers discovered 

For their investigation, the researchers set out to document the wide array of bivalves consumed by humans, gathering data from more than 100 prior studies, and identifying patterns among the 801 species. 

Notably, the experts found that bivalves desirable for harvesting often share characteristics like large bodies, shallow-water habitat, wide geographic distribution, and an ability to survive in diverse temperatures. These traits, apart from making them desirable to humans, also fortify them against extinction pressures known from the fossil record.

“It is somewhat ironic that some of the traits that make bivalve species less vulnerable to extinction also make them far more attractive as a food source, being larger, and found in shallower waters in a wider geographical area,” said Huang. He emphasized the need for global recognition and responsible fishing to avoid over-exploitation.

Study implications 

The significance of these findings extends beyond academic curiosity. The researchers hope that the data will guide future conservation and management decisions. Specific regions and species were identified as particularly prone to extinction, which could direct further studies assessing their risk.

“We want to use what we learned from this study to identify any bivalves that are being harvested that we don’t already know about,” said Edie. “To manage bivalve populations effectively, we need to have a full picture of what species people are harvesting.”

This research represents a vital step in the ongoing effort to understand and preserve marine biodiversity. The study was aupported by institutions including the Smithsonian, the German Research Foundation, the National Aeronautics and Space Administration, and the National Science Foundation.

The work aligns with broader initiatives like the Ocean Science Center and the Smithsonian’s Life on a Sustainable Planet initiative, aiming to promote sustainability, environmental conservation, and climate change solutions.

More about shellfish

Shellfish is a broad term used to describe aquatic animals that have a shell or shell-like exoskeleton. This group includes a wide variety of species, primarily categorized into two main groups: crustaceans and mollusks.

Crustaceans

Crustaceans include animals like crabs, lobsters, shrimp, and crayfish. These creatures typically have a hard exoskeleton made of chitin and calcium carbonate that protects their body.

Crabs

Known for their distinctive sideways walk, crabs are found in oceans, freshwater habitats, and on land. Their claws are used for capturing food and defense.

Lobsters

These large marine creatures are highly prized in cuisine. They are primarily found in the oceans and have a diet that includes fish, other crustaceans, and algae.

Shrimp

Shrimp are smaller crustaceans, found both in fresh and saltwater. They play a vital role in the food chain, serving as a food source for larger fish.

Mollusks

Mollusks include bivalves, gastropods, and cephalopods. Bivalves like clams, oysters, mussels, and scallops were the focus of the study mentioned earlier.

Bivalves

These animals have two hinged shells and include species such as clams, oysters, and mussels. Many are filter feeders, which means they feed by filtering plankton and other small particles from the water.

Gastropods

This group includes snails and slugs. Some, like the abalone, are harvested for food, while others, like certain sea slugs, are known for their beautiful colors.

Cephalopods

This intriguing group includes octopuses, squids, and cuttlefish. Known for their intelligence and ability to change color, they are carnivorous predators that hunt fish, crustaceans, and other mollusks.

Importance of shellfish

Shellfish play a crucial role in aquatic ecosystems. They are a vital food source for many marine animals, including fish, birds, and mammals.

Shellfish are a significant part of the global seafood industry, providing livelihoods to millions of people.

Many shellfish, especially bivalves, help maintain water quality by filtering impurities from the water. They also hold cultural value in many coastal communities, often being central to traditional diets and practices.

The research is published in the journal Nature Communications.

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