Overfishing could see oysters become the “dodos of the sea,” warns a new study.
Researchers have compiled a list of more than 800 shellfish species – including clams, oysters, mussels and scallops – harvested by humans for the first time.
They say the traits which make the species targets for harvest also make them less prone to extinction.
But the team of British and American scientists flagged certain ocean regions – such as the east Atlantic and northeast and southeast Pacific -as areas of “special concern” for management and conservation.
The study, published in the journal Nature Communications, found that humans exploit 801 species of bivalves – defined as aquatic mollusks with compressed bodies enclosed within a hinged shell.
Scientist and geologist Stewart Edie, of the Smithsonian Museum of Natural History, explored how many of the same traits which make bivalve species attractive to humans luckily also lower their risk of extinction.
These species live in a range of climates all over the world with an equally wide range of differing temperatures.
This adaptability of bivalves makes them incredibly resistant to natural drivers of extinction.
However, at the same time, growing human demand for these species puts them and their ecosystems at greater risk.
“We’re fortunate that the species we eat also tend to be more resistant to extinction,” Dr. Edie, who is the curator of fossil bivalves at the Smithsonian Museum of Natural History, said.
“But 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.”
Dr. Shan Huang, a macro-ecologist at the University of Birmingham, added it was ‘ironic’ how the same traits which make bivalves more attractive also protect them from extinction.
“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,” Dr Huang said.
“The human effect, therefore, can disproportionately remove the strong species.
“By identifying these species and getting them recognized around the world, responsible fishing can diversify the species that are gathered and avoid making oysters the dodos of the sea.”
Bivalve mollusks have filtered water and fed humans for thousands of years now – and have even provided building material for some ancient civilizations.
In Estero Bay in Florida, the southeasternmost US state, the indigenous Calusa tribe once sustainably harvested an estimated 18.6 billion oysters and constructed an entire island with 30-foot high mounds out of their shells.
However, human history is also rife with examples of overexploitation of bivalves by humans – often by European colonizers and commercial fisheries.
This overexploitation has in some cases led to collapses of oyster populations in Chesapeake Bay – the largest estuary in the US in the mid-Atlantic – San Francisco Bay on the US west coast and Botany Bay near Sydney, Australia.
After studying scientific literature and coming to the realization that there was no comprehensive list of all the species known to be targeted by fisheries, Dr. Edie and his co-authors decided to compile a list of bivalves harvested by humans.
Having collated species identified in more than a hundred previous studies the researchers began investigating possible similarities and patterns amongst the 801 bivalves on the newly-compiled list.
The collaborative study team closely examined which traits make a bivalve exploitable by humans and how those traits relate to their risk of extinction.
They discovered that humans tend to harvest bivalves that are large-bodied, occur in shallow waters, occupy a wide geographic area and survive in a large range of temperatures.
These final two traits also make most exploited bivalve species less susceptible to extinction pressures and risks that have wiped out species from the fossil record in the previous centuries.
The researchers hope their new data – which identifies specific regions and species particularly prone to extinction – improves future conservation and management decisions.
Their list may also help to identify species that require further study to assess their risk of extinction.
Dr. Edie and his team next aspire to use the traits associated with exploited bivalves to investigate species not currently known to be harvested by humans.
He explained: “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.
“To manage bivalve populations effectively, we need to have a full picture of what species people are harvesting.”
The research is part of the Smithsonian’s Ocean Science Center, which seeks to catalyze change and action by advancing knowledge of the ocean and sharing it with the scientific community, policymakers and the general public.
The research also supports the Smithsonian’s Life on a Sustainable Planet initiative; a major effort to collect new data about our changing planet, implement holistic and multi-scale approaches to environmental conservation and educate the world about why and how sustainable solutions to climate change can benefit people and nature.
Produced in association with SWNS Talker
