September 20, 2001

2 min read

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Genetic Markers Could Help Combat Poaching of Atlantic Cod

By Kate Wong

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Humans have fished for Atlantic cod for hundreds of years, but over the last century demand has surpassed supply. As a result, cod stocks around the world are now tightly regulated, if not closed altogether. Enforcing these regulations, however, has proved difficult. Now researchers have developed molecular techniques, described today in the journal Nature, that should make enforcement more feasible.

Einar E. Nielsen of the Danish Institute for Fisheries Research in Silkeborg and colleagues studied the three principal cod populations that inhabit the northeastern Atlantic¿those from the North Sea, Baltic Sea and Arctic Ocean. Analyzing tissue samples collected from the groups, the team identified so-called microsatellite genetic markers that correlate to the different populations. These markers, they found, can assign individual cod to their population of origin with better than 95 percent accuracy. In fact, the researchers report, "assignment is so reliable that testing as few as two or three individuals can provide an unambiguous conclusion about the origin of a sample that is claimed to originate from any one of the three samples populations, representing the majority of cod landings in the northeastern Atlantic."

Armed with techniques to identify the population of origin of individual cod in commercial landings and at fish markets, officials should have a much easier time of policing cod fishery regulations and identifying poachers. Furthermore, the researchers note that simply by adding more baseline samples, they could extend their identification repertoire to include other cod populations and populations of other species. "Similar analyses should prove valuable in ensuring that exploitation of fish stocks is sustainable," they write, "and that genetic resources are conserved in commercially important marine species."

Kate Wong is an award-winning science writer and senior editor for features at Scientific American, where she has focused on evolution, ecology, anthropology, archaeology, paleontology and animal behavior. She is fascinated by human origins, which she has covered for nearly 30 years. Recently she has become obsessed with birds. Her reporting has taken her to caves in France and Croatia that Neandertals once called home to the shores of Kenya’s Lake Turkana in search of the oldest stone tools in the world, as well as to Madagascar on an expedition to unearth ancient mammals and dinosaurs, the icy waters of Antarctica, where humpback whales feast on krill, and a “Big Day” race around the state of Connecticut to find as many bird species as possible in 24 hours. Wong is co-author, with Donald Johanson, of Lucy’s Legacy: The Quest for Human Origins. She holds a bachelor of science degree in biological anthropology and zoology from the University of Michigan. Follow her on Bluesky @katewong.bsky.social

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