counting fish tagged posts

New world map of fish genetic diversity

Spot-tailed grunts in the waters of Cabo Pulmo National Park in Mexico

In a population of animals or plants, genetic diversity can decline much more quickly than species diversity in response to various stress factors: disease, changes to habitat or climate, and so on. Yet not much is known about fish genetic diversity around the world.

Help on that front is now on the way from an international team of scientists from French universities and ETH Zurich. They have produced the first global distribution map for genetic diversity among freshwater and marine fish. Furthermore, they identified the environmental factors that are instrumental in determining the distribution of genetic diversity. Their study was recently published in the journal Nature Communications.

Genetic diversity is unevenly distributed

To begin their study, the researchers analysed a database...

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Scientist Counts Fish in Marine Reserve in 8 Days

Spot-tailed grunts in the waters of Cabo Pulmo National Park in Mexico

A scientist sent sound waves into the waters of Cabo Pulmo National Park in Mexico, single-handedly surveying the entire 27-square-mile (71 square km) marine reserve twice in just eight days. By shooting sound through the water column in horizontal transects and analyzing how the sound waves behaved, the researcher gathered data that he and his colleagues later used to calculate an estimate of how many fish were swimming in the preserve off the tip of Baja California – and their size.

By doing the same thing in the ocean outside the reserve, the researchers determined that the density of fish was nearly 300 percent higher inside Cabo Pulmo. The fish were also 52 percent larger.

This new application of hydroacoustic technology could lead to much cheaper ways of keeping tabs on ocean lif...

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