Larval fish travel hundreds of kilometres!

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A study of reef fish has found that larvae can travel surprisingly long distances and that this information can be used when planning networks of marine protected areas.

The study that was undertaken by researchers from Canada found that connectivity of reef fish can be highly important when planning protected areas, as larval fish can travel hundreds of kilometres.

Using genetic analysis, researchers studied dispersal and connectivity of seven populations of the Caribbean bicolor damselfish (Stegastes partitus) from Belize and Mexico. They found that the fish could travel long distances and that dispersals varied from year to year depending on oceanographic currents and weather.

Lead Author Derek Hogan of the University of Windsor, now at University of Wisconsin said: "This is the first time that genetic 'assignment tests' have been used to delineate the pattern of connectivity for a marine fish in a region of this size (approximately 6,000 square km).We found that larvae of this species, on average, travelled 77 km from home in the 30-day larval period. Although some fish remained close to home in the same period, some travelled almost 200 km - an impressive feat for a larva about the size of a baby fingernail."
 
The study found that rates of self-recruitment (where larvae return to their birth site) and dispersal distances varied from year to year which had significant impacts on reserve planning.
 
"These studies are invaluable for understanding how to design networks of marine protected areas effectively," says Dr Hogan. "The functioning, and therefore the success, of networks of MPAs designed for conserving species depends fundamentally on our deep understanding of larval migrations."

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