Posted by: stiltsville | May 19, 2011

Bonefish spawning sites discovered

Though bonefish are one of the most sought-after tropical sport fish in the world, drawing thousands of anglers to Caribbean waters every season, until recently the only information scientists had about their spawning habits were anecdotes and fish tales.
Now, University of Massachusetts Amherst researcher Andy Danylchuk and colleagues from several other institutions know far more about bonefish spawning habits after using ultrasonic transmitters to tag and track bonefish movements off Eleuthera in the Bahamas. Their results appear in an early online issue of the journal Marine Biology. Results should help focus habitat conservation efforts.
What Danylchuk and colleagues found by tagging these popular sport fish is that bonefish gather in schools of over 1,000 at pre-spawning aggregation sites for a few days twice a month from October to May, primarily around the new and full moon. At dusk, these large schools begin to move offshore to the edge of deep abyssal waters, over 1,000 feet deep, very unlike the shallow flats were anglers normally encounter them. There, as night falls, the fish spawn under cover of darkness.
“This is the first time movement patterns of bonefish to deep water have been formally described,” says Danylchuk, an expert on coastal fish stocks, the impact of angling and how to protect ecosystems. Although surprising, this movement to spawn in deeper water makes some sense, he adds. “One possible benefit of bonefish migrating to offshore locations to spawn is that it increases the dispersal of their fertilized eggs, especially with the high tides that happen with the new and full moons.”

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