May 14, 2012
Fishermen are optimists, there’s just no other way to describe us. Every new day that we step onto a boat or wade off a shoreline, there is a new sense of hope that it will be a great day of fishing. Fishermen also tend to be adventurous, whether exploring new water or just excited with new ideas for another day on the water. And many of us are constantly in search of new information about the gamefish we fish for – what they eat, their movement patterns, their behavior – that will improve our ability to find and catch more fish.
Two of the more pressing questions from guides, anglers, and scientists have been – what are bonefish movement patterns, and where do bonefish spawn? In other words, are the fish you find on a favorite flat always the same fish, or are bonefish constantly coming and going? Are there areas we should identify for protection to ensure bonefish can safely spawn to provide future generations of gray ghosts?
The conventional wisdom on bonefish has always been that they are homebodies – those fish you find on your favorite flat on the rising tide are the same fish day after day. But until recently, this was never tested. The results of what has been learned, and we continue to learn, may surprise you.
More than ten years ago, Jerry and his graduate students began a tagging program for bonefish in theFlorida Keys. Prior to the initiation of this project, no one had ever examined bonefish movement patterns. Despite conventional wisdom, we really had no idea how bonefish behaved – whether they had small home ranges or were creatures suffering from wanderlust.
Over the project period, Jerry and his students, working closely with guides, have tagged more than 8,000 bonefish in the Keys with what are commonly called dart tags. So far, anglers have recaptured over 300 tagged bonefish, which is right on par with recapture rates from the majority of fish tag-recapture programs.
When fishing for bonefish, you can’t expect a single answer when it comes to strategies for finding and catching them. It’s no different with the science of bonefish. The results of theFlorida Keystagging study show a range of movement patterns. The majority of bonefish stick close to home for extended periods – 42% have been recaptured at or near the tagging location; 70% were recaptured within five miles of the tagging location. So to some extent, as you are getting to know a bonefish flat, the fish are getting to know you too.
But some bonefish have been long-distance champions, and have been recaptured more than 100 miles from where they were tagged. Some of the fish tagged in Biscayne Bay, for example, were recaptured in the lowerFlorida Keys. And two fish that were tagged in the upper Florida Keys were recaptured by anglers fishing onAndrosIslandin The Bahamas. This is a distance of more than 100 miles, and across the deep and fast-moving water of theGulf Stream. The question now is whether this Florida-Bahamas movement is a regular occurrence or whether these two fish somehow got terribly lost.
These results tell us a few things. First, it’s important to protect habitats and locations where we find and fish for bonefish because these are probably the home waters of these fish. But it’s also important to protect large, continuous tracts of habitat because bonefish do undertake long distance movements.
The Bahamas and Belize
To test whether the findings in the Florida Keys will hold true elsewhere, BTT is also sponsoring bonefish tagging in The Bahamas andBelize. Will these bonefish also undertake long distance movements, or stay close to home? So far, results in these other locations are following what we learned in the Keys – that most bonefish seem to remain in small areas, but there is also a good bit of long distance movement. In Abaco, for example, where over 700 bonefish have been tagged, all of the recaptured fish have been caught within a few miles of where they were tagged. And one was caught in the exact same spot it had been tagged a year earlier.
In contrast, a study by Vanessa Haley on north Andros during spawning season, in which bonefish were tagged with sonic tags, revealed that some bonefish undertook migrations of more than 100 miles round trip to reach spawning grounds, returning days later to the areas where they were tagged. So maybe the long-distance movements in the Keys were the result of the same type of spawning migration. We’ve just started tagging bonefish inBelize, and it will be interesting to find if their movement patterns are the same.
Until recently, we didn’t know where or when bonefish spawned. Recent research that BTT helped to fund at the Cape Eleuthera Institute, in The Bahamas. Andy Danylchuk and his colleagues at CEI used sonic tags to discover that bonefish spawn on full and new moons between October and April/May. They also discovered that the bonefish spawned at night in offshore waters – not water that was just 30’ deep, but that was hundreds to thousands of feet deep. Near dawn, the bonefish returned to the shallows. Since the work at CEI, BTT has funded research inAndros, and is currently funding research on Abaco, to identify spawning locations so that these locations can be protected. We are also now working to determine exactly how far bonefish travel to reach a spawning site, whether each location have a single spawning location or are there many spawning locations, and whether bonefish return to the same spawning site year after year.
Why is this important? Knowing the range of movement is important for effective management. Habitat protection of a particular flat, for example, although important, might be insufficient if bonefish regularly move among many flats that are separated by miles. If bonefish move across international boundaries, then countries that share bonefish populations are going to have to cooperate to ensure their fisheries remain healthy. And since it appears that many of the long-distance movements by bonefish are related to spawning, it’s now obvious that spawning locations need to be identified and protected, because each location likely supports a bonefish population that is spread over a large area.
Aaron Adams, PhD. is Director of Operations for Bonefish & Tarpon Trust and a Senior Scientist at Mote Marine Laboratory. Jerry Ault, PhD. is a Professor of Fisheries and Michael Larkin is a Ph.D. candidate at theUniversityofMiami, Rosenstiel School of Marine and Atmospheric Science.
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