Source: Miami Herald
For the past 18 months or so Nova Southeastern University graduate student Travis Moore has been a fixture at South Florida offshore fishing tournaments.
Moore and an assistant usually are found standing at a table near the scales waiting for dolphin, tuna, wahoo, kingfish and other species to sample.
When an angler presents the researchers with a fish, Moore carefully removes the stomach, liver, and gonads and slices off a small piece of muscle tissue. Then the angler gets the fish back to take home and eat.
Moore wants to learn what these popular recreational species eat, what position they occupy in the marine ecosystem, and –eventually—whether they were affected by last year’s massive BP oil gusher in the Gulf.
“There are really no studies of these fish in South Florida. We’ve got to start accumulating data on these fish,†Moore said. “You can go a mile offshore and catch all these fish together in the same area. Are these fish competing with each other for prey items? If you remove a predator fish, will another species take its place?â€
Since launching the study a few weeks before last year’s oil spill, Moore has collected 180 samples of kingfish; Spanish mackerel; blackfin tuna; little tunny; Atlantic bonito; skipjack tuna; dolphin, and wahoo.
He’s on track to analyze up to 130 more fish before the two-year study concludes in 2012. Eventually, he’ll publish his findings as a master’s degree thesis in fisheries biology.
Not surprisingly, Moore has found that his study subjects are mid-to-upper-level predators in South Florida’s coastal marine ecosystem, ranked just below apex predators such as marlin and sharks. But some of his findings about their eating habits may raise a few eyebrows among anglers.
For example, an analysis of the stomach contents of some 15 wahoo – nearly all caught off Islamorada — showed they mostly ate squid. However, their relatives, the king mackerel, ate almost no squid. Instead, the kings’ bellies contained mostly bony fish, such as goggle eyes, flying fish, blue runners and round scad.
Dolphin, not surprisingly, ate whatever they could get into their mouths, Moore found. The most well-rounded diet belonged to the blackfin tuna — which favored flying fish — but also consumed squid, blue runners, threadfin herring, shrimp and goggle eyes. Several tuna stomachs also contained seahorses — a species not often associated with pelagic fish, but Moore theorized those came from sargassum patches.
“They’re just swimming along at fast speeds, open wide, catching a baitfish, and getting some of that sargassum at the same time,†he said.
Still to come is an analysis of the fish livers for traces of hydrocarbons – an indicator they might have been exposed to oil from the BP spill. Those results are not expected for a few more months.
Moore says he’ll continue to make regular sampling trips to local tournaments from West Palm Beach through the Keys into next year. His research is funded by the Gulf Research Initiative, endowed by BP after the spill, and by the Yamaha/Contender Miami Billfish Tournament.