Saturday, June 19, 2010

Bahamas' Sharks: a moment's scarcity with disturbing implications

I returned late Thursday night from a video assignment in the Bahamas as director of photography - hence, the lack of postings over the last few days. The crew was out there to film sharks but, as it turned out, we had to look far and wide to find what we were looking for. In the "usual places" where we would expect to find numerous lemon, tiger, and Caribbean reef sharks, we were being skunked - a highly unusual experience.

The boat captain made radio calls to other boats in the area only to find that they were also experiencing the same lack of sought-after quarry. So, we were not the only ones and apparently this had being going on for several weeks. Two possible theories were being bandied about - either of which raised concerns as they illustrated the fragility of a marine ecosystem.

Hunting for sharks:
One of the dive operators that regularly works the area off the Bahamas related a rumor that a tiger shark, possibly a pregnant female, was taken by a fisherman the week before. Had the sharks, in response, moved away from their usual haunts, perhaps deeper or farther out to sea? Possibly - although the theory demands a multi-species reaction to a singular event that may not be that plausible. But it's a tantalizing idea: what would be the response by schooling predators like lemon and tiger sharks to life-threatening events? No matter how much bait or chum was used, at sites where we would normally have so many sharks on hand, you could almost walk across the water on their backs, there were virtually none.

Rising temperatures:
The other theory, which we were experiencing first hand, was an increase in water temperature. We found the temperature in be in the mid-80's from the surface (which is to be expected this time of year) to as deep as 60 feet before it abruptly dropped about ten degrees. Could this abnormal wider range of warmer water have pushed the sharks to deeper and more comfortable depths? Several of the locations where one would typically be surrounded by sharks are in the 20-foot depth range - and we had no luck at those sites. Ultimately, on the last day of shooting, we came upon a small but suitable number of Caribbean reef sharks at 80 feet. My B-camera operator, Scott Cassell, commented to me that he also noticed a lot more algae growing on the reefs in the shallower, warmer depths, versus the more colorful sponges and corals.

In the end, the production crew was able to get the footage it needed, but it was challenging to say the least. And disturbing to think about the implications to a balanced and healthy marine ecosystem when normal conditions are disrupted. In the end, either of these two mitigating factors - fishing or water temperature - which impacted the number of sharks we encountered could be mere anomalies. But it did provide a disturbing indication as to the impact of shark fishing and climate change.

In a couple of weeks, all we experienced could be forgotten and the frequency and range of the Bahamas' sharks could return to normal. But it was sobering to think what the future may hold in store.

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