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For reef sharks, commercial shark fishing isn't the only thing that threatens their survival. In reef communities near populated islands, an additional threat comes from the taking of fish by local fishermen - fish that often constitute a major portion of the sharks' diets. When local and/or commercial fishermen compete for the same food source as reef shark species, it can be a crippling blow to the shark population.
A recent study by Hawaii's Joint Institute for Marine and Atmospheric Research showed a drastic reduction in reef shark populations around populated islands in Hawaii as opposed to more uninhabited islands or pristine reefs.
"We found 90-97 percent decline in reef shark abundance: white tip,
grey, galapagos and nurse sharks," said Marc Nadon, a researcher with
the Institute.
The researchers have not been able to determine a more specific cause but look to accidental bycatch (sharks are now more protected, at least from legal commercial shark fishing, due to recent legislation) and overall fishing pressure as contributing factors.
"70 percent of reef shark diet is reef fish, so if you remove the food
source it would be logical that reef shark would follow the same trend
and decline," said Nadon.
While the researchers will be doing more studies this fall, their research's concern with competition for food has support based on what has been observed in other island nations. Both Samoa and the Marianas have seen major declines in reef shark populations around populated islands compared to other unspoiled reefs.
5/21/12 - As a follow-up, I received some information from Dr. Chris Lowe, director of the Shark Lab at the California State University at Long Beach. He has some concerns regarding the accuracy of the researcher's claims based on the reliability of the study's methods. We'll have to wait and see what future studies produce. Here are Chris' comments:
"Don't buy the 97% decline.
There are some methodology problems here. I don't dispute that there
are more sharks in the Northwestern Hawaiian Islands, but not by 97%.
These numbers are based on towboard diver surveys and anyone who has ev...er
dived in a remote location knows that a diver is a novel things -
sharks come flocking to you. However, in places like the main Hawaiian
Isl. sharks tend to avoid divers (spearfishermen) - who shoot at them
when they approach their fish. We've set 100s of short longlines all
around the most populated island (Oahu) to catch sharks to tag and have
caught a lot of sharks even though we rarely saw them diving in those
areas. This suggests there are behavioral responses of sharks to divers
in these areas that make it likely to overestimate sharks in remote
locations, while underestimating them in populated locations. In
addition, diver surveys are limited to 100', but we know that reef
sharks are deeper around the Main Hawaiian Isl. and this is probably
because there is more food at those depths. This depth shift could be
due to human depletion of reef fishes, but it doesn't mean there are 97%
fewer sharks, they are just outside their survey area."
Source: KITV.com
It hasn't been a particularly good couple of weeks for sharks.
First there was the large 20-foot, 4000-pound female white shark that was caught in the Sea of Cortez. Reportedly caught accidentally in the fishing nets of some local fishermen, it garnered media attention because of its massive size. As it turns out, it apparently had a research tag showing it had traveled from the coast of central California. Conjecture is that it traveled to the Sea of Cortez to give birth as this is a popular theory being proposed and studied by researchers.
The Sea of Cortez is an area that is being heavily fished by local fishermen and several species are being hard hit by the overall level of the catch. If juvenile white sharks are being taken - evidence of which has been seen in local fish markets - and females are being caught, either accidentally or deliberately, for a slow-reproducing animal like the great white shark, this is not good news.
Next up was the unfortunate fatal attack on a bodysurfer in South Africa. There have been fatal attacks throughout the years, but what raised the hackles of locals and caught the attention of the media was the fact that a film production company/research group was in the area apparently chumming to attract sharks for tagging purposes. South African government officials, who had issued the permits to allow the research, pulled those permits and from there it's been a media communications nightmare of accusations and a lot of CYA.
The production company had been filming in the past for National Geographic Channel's Shark Men series, but Nat Geo issued a response saying that they had not been working with this particular company for some time. South African government officials are being accused of faulty vetting of the operation in issuing the permits, but it's been said that there were scientists on board to ensure that no reckless behavior for the sake of dramatic film footage was taking place. And the production company claims that their actions were well within acceptable practices.
Then along comes a preliminary research study from Australia that says there may be a causal link between chumming used by shark diving operators and behavioral changes in white sharks. The report itself says it's not conclusive and does not imply that, because of chumming, white sharks are purposely seeking out humans, but it certainly added fuel to the fire of the anti-shark locals. It's quite a media mess and at this point it's hard to tell what the final results might be as to whether we'll see some knee-jerk reactions against the sharks by officials trying to placate those who believe they have greater rights to the seas than do the sharks. At the very least, it's bad P.R. for the sharks; the spectre of shark nets or a crack down on all shark diving operators always looms in the background.
Finally, the media outlets have been jumping all over a new study from the University of Hawaii and British Columbia's University of Victoria which says that Pacific reef shark populations have declined by as much as 90 percent or more in the past few decades. This decline has been noted in other studies, but this particular study had an interesting twist to it, as reported by The Washington Post's environmental writer, Juliet Eilperin.
The researchers study shark populations over 46 islands in the Pacific and not only found a decline but, conversely, found increases in shark populations wherever human populations decreased over the years and the productivity and temperature of the ocean increased.
“Our results suggest humans now exert a stronger influence on the
abundance of reef sharks than either habitat quality or oceanographic
factors,” said the researchers.
Many of the islands involved in the study have laws and regulations in place to protect sharks but, as is the case with many conservation regulations worldwide, enforcement is lacking either due to lack of resources or political will.
Julia Baum, assistant professor at the University of Victoria and co-author of the study, said, “To me, enforcement of these islands is a major unsung conservation
challenge, and I suspect that if this is not effectively addressed [as
soon as possible], the reef sharks on these islands will be fished out
within the next 10 years.”
The Muppets' Kermit the Frog once sang, "It's not easy being green." It's not easy being a shark either. We need our green puppets for comic relief; and we need our sharks for something far more important: the preservation and natural balance of the sea's marine life.
Source: Sacramento Bee
Source: Mail & Guardian Online.
Source: The Washington Post
Photo: Brian Skerry
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.
An article that ran in the New York Times on shark diving in Fiji has been making the rounds of several of the shark-related blogs, not because the article is some scathing expose but because it is a well-balanced look at shark eco-tourism as practiced at Beqa Adventure Divers.
What caught my attention was how the article, in a broad sense, highlighted the fact that shark eco-tourism (or shark diving, if you like) is a varied activity - something that proponents, and even opponents, need to keep in mind when discussing it. Unfortunately, it often is generalized under one heading: "You've gotta be crazy." But there's much more to it than that.
When discussing shark eco-tourism you have to consider the location, the species of shark involved, and the methods involved.
Location:
Shark diving should only take place in areas where there are recognized or resident populations of sharks. The anti-shark furor that occurred in Oahu several months back was initiated because someone wanted to start an operation in an area not known for sharks but highly populated by recreational beach goers. Bad business move.
In Fiji, the shark diving operations work in areas where the reefs are healthy and protected from overfishing (ie: a healthy reef includes resident sharks as part of a balanced marine ecosystem) and the boats keep an eye out to preserve what is a valuable source of tourism revenue for the islands.
Shark Species:
Great whites, tigers, lemons, bulls, Caribbean reef, Galapagos, whale, and many more species have been the center of attention with different operators around the globe. But each species has its own behavior, it's own level of interest or disinterest in the participants; and so each species requires its own set of protocols so as not to endanger the shark or the diver.
In Fiji, there are large groups of various reef sharks that can be active and put on quite a "show", but at deeper depths, bull sharks require more specific handling. And the great white sharks, that I have spent so much time with, require close attention not so much because of their size but their curiosity.
Methodology:
So, because of various behaviors presented by different species, the methods by which divers can be safely exposed to these animals can also vary. From open water experiences to using 
chain mail suits to working within a cage - these decisions must be carefully considered to insure both the most educational and enlightening experience while also being the safest for the divers.
And there must be consideration as to any adverse or disruptive behavioral impact on the sharks and their surroundings. To date, the available research seems to indicate that, if carried out responsibly, there is, at worst, only a temporary effect on the shark's conditioning behavior and that there is nothing that indicates negative changes in their natural feeding or migratory behaviors.
Shark eco-tourism can be an effective way to communicate the importance of shark conservation whether to a specific audience of participants or to a non-participating public at large - if it is done right. And it must be done right because shark diving doesn't fly under the radar of media scrutiny.
Congrats to Beqa Adventure Divers for some well-deserved and balanced media coverage. One of these days, I'll get back to Fiji and you guys can introduce me to some of your sharky friends!
Read NY Times article.
