Ongoing collapse of coral reef shark populations
Investigators have revealed that coral reef shark populations are in the midst of rapid decline, and that “no-take zones”—reefs where fishing is prohibited—do protect sharks, but only when compliance with no-take regulations is high. The findings, reported by William Robbins and colleagues at James Cook University and its ARC Centre of Excellence for Coral Reef Studies, appear in the December 5th issue of Current Biology.
Reef sharks are so-called apex predators on tropical coral reefs and are therefore of significant potential importance to the functioning of coral reef ecosystems. The reproductive biology of reef sharks makes them particularly vulnerable to fishing, but until now, there have been no studies of the response of these sharks to fishing pressure.
The new work focused on Australia’s Great Barrier Reef, which is widely considered to be one of the world’s least degraded, and best managed, reef systems. For balancing conservation with sustainable use, the Great Barrier Reef is regulated through an extensive series of management zones in which different areas are open to different levels of fishing. In their study, the researchers determined the status of two species of reef shark—the whitetip and grey reef sharks—by employing a unique combination of fisheries-independent abundance estimates and measurements of the survival and reproduction of individual sharks. Their findings show that reef shark abundance on reefs open to fishing are about ten times lower than on unfished reefs. Moreover, high reef shark abundance was only apparent on the most strictly enforced of the no-take zones, suggesting that even moderate levels of poaching can derail attempts to protect shark populations. These observations, coupled with population modeling showing ongoing, rapid declines in population size in fished areas, lead the authors to conclude that reef sharks are approaching “ecological extinction”—that is, becoming so rare that they can no longer perform their natural role in the functioning of coral reef ecosystems.
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The researchers include William D. Robbins and J. Howard Choat of the School of Marine and Tropical Biology at James Cook University in Townsville, Queensland, Australia; Mizue Hisano and Sean R. Connolly of the Centre of Excellence for Coral Reef Studies and School of Marine and Tropical Biology at James Cook University in Townsville, Queensland, Australia.
This work was supported by grants from the Australian Coral Reef Society, Professional Association of Diving Instructors (PADI) Aware, Great Barrier Reef Marine Park Authority (GBRMPA), the National Geographic Society, the Queensland Government/Smithsonian Institution collaborative research program, and the Nancy Vernon Rankine write up scholarship. Great Barrier Reef collections and entry into no-entry zones were conducted under GBRMPA permit.
Robbins et al.: “Ongoing Collapse of Coral-Reef Shark Populations.” Publishing in Current Biology 16, 2314–2319, December 5, 2006 DOI 10.1016/j.cub.2006.09.044. www.current-biology.com
There will be days when the fishing is better than one's most optimistic forecast, others when it is far worse. Either is a gain over just staying home.
So the reef shark population of the GBR is on the verge of collapse or "ecological extinction". This with no commercial or recreational shark fishery and a fishing pressure 1/100th of what is regarded as sustainable on overseas reefs.
Sounds like their "unique" estimates are very unique indeed! And look who it is funded by; a dive association and the GBRMPA. This might be one for Dr Starck to comment on.
Are they saying that the taking of sharks for consumption is the reason for their decline. I am by no means an expert, in fact, I only fish the reef a couple of times a year. The areas i fish are targeted by both recs and pro's and i don't think i have ever seen a shark kept there. Many hooked after taking a trout or something else, but not kept or targeted. Why would a rec keep shark when fishing for trout or emporer.
Jim
The study has been brought to Dr Starck's attention and he has offered the following comments:
"I haven't seen the full study, only the abstract, but I am certain for the reasons you mention as well as direct personal observation that the collapse of shark population on the GBR is simply untrue. While their low growth rates and reproductive capacity do make them particularly vulnerable to over fishing their populations nevertheless remain substantial around many Pacific island areas where they are subjected to much greater fishing pressure than they are on the GBR.
Estimating their actual populations would be extremely difficult and uncertain. I assume that in the case of this study some kind of underwater counts of sharks sighted was probably used. While such methods work well for most reef fishes it can be highly misleading with sharks. If you dive in an area where divers have previously been rare or absent ( i.e. a no-go zone) initial dives attract sharks. Often in such circumstances a half dozen to a dozen or more may come in and circle around shortly after you arrive. Most stay only a few minutes before moving on. If you remain in the area for a few days the number appearing when you get in drops away and after several dives you tend to see just an occasional scattered individual. Spear a struggling fish however and they quickly appear in numbers.
On frequently dived reefs most sharks simply avoid divers. They hear us and even see us beyond the limits of our ability to see them and from aerial observation I have repeatedly seen them come toward a diver and circle or veer away beyond the limit of our visibility without the diver ever being aware of them. Using underwater counts to assess populations of sharks would produce highly dubious results. Some kind of standardized and repeated baiting employing remote underwater viewing via video would yield much better results.
Unfortunately very few researchers have the depth and breadth of experience to reasonably assess what they observe in the occasional times they spend in the field. They tend to approach things with preconceived ideas which they then seek evidence to support. For both psychological and physiological reasons divers tend to be very one-track minded. They focus on what they are looking for and don't see much else. One common manifestation of this involves the discovery of new species or previously unknown behaviour of marine life. Soon after being brought to notice for the first time they are often reported soon after from numerous other areas. They were of course there all along, they were just unrecognized until attention was drawn to them.
If you start with the idea that the GBR is overfished you can always find evidence, however dubious, to support this and simply ignore everything that does not. The bottom line in this case however is that most of the GBR is rarely or never fished, there is no shark fishery, and the reefs sharks in question are in fact widely abundant. If you want to know the reality just ask any dedicated spearo or commercial line fisherman. Unfortunately in today's world direct real world knowledge and common sense has little credibility against credentialed theorizing".
Just send those researcers out to Swains( a popular fishing destination) and see how many sharks they see up in the reef. especially if you have a hot bite going on.
Plenty ,,,,, too bloody many
end of story
ITs interesting to see how they define gray reef sharks in the IUCN Red List of threatend species . Red List Category & Criteria LR/NT meaning
LOWER RISK (LR) - A taxon is Lower Risk when it has been evaluated, does not satisfy the criteria for any of the categories Critically Endangered, Endangered or Vulnerable. Taxa included in the Lower Risk category can be separated into three subcategories:
Near Threatened (nt). Taxa which do not qualify for Conservation Dependent, but which are close to qualifying for Vulnerable.
http://www.iucnredlist.org/search/details.php/39365/all
http://www.iucnredlist.org/info/cate...994#categories
One must also look at the Distribution of the species
There will be days when the fishing is better than one's most optimistic forecast, others when it is far worse. Either is a gain over just staying home.
Rando,
Yes it is rather sad that it takes a few fisherman to see the JCU study for what it is - junk science to please its funders!
All I can do is shake my head in amazement, Billfisher. Neither you, nor Dr Starck have actually read the paper, or talked to the researchers involved, yet you summarily dismiss the work. If I wasn't sure of your blind bias previously, now I am. Please note that that's not to say that your or Dr Starck's comments are incorrect, just that you automatically pre-judge if reseach disagrees with your particular narrow world-view. I looked up the researchers and they are not juniors, you may want to note that they are very experienced senior field researchers. Yet without proof, talking to them or even reading the paper (simply amazing!) you accuse them of deliberately fudging research to please their funders. Practically litigious!
Before I judge the research and researchers myself, I think I may actually read the paper and send them an e-mail. Perhaps you should do the same.
pjw,
The abstract is not likely to significantly differ from the paper as a whole. I was just responding to the original post (ie the abstract). I would be interested to see the paper if it was readily available (it would shed some light on their counting technique), but from the abstract it is very clear what they are saying.
All Dr Starck and others such as myself are saying is that their conclusions are not consistent with what is happening in the real world. Ie no recreational or commercial shark fishery on the GBR, and extremely light overall fishing pressure. Dr Starck also pointed out that counts by divers of reef sharks are likely to be inacurate and overestimate numbers on closed reefs.
We have already seen JCU studies on green zones after 2 years trumpeting huge increases in coral trout numbers being eagerly promoted by the GBRMPA and green activists. Scruitiny has shown these studies to be less than rigorous to put it mildly. So yes, you have to question the integrity and professionalism of some of these researchers.
So pjw thinks my comments are litigious. Well I think that is exactly what we need - a few well publicised court cases. So called conservation groups are allowed to lie with impunity in their campaigns for marine parks. The results have been law abiding citizens having their lives ruined by criminal convictions for fishing in the wrong place. Coastal communities have lost 100s of millions in income. Businesses and livelhoods have been lost - often without compensation. As I have been trying to point out the conservation benifits of these parks and the science behind them is highly dubious.
Pjw, we all agree that science is not perfect. The problem that is becoming more and more evident however, is that studies published from JCU of late appear to be weighted in one direction. Now I know you will say that is what the evidence points to, but on numerous occasions these studies have been found to be flawed, questionable or have conclusions drawn from guesswork. If they wish Their studies to be taken seriously, their science should equally err occasionally in the other direction, but it never does.
Unfortunately when an establishment frequently produces results like this, they start to lose their respect. It has been said before, most studies will find exactly what there writers believe.
Science should be unbiased and transparrent. Somewhere between the left and the right is the truth. I question where the balance is coming out of JCU at the moment.
This is just my opinion and not meant to be personal.
Jim
"Science should be unbiased and transparrent. Somewhere between the left and the right is the truth. I question where the balance is coming out of JCU at the moment. "
I wholly agree, and that's precisely the point I made in another thread. Note that I didn't say that I automatically agreed with the JCU research, but said that I wouldn't automatically dismiss it. On the same token, nor would I take Dr Starck's word as gospel.
The tone of the abstract, with its dire forecasts, is very similar to the Worm report pjw put up earlier (ie world fish stocks to collapse in 50 years).
These comments applied to the "Worm" report but describes these people perfectly:
At the core of the controversy is what critics call the growing "enviro-sensationalism" trend of environmental news, said Steve Ralston, senior fishery biologist with the National Oceanic and Atmospheric Administration's National Marine Fisheries Office in Santa Cruz. Ralston describes himself as "an ardent conservationist," but said he worries that public exaggerations of environmental problems erode the credibility of scientists and the conservation movement.
I'm with pjw on this one. It appears clear that Billfisher has jumped the gun and does not understand the scientific process and research. Until I see the actual article and can assess its credibility in terms of methodology used and the statistical analyses used, I reserve my judgment. Rabid rants accusing researchers of bias on the grounds of funding sources is just silly. The findings of the researchers can only be bebutted by logical critique and by showing the data collection methods were flawed or not valid for the purpose.Originally Posted by pjw200371
Brenden
Just did some checking - the original post is NOT the article abstract. Seems to be more of a press release piece. I also found out the journal that published the article is Peer-Reviewed; e.g. high credibility. The first author's email address is will.robbins@jcu.edu.au Email him and he will send you a copy of the article. Then we could have some measured discussion based on what is actually in the article and what evidence is offered to support the author's conclusions.
Yeah? What scruitiny? Where? By who?
Brenden
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