Blog about "The World's best Shark Dive" by Beqa Adventure Divers.
Featuring up to eight regular species of Sharks and over 400 different species of fish, Shark diving doesn't get any better!
(A) Map of the study location. (B) The genetic network
of adult lemon sharks. Each individual is indicated by a node labelled
by shark ID. Circles and squares indicate females and males respectively
and symbol size is indicative of the body length of the shark. Node
colour corresponds to the three defined residency groups. Dyads sharing a
first-order genetic relationship are connected by a line, with line
thickness indicating the strength of the genetic relationship
(proportional to R values). (C) Genetic degree (number of first-order
genetic relationships an individual has) distribution within the
population - click for detail!
I was somewhat underwhelmed, and said so - which led to a personal visit by the very charming Eric Clua, and to a real interesting ongoing dialogue with Johann Mourier. And despite of a toothy (!) public debate between Juerg and Jon and the authors, everybody remains on best terms and is eager to share and discuss. That's how science advances and as Eric stated, everybody agrees that nous jouons dans la même équipe and that everybody profits by sharing ideas and engaging in spirited discussions.
The feeding paper did raise the concern that the observed increased residency of some Lemons might lead to increased inbreeding - and from what I understand, this paper comes to the conclusion that it probably does not.
Whereas there are only about two dozen resident adult Lemons in Moorea, the species has evolved patterns to mitigate the according risk of inbreeding insofar as the Sharks will travel to both mate and pup (= migration), and that some individuals will travel to take residence in other islands (= dispersal), all of which is conducive to gene flow. Having said that, the degree of inbreeding of the Lemons in French Polynesia remains never the less relatively high, this likely due to small overall numbers and the relatively high isolation between islands and between archipelagos.
And the take away message after this rather epic 5y investigation?
I believe it boils down to this - and I trust that Johann will correct me if not.
Like Juerg's Fiji paper, it once again confirms that provisioned Sharks appear to disperse normally, or as Juerg puts it, that Chumming and food provisioning are unlikely
to fundamentally change movement patterns at large spatial and temporal
scales, and seem to only have a minor impact on the behaviour of large
predatory sharks; hence, the creation of behavioural effects at the
ecosystem level seems unlikely.
Obviously, this is the one aspect I'm most concerned about - and I sure hope that Johann will agree with this conclusion!
That said, Lemons are not Bulls and French Polynesia is not Fiji. There remain some local effects that are a possible cause for concern, foremost of which the observed increased residency that could eventually result in lower numbers of Lemons dispersing which in this generally small population might have a significant negative effect on gene flow and thus the fitness of that local population.
The second possibly negative effect is the observed increased aggression. I continue to question whether the observed increased brawling among male Lemons is really relevant in view of the animals' quasi magical healing powers. But what is certainly worrisome are the reports of increased strikes on humans, see the testimony by Moorea Natural Diver Lover in the comments section here. To me, they are the direct result of poor procedures, foremost of which the surface feeding mentioned here. However Johann tells me that there's only one remaining operator that feeds the Sharks, so maybe that problem has been resolved - that is, provided that the operator is taking the necessary precautions which is not necessarily a given and certainly worth keeping an eye on!
All-in-all, a really brilliant job, and big kudos to everybody involved!
Mike did not set up BAD but only became a shareholder later, after bailing them out following a shareholder dispute. And Mike did not set up the Shark dive on Shark Reef.
The dive was already in existence but the site was not protected.
Mike mediated the talks between the Fijian government and the village of Galoa that led to the establishment the SRMR, a locally managed MPA, and where BAD were simultaneously appointed as trustees and the only dive op allowed to conduct baited Shark dives there.
They are the original feeders but since then, we've trained several new feeders among which Rusi's son Mavoa and Manasa's son Tumbee.
But the gist of the story is correct! :)
But I'm digressing.
Johann is an experienced Shark diver and knows what he's talking about. Of course there are localized effects but the principal statement as I see it is
Si l'activité est bien gérée et j'insiste, si elle est bien gérée, il n'y a pas de risques majeurs pour l'homme.
Hand feeding data from the studies that have been done do not show any long-term changes in behavior. There are temporal changes in activity around feeding, but after feeding sharks appear to go back to biz as usual. I'm not an apologist for shark feeding... I remain skeptical as well. But the data to date does not appear to indicate negative behavior change IF STRINGENT PROTOCOLS ARE FOLLOWED.
Indeed!
As people are regularly and painfully reminded of, it's not WHAT you do, it's HOW you do it!
And I repeat my assertion that Shark dives may well be safer than normal dives, this because we in the industry know of the risks and are extra vigilant!
This is quite obviously something we need to explore.
We do keep a census of our Blacktips and Whitetips at the 4m feeding station but it may be interesting to compare that with an aerial survey (see some of those Sharks in the drone footage here!) and also test our hypothesis that when the tide is very low, the Blacktips retire to the back of the reef.
I found the abstract an absolute abomination of technical hieroglyphic gibberish, and said so - but it really does appear that some aspects of science remain reserved for the initiated only, as even Johann's "popularization" remains rather obscure, at least to me.
I guess the whole exercise was aimed at finding out how fast those neonate Sharks evolve from drawing energy from reserves that have been provided by their parents (in this case = from the yolk sac and later, via the placenta) and are being stored in the liver and fatty tissue, to feeding independently. And later, the same analysis could shed light on shifts in diet as they progress from neonates to juveniles to subadults to adults.
And I gather that the paper comes to the conclusion that a) those shifts happen and that b) there are, unsurprisingly, differences among species, locations and even individuals.
Following their epic dives in Tetamanu and the many experiments they have made, the team around Laurent Ballesta have published their observations about the interactions between the Grey and Whitetip Reefies when nailing that Grouper spawning aggregation.
We are pleased to share our latest paper in @ESAEcology
Using an unprecedented number of nocturnal underwater observations, we report for the 1st time an heterospecific foraging association of two shark species and describe its outcomes & benefits (1/3)https://t.co/ZAvWejMUnspic.twitter.com/QXfSllmEu1
They are just that bit bigger and bolder than the other reefies, and will thus tend to dominate any competitive exchange, much like described in this paper from Osprey Reef.
And here in the Reserve, they will equally try to dominate the other reefies during the shallow feeds, something we try and counteract by hand feeding selectively so that the Blacktip and Whitetip Reefies always get their fair share.
Turns out that contrary to being strictly confined within rather limited reef habitats, (some) Blacktip Reefs in Moorea are embarking on a rather perilous inter-island crossing to Brando's Tetiaroa in order to give birth in the nursery there - and vice versa! Is that because they were born there? Very possibly, the more as it appears that the females always visit the same nursery!
I'm literally off to DEMA so this will have to be short.
And here and here are some synopses - and since I find them partially misleading, here's what I understand.
Fakarava Atoll has two main passes, Garuae in the North and Tetamanu, where this research happened, in the South. Like in other atolls in the Tuamotu archipelago like e.g. the spectacular trou au requins in the pass of Apataki, they are home to aggregations of resident (and semi-resident) Grey Reefie comprising, if memory serves me right, adult females and numerous juveniles/subadults of both sexes. The passes are great Reef Shark habitat because the Sharks can remain quasi-stationary by lazily riding the currents whilst engaging in ram ventilation, and because especially Tetamanu with its comparatively mild currents supports a good numbers of resident Fishes and acts as a migratory corridor for other prey species that regularly enter and leave the lagoon in line with the tides and the seasons.
Yet, the researchers postulate that since the pyramid of productivity inside of Tetamanu is inverted, the available prey biomass would not be sufficient to sustain even only the local population of highly resident Sharks. This means that in order for the Sharks to be able to reside there without having to forage farther afield, their food/energy requirements would somehow need to be subsidized.
That subsidy happens over several months during the Austral Winter. Then, huge numbers of several species of bony Fish successively aggregate in the passes in order to spawn = in essence, as the prey representing the productivity of the adjacent lagoon travels to the Sharks, the Sharks don't have to travel to the prey. This opportunity attracts the majority of transient Reefies (= likely the adult males) along with the less resident ones, meaning that the Grey Reef concentration in Tetamanu nearly triples. Still, during that time, the biomass of prey is vastly larger than that of the Sharks and all Sharks have ample opportunities to feed.
Once the spawning season is over and water temperatures, and consequently, the Sharks' metabolic requirements increase, the Reefies gradually disperse again, and residency at Tetamanu decreases as even the highly resident individuals are forced to sometimes roam in search of prey.
My takeaway?
There is no inverted trophic pyramid in Fakarava Atoll. Yes in the passes there are local Shark aggregations and because of that, the trophic pyramid is locally skewed - but just like in the case of Sala's remote islands, there are external subsidies and the Sharks also roam, meaning that the relevant area one has to consider is far, far larger than the mere area of the passes. And over that whole area that comprises the lagoons but also the outer slopes, the pyramid is clearly normal as the biomass of Sharks is orders of magnitude smaller than that of lower trophic levels. Incidentally, that's not that dissimilar from our feed on Shark Reef where the astounding temporary predator biomass is in no way representative for the trophic pyramid of Beqa Lagoon let alone the whole of Fiji!
For me, these latest findings mean that until somebody comes up with solid evidence in line with the data collected by Johannet al, I will continue to call BS on Sala's hypothesis of there being inverted trophic pyramids on pristine reefs!
And yes, we need to protect the prey and not only the predators! And the prey of the prey, and the prey of the prey of the prey, etc! And the habitat they reside in! In brief, Shark conservation needs to migrate away from a focus on species towards a more holistic approach = yes healthy reefs may need Sharks, tho the evidence is scarce and increasingly contested; But Reef Sharks definitely need healthy reefs!
I've witnessed the Grouper spawning aggregation in Tetamanu ages ago and it remains one of the highlights of my diving career. Last year, a group of French and Swiss researchers and cinematographers did embark on a major mission to document the event, and this is finally the program depicting that expedition. Featuring renown marine biologist and adventurer Laurent Ballesta, it will also document a 24-hour rebreather dive at the height of the spawning cycle when the local Grey Reefies go on a rampage (and here!) among the Groupers.
This being Arte, I expect nothing short of epic - so make sure you don't miss it!
It comes to the conclusion that ecologically, provisioning can have effects at the individual, group and population level, and that those effects are generally neutral to negative.
Well what can I say - probably that's true!
It just so happens that every single one of the authors is a pal of mine - and because I know them, I also suspect that on top of the science that is probably pretty much irrefutable, the paper also has a political agenda, and that is, to obliquely address the mess that is Shark diving in French Polynesia, see the link at the top.
Now don't get me wrong here.
Shark diving in French Polynesia is nothing short of stellar.
But when it comes to the feeding dives, most local moniteurs appear to believe that they're god's gift to Shark diving, meaning that they are entirely impervious to accepting even the most common-sense advice (steel mesh gloves anybody?) - and as a consequence, bites are rife. So far, most of the accidents did involve the comparatively harmless reefies - but now that everybody and his dog is flocking to the new, completely unregulated and multi-user Tiger Shark dive just outside of Papeete, the risk profile has risen astronomically and once again, it's really only a matter of time til things will end up in tears. Same-same for the stupid idea of having snorkeling tourists hand feed the small reefies - seriously, WTF?
It's same old same old, so I'm really not gonna dwell, the more as having been there, the discourse is way too ego-driven and frankly leads to nowhere, meaning that the situation appears pretty much hopeless unless the regulator decides to finally regulate.
Hint hint! :)
But I'm digressing.
I can't really say that I love the paper because its conclusions are pretty much obvious, and because it does not really address the principal cause of most of the enumerated problems = bad procedures. As an example, the much-cited disaster at Stringray City is entirely the consequence of piss-poor management and regulations!
Anyway - worth reading!
My take-away: better procedures and more research into those possibly negative effects - pretty much done on the former (tho always learning and always adapting!), and very much working on the latter, so keep watching this space!
And one last thought if I may.
The problem is not Shark diving - not for the animals and not for the people.
Compared to the overfishing and the habitat degradation, the inconvenience caused by the industry is nothing. And yes there have been many, mostly accidental bites - but as far as I know, during literally innumerable provisioned Shark dives, there has been a grand total of ONE documented fatality. Compare that to the same time spent engaging in ordinary SCUBA and ask yourself the question, which is by far the safer activity?
Just sayin'!
So, lets please keep things in perspective - and let's also never forget to always mention the industry's enormous contribution to both conservation and research that outweighs any of those possible minor deleterious effects by far!
This is a Sicklefin Lemon - forget the fins: notice the black dot on the nose? That's how you identify them!
Check this out.
This is another real interesting interview by WhySharksMatter . David: well done & keep ‘em coming – so far, yer getting 10 out of 10!
Very cool! Monsieur Clua is of course non other that the co-author of the Moorea Lemon Shark feeding paper and consequently, I continue to sense the same anti-feeding bias. But at the same time, we learn that there are three dive ops feeding on that site, meaning that as expected, it is a multi-user site with all the resulting problems, and Johann Mourier’s answer on our Facebook stating that The feeding practices implemented by some diving center(for example feeding sharks from the surface) have led to a change in shark's behaviour, with bottom living lemons starting to come on the surface further leads me to believe that the real problem (if there is one) may well be procedures-related as I assumed in my post – and if so: everybody is herewith invited to come see what we do here, FOC, and discuss the possible implications for French Polynesia!
I actually tried to have that conversation there and although we are friends and everybody seemed interested, it was equally clear that nobody believed that the different interests would ever come around a table and agree on anything – I may add, very much like here in Fiji!
Anyway, the info about the value of Sharks was really interesting! I remember seeing a direct value of approx USD 20,000 per shark per year from the Maldives, one operator in SA reports a value of approx USD 15,000 and the value of Shark tourism to the Bahamas is apparently USD 78m per year. Now, Clua postulates USD 50,000 per Shark per year for Moorea’s Lemons which is great – and also an indication of the price level of that particular corner of paradise!
Here’s the back-of-the-envelope calculation for Fiji. We turn over FJD 1m with two boats, and it’s fair to assume that the guys down the road turn around half of that with one boat. Let’s also assume that all of it gets re-invested in Fiji, which is what we do. Add the ancillary revenues as in flights, hospitality, restaurants, cabs, excursions, souvenirs etc and assume that the ratio may well be 2:1 (it is probably higher) – makes FJD 4.5m in total which two small dive ops earn with approx 100 regular Sharks. Thus, the direct value of one of those Sharks to the Fiji economy is FJD 45,000 or USD 23,000 for every year it lives – as opposed to 300 bucks for its fins, once! Pretty darn impressive, huh!
Clua also mentions the indirect value of Sharks to the Country citing improved fisheries etc. Absolutely!
In my conversations with Government, I say this. Some Sharks (not all: some are clearly mesopredators that would wreak havoc on the lower throphic levels if their population were not held in check), notably the larger predatory ones are probably keystone species that have a profound effect on the health of the reefs, meaning that if they were removed, the reef ecosystems could well collapse.
With Fiji being an island state, it is fair to assume that the principal, if not the only reason why tourists come and visit are its pristine reefs and waters, meaning that if the reefs were to be degraded, Fiji (and French Polynesia, and the Bahamas, and the Maldives, and Palau!) could kiss their tourism industry goodbye! That’s millions upon millions of dollars, often the country’s principal sector of GDP and source of foreign exchange!
Keep this in mind next time you talk about Sharks, OK?
This is quickly turning into a marketing nightmare!
Turns out that those background Sharks are nothing but an optical illusion - because the latest, greatest, life-saving science teaches us that they simply cannot be there!
And there's more!
Since those Sharks can't see from far but only perceive things in the last few seconds before the attack, it also unequivocally follows that the infamous nikitating membrane is a) either transparent or more likely, b) never existed in the first place! Elementary my dear Watson!
Ain't science a wonderful thing!
So what about those Sea Snakes. This is obviously a bold-faced lie, and this video simply did not happen - and shame on AIMS for aiding and abetting such a shameless hoax!
At first glance, it comes across as a rather epic multidisciplinary tour the force that even includes cultural anthropology no less!
But beware - the guy is quite obviously nothing but a brazen liar and moocher who wants to make himself important and is angling for fame and possibly even royalty payments! In going with a remarkable, and equally frequent bonmot by one of the greatest luminaries in Shark conservation, one does not need a Ph.D. to figure that his story is just simply impossible because the Professor (!) has only made his groundbreaking scientific discovery now!
Elementary!
Long story short?
Buy that Shark repellent wetsuit as it will save your life - as unequivocally proven here!
Any GWS barreling up at 100 miles per hour because it has mistaken you for a Seal and wants to eat you only wants to give you a hug will immediately cease and desist, inches away, because it will realize that you're actually a venomous Sea Snake on a surf board!
I was staying at Sané and Annabelle's epic Tetamanu Village and was fortunate to catch the magic moment when the sun reflects off the Sharks on an early morning incoming tide - and for you insiders, the first two clips are from the challenging trou aux requins in Apataki.
Notice how the Sharks are barely moving?
They are literally surfing the current - and here's the according paper courtesy of Yannis, Johann, Serge, Charlieet al, inclusive of how they use a conveyor-belt positioning system to ensure that the groups remain stationary over the most advantageous spots.
And there's plenty more pictures here - notice anything?
Yes as everybody with two eyes can see, every single one of them features a dark spot on the tip of the snout. THAT, and not some equivocal falcate fins and the like is the principal physical attribute differentiating them from ordinary Lemons - and I'm yet to come across a single ID book mentioning it!
Johann - do you agree?
And what about that kink in the gills - do you see anything confirming it below? And that line originating above the gills - where does it curve down to, and why doesn't the upper Shark feature it?
Like I hinted then, the scavenging scene was staged.
The pictures above, likely screen grabs, are however most probably genuine. Johann is a very serious researcher and I am sure that he has done all the required due diligence before publishing his take.
May Monsieur Mourier have an agenda?
Check out his pre-emptive statements about Shark feeding here.
Then, compare to excerpts of this new paper he has co-authored.
Behavioural response of the sicklefin lemon shark Negaprion acutidens to underwater feeding for ecotourism purposes Eric Clua*, Nicolas Buray, Pierre Legendre, Johann Mourier, Serge Planes *Email: EricC@spc.int
ABSTRACT: The feeding of marine predators is a popular means by which tourists and tour operators can facilitate close observation and interaction with wildlife. Shark-feeding has become the most developed one around the world in spite of its controversial nature. Amongst other detrimental effects, the long-term aggregation of sharks can modify the natural behaviour of the animals, potentially increase their aggression toward humans, and favour inbreeding. During 949 diving surveys conducted over 44 months, we investigated the ecology and residence patterns of 36 photo-identified adult sicklefin lemon sharks (Negaprion acutidens). The group contained 20 females and 16 males. From this long-term survey, we identified 5 different behavioural groups that we described as “new sharks” (7), “missing sharks” (4), “resident sharks” (13), “unpredictable sharks” (5) and “ghost sharks” (7). In spite of in-and-out movements of some males and females, probably related to mating, the general trend is that residency significantly increased during the study, particularly in males, showing a risk of inbreeding due to the reduction of shark mobility. Intra and inter-specific aggression was also witnessed, leading to an increased risk of potentially severe bites on humans. Our findings suggest the need for a revision of the legal framework of the provisioning activity in French Polynesia, which could include a yearly closure period to decrease shark behavioural modifications due to long-term shark-feeding activities.
From the paper
INTRODUCTION
Large predators, which are potentially dangerous to humans and often feared, account for a substantial proportion of ecotourism activities based on animal sightings.However, because of their generally elusive nature and locally low population densities, such predators are often difficult to observe. Sharks are shy animals (Bres 1993), and provisioning is necessary to produce reliable and impressive aggregations of animals. The last decade has seen tremendous development of ecotourism based on the sighting of top marine predators (Orams 2002, Topelko & Dearden 2005). The practice of shark-feeding is widespread throughout the tropical and subtropical seas of the world, e.g. in the Bahamas, Fiji, South Africa, Australia and French Polynesia, and it is becoming controversial, with little consensus about how it should be managed.
Deliberate and long-term shark-feeding is suspected to generate problems for both animals and humans (Dobson 2006, Newsome & Rodger 2008).It may alter the natural behavioural patterns of sharks, generating biological (for the animal themselves) and ecological (for the ecosystem) effects. Provisioning may cause habituation to human contact and increase aggression towards humans by associating divers with food (Burgess 1998, Orams 2002). However, feeding wildlife can be a positive tool for assisting in the conservation of vulnerable and endangered species, through attaching economic value to wildlife and educating tourists about the need for conservation (Bookbinder et al. 1998, Halpenny 2003); it can also increase the probability of a shark encountering a partner as a result of aggregation (Orams 2002).
Despite the controversy, few, if any, comprehensive reports have measured the impact of shark-feeding, which is now widespread and growing around the world. To date, studies have been conducted on the effect of chumming on white shark Carcharodon carcharias in South Africa (Johnson & Kock 2006, Laroche et al. 2007), as well as sandbar Carcharhinus plumbeus and Galapagos C. galapagensis sharks in Hawaii (Meyer et al. 2009).These studies all concluded that moderate levels of provisioning of cage-diving ecotourism probably had a minor impact on the behaviour of the sharks and no risk of increased attacks on humans in adjacent areas.
In South Africa, Johnson & Kock (2006) showed that conditioning only arises if white sharks gain significant and predictable food rewards, which only happens if operators contravene permit regulations prohibiting intentional feeding of sharks.White sharks are lured to the boat with baits (typically, mashed sardines and fish oil; Laroche et al. 2007) that are significantly different from their usual prey in the area, Cape fur seals Arctocephalus pusillus pusillus (Ferreira & Ferreira 1996).
In Hawaii, Meyer et al. (2009) showed that cage-diving activities did not increase the number of attacks on humans, probably due to the fact that the shark tours use a small amount of fish scraps, mimicking the activities of crab fishing vessels which have been operating in the same area for over 40 yr. In both cases, while some food is used to attract sharks to the cages for observation and photography, the quantities involved are small, so this activity cannot be considered as real ‘provisioning’.
Light baiting is also used at Aliwal Shoal (South Africa) for attracting tiger sharks Galeocerdo cuvier and allowing encounters with snorkelers in open water (Dicken & Hosking 2009).
However, the available scientific data focus on the economic value of the recreational activity, and do not address its effects on the behaviour of these potentially dangerous sharks (ISAF 2010).Bull sharks Carcharhinus leucas, another dangerous species (ISAF 2010), have been attracted to an ecotourism site in Beqa (Fiji Islands) since 2002 through a real feeding and conditioning process based on the release of several tuna heads during each dive (E. Clua pers. obs.); here again, however, the only data provided are socio-economic (Brunnschweiler 2010), with no reference to the biological issues of provisioning of carnivorous animals.
Given the controversial nature of shark-feeding, there is a critical need for empirical studies that focus on potentially dangerous sharks, and address both the potential disruption of their natural behaviour, which underpins their resilience, and the increasing risk of fatal attacks on humans (Garrod & Wilson 2006).
In French Polynesia, sharks are fed daily during diving activities.The main species involved, the sicklefin lemon shark Negaprion acutidens, can reach over 3 m in length and is considered to be potentially dangerous to humans (Maillaud & Van Grevelynghe 2005, ISAF 2010). This coastal shark is widely distributed in the Indo-Pacific, from Eastern Africa to French Polynesia. However, very little is known about the ecology of the sicklefin lemon shark in the Central Pacific. Despite its commercial value (Compagno 1984), only a few studies have been conducted in the Indian Ocean (Stevens 1984) and in Western Australia (White et al. 2004) besides a recent global genetic study (Schultz et al. 2008). The ecology of its sister species, the Atlantic lemon shark N. brevirostris, has been well documented during past decades (Gruber 1982, Chapman et al. 2009), mostly in the central Western Atlantic Ocean. However, while its early life has been extensively studied (Morrissey & Gruber 1993, DiBattista et al. 2007), very little is known about the adult stages of N. brevirostris and even less about N. acutidens.
Moorea Island (French Polynesia) is among the few locations worldwide where it is possible and feasible to have daily encounters with several wild adult sicklefin lemon sharks in their natural environment. This characteristic provided us with an opportunity to investigate the behaviour and residency pattern of an adult population of this reef shark species through daily underwater observations at a provisioning tourism location. Here, we describe the population size and structure of this species, aggregated for ecotourism purposes at a site on the northern outer reef of Moorea Island. We divided the population into co-occurrence groups and describe the residence patterns and behaviour of these groups. We also tested the hypothesis that shark-feeding increases the fidelity of lemon sharks to the site, and discuss the potential long-term effects on population resilience and behaviour, including the risk of increased interactions with humans. From the
DISCUSSION
….Assuming similarity in the natural behaviour of these 2 sister species (Editor: Common and Sicklefin Lemon Sharks), our findings could be linked to an aggregating effect of shark-feeding, which decreases the mobility of animals, mainly the males, and may contribute to increased inbreeding. This trend may lead to long-term loss of genetic variability in the Polynesian lemon shark populations, even though natural philopatry in N. acutidens, which would have been a detrimental factor, seems to be low (Schultz et al. 2008).
Increasing residency was a general trend for the shark population. For all groups except Group B, which was composed of animals that disappeared, the linear regressions had positive slopes (Fig. 4), indicating an increase in shark abundance over time, and their site fidelity increased over the 44 mo, particularly for the ‘resident’ subgroups, C1 and C2 (Table 1). This means that, despite some sharks leaving and othersarriving, the number of days with sharks present and the number of sharks at the site both increased. This trend is explained by the increased attraction of sharks by provisioning, suggesting that learning plays a strong role in optimising their food search (Guttridge et al. 2009). Our findings are consistent with similar situations where other elasmobranchs (rays) learned to associate specific locations with food rewards, with detrimental effects on their behaviour, and indirect effects on the surrounding marine ecosystems, leading to the concept of an ‘ecological trap’ (Corcoran 2006, Gaspar et al. 2008, Semeniuk & Rothley 2008).
In the case of lemon sharks, their increased site fidelity can have a negative effect on gene flow, as mentioned previously, and can also affect their role as top predators in the area, as shown for top terrestrial predators such as dragons Varanus komodoensis in the Komodo National Park, where provisioning was eventually banned (Walpole 2001).
Among the negative effects, we observed intraspecific interactions generated by the provision of a limited amount of food. Not all sharks present during a dive acquired food, and this resulted in exacerbated competition among the animals. This pattern can lead to increasing the number of intraspecific dominance actions and the aggression of sharks to acquire food (Ritter 2001), as shown for rays (Semeniuk & Rothley 2008). Dominance is often driven by the size (length) of the sharks in social groups (Allee & Dickinson 1954, Myrberg & Gruber 1974). During several feeding sessions, the largest resident male, M04, appeared to be the most inquisitive, approaching the divers closer than any other individual did. Since males M07 and M18 were dominant in 2005, M04 definitely acquired increasing dominance behaviour with respect to other individuals, which turned into deliberate aggression towards other males when several of them were present.As was previously observed in 2005 for its 2 predecessors, from 2006 onwards M04 often arrived in the morning with fresh scars or notches that can be attributed to intraspecific fights (N. Buray pers. obs.). Aggression increased significantly when resident males came back to the feeding site after the mating period, probably in the context of a reorganisation of the hierarchy, as shown by serious wounds on males that were quite different in their severity and locations from those inflicted on females during mating (Fig. 5).
In natural conditions, sicklefin lemon sharks cannot be considered a gregarious species (Stevens 1984), except during the mating period, and animals usually feed separately.Therefore, intraspecific aggression linked to the feeding process, even though natural among carnivorous animals, can be interpreted as deviant behaviour, exacerbated by human activity.Although managers may consider this process of increasing intraspecific aggression to be acceptable among sharks, it represents a real issue regarding the safety of divers for whom the risk of accidental bites has increased critically (Burgess 1998).Between 1979 and 2001, 47% of shark bites in French Polynesia were experienced in the context of shark-feeding activities (Maillaud & Van Grevelynghe 2005). Although anecdotal, this was confirmed by a serious bite by shark M04 on the left hand, which was not holding any food, of the diver doing the feeding in January 2006 (N. Buray pers. obs.).
The results of this study indicate that in spite of the provisioning activity, several male and female sicklefin sharks seem to have left the study site while others came back to it for mating.This positive aspect from the perspective of maintaining gene flow between this shark population and adjacent ones is mitigated by the increasing pattern of residency for the overall population during the study. At present, the population seems to be a balanced mix of resident and non-resident individuals, which favours population mixing. However, if the resident sharks increase their numbers and their attachment to the feeding site, group living can generate costs for animals which are normally solitary foragers, such as injuries, predation, increased stress hormone levels and exposure to parasites due to increased transmission rates between individuals (Semeniuk & Rothley 2008).If supplemental feeding can be perceived as an artificial support to sharks by providing easy-to-access resources (Milazzo et al. 2006, Laroche et al. 2007), and can allow increasing energy allocation to other fitness-related activities such as rest and reproduction (Orams 2002), long-term unnatural aggregation can also have long-term fitness consequences for the population. Because the studied population is small, daily aggregations at the same location could result in increased social interactions and increased mating between close relatives, reinforcing the risk of inbreeding. As lemon sharks are known for their polyandry (Feldheim et al. 2004), the potential negative effect on gene flow linked to the increasing residency pattern might be buffered by the multiple paternity process; this needs to be thoroughly monitored.
This factor, added to the development of aggression and incremental risk of accidental bites to divers, should lead managers to seriously consider a revision of the regulations on shark-feeding in French Polynesia in order to reduce these risks.An annual cessation of the feeding activity for several months, preferably encompassing the mating period, is an obvious solution.Whereas our study allowed us to draw these preliminary conclusions, additional field investigations are required to better understand the long-term effects of provisioning on shark populations. Further work may also enable us to better understand the risks induced by feeding predators.
Hmmmmmm…
Quick ‘n dirty assessment: interesting - but both prejudiced and highly speculative!
But first things first: this is what I like.
Scientists are finally discovering the Shark feeding industry and publishing a first set of baseline studies, of which this is a (I believe: rather poor) example. And although I do not concur with the conclusions, see below, I do commend the authors for having taken the time to compile and analyze a long term set of data. As the always brilliant CJA Bradshaw remarks, monitoring has long been the ugly cousin of the fashionable experimenting and is only now being recognized as an invaluable tool for trying to decipher complex systems where causal relationships are not immediate and thus difficult to manipulate selectively.
Which brings me straight to my principal critique.
Where is the control group, as in a comparable group of Lemons that are not being fed? If they got nothing to compare them to: how can the authors postulate that any of the described phenomena are caused directly by the human interference and not due to chance variability, or to natural fluctuations in population, or to climate fluctuations like ENSO or the like?
But let’s quickly examine the allegations.
The observed increased residency may lead to reduced gene flow and inbreeding.
Indeed, maybe! But many Shark species, among which Lemons, do wander off during mating season and indeed, so did the studied animals! The increased residency during the remainder of the year is utterly irrelevant in terms of gene flow as the animals do not mate during that time – or are we to believe that Lemon Sharks may engage in protracted dating prior to having sex?
Plus – was the increased residency the direct consequence of the feeding, see above?
Increased intra-specific aggression.
Here, the authors blame the limited amount of food leading to exarcerbated competition; and on the other hand, they seem to postulate (?) that a higher concentration of resident Sharks led to more hierarchical fights and subsequent wounds in males.
Probably! But having witnessed how fast Sharks recover from horrific wounds contracted during the mating season, what is the point? Did any of the bitten Sharks die or end up being permanently inconvenienced as a consequence - and how does that compare to the “natural” mortality and/or bite frequency of non fed Lemon Sharks?
Plus, what’s that tale about M04? M04 often arrived in the morning with fresh scars or notches (that were hence not contracted during feeding time!) that can be attributed to intraspecific fights (N. Buray pers. obs.). Interesting – but is it science?
Knowing that all individual Sharks have different characters: was he maybe just a notorious brawler – and not a very successful one since it was him, the supposedly dominant Shark, coming back with those wounds and not his assumed victims? And who did he brawl with: females or males?
Increased inter-specific aggression - what is the other species: humans?
If so, we learn that 47% of shark bites in French Polynesia occur during Shark feeds and that M04 bit a feeder in the hand. Both, we learn, prove that the risk of accidental bites has increased critically.
Well, gee, what a mind-boggling insight! Tremendous development of shark dives is leading to more bites!
I’ve blogged about it in extensohere and don’t need to repeat myself more than that: the precondition for a Shark bite is that a human and a Shark be in the same place at the same time (hellooooo…) and thus, feeding sharks does indeed increase the risk of getting bitten and more Shark feeds will indeed lead to more bites!
This is so trivial, it is painful!
By the same token, the act of commuting in aeroplanes increases the risk of fatal plane crashes - yes, believe it or not: it does!!!
So going back to square one: do we prohibit aviation as a consequence? No, we ask that anybody engaging in the activity, especially commercially, follow a regimen of strict safety protocols!
Right?
Now, it just so happen that I’ve done a multitude of Shark dives in French Polynesia.
Many of them were Shark feeds with mainly Greys and Silvertips - and yes, I’ve also witnessed several of the Moorea Lemon Shark feeds.
Any Shark bites?
Certainly: four of them, one by a Silvertip and three by Grey Reefs!
The cause: multi-user sites combined with Gallic panache and improvisation: poor Shark diving briefings leading to unpredictable behavior of the clients, ever changing procedures and feeders, creative chaos and heaps of bravado, zero protection of the feeders and clients alike – in brief, the recipe for certain disaster!
With that in mind, the described bite comes at no surprise whatsoever!
BUT!
Was that bite by M04 really aggression – and if so, due to what? Did the behavior of the feeder piss off the Shark? Did the Shark mistake him for a competitor? Is aggression really the most plausible explanation?
Here in Fiji, all of our clients have to wear dark gloves. The reason is that anybody without gloves will get nailed by the ever greedy Giant Trevally and Red Bass who mistake the pasty hands sticking out of dark wetsuits for bait. This is not aggression, this is a mistake!
Would it not be much more plausible to assume that M04 might have made the exact same mistake when in a hurry due to a competitive situation?
Bull Sharks are not Sicklefin Lemons and anybody who knows about Sharks knows that different Shark species have very different behavioral traits and that one cannot make generic statements across species - and certainly not make comparisons to, of all animals, Komodo Dragons!
Keeping in mind the above caveat, this is what we do in Fiji in order to increase the safety of everybody:
- This is a one operator site, meaning that we can enforce a uniform protocol that is always highly predictable – for the animals, not us!
- By the same token, the people feeding are always the same, to the point that they have developed personal relationships with individual Sharks
- Feeders wear chain mail gloves and clients, full body dark wetsuits and black gloves
- There is separation between the large Bull Sharks and the customers (remember the precondition above!)
- There are extensive dive briefings so that the clients know exactly how to behave and don’t startle the animals
- There is ample food and the animals are conditioned to follow a set routine, meaning that we are trying to minimize competitive pressure. We also always control the amount of food being introduced, meaning that when we sense any incipient tension, we can discontinue the feed and wait until everybody has calmed down again.
Could some of it be replicated in Moorea! Sure!
Long story short: the obvious solutionis not the annual cessation of the feeding activity for several months that implies the necessity to re-establish the feed, the relationships and the training of the animals - it is to improve the feeding protocols!
As to the other grievances about inbreeding and intra-specific aggression: not with our Bulls!
We’ve been keeping highly detailed tabs for 7 years now and none of the Bulls has taken up residency, let alone established a territory necessitating defense against conspecifics.
Instead, although the numbers continue to increase, we’re being faced with a continuous rotation of individuals who clearly lead a free life and are not dependent on Shark Reef for sustenance. Plus, they all vanish during the mating season which is a good indication for them doing plenty of walkabout and mixing of gene pools once they get horny!
The tally:
Bulls biting feeders: zero;
Bulls biting clients: zero;
Bulls biting Bulls: one documented case (we always have at least one camera rolling) where two homed in on a Tuna head and one very obviously missed the head and bit the other – yes, camera rolling! We have certainly never witnessed a single case of a Bull Shark resorting to biting in order to assert its dominance, and this in thousands of Shark dives – but then again, it’s a different species.
Fatalities among our 100 individually named animals, of a total of approx 300: only Jaws who has been missing since 2006.
All others are friendly, well fed and above all, locally protected - and I believe, perfectly happy!
Hence, what is the relevance of this paper to what we do and to Shark feeding in general?
You be the judge of that.
Finally protected - Shortfin Mako, stellar pic by Ozzie Sam!
Bloody excellent news!
After protecting all Sharks but the Shortfin (not the Longfin) Mako in 2006, French Polynesia has just abolished that exception. Not that it really matters: but with slightly less than 5million square kilometers, this may well be the world's largest Shark sanctuary.
It did generate a spirited debate where I once again reiterated my personal distaste for the all-pervasive duplication and lack of coordination in Shark research, and the resulting frustration of both the donors and the divers alike. Once again, the gist of my post is not that I believe that Ryan's initiative is a bad thing in itself - what I bemoan is that lacking the necessary coordination with other data bases, it further fragments the global effort which ultimately leads to worse, not better science.
Now Christine has attempted to chime in, but her comment was truncated due to the space limitations of the comments section of Blogger.
Here it is in its entirety.
Hi all,
A few comments from my experience…
If people are taking their (limited) time to submit data, the goal should be to get as much useful information efficiently. In 2004, I started collecting a lot of information, but quickly found that there were too many missing records for many of the variables that were being collected, such as sex, behaviour, habitat, depth, etc. Generally, if a question will generate >5% missing data then it is removed from the analysis and therefore a waste of time to collect in the first place. Data for data sake is not my goal. People are busy and donating their time, so I only aim to collect data that I can use.
To reiterate Mike’s point, I think we can safely move beyond collecting data on single species groups, such as sharks. I started with just sharks and rays as proof that recreational divers could provide useful data that the scientific community and governments would accept and use to inform conservation and management strategies. And they have! I was told that the results of the eManta_eShark survey (paper was in review at the time) were used in back room conversations at CITES COP 2013 and were influential for at least 2 countries in voting to list mantas on Appendix II. Similarly, the Bahamas protected their sharks following a paper that was published in 2010 that used the REEF.org data – recreational diver generated dataset - which showed the uniqueness of the Bahamas shark populations. Note: The REEF.org dataset is the most valuable dataset that I use and I could not do my work without it. It is the template that I used to create eShark and allows me to fill the gap that Johann M identifies, which is the accuracy of reports. However…
I think we – those coming from the scientific side of things - need to be careful not to suggest that scientific divers are perfect, or that recreational divers are not good at identification. Way back when, when I started this work, many scientists said I couldn’t use recreational diver data because they couldn’t identify/count them properly …something about them “worrying about keeping their masks on their face”, which is so ridiculous in my opinion. So, I tested the shark scientists, fish biologists, recreational divers, and the general public on their shark identification abilities – covering people from around the world. Let's just say that the only person that got 100% on the test had never dived in their life and was only half way through their undergraduate degree - she just loved sharks. In fact, throughout my interviews, I have been amazed at the accuracy of not only the identifications (photo verification), but of people’s memories. Many people have photos that correspond with their observations. I’ve used these dated photos to verify memory accuracy. Especially for the rare observations, some people could remember the exact month when an observation took place more than 5 years earlier. However, I always err on the side of my memory ability, which is really not very good. These inaccuracies, whether by recreational divers, dive masters/instructors or scientists, can be managed with good survey design, reasonable assumptions, awareness of limitations and responsible analysis.
When (the late) Ransom Myers and I developed the idea of using divers to census shark and ray populations, an important first step was to ask the dive community about potential concerns for data. I specifically asked this question when I was at DEMA and ADEX with Project Aware, which enabled me to cover a wide variety of perspectives and regions of the world. The most important concern raised was that I was creating a dataset that included the location of species that were vulnerable/endangered and still targeted. So, although I think scientists should be open to collaboration, and I certainly am, I think it is irresponsible to make these data freely available or open source and I think we need to be careful who we share it with. To get around this, I provide data summaries to different people or groups that request it - e.g., I give (almost) monthly summaries to Shark Guardian on their progress in Thailand - and have contributed data to OBIS, which is open source, but the data are shared according to OBIS recommendations for sensitive species (10x10 degree cells - you can't even tell what country they are in!) so that the lat/lon and seasonality cannot be used by people that aim to do harm to these populations.
I agree with you Mike – more collaboration would be valuable. I am always on the lookout for other groups that share the my mission and are aligned with eShark. There are a few, including REEF.org, eBird.org, Marine Debris Tracker, and Redmap –Australia that are great and run by very good scientists that know how to use the data. Three of these I featured on eOceans.org for an Oceans Day event in 2014. I didn’t have time to organize this event again this year…
I am encouraged by the number of different citizen science surveys now available – we have come a long way since those naysayers of 2004, some of which have actually gone on to create their own diver surveys now! But I do appreciate and share Mike’s comments and concerns about diluting and frustrating the people that want to contribute in the best way they can. Of course people cannot contribute to all the existing surveys – I can barely keep track of them all at this stage.
The advice I have for potential contributors is to look at the goals and results of the organization running the survey and ask:
i) Do they have publications to support their motivation to collect the data?
ii) Do they have the scientific and statistical expertise to use the data?
iii) Do they specifically state who will use the data, or do they just generally say ‘collecting for science’?
iv) Does the organization intend to use the data responsibly and keep it protected from people that may wish to exploit it, or do they have it open source/freely available?
I personally value locally collected data that feeds into a larger picture, which is why Shark Guardian and the Great Fiji Shark Count are so effective and both received awards from Project Aware for their efforts.
Case in point, this article about the research by Cécile Berthe who confirms that the Eagle Ray of French Polynesia is not the Spotted Eagle Ray Aetobatus narinari but the Whitespotted Eagle RayAetobatus ocellatus. And with the Marquesas being so far east and featuring a scenery and fauna that are reminiscent of the Western coast of the Americas, it is quite possible that they may be also harboring one more cryptic species, i.e. the Pacific Whitespotted Eagle RayAetobatus laticeps that is found in Baja!
Those Eagle Rays can be reliably seen in Rangiroa in Dec/Jan.
That's when they form large mating aggregations, see at top, that are in turn stalked by ginormous but very shy Great Hammers. And, it's bloody deep, at least (!) 40m but in crystal clear viz on the incoming currents - and then you'll have to negotiate the ripping current in the pass, quite possibly whilst managing multiple decompression stops!
Here in Fiji we may be possibly witnessing something similar - at least, that is our working hypothesis although we're still debating about how to test it. Maybe you remember this paper, and this picture.
It is an old graph of Bull Shark sightings.
In essence, it shows how the Bulls disappear at year end for pupping and mating, and how they then return for the Running of the Bulls in late December/January.
But there's also another detail - see it?
Every March/April, an this usually around the Full Moon, we get a notable temporary dip in the number of Bull Sharks. Our hypothesis is that they are being drawn away by some event that is likely linked to predation - and it just so happens that many Fishes like incidentally those Surgeonfish form spawning aggregations around the Full Moon, this because the associated strong tides favor maximum dispersion of the fertilized eggs.
Obviously, so far, this is only a correlation and thus merely speculative - but it is a testable hypothesis and if certain things come to pass like we plan them to, we may soon be nearer to solving that riddle!
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