It really sucks doesn't it.
As a reminder and despite of our very best efforts, most marine species are still faring better - at least for now, tho for some cetaceans with limited geographical distribution, the writing is clearly on the wall.
Showing posts with label Extinction. Show all posts
Showing posts with label Extinction. Show all posts
Sunday, August 11, 2019
Monday, January 01, 2018
Thursday, February 16, 2017
Anthropocene Defaunation - Papers!
Did you know? Click for detail. Source.
Very disheartening.
Remember these posts?
Back then I was more optimistic - and now, a tad less.
This remarkable paper analyzes the patterns of global defaunation (extinctions and decline in abundance of individuals within populations), and the findings are depressing indeed. Couple that with this analysis of the particular vulnerability of large animals (paper here), and the future looks grim = e.g., I'm personally convinced that any large animal living in Africa is essentially toast.
CNN interactive exposé here.
CNN interactive exposé here.
And the Sharks?
The oceans are a very large piece of real estate, and methinks there still is hope - tho time is definitely of the essence.
Anyway, essential reading.
And the bloody conservation drudgery continues.
Tuesday, June 03, 2014
Saturday, December 11, 2010
About Shark Attacks
Undoubtedly, one of the Mossad Sharks!Time for a preliminary post mortem.
Like everybody interested in Sharks, I’ve been closely following the news tidbits trickling out from Sharm El Sheikh and the various opines in the media and the blogosphere.
There’s much of the usual fluff and idiocy - but there’s also some stellar stuff.
Take the “experts”. Whilst many prate and pontificate, I found this remarkable interview with Avi Baranes. Now THIS is the kind of person you gotta consult, a highly reputable Shark researcher who has been investigating those very waters for a very long time – and accordingly, the interview brims with factual information and quietly addresses and dispels the usual myths. Bravo!
Equally noteworthy are the posts by Richard, by the SOSF and by Michael Scholl - however with some caveats that I’d like to address below.
The way I see it, in this specific case, one needs to try and answer the following queries
Whilst the mainstream media revel in the image that all Sharks are indiscriminate man hunting killers, the pro-Shark faction claims the exact opposite, that Sharks never prey on humans and that all attacks are the result of mere investigation or mistakes.
Both I believe are wrong.
Shark attacks can be defined as incidences where Sharks bite people.
The term thus covers a very wide spectrum of species, behaviors, motivations, triggers etc and any generalizations will inevitably lead to mistakes – thus, please correct me if you think I’m wrong!
Also, barring a personal interview with the perpetrators, the exact causes for these specific attacks will never be known, so whatever conclusions will emerge will only be (hopefully) plausible but ultimately always untestable hypotheses.
In very general terms, Shark attacks can be divided into the following categories.
1. Attacks associated with feeding events, i.e. predation and scavenging.
The most notorious species implicated in this category of attacks are the large predatory Sharks Great White, Tiger, Bull and Oceanic Whitetip.
Whilst large adult GWs appear to be specialist hunters of mammal blubber, the other species are generalists with a broad spectrum of prey and consequently, hunting techniques. It should thus not come as a surprise that the track record here is unequivocal: these Sharks will sometimes attack and prey on humans!
Granted, these events are exceedingly rare.
It is obvious that humans are not the primary prey of any Shark species and let me spare you the long winded and pathetically trivial explanations as to why evolution could not possibly have selected for it. Also, granted, sometimes the Sharks appear not to like (whatever that may mean) what they have attacked and either spit it back out or not bother to come back to completely consume the meal. In GWs, this may be linked to the fact that we may indeed be too lean for a specialized hunter of blubber. In other species, it may be an indication of the fact that the Shark was not very hungry, or that something disturbed it whilst it may have hung off waiting for the victim to stop struggling.
But when limbs go missing and Sharks hang on, those are predatory attacks, period!
Which brings me straight over to the whitewashing.
Yes we love Sharks, yes Sharks are much maligned and we need to work at improving their reputation: but the fact is that large predatory Sharks are dangerous and that they need to be treated with respect and with circumspection!
That makes them neither bad, nor good – that just makes them large predatory Sharks! I’ve said it before – we need to remain fact based and refrain from creating our own unhelpful stereotypes!
The common pattern of predatory Shark attack has been called Sneak Attack whereby a Shark suddenly turns up (in fact, many survivors claim that they never saw the Shark prior to the attack) and persistently attacks, very much like what happened in Sharm is being described. This is not surprising and only consistent with most attacks by terrestrial predators who relay on the element of surprise in order to approach their prey.
Great Whites sometimes attack Seals and Sea Lions which are close to the surface by sneaking up close to the bottom and then attacking more or less vertically at high speed, resulting in the much publicized predatory breaches.
Some surfers have been attacked in the same way, leading John McCosker to develop the hypothesis of Mistaken Identity, meaning that the GWs attacking a silhouette at high speed may have mistaken a surfer for a Pinniped, especially in murky water. This is certainly plausible, the more as GW are being routinely induced to attack decoys in the same manner.
BUT: this is strictly GW lingo!
This cannNOT just simply be applied to other species! Specifically, this is not how Tigers prey on Turtles (and no film maker goes potting around Hawaii towing Turtle decoys) and it does not apply to each and every “mistake” a Shark may make! Thus, asserting that most Shark attacks are due to Mistaken Identity is a fallacy and as such, nothing more than pseudo-science!
The same applies to Investigative Bites.
Once again, this is GW lingo, as Great Whites are known to test objects and people by (more or less, see Rodney Fox) gently nibbling at them. Rather than being a strictly predatory behavior, this is probably linked to testing food when scavenging and may, or may not result in subsequent feeding.
Other species known to investigate people, snorkelers and divers alike, by mouthing are Tigers and I hear, Lemons – yes, as in TB!
Not Oceanic Whitetips!
They are the picture child for investigation via bumping. They will circle ever closer, the frequency of bumps will increase and if not countered vigorously or if the affected person does not leave the water, this will likely result in a predatory attack, sometimes referred to as Bump and Bite attack. Check out the video here: this is typical behavior and it is pretty obvious that this Shark would not suddenly slow down to apply a gentle test bite! The same apparently applies to Bull Sharks.
Of note, this is different from the ramming with snout mentioned in Martin 2007 that is related to aggression, not predation. Incidentally, Martin does not cite ramming with snout as an agonistic display in OWTs, a further confirmation that in this species, that behavior is linked to predation!
Once again, attributing Investigative Bites to species other that GWs, Tigers and maybe Lemons is mere whitewashing and pseudo-science! It also looks like an attempt to exonerate the Shark from having had bad intentions or the like, something that I find rather peculiar to say the least!
2. Attacks associated with self defense
You may want to go and re-read this: several species of Sharks display behavior that is called agonistic and is linked to self defense. Failure to identify and adequately react to that behavior may lead to what are generally open-mouthed, slashing bites that result in cuts rather than missing tissue.
Attacks on surfers and bathers by small piscivorous Sharks like Blacktips and Spinners (see Volusia County) or the frequent nips on the feet of waders by subadult Blacktip Reef Sharks are commontly referred to as Hit & Run attacks and generally result in mere harmless cuts. They, too, are believed to be the result of self defense as the Sharks may simply have been startled and may have wanted to fend off a perceived attack, or may have previously displayed agonistic behavior that was never noticed by the victims.
These are, by far, the most frequent Shark attacks on people.
Finally, there are the Provoked Attacks, where the people have touched the Sharks, as in the retaliatory bites by Wobbegongs and Nurses that get dragged out from their covers by the tails.
3. Attacks associated with competition
Typically associated with spear fishing, Sharks may bite people when competing for the speared fish. These attacks are thus not aimed at preying on the person but rather, at chasing away a perceived competitor.
Incidentally, the same happens between different Shark species (but apparently not between individuals of the same species): I’ve personally witnessed a Silvertip biting a Nurse to dislodge him from some bait, and filmed one of our Bulls biting away a Lemon who wanted to approach a feeder.
Consequently, when referring to site fidelity in Sharks, one should always talk about residency as opposed to territoriality. The latter implies defense against conspecifics, a behavior that has been observed in many Fishes but apparently, never in any species of Shark!
This is again different from aggression associated with rank.
Sharks do display behavior that may be interpreted as “posturing” and there are even anecdotal accounts of actual bites on conspecifics in the context of social interactions.
Yes, it’s complicated!
4. Attacks associated with mistakes
Sharks make mistakes.
Considering the impressive array of senses they dispose of, this may seem surprising: and yet, they hunt, attack and bite a vast array of objects like boat propellers, metallic structures, decoys, and ingest completely inedible items like the famous number plates and car tires - and most often and fatally, they will be fooled by fishing bait and lures!
Mistaken attacks on humans are mostly associated with Shark feeding and baiting.
Many species of Sharks (and Fish!) are highly competitive and uncontrolled Shark feeding events can quickly develop into Feeding Frenzies where the animals get highly agitated and may end up biting other Sharks or the human spectators by mistake. Equally, Sharks may accidentally bite the feeders’ hands during hand feeding shows, etc.
Again, these are genuine mistakes and neither competitive nor predatory in nature – the latter much contrary to the opinion of the anti-feeding lobby.
Talking of which, you may want to check out these latest statements by Burgess: apparently, the perpetrator of at least two attacks is one and the same Shark! Amazing!
Plus, there’s this: "These are open-ocean sharks that are living in an environment that is food-poor," says Burgess. "So when you do find food, you darn well better take advantage of it. Do they remember things? Sure, they remember where the good places to eat were, and they'll come back." Surprise surprise: I happen to totally agree - re-read this! But... Sharks that may have been conditioned to come and feed on Tuna heads learn to… feed on Tuna heads! Not humans!
There you have it I believe - and again, if I'm factually wrong, feel free to correct me!
Long story short: if we want to be credible Shark advocates, we got to do our homework and first of all, be informed about the animals we love!
Science is always in flux and today’s insights may quickly become tomorrow’s fallacies, meaning that we must keep abreast of the latest research results and not base our knowledge on old publications and approximate hearsay. Most importantly, we the amateur naturalists should never make up things on the fly, nor should we idly re-interpret what is considered to be the accepted consensus.
This does not mean that we should not challenge the current status quo, as that is precisely the process by which knowledge is being advanced!
BUT: the only accepted technique for doing so is the Scientific Method and as always, let me warn against the siren calls and intellectual shortcuts of the self promoters, quacks and charlatans!
All researchers I’ve ever met have always been eager to engage in informed discussions and to entertain different hypotheses, if adequately supported by according observations. Those researchers are not omniscient and also, not omnipresent and often, observations by common mortals like us have greatly contributed to the advancement of scientific insights - so even if you have no academic background, don’t be shy and speak up!
But do your home work first!
In diesem Sinne!
PS read this brand new report - so, how do you interpret it? :)
Like everybody interested in Sharks, I’ve been closely following the news tidbits trickling out from Sharm El Sheikh and the various opines in the media and the blogosphere.
There’s much of the usual fluff and idiocy - but there’s also some stellar stuff.
Take the “experts”. Whilst many prate and pontificate, I found this remarkable interview with Avi Baranes. Now THIS is the kind of person you gotta consult, a highly reputable Shark researcher who has been investigating those very waters for a very long time – and accordingly, the interview brims with factual information and quietly addresses and dispels the usual myths. Bravo!
Equally noteworthy are the posts by Richard, by the SOSF and by Michael Scholl - however with some caveats that I’d like to address below.
The way I see it, in this specific case, one needs to try and answer the following queries
- What species are involved. Apparently, the species implicated are Oceanic Whitetip(s) and Mako, both pelagic as opposed to coastal species, which is certainly surprising. I’m particularly surprised to hear about the Mako, because this is very much a specialist predator of fast pelagic Fishes like Tuna and Billfishes, features a very specialized dentition aimed at grabbing rather than cutting, and is exceedingly rarely implicated in attacks on humans. OWTs on the other hand appear to have a much broader feeding spectrum and have the typical generalist dentition of “grabbers” in the lower jaw and “cutters” in the upper jaw, like the equally pelagic and generalist Blues and most Carcharhinids in general. Consequently, OWTs (not Makos) are frequently found feeding on floating carcasses, mainly of cetaceans, where they are able to cut out chunks of meat. They have a well deserved reputation for being highly inquisitive to the point of chasing people out of the water, and have been implicated in a plethora of attacks mainly on shipwreck victims.
- What induced those pelagic Sharks to come close to that coast where the attacks happened. In the Red Sea, OWTs are normally regularly sighted hundreds of miles further south and I would have expected them to move north, if at all, following their preferred temperature gradient, often in line with migrations of their habitual pelagic prey. Yes they are also known to follow ships but with the above in mind, my gut tells me that the most likely explanation might be environmental, as in weather/temperature/currents/movements of prey rather than the much cited paucity of natural food due to overfishing or selected anthropogenic interventions like chumming and baiting that would only draw in Sharks from a much smaller radius. Of note, the cited dumping of sheep carcasses happened at the end of September and cannot be credibly considered to be causal for events occurring in December.
- The cause for the attacks, and their interpretation. This may sound trivial but to me, the immediate causes are obviously location, opportunity and stimulus. Firstly, it has to be noted that the coastline drops off precipitously, meaning that snorkelers and swimmers venturing away from shore quickly find themselves in very deep water indeed. Secondly and due to the massive increase of the local tourism infrastructure, the ocean is teeming with aquatic recreationists, greatly increasing the chances for such an encounter. Thirdly, people splish-splashing at the surface send out the exact stimuli that predatory Sharks will consider worth investigating. As to the interpretation of what happened once the Sharks encountered the victims, see below.
- What can be done so that this will never ever happen again. Barring the complete prohibition to swim and snorkel, or the complete fencing off of areas where people swim and snorkel: nothing at all! As long as people will frequent the Ocean and Sharks will hopefully exist, occasional attacks will continue to occur - but one can certainly minimize the risk by following a set of sensible recommendations, the first one being don't be stupid!
Whilst the mainstream media revel in the image that all Sharks are indiscriminate man hunting killers, the pro-Shark faction claims the exact opposite, that Sharks never prey on humans and that all attacks are the result of mere investigation or mistakes.
Both I believe are wrong.
Shark attacks can be defined as incidences where Sharks bite people.
The term thus covers a very wide spectrum of species, behaviors, motivations, triggers etc and any generalizations will inevitably lead to mistakes – thus, please correct me if you think I’m wrong!
Also, barring a personal interview with the perpetrators, the exact causes for these specific attacks will never be known, so whatever conclusions will emerge will only be (hopefully) plausible but ultimately always untestable hypotheses.
In very general terms, Shark attacks can be divided into the following categories.
1. Attacks associated with feeding events, i.e. predation and scavenging.
The most notorious species implicated in this category of attacks are the large predatory Sharks Great White, Tiger, Bull and Oceanic Whitetip.
Whilst large adult GWs appear to be specialist hunters of mammal blubber, the other species are generalists with a broad spectrum of prey and consequently, hunting techniques. It should thus not come as a surprise that the track record here is unequivocal: these Sharks will sometimes attack and prey on humans!
Granted, these events are exceedingly rare.
It is obvious that humans are not the primary prey of any Shark species and let me spare you the long winded and pathetically trivial explanations as to why evolution could not possibly have selected for it. Also, granted, sometimes the Sharks appear not to like (whatever that may mean) what they have attacked and either spit it back out or not bother to come back to completely consume the meal. In GWs, this may be linked to the fact that we may indeed be too lean for a specialized hunter of blubber. In other species, it may be an indication of the fact that the Shark was not very hungry, or that something disturbed it whilst it may have hung off waiting for the victim to stop struggling.
But when limbs go missing and Sharks hang on, those are predatory attacks, period!
Which brings me straight over to the whitewashing.
Yes we love Sharks, yes Sharks are much maligned and we need to work at improving their reputation: but the fact is that large predatory Sharks are dangerous and that they need to be treated with respect and with circumspection!
That makes them neither bad, nor good – that just makes them large predatory Sharks! I’ve said it before – we need to remain fact based and refrain from creating our own unhelpful stereotypes!
The common pattern of predatory Shark attack has been called Sneak Attack whereby a Shark suddenly turns up (in fact, many survivors claim that they never saw the Shark prior to the attack) and persistently attacks, very much like what happened in Sharm is being described. This is not surprising and only consistent with most attacks by terrestrial predators who relay on the element of surprise in order to approach their prey.
Great Whites sometimes attack Seals and Sea Lions which are close to the surface by sneaking up close to the bottom and then attacking more or less vertically at high speed, resulting in the much publicized predatory breaches.
Some surfers have been attacked in the same way, leading John McCosker to develop the hypothesis of Mistaken Identity, meaning that the GWs attacking a silhouette at high speed may have mistaken a surfer for a Pinniped, especially in murky water. This is certainly plausible, the more as GW are being routinely induced to attack decoys in the same manner.
BUT: this is strictly GW lingo!
This cannNOT just simply be applied to other species! Specifically, this is not how Tigers prey on Turtles (and no film maker goes potting around Hawaii towing Turtle decoys) and it does not apply to each and every “mistake” a Shark may make! Thus, asserting that most Shark attacks are due to Mistaken Identity is a fallacy and as such, nothing more than pseudo-science!
The same applies to Investigative Bites.
Once again, this is GW lingo, as Great Whites are known to test objects and people by (more or less, see Rodney Fox) gently nibbling at them. Rather than being a strictly predatory behavior, this is probably linked to testing food when scavenging and may, or may not result in subsequent feeding.
Other species known to investigate people, snorkelers and divers alike, by mouthing are Tigers and I hear, Lemons – yes, as in TB!
Not Oceanic Whitetips!
They are the picture child for investigation via bumping. They will circle ever closer, the frequency of bumps will increase and if not countered vigorously or if the affected person does not leave the water, this will likely result in a predatory attack, sometimes referred to as Bump and Bite attack. Check out the video here: this is typical behavior and it is pretty obvious that this Shark would not suddenly slow down to apply a gentle test bite! The same apparently applies to Bull Sharks.
Of note, this is different from the ramming with snout mentioned in Martin 2007 that is related to aggression, not predation. Incidentally, Martin does not cite ramming with snout as an agonistic display in OWTs, a further confirmation that in this species, that behavior is linked to predation!
Once again, attributing Investigative Bites to species other that GWs, Tigers and maybe Lemons is mere whitewashing and pseudo-science! It also looks like an attempt to exonerate the Shark from having had bad intentions or the like, something that I find rather peculiar to say the least!
2. Attacks associated with self defense
You may want to go and re-read this: several species of Sharks display behavior that is called agonistic and is linked to self defense. Failure to identify and adequately react to that behavior may lead to what are generally open-mouthed, slashing bites that result in cuts rather than missing tissue.
Attacks on surfers and bathers by small piscivorous Sharks like Blacktips and Spinners (see Volusia County) or the frequent nips on the feet of waders by subadult Blacktip Reef Sharks are commontly referred to as Hit & Run attacks and generally result in mere harmless cuts. They, too, are believed to be the result of self defense as the Sharks may simply have been startled and may have wanted to fend off a perceived attack, or may have previously displayed agonistic behavior that was never noticed by the victims.
These are, by far, the most frequent Shark attacks on people.
Finally, there are the Provoked Attacks, where the people have touched the Sharks, as in the retaliatory bites by Wobbegongs and Nurses that get dragged out from their covers by the tails.
3. Attacks associated with competition
Typically associated with spear fishing, Sharks may bite people when competing for the speared fish. These attacks are thus not aimed at preying on the person but rather, at chasing away a perceived competitor.
Incidentally, the same happens between different Shark species (but apparently not between individuals of the same species): I’ve personally witnessed a Silvertip biting a Nurse to dislodge him from some bait, and filmed one of our Bulls biting away a Lemon who wanted to approach a feeder.
Consequently, when referring to site fidelity in Sharks, one should always talk about residency as opposed to territoriality. The latter implies defense against conspecifics, a behavior that has been observed in many Fishes but apparently, never in any species of Shark!
This is again different from aggression associated with rank.
Sharks do display behavior that may be interpreted as “posturing” and there are even anecdotal accounts of actual bites on conspecifics in the context of social interactions.
Yes, it’s complicated!
4. Attacks associated with mistakes
Sharks make mistakes.
Considering the impressive array of senses they dispose of, this may seem surprising: and yet, they hunt, attack and bite a vast array of objects like boat propellers, metallic structures, decoys, and ingest completely inedible items like the famous number plates and car tires - and most often and fatally, they will be fooled by fishing bait and lures!
Mistaken attacks on humans are mostly associated with Shark feeding and baiting.
Many species of Sharks (and Fish!) are highly competitive and uncontrolled Shark feeding events can quickly develop into Feeding Frenzies where the animals get highly agitated and may end up biting other Sharks or the human spectators by mistake. Equally, Sharks may accidentally bite the feeders’ hands during hand feeding shows, etc.
Again, these are genuine mistakes and neither competitive nor predatory in nature – the latter much contrary to the opinion of the anti-feeding lobby.
Talking of which, you may want to check out these latest statements by Burgess: apparently, the perpetrator of at least two attacks is one and the same Shark! Amazing!
Plus, there’s this: "These are open-ocean sharks that are living in an environment that is food-poor," says Burgess. "So when you do find food, you darn well better take advantage of it. Do they remember things? Sure, they remember where the good places to eat were, and they'll come back." Surprise surprise: I happen to totally agree - re-read this! But... Sharks that may have been conditioned to come and feed on Tuna heads learn to… feed on Tuna heads! Not humans!
There you have it I believe - and again, if I'm factually wrong, feel free to correct me!
Long story short: if we want to be credible Shark advocates, we got to do our homework and first of all, be informed about the animals we love!
Science is always in flux and today’s insights may quickly become tomorrow’s fallacies, meaning that we must keep abreast of the latest research results and not base our knowledge on old publications and approximate hearsay. Most importantly, we the amateur naturalists should never make up things on the fly, nor should we idly re-interpret what is considered to be the accepted consensus.
This does not mean that we should not challenge the current status quo, as that is precisely the process by which knowledge is being advanced!
BUT: the only accepted technique for doing so is the Scientific Method and as always, let me warn against the siren calls and intellectual shortcuts of the self promoters, quacks and charlatans!
All researchers I’ve ever met have always been eager to engage in informed discussions and to entertain different hypotheses, if adequately supported by according observations. Those researchers are not omniscient and also, not omnipresent and often, observations by common mortals like us have greatly contributed to the advancement of scientific insights - so even if you have no academic background, don’t be shy and speak up!
But do your home work first!
In diesem Sinne!
PS read this brand new report - so, how do you interpret it? :)
Friday, December 04, 2009
Shifting Baselines
Do you know what this is?
If so, you must be older - like, for example, yours truly.
When I was a kid, I would visit my granddad in Northern Germany and we would rig up a disgusting slimy knot of earth worms and go catch European Eels, one of Europe's most fascinating, albeit equally wriggly and slimy Fishes. This used to be one of the region's most abundant Fishes and staple diets, either fresh as grüner Aal or as Räucheraal, the smoked version that would end up in dishes like the iconic Hamburger Aalsuppe.
I've called the Eel fascinating because of its life history.
All of Europe's Eels are born thousands of miles away in the Sargassum Sea, from where they gradually migrate to the European rivers (and by crawling on land, to remote lakes and ponds, too!), only to return back to the Sea as "yellow", and then "silver" Eels in order to mate and then perish, truly a titanic endeavor. This makes them diadromous catadromous, as opposed to Salmon which are anadromous and our Bull Sharks which are amphidromous (but are they philopatric? Or may they even display natal philopatry? Now that sure would be questions worth exploring! Juerg?).
Yes it sounds complicated but it's actually easy - and fascinating!
Thing is, whilst I was busy doing things with Sharks, the Eels have all but vanished (also read this) and are now classified as Critically Endangered. Shocking!
And they're not alone: according to a new study, 95% (yes, again one of those numbers...) of many of the North Atlantic's migratory Fishes have been wiped out. And yes, the culprits once again would be us:
Limburg and Dr. John Waldman, of Queens College of the City University of New York, report that a complex combination of habitat loss (caused largely by the construction of dams that prevent fish access to traditional spawning areas), urban sprawl, overfishing, pollution and climate change have led to the precipitous decline. Compounding the problem, they say, is the evolving knowledge of the humans who make decisions about how natural resources are managed.
"We're looking at shifting baselines here," Limburg said. "Every human generation gains knowledge about the world and establishes a baseline for what's normal. But there is no institutional memory about how things used to be."
No shifting baseline here.
I remember - and lemme tell you, this really sucks big time!
Please, read this, watch this and explore the website!
Friday, November 27, 2009
Marine Extinction - one
Talking about getting the facts right.
When writing that post, I was reminded of a recent lunch with a fellow Shark conservationist.
We were comparing the image of terrestrial vs aquatic apex predators and he looked at me and said that contrary to the fishermen, the hunters had never led to the extinction of a species.
Passenger Pigeon (mass ornicide) anybody? Quagga, pictured above?
I of course went looking and found these lists.
Heaps upon heaps of terrestrial animals, be it Mammals, Birds, Reptiles, Amphibians and even Insects! And freshwater Fishes! Many of which certainly hunted, and fished to extinction! But of course the man was partly right: modern hunters have indeed changed their ways and don't do those things anymore - and I may add, contrary to the game fishermen who still target pregnant Sharks in their stupid quest for trophies!
And how about the Ocean?
How many marine Mammals have gone extinct during the Holocene, i.e. from approx. 12,000 years ago til now? Steller's Sea Cow (hunted to extinction). Caribbean Monk Seal (overhunted). Japanese Sea Lion, possibly only a sub-species (hunted to extinction). Sea Mink, more coastal than marine (hunted to extinction - even before being scientifically described!).
Incidentally, I could not find any marine Cetaceans - yet.
Marine Reptiles?
Can anybody name a single one?
And how about a single marine Fish, Sharks included?
Don't get me wrong: I'm by no means suggesting that the situation is OK.
It is certainly very dire and we must continue working very hard in order to prevent what appears to be the imminent collapse of some of the most threatened species, like the Northern Bluefin, the Flapper Skate, many Sharks and the whole sad lineup on the Red List, many of which Corals. Still, the Ocean is a very very big place and it appears that so far and despite of our very best efforts, its Fishes have managed to dodge everything we've thrown at them, from reckless overfishing to reckless pollution.
Let's just keep that in mind when faced with the apparent hopelessness of our efforts.
It is not hopeless, and we can turn things around.
When writing that post, I was reminded of a recent lunch with a fellow Shark conservationist.
We were comparing the image of terrestrial vs aquatic apex predators and he looked at me and said that contrary to the fishermen, the hunters had never led to the extinction of a species.
Passenger Pigeon (mass ornicide) anybody? Quagga, pictured above?
I of course went looking and found these lists.
Heaps upon heaps of terrestrial animals, be it Mammals, Birds, Reptiles, Amphibians and even Insects! And freshwater Fishes! Many of which certainly hunted, and fished to extinction! But of course the man was partly right: modern hunters have indeed changed their ways and don't do those things anymore - and I may add, contrary to the game fishermen who still target pregnant Sharks in their stupid quest for trophies!
And how about the Ocean?
How many marine Mammals have gone extinct during the Holocene, i.e. from approx. 12,000 years ago til now? Steller's Sea Cow (hunted to extinction). Caribbean Monk Seal (overhunted). Japanese Sea Lion, possibly only a sub-species (hunted to extinction). Sea Mink, more coastal than marine (hunted to extinction - even before being scientifically described!).
Incidentally, I could not find any marine Cetaceans - yet.
Marine Reptiles?
Can anybody name a single one?
And how about a single marine Fish, Sharks included?
Don't get me wrong: I'm by no means suggesting that the situation is OK.
It is certainly very dire and we must continue working very hard in order to prevent what appears to be the imminent collapse of some of the most threatened species, like the Northern Bluefin, the Flapper Skate, many Sharks and the whole sad lineup on the Red List, many of which Corals. Still, the Ocean is a very very big place and it appears that so far and despite of our very best efforts, its Fishes have managed to dodge everything we've thrown at them, from reckless overfishing to reckless pollution.
Let's just keep that in mind when faced with the apparent hopelessness of our efforts.
It is not hopeless, and we can turn things around.
Wednesday, June 10, 2009
Gone
I've followed my own advice and browsed the Website of The End of the Line.
Kudos to the authors for having followed up by posting a lot of pertinent information.
There's a really interesting News section and that's where I learned that the Atlantic , or Northern Bluefin Tuna is all but gone. Roberto Mielgo Bregazzi has researched the topic and I invite everybody to read this shocking synopsis of his findings. Nothing new really, but what had been depicted as imminent in 2006, 2007 and 2008 has apparently eventuated - basically, it's over.
Barring a miracle that is - but alas, I'm not hopeful.
The very much not aptly named International Commission for the Conservation of Atlantic Tuna (ICCAT) has only one track record - and that is, to continue applying unsustainable quotas despite all evidence pointing to the imminent catastrophe. It's the bloody same farce every time they meet: politicians and functionaries trying to "negotiate" against scientific facts - last time in November where they didn't adopt the recommendations by their own scientists and then managed to congratulate themselves for the fiasco!
Want to know the full extent of the debacle - involving mismanagement, fraud and piracy?
Read this!
Like in the case of Sharks, we are faced with a supply limited fisheries with zero price elasticity where the Tragedy of the Commons is preventing any useful consensus about applying sustainable quotas, let alone a fishing moratorium where stocks would be allowed to replenish. Contrary to Sharks which are extremely slow breeders, Tuna reach sexual maturity between 3 and 5 years and such a strategy could really lead to positive results within a comparatively short period of time.
Alas, it's not likely to happen.
The policy makers will continue to drag their feet and Bluefin Tuna will become a prized delicacy for the rich, then the very rich and finally, only the select few.
And then, it'll be gone for good. Forever.
Oh well.
Back to the Sharks.
Kudos to the authors for having followed up by posting a lot of pertinent information.
There's a really interesting News section and that's where I learned that the Atlantic , or Northern Bluefin Tuna is all but gone. Roberto Mielgo Bregazzi has researched the topic and I invite everybody to read this shocking synopsis of his findings. Nothing new really, but what had been depicted as imminent in 2006, 2007 and 2008 has apparently eventuated - basically, it's over.
Barring a miracle that is - but alas, I'm not hopeful.
The very much not aptly named International Commission for the Conservation of Atlantic Tuna (ICCAT) has only one track record - and that is, to continue applying unsustainable quotas despite all evidence pointing to the imminent catastrophe. It's the bloody same farce every time they meet: politicians and functionaries trying to "negotiate" against scientific facts - last time in November where they didn't adopt the recommendations by their own scientists and then managed to congratulate themselves for the fiasco!
Want to know the full extent of the debacle - involving mismanagement, fraud and piracy?
Read this!
Like in the case of Sharks, we are faced with a supply limited fisheries with zero price elasticity where the Tragedy of the Commons is preventing any useful consensus about applying sustainable quotas, let alone a fishing moratorium where stocks would be allowed to replenish. Contrary to Sharks which are extremely slow breeders, Tuna reach sexual maturity between 3 and 5 years and such a strategy could really lead to positive results within a comparatively short period of time.
Alas, it's not likely to happen.
The policy makers will continue to drag their feet and Bluefin Tuna will become a prized delicacy for the rich, then the very rich and finally, only the select few.
And then, it'll be gone for good. Forever.
Oh well.
Back to the Sharks.
Sunday, December 21, 2008
Population Bottleneck
I came across this piece about Cheetahs and had to think of the Sharks.
Dunno if anybody has focused on this yet - but with 90% to 98% of the oceanic Shark populations already gone, we may well be facing the exact same outcome even if we did manage to pull them back from the brink of extinction. Deprived of Genetic Diversity, the population will eventually crash - regardless of numbers and of whether they are still being hunted.
Not that I really had any high hopes anyway - but alas, it just shows how incredibly complex the issues are, and how difficult it is to restore a viable balance once the damage has progressed beyond its tipping point. And let there be no doubt that when it comes to pelagic Apex Predators, it probably has already.
It's a complicated topic but if you're interested, you may want to start with this and then take it from there. There is also this about the (controversial) concept of Minimum Viable Population Size. And if you like formulas, this (sort of) explains Effective Population Size.
It will be interesting to see the results of the ongoing genetic studies that are presently being conducted on various Shark species, among them one about Bull Sharks to which we have and are continuing to contribute.
Luckily, when it comes to coastal Sharks, the damage to stocks looks less irrevocable - so far. Shark Conservation has gained considerable traction and I believe that we really do have a fighting chance - but we need to do something right now.
Fingers crossed that we're not too late.
Friday, September 19, 2008
Quod erat demonstrandum........
I cite.......
"The group is collecting information about the species to help the government of Canada to determine whether or not to list Basking Sharks as endangered off the coast of B.C (my emphasis).
After the sharks clashed with fishing equipment mid-century, the Federal Government embarked on a Basking Shark eradication program from the late 1940s until the 1960s. Blades were attached to the front of boats and driven through the gentle giants and since the 1990s, there have only been sporadic sightings of Basking Sharks on the West Coast of Vancouver Island.
Researchers previously scanned the waters on the West Coast in the spring and last fall and didn't come up with any sightings."
The article I'm citing from is titled "One year and no sightings of Basking Sharks" and describes the futile search for Basking Sharks by some scientists from Canada's Pacific Biological Station. Not having found any at all (in fact, the last sighting of a Basking Shark dates back to two summers ago), the group is planning to go back in October to "hopefully collect more baseline information", undoubtedly at more cost to the Canadian taxpayer.
Beg you - what???
"Baseline information"???
As in: there's no more Sharks???
And I cite again:
I've just blogged about it and here is the case in point: Fisheries Biologists "collecting data", Governments "considering", Conservation being "developed". In the meantime, the species has gone locally extinct and this thanks to, of all things, a Government eradication program.
Bet it didn't take years to ponder about that one, huh?
Enough said.
Beg you - what???
"Baseline information"???
As in: there's no more Sharks???
And I cite again:
"After that, the Federal Government will consider whether or not to add the sharks to the endangered list of species. If they do, McFarlane said, following that decision would be the requirement to develop a recovery program for the species."
I've just blogged about it and here is the case in point: Fisheries Biologists "collecting data", Governments "considering", Conservation being "developed". In the meantime, the species has gone locally extinct and this thanks to, of all things, a Government eradication program.
Bet it didn't take years to ponder about that one, huh?
Enough said.
Wednesday, July 30, 2008
About shooting Orang Utans
Have you read "The Malay Archipelago"?
First published in 1869, this captivating book chronicles the scientific explorations of Alfred Russel Wallace, a naturalist, explorer and biologist who traveled through the Malay Archipelago or East Indies (now Malaysia and Indonesia) to collect specimens for sale and to study nature. His observations of the marked zoological differences across a narrow strait in the archipelago led to his proposing the zoogeographical boundary now known as the Wallace Line. Wallace collected more than 125,000 specimens in the Malay Archipelago (more than 80,000 beetles alone). More than a thousand of them represented species new to science. While he was exploring the archipelago, he refined his thoughts about Evolution and had his famous insight on Natural Selection.
Among his fascinating descriptions of foreign landscapes and peoples and mysterious animals, we can read a meticulous account about how he hunted, shot, and the number of bullets it took him to kill several Orang Utans.
Not cool.
But only by today's standards.
Back then, people like Wallace were merely providing specimens for naturalist collections set up for the advancement of scientific knowledge. In fact, the rarer the animal, the more sought-after and valuable it was and there are documented incidents where some collectors commissioned entire hunting expeditions, and then prided themselves in owning the very last specimen ever recorded of a particular species. Killing, and even exterminating animals for scientific purposes in order to "preserve them for posterity" was perfectly acceptable.
According to Inuit myth, a urine-soaked cloth was once whipped from an old lady's hand and carried out to Sea, where it turned into a sea monster called "skalugsuak". Of its legendary peculiarities, skalugsuak lives for 200 years, has thousands of teeth, weighs over a ton, eats caribou whole, has skin that can destroy human flesh, and may even possess—in place of eyes—living, glowing creatures which lure its prey.
But skalugsuak isn’t a fable—it’s a real Shark, whose flesh is so packed with urea that it smells and tastes like urine. Commonly known as the Greenland Shark, the animal is the apex predator of the eastern Arctic. When their carcasses have washed up, scientists have opened their stomachs to find eels, sharks, beluga whales, sea birds, dog, horse, polar bear, reindeer, a human foot, and a lot of fish, and they’ve even been reported to hunt caribou in the manner of a crocodile ambush.
Very little work is currently being conducted on the smelly monster, and virtually nothing is known about its behavior.
In the name of science, University of Windsor's Aaron Fisk hauls monster Greenland Sharks out of the frigid Arctic depths, then guts them to see what they had for dinner. Research has shown they grow very slowly -- about one centimeter a year - so the Sharks Fisk has studied that measure three to four meters probably lived several hundred years.
Somebody has to do it, says Fisk.
Yeah - right (and yes, I'm about to embark on yet another rant....... again).
"Somebody" just has to go kill an animal that is several hundred years old in order to find out what it eats. With a name like Somniosus microcephalus, i.e. the sleepy tiny brained one, it's likely to be too sluggish, and too dumb to notice anyway.
After all, it's all being done for the advancement of scientific knowledge: thus in the Big Scheme of things, the small sacrifice of a few individuals is absolutely irrelevant.
Correct?
Try substituting "Greenland Sharks" with another arctic top predator and see how you feel about that. How about
"Beluga Whales"?
"Polar Bears"?
"Walruses"?
When i was a student in the 70ies, Biology was largely being pursued for the sake of increasing scientific knowledge per se.
All too often, the objects of the research were just that, Objects: to be examined in an objective , dispassionate, analytical way. Any emotional attachment, let alone Love and Awe for the animals was being frowned upon as being highly suspect of carrying the risk of unduly influencing the findings.
Thus, to make an example, killing a couple dozen Sharks in order to explore the anatomical peculiarities of their vision was perfectly acceptable, the same way as it was acceptable to kill a dozen Orang Utans in the 19th century.
But in the 21st century, the Big Picture I believe is this:
In this day and age where the Planet is going to shit largely because of us, Life is just too precious - even that of a greedy, ungainly, smelly, poisonous, stupid and ugly deep-sea monster.
Today, investing scarce and valuable scientific resources both in terms of brainpower and funds can only have one possible justification, and that is that to preserve what's left and hopefully, to reverse the tide of ecological degradation and species extinction.
Thus, I believe, modern age Biological Research has to be able to withstand the following double test:
- are the purpose of the research, and its likely results, aimed at achieving those aims?
- and, is the method employed to collect the required data the least invasive one possible?
Everything else is not only frivolous and wasteful, it is also profoundly unethical - especially when it involves killing wildlife.
And guys, please: show the Love and the Respect!
This is precisely why before engaging in Research on Shark Reef, we spend an inordinate amount of time discussing the Why and the How.
This is why instead of attaching our radio tags externally where they would be happily beeping away for years to come whilst however greatly irritating the skin, we prefer to feed them to the animals, this despite the fact that we will only be able to collect a maximum of two weeks' data.
This is also why when we deploy satellite tags on the Bull Sharks, we do it underwater, at the risk of losing the tags at a rate of several thousand dollars a pop. The alternative would be catching them, hauling them aboard and using a drill to secure the tags to the dorsal fin . Very effective for sure - but at what consequence to the animals?
Investigating a Shark's diet may conceivably allow for the formulation of better-adapted Conservation strategies and thus, contribute to its survival.
But is it equally cool to go out of one's way, undoubtedly at great expense of money and personal hardship, to go catch, and then kill them in person when there must already be thousands of available and equally valuable specimen caught by local fishermen? In a sub-zero environment where carcasses don't rot?
You be the Judge of that.
First published in 1869, this captivating book chronicles the scientific explorations of Alfred Russel Wallace, a naturalist, explorer and biologist who traveled through the Malay Archipelago or East Indies (now Malaysia and Indonesia) to collect specimens for sale and to study nature. His observations of the marked zoological differences across a narrow strait in the archipelago led to his proposing the zoogeographical boundary now known as the Wallace Line. Wallace collected more than 125,000 specimens in the Malay Archipelago (more than 80,000 beetles alone). More than a thousand of them represented species new to science. While he was exploring the archipelago, he refined his thoughts about Evolution and had his famous insight on Natural Selection.
Among his fascinating descriptions of foreign landscapes and peoples and mysterious animals, we can read a meticulous account about how he hunted, shot, and the number of bullets it took him to kill several Orang Utans.
Not cool.
But only by today's standards.
Back then, people like Wallace were merely providing specimens for naturalist collections set up for the advancement of scientific knowledge. In fact, the rarer the animal, the more sought-after and valuable it was and there are documented incidents where some collectors commissioned entire hunting expeditions, and then prided themselves in owning the very last specimen ever recorded of a particular species. Killing, and even exterminating animals for scientific purposes in order to "preserve them for posterity" was perfectly acceptable.
According to Inuit myth, a urine-soaked cloth was once whipped from an old lady's hand and carried out to Sea, where it turned into a sea monster called "skalugsuak". Of its legendary peculiarities, skalugsuak lives for 200 years, has thousands of teeth, weighs over a ton, eats caribou whole, has skin that can destroy human flesh, and may even possess—in place of eyes—living, glowing creatures which lure its prey.
But skalugsuak isn’t a fable—it’s a real Shark, whose flesh is so packed with urea that it smells and tastes like urine. Commonly known as the Greenland Shark, the animal is the apex predator of the eastern Arctic. When their carcasses have washed up, scientists have opened their stomachs to find eels, sharks, beluga whales, sea birds, dog, horse, polar bear, reindeer, a human foot, and a lot of fish, and they’ve even been reported to hunt caribou in the manner of a crocodile ambush.
Very little work is currently being conducted on the smelly monster, and virtually nothing is known about its behavior.
In the name of science, University of Windsor's Aaron Fisk hauls monster Greenland Sharks out of the frigid Arctic depths, then guts them to see what they had for dinner. Research has shown they grow very slowly -- about one centimeter a year - so the Sharks Fisk has studied that measure three to four meters probably lived several hundred years.
Somebody has to do it, says Fisk.
Yeah - right (and yes, I'm about to embark on yet another rant....... again).
"Somebody" just has to go kill an animal that is several hundred years old in order to find out what it eats. With a name like Somniosus microcephalus, i.e. the sleepy tiny brained one, it's likely to be too sluggish, and too dumb to notice anyway.
After all, it's all being done for the advancement of scientific knowledge: thus in the Big Scheme of things, the small sacrifice of a few individuals is absolutely irrelevant.
Correct?
Try substituting "Greenland Sharks" with another arctic top predator and see how you feel about that. How about"Beluga Whales"?
"Polar Bears"?
"Walruses"?
When i was a student in the 70ies, Biology was largely being pursued for the sake of increasing scientific knowledge per se.
All too often, the objects of the research were just that, Objects: to be examined in an objective , dispassionate, analytical way. Any emotional attachment, let alone Love and Awe for the animals was being frowned upon as being highly suspect of carrying the risk of unduly influencing the findings.
Thus, to make an example, killing a couple dozen Sharks in order to explore the anatomical peculiarities of their vision was perfectly acceptable, the same way as it was acceptable to kill a dozen Orang Utans in the 19th century.
But in the 21st century, the Big Picture I believe is this:
In this day and age where the Planet is going to shit largely because of us, Life is just too precious - even that of a greedy, ungainly, smelly, poisonous, stupid and ugly deep-sea monster.
Today, investing scarce and valuable scientific resources both in terms of brainpower and funds can only have one possible justification, and that is that to preserve what's left and hopefully, to reverse the tide of ecological degradation and species extinction.
Thus, I believe, modern age Biological Research has to be able to withstand the following double test:
- are the purpose of the research, and its likely results, aimed at achieving those aims?
- and, is the method employed to collect the required data the least invasive one possible?
Everything else is not only frivolous and wasteful, it is also profoundly unethical - especially when it involves killing wildlife.
And guys, please: show the Love and the Respect!
This is precisely why before engaging in Research on Shark Reef, we spend an inordinate amount of time discussing the Why and the How.
This is why instead of attaching our radio tags externally where they would be happily beeping away for years to come whilst however greatly irritating the skin, we prefer to feed them to the animals, this despite the fact that we will only be able to collect a maximum of two weeks' data.
This is also why when we deploy satellite tags on the Bull Sharks, we do it underwater, at the risk of losing the tags at a rate of several thousand dollars a pop. The alternative would be catching them, hauling them aboard and using a drill to secure the tags to the dorsal fin . Very effective for sure - but at what consequence to the animals?
Investigating a Shark's diet may conceivably allow for the formulation of better-adapted Conservation strategies and thus, contribute to its survival.
But is it equally cool to go out of one's way, undoubtedly at great expense of money and personal hardship, to go catch, and then kill them in person when there must already be thousands of available and equally valuable specimen caught by local fishermen? In a sub-zero environment where carcasses don't rot?
You be the Judge of that.
Saturday, July 26, 2008
Olympic Shark Savers
The Beijing Olympics are less than two weeks away and the celebrations will undoubtedly include thousands of portions of Shark fin soup.
This dish is one of the principal causes for the global extermination of Sharks, at a staggering rate of somewhere between 40 and 100 million killed every year. As a result, the numbers of some species have dropped by as much as 80% over the last 50 years, with devastating consequences for the ecosystems they once lived in, where the food chains and the fisheries depending on them are collapsing .
A comprehensive and chilling summary of the Global threats to Sharks can be downloaded here.
Much of the trade in Sharks' fins is derived from fins cut from living Sharks; this process is called finning. Because Shark meat is worth much less, the finless and often still-living Sharks are thrown back into the sea to make room on board the ship for more of the valuable fins. When returned to the ocean, the finless Sharks, unable to move, die from suffocation.
Apart from being wasteful, the practice of Shark finning is brutal, cruel and unethical.
In case you've never seen it, you may want to watch the following clip.
This dish is one of the principal causes for the global extermination of Sharks, at a staggering rate of somewhere between 40 and 100 million killed every year. As a result, the numbers of some species have dropped by as much as 80% over the last 50 years, with devastating consequences for the ecosystems they once lived in, where the food chains and the fisheries depending on them are collapsing .A comprehensive and chilling summary of the Global threats to Sharks can be downloaded here.
Much of the trade in Sharks' fins is derived from fins cut from living Sharks; this process is called finning. Because Shark meat is worth much less, the finless and often still-living Sharks are thrown back into the sea to make room on board the ship for more of the valuable fins. When returned to the ocean, the finless Sharks, unable to move, die from suffocation.
Apart from being wasteful, the practice of Shark finning is brutal, cruel and unethical.
In case you've never seen it, you may want to watch the following clip.
Many Shark diving operators like us are trying to buck the trend via Sustainable Tourism, Habitat Protection , Education and by sponsoring Research, often with help from NGOs like in our case, the Shark Foundation and Save our Seas Foundation.
Other more powerful organizations operate mainly via media campaigns and by influencing legislation. Two of those, WildAid and Oceana have captured the occasion by airing a series of smart video clips featuring two of the best-known, and most charming American Olympic swimmers.
We say: Well Done and Good on You!
Other more powerful organizations operate mainly via media campaigns and by influencing legislation. Two of those, WildAid and Oceana have captured the occasion by airing a series of smart video clips featuring two of the best-known, and most charming American Olympic swimmers.
We say: Well Done and Good on You!
Thursday, July 17, 2008
Good on 'ya, Google!
The plight of Sharks continues unabated, as witnessed by these shocking statistics for Shark landings (that is, EXCLUDING finning where the carcass is dumped) for June in Ecuador - the same country already infamous for its ineptitude in managing the Galapagos National Park.
As always, well done to Shark Diver for having found and posted them.
But for once, where there's plenty of shadow, there is some light as well.
Whilst Yahoo's Alibaba portal continues to brazenly ignore the petitions by Conservationists and offers a "choice" of hundreds of sites selling Shark fins, one of its principal competitors has obviously decided to forgo those earnings in favor oft ethical considerations.
As of today, I believe, Google has updated its Advertising Policies that exclude the sale of products obtained from endangered or threatened species to explicitly mention Sharks.
This of course is not only laudable, but smart business sense as well, as anybody loving Sharks should, and probably will completely refrain from conducting any business with Yahoo and its despicable subsidiary but deal on Google instead.
Thank you Helen for he heads-up about this wonderful piece of news.
As always, well done to Shark Diver for having found and posted them.
But for once, where there's plenty of shadow, there is some light as well.
Whilst Yahoo's Alibaba portal continues to brazenly ignore the petitions by Conservationists and offers a "choice" of hundreds of sites selling Shark fins, one of its principal competitors has obviously decided to forgo those earnings in favor oft ethical considerations.
As of today, I believe, Google has updated its Advertising Policies that exclude the sale of products obtained from endangered or threatened species to explicitly mention Sharks.This of course is not only laudable, but smart business sense as well, as anybody loving Sharks should, and probably will completely refrain from conducting any business with Yahoo and its despicable subsidiary but deal on Google instead.
Thank you Helen for he heads-up about this wonderful piece of news.
Sunday, June 22, 2008
99.99%
Rome: A new scientific study funded in part by the Lenfest Ocean Program has concluded that all shark species assessed in the Mediterranean Sea have declined by more than 97 percent in abundance and “catch weight” over the last 200 years.
The findings of the study, Loss of large predatory sharks from the Mediterranean Sea, published in the journal Conservation Biology, suggest several Mediterranean shark species are at risk of extinction, especially if current levels of fishing pressure continue. There used to be 47 species of Shark in the Mediterranean, of which 20 were considered "top predators". Now, some of the big Sharks are virtually extinct.
Hammerhead Sharks have declined the fastest, with no recorded sightings in the Mediterranean since 1995. Hammerheads are estimated to have declined by 99.99%
Hammerhead Sharks have declined the fastest, with no recorded sightings in the Mediterranean since 1995. Hammerheads are estimated to have declined by 99.99%
Blue Sharks have declined by 96.53% in abundance and by by 99.83% in biomass in the last 50 years, with the steepest decline in the waters around Spain
The two Mackerel Sharks (Porbeagle and Shortfin Mako) have declined by more than 99.99% in both abundance and biomass over the last 100 years.
Thresher Sharks are the only species detected in coastal waters in recent times. Threshers have nonetheless declined by more than 99.99% over the last 100 years.
"Usually at the apex of trophic chains, large sharks are expected to play an important role in the structure and functioning of marine ecosystems .
Thus, the decline of large sharks may have marked ecological consequences. In the Gulf of Mexico predator and competitor release effects have been evident after the depletion of large sharks . In the northwestern Atlantic the decline of great sharks from coastal ecosystems has triggered a trophic cascade that collapsed a century-old fishery for bay scallops. Moreover, food-web models from the Caribbean suggest that large predatory sharks are among the most strongly interacting species, and that their overfishing may have caused trophic cascades that contributed to the degradation of Caribbean ecosystems ."
Thus, the decline of large sharks may have marked ecological consequences. In the Gulf of Mexico predator and competitor release effects have been evident after the depletion of large sharks . In the northwestern Atlantic the decline of great sharks from coastal ecosystems has triggered a trophic cascade that collapsed a century-old fishery for bay scallops. Moreover, food-web models from the Caribbean suggest that large predatory sharks are among the most strongly interacting species, and that their overfishing may have caused trophic cascades that contributed to the degradation of Caribbean ecosystems ."
"Our analysis, combined with previously published information, indicates that the Mediterranean Sea is losing a wide range of its predator species. In addition to large predatory sharks, cetaceans, pinnipeds, turtles, and large bony fishes have declined similarly.
The wider ecosystem consequences remain to be investigated. Nevertheless, in various other systems, it has been demonstrated that predators can play an important role in structuring communities by controlling prey populations and preventing ecological dominance. Losing top predators can induce strong increases in midlevel consumers, shifts in species interactions, and trophic cascades."
The wider ecosystem consequences remain to be investigated. Nevertheless, in various other systems, it has been demonstrated that predators can play an important role in structuring communities by controlling prey populations and preventing ecological dominance. Losing top predators can induce strong increases in midlevel consumers, shifts in species interactions, and trophic cascades."
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