Excellent Info for Shark Conservationists!

Heartbreaking - click for detail!

Overview

• Commercial fisheries targeting sharks exist throughout the world. Sharks are sought primarily for their fins (for shark fin soup) and their meat but also for their cartilage,liver and skin.


• 73 million sharks are killed every year, according to a 2000 analysis of the Hong Kong shark fin trade. Many scientists estimate that at least 100 million sharks are killed annually, including sharks caught for other products, such as meat.


• Shark populations have declined by as much as 70 to 80 percent, according to global reports. Some populations, such as the porbeagle shark in the northwestern Atlantic and spiny dogfish in the northeastern Atlantic, have been reduced by up to 90 percent.


• Thirty percent of all shark and ray species are now Threatened or Near Threatened with extinction, and accurate scientific assessments cannot be done on an additional 47percent of the species because of a lack of data.


• The highest numbers of reported shark landings are from: Indonesia; India; Taiwan, Province of China; Spain; and Mexico.


• The catching of sharks in fisheries that target other species (bycatch)is frequently reported in open-sea longline fisheries targeting tuna and swordfish and can represent asmuch as 25 percent of the total catch. This bycatch is considered to be a major source of mortality for many shark species worldwide.


• Blue sharks make up a particularly large proportion of shark bycatch in open-sea fisheries (47 to92 percent).


• The value of shark fins has increased with economic growth in Asia (particularly China), and this increased value is a major factor in the commercial exploitation of sharks worldwide. One bowl of shark fin soup can cost US$100.


• Sharks play an important role in maintaining the structure and function of the ecosystem. They regulate the variety and abundance of the species below them in the food chain. Impacts from the loss of sharks can be felt throughout the entire marine environment.


• Live sharks have a significant value for marine ecotourism (such as recreational diving, snorkelling, and shark watching) that is more sustainable and often far more valuable than their worth to fisheries. Whale shark tourism, for example, is estimated to be worth $47.5 million annually worldwide, and shark tourism activities in the Bahamas generate $78 million annually for the Bahamian economy.


• To reverse declines in shark populations, shark sanctuaries should be established, and strong, science-based management should be put in place by all fishing countries and international bodies that regulate shark fishing and trade
  

Once again, I must commend the Pew.
They have just published Sharks in Trouble: Hunters Become the Hunted and I must say, this is now the Bible for Shark conservationists.
Required reading!

Kudos also to Bush Warriors for this piece.
It's an excellent overview and contains very useful tips for anybody wanting to get active. But before you embark on your crusade: do your homework first!

Sharks and Oxygen - again?

 

 

 

Check this out, it's great.  

 

Kudos to filmmaker Jonathan Ali Khan. 

His Sharkquest Arabia is a highly important project that focuses on an important, difficult to access and thus largely overlooked region where millions of Sharks are being killed for the Asian Shark fin market. I've dived the Red Sea extensively in the late seventies and early eighties and have been fortunate to witness it in all it splendor, and have had a profusion of Shark encounters with the ubiquitous Whitetips, Grey Reefs, Silvertips and Scalloped Hammerheads all the way the more unusual Silkies and Threshers. Especially the Sudan with iconic sites like Sanganeb and Sha'ab Rumi but also Angarosh and Dungonab Bay was once one of the global hot spots of Shark diving. Yes even then the local fishermen were already targeting Sharks, mainly further south in Yemen where we came across several boats with dead Hammerheads - but seeing the obvious dramatic depletion is never the less simply heartbreaking. 

This project is really a great undertaking! 

 

But then, I stumble onto this interview. 

Among many good statements, I unfortunately find this. 

With 92% of our living biosphere being aquatic, almost 80% of our planet’s air is generated by the algae and microscopic phytoplankton that are found in the sea. Many thousands of fish species and other marine organisms feed on phytoplankton and algae. Sharks on the other hand prey on the fish that feed on plankton; right up through to the top of the food chain. So if we remove the sharks, as we are systematically doing at an unsustainable rate of over 70 million sharks a year, then it leaves the plankton feeders free of predation and free to gobble up the main source of our planet’s main oxygen supply! Therefore, it is in our interest to maintain a healthy source of oxygen and air, if we want to keep on breathing!Some seas, such as around Japan, are already struggling with harmful algae blooms, forming red tides and anaerobic conditions that are causing explosions of super-jellyfish populations that are creating havoc with marine diversity, dominating and taking over what were once rich fishing grounds. Those same areas were once managed by a wide range of shark species that controlled the ecosystem effectively by feeding largely on the fish that preyed on the plankton feeders. Ever since those sharks were fished out from around the coast of Japan, the resulting imbalance has proven catastrophic. To a lesser degree, we have already seen similar results in the Red Sea and Arabian Gulf with red tides and toxic algae blooms. 

 This is just total bullshit. 

There are so many wrong assertions here that I'm quite at a loss at where to begin. 

 

Maybe re-read this as a first fact check.  

Algal Blooms, harmful and not? Apart from the fact that red tides consist of oxygen-producing phytoplanktonic algae (!), the causes for their occurrence are varied, ranging from anthropogenic water eutrophication (the likely cause in Japan) to Climate Change to totally natural occurrences like iron dust influx from large desertic areas, the likely cause in the Arabian Seas. Nothing whatsoever to do with Sharks! 

 

Jellyfish Explosion? 

Causes? Probably primarily Climate Change and pollution, to a lesser extent overfishing of their natural predators. Nothing to do with Shark fishing!  

 

Trophic Cascades? 

Food webs are exceedingly complex, and pseudo-scientific intellectual shortcuts attributing causal top down-effects from the apex predators all the way down to the lowest trophic levels are inevitably destined to be fallacious, the more as in food webs as opposed to proper food chains that are rare, there's ample scope for substitution both of prey and of predators. Plus, we don't target only the predators but also their prey and we fish down the food web once we have dispatched the higher trophic levels, and are thus unwittingly assuming the regulatory role of apex predators as a consequence. 

 

Yes it's complicated! 

Anyway, the principal predator of Phytoplankton is Zooplankton, an incredible array of animal organisms spanning the whole gamut of taxonomic groups, from the unicellular all the way to complex Fish larvae. But whereas Zooplankton can certainly quickly respond to increases in Phytoplankton abundance, it is equally certainly NOT the principal determining factor for that abundance! The abundance of Phytoplankton is principally correlated to physical factors like ambient nutrient concentrations, temperature and light - not predator abundance and even less so abundance of Sharks! Yes the theory of correlations between trophic levels is sound - but much more when viewed bottom up. Top down - not so much! 

 

Long story short? 

Like many other Shark activists, Mr. Khan is a seriously good bloke doing seriously good, important stuff. But like all of us, if he wants to be taken seriously, he's got to get his facts right and not make up things on the fly - especially when addressing himself to the media! 

Simple - right? 

 

 End of rant! 

 

Weekend Rant!

Time for a rant!

From a message by a friend

Agree that there is much breathy hyperbole and blatant nonsense written about sharks and conservation, but I suppose that this is inevitable when concern is high but facts are few, with the most solid data residing in relatively inaccessible scientific papers.

Generally I take a sanguine or even charitable view toward the popular Jeremiads you have castigated since the goals of the authors are generally in concordance with mine, and these often painfully well-intentioned folks are far more able to communicate values effectively and educate a large audience than someone who uses words like sanguine or Jeremiad, no?
And education does seem to work in the long run.

Totally agree – BUT!
I’m getting terminally irritated that people who purport to be Shark conservationists and are perceived to represent the whole movement continue to make public statements containing ludicrous assertions and statistics.
This is not only not helpful - it directly undermines our efforts by allowing the other side to assert that we’re nothing but a bunch of lunatics who operate with false claims.
Is that what we want?

Yes it’s an old grievance of mine – but enough is enough.
So there.

But first, check out this piece of equine manure!
Very timely indeed – thank you!



Wow!
Pure sharkitarian snake oil!

There are no Shark attacks?
Right!
Please re-read this!

Sharks?
When talking conservation, talking about “Sharks” is utterly useless!
The fact is that “Sharks” are neither threatened with extinction, nor are "they" apex predators – only a small minority of species are apex predators, let alone keystone species, and the species that are particularly at risk of extinction are several large predatory Sharks, many of which are pelagic; possibly some deep water Sharks; and maybe Whale Sharks – full stop!
Other species are doing no better and no worse that any other Fish that is not subjected to exceptional fishing pressure – meaning not particularly great but not particularly catastrophically, either.
List here (search for "Sharks"), criteria here.

The numbers?
The numbers are just that, numbers.
If one does not put them into context by comparing them to what we know about individual species in specific locations, they say nothing about sustainability which is the only thing that counts.
Yes we all know without having to resort to peer reviewed science that many local, and possibly even some global populations of some Sharks have been severely depleted, and that their disappearance is of concern – but for the time being, that’s basically all we can assert.

So far, there has been one single paper trying to shed a light on the actual numbers being caught, and this only based on data from the Shark fin trade. Read it!
The paper is based on a series of (probably plausible) assumptions that are heaped upon more assumptions, and consequently, the results are merely expressed in orders of magnitude. Specifically, the authors come to the conclusion that the fins traded annually came from between 26 and 73 million Sharks, with a median number of 38 million.
Does that really allow us to honestly state that up to 73 million Sharks are being killed each year, as everybody and his dog has started to assert?
Kudos to Seafood Watch for doing it right: It's estimated that tens of millions of sharks are killed around the world each year for their fins is much better - but then again, have they been killed for their fins?

As I said, the above numbers are only about the global Shark fin trade alone.
They do not cover many other Shark fatalities due to bycatch or targeted food fisheries where the fins are not being introduced into the fin trade. Also, that was then and the trade has very likely increased since. It is thus entirely plausible to assume that the “real” number is higher, and it is perfectly OK to say so.
It is however totally unacceptable to make up numbers on the fly, be it as many as 100 million, let alone over 200,000 million (!!!) which is just plain ludicrous and quite frankly, a total disgrace! Yes, I'm being frank! :)
The good news is that I know that somebody is working on a peer reviewed paper about the global number of Shark being killed – but once again, unless put into context, those numbers will mean absolutely nothing!

And what about the Rate of Depletion?
Is it really true that 90% (or 99, or 70 – whatever!) of global Shark stocks have already been wiped out? Compared to which original baseline count, done when, where and by whom?
Where are the data?

And is it really true that Some marine biologist have suggested as soon as 2020 these magnificent creatures may be extinct – and if so, who is claiming such utter baloney?
Those endangered species of Sharks will become commercially extinct long, long before they will become biologically extinct! But there's a caveat: it is however probable that some local populations may have shrunk to the extent that they may have accumulated extinction debt and that they may be too small to be able to withstand the pressure of a large environmental shock, like the current anthropogenic Climate Change – re-read this post!

Shark Finning?
Shark finning does not equal catching Sharks. It is a specific, particularly wasteful and particularly cruel harvesting technique and for these reasons alone, it certainly needs to be stopped.
But is everybody aware that stopping the finning does not necessarily stop the fishing? The most widespread remedy against Shark finning is to legislate that the Sharks must be landed with their fins attached. This reduces the number of Sharks that are being killed as the carcasses take up a lot of space in the hold of the vessels – but as many examples show, Sharks are still being landed with their fins attached in what clearly appear to be unsustainable numbers.
Also, in many third world countries, local fishermen (and poachers!) have already wiped out many of the traditional food fisheries and as a consequence, many people have added Sharks to their menu, meaning that there is a substantial and increasing Shark food- , as opposed to Shark fin fisheries.
Thus, if we want to save Sharks stocks from overfishing, Stop Shark Finning! petitions alone are simply not adequate – we must also campaign for their protection!

Also, not every fin that is being sold has been finned!
Statements like over one hundred million sharks are caught and finned alive are thus doubly misleading!

Cascading Effects?
Yes there is a seminal paper by Myers et al. that essentially shows how the removal of large predatory coastal Sharks in the Northwest Atlantic led to the explosion of the population of Cownose Rays who in turn wiped out the Scallops, and the industry depending on them, in Chesapeake Bay. More details here.
Great paper – but it has one weakness: nobody was harvesting those Cownose Rays!

But in the real world, coastal Sharks are not being selectively removed alone.
Instead, fishermen target both the apex- and the mesopredators (and the prey), meaning that asserting that removing the big Sharks will inevitably lead to a population explosion of mesopredators (many of which are incidentally Sharks!) who in turn will wipe out the grazers which in turn will lead to an explosion of algae who in turn will smother the reefs can be totally wrong.
In a way, it is now us who have unwittingly assumed the role of apex predators and are keeping the lower trophic levels in check – see many terrestrial habitats where most apex predators have all but disappeared but where there has not at all been a total collapse of the system!
I’m not saying it is not so: I’m just saying that the empirical evidence is scarce and that once again, those effects will vary according to habitat and species composition.
See Ferretti et al. for more details!

As to the role of Sharks in their habitat and the widespread explanation that they weed out the sick and dying and thus keep the gene pool of their prey healthy, etc?
Certainly intuitively plausible: but to my knowledge, whereas there is plenty of research about the role of terrestrial predators, such effects have not been conclusively documented for Sharks – yet!

Which brings me straight over to Climate Change and Oxygen Production!
Check this out.



Did you hear that?
Who has come up with the glorious idea of linking Shark conservation to the Oceans’ production of oxygen?
Yes the Oceans provide for about half of the planet’s oxygen production through the photosynthesis by phytoplanktonic Algae and Cyanobacteria (but then again, probably not!). This (incidentally, to a very small extent), and the sea water’s capacity to dissolve CO2 make it that the Oceans are also Earth’s largest active carbon sink.
It is also certainly true that the Oceans have a great influence on the weather, and that millions of people depend on them for food.

But this got nothing to do with Sharks!
The principal threats to oceanic ecosystems are probably Climate Change, Acidification, Overfishing, Pollution and Habitat Degradation – not the fisheries for Sharks!
It is just not plausible and there is certainly no scientific evidence indicating that if one selectively removed all Sharks
- the oxygen production would cease due to the disappearance of phytoplankton
- the oceans would cease to be a carbon sink
- the weather would change
- fisheries would collapse and humankind would starve
or any other similar stupidities that happen to be en vogue among some Shark activists!

Shark Intelligence?
This very much smells like the newest up-and-coming Shark conservation fad.
Does the fact that some Sharks migrate and that they are capable of memorizing locations automatically mean that they are particularly intelligent? Why are some quarters asserting that it is so, when this is in no way being claimed by the authors of those migration papers?
Sorry Richard – I still think you rock! ;)

Are Monarchs particularly intelligent? Wildebeest?
What about Bees who are not only capable of finding and memorizing the location of a food source, but then also fly back to the hive and convey that information to the other bees – so effectively. that those other bees can find the food without being guided there by the finder?
Hell, that’s even smarter than what we know about the so much hyped Dolphins!

Frankly, I dunno.
My gut tells me that migration and spatial orientation are not good indicators for intelligence. Yes it is amazing behavior – but animals doing amazing things are more often than not simply well adapted to their ecological niche, and behavior that comes across as being remarkably clever is often hard wired and the result of evolutionary selection as opposed to volition.
Example? The amazing Anglerfish!
Perfectly camouflaged and provided with an ingenious lure, they are highly successful at ambushing their unsuspecting prey. Totally clever – and yet one of my ichthyological gurus assures me that they dispose of the lowest brain-to-body mass ratio of all Fishes!

Sharks BTW have a relatively high brain-to-body mass ratio, somewhere between Teleost Fishes and Mammals..
But although we all intuitively know what intelligence means conceptually, it is nevertheless difficult to define, especially in animals - and even more difficult to compare, see the Bees and the Dolphins!

When it comes to Sharks, the one person who knows most about the topic is probably Doc who has demonstrated remarkable learning and problem solving capacity in Lemons, very much in line with what we experience daily with our Bulls.
My gut feeling is that as always, different species will display different abilities, and that those predatory species with the widest trophic niches requiring the widest range of predatory strategies and thus the highest adaptive capabilities will be perceived as the most intelligent - but then again, a friend may be on to something when he remarks
Incidentally, since humans filled a generalist predator niche at one time before we graduated to planetary predator class, would we not inevitably tend to think that other generalist predators like sharks are particularly intelligent?
Yes, it's complicated!

Still, I fully agree with Wolfgang that Tiger Sharks come across as being way smarter than, say, Whale Sharks that I incidentally perceive as being particularly dumb - and who incidentally migrate like crazy!

But those are clearly personal perceptions, not objective data.
Whereas I’m convinced that all of our Bull Sharks have distinct personalities and that they develop affinities to specific persons, I also know that we humans have a fatal propensity for anthropomorphism, i.e. for attributing human faculties to animals.
So, yes, let’s love them like crazy – but let us not assert that our feelings are being equally reciprocated, or the like!
Yes Emma very much appears to love Jim (and there’s absolutely no doubt whatsoever that Jim loves Emma!) – but she is very likely being bribed with massive amounts of juicy handouts and is just being the opportunistic feeder Tiger Sharks are!

Having said that, there appears to be clear evidence that the behavior of some Sharks goes well beyond that of mere automatons that are solely driven by genetic programming.
In fact and going back to, say, Tigers and Bulls, aren’t high flexibility and adaptive capability precisely what we would expect evolution to select for in a generalist predator – meaning that some of what we perceive as being intelligent behavior may be genetically encoded, but that there must also be scope for individual decision making, individual learning, individual preferences, individual personality, etc. which may indeed be good indicators for intelligence.
Again, I don’t know - but precisely because of that, I would never proffer any strong statements one way or the other!

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 - see on top!

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 neither omniscient nor 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!

Or, as I said before .

Can we maybe just be a little more humble and less righteous, the more since Conservation is so complicated?
Maybe progress towards more facts and less truthiness (read this!)?
Can we maybe just open our eyes and wonder at the magnificence of what IS instead of trying to make things up?

We are the amateurs.
Can we please listen to what the professionals are telling us – the principal message being that extreme positions (on both sides!) are inhibiting Conservation and appropriate Management measures?
Recent example? Right here – like it or not, the man has a point!

If we want to educate others – let’s educate ourselves first!

And here endeth the weekend rant!

PS Patric's take: WOW!!!

Scanning the Horizon

Caribbean Lionfish Hunter (yup this is a link)

A large group of smart people have gotten together this September and defined some nascent conservation issues for 2010, both threats and opportunities.

The resulting paper is called A Horizon Scan of Global Conservation Issues for 2010 and you can download it here, and yes, as you should, you would have to pay for that. Or, you may want to consult the useful synopses posted on Conservation Bytes and Planet Earth Online.

It spans a list of 15 topics, some of which surprising like International Farmland Acquisitions by foreign governments, some somewhat obscure and eclectic like the effects of Nanosilver in Wastewater, some visionary as in Synthetic Meat or releasing Aerosols into the Stratosphere to combat Global Warming to outright scary as in Artificial Life.
In very general terms, they all illustrate the complexity of our environment and the vast, and often totally unexpected ramifications of our actions upon it.

As in the case of the Lionfish invasion of the Western Atlantic.
Likely the progeny of aquarium pets that escaped or were discarded in Florida during the early nineties, they have completely overrun the Caribbean and are inexorably threatening South America.

You can check out the progression here.

This what the paper says (links are mine).

Invasive Indo-Pacific Lionfish.
Small numbers of predatory Indo-Pacific lionfish (mainly Pterois volitans) were first recorded in waters along the eastern coast of the United States in 1992 .
The source of introduction is uncertain. The rate of lionfish range expansion was initially slow, but increased markedly after the colonisation of Bahamian coral reefs in 2004.
Lionfish are now established throughout most of the northern Caribbean and have been recorded as far north as Rhode Island and south to Colombia. Where they are established, lionfish are found at densities far exceeding those reported for their native range (e.g. > 390 lionfish/ha in the Bahamas compared to about 80/ha in the Red Sea).
Lionfish grow to a maximum length of about 45 cm, and prey on a wide variety of fish and invertebrates. On experimental reefs in the Bahamas, young lionfish reduced the recruitment of native coral reef fish by nearly 80%; the effects of lionfish on natural reefs are still unmeasured.
Lionfish are protected by venomous spines, and while small lionfish can be eaten by large groupers, such predators are rare throughout the Caribbean.
Lionfish are, however, now being fished and offered on the menu of some Bahamian restaurants.

The pests obviously have no "natural" predators in the Caribbean and the local predators that could fulfill the role of regulating their population, like the larger Groupers and the Sharks, are severely depleted. I fear that despite of the valiant efforts of those who promote fishing and eating them (nice collection of recipes here), they are there for good, like, say, the cane toad in Oz (and alas, in Fiji as well).
Maybe, eventually, the Lionfish populations will somewhat balance out, the more as there is evidence that all individuals are the descendants of very few females and that, at least in theory, after experiencing such a severe population bottleneck, they would eventually have to crash back to their effective population size, like the Cheetahs. Maybe, some local predators, parasites or pathogens will learn to exploit the new resource and thus keep the numbers in check.
But it sure is a very very long bet and not likely to happen anytime soon, at least not soon enough to be of real practical use.

Thing is that ever since we've "evolved" to become a global nuisance, these migrations and infestations have become so frequent to constitute the norm rather than the exception.
Just think about our animal baggage, be it domesticates, many of which have gone lethally feral, stupidly introduced species like Fiji's ubiquitous and invasive Minah and Mongoose, or unwanted followers like the Norvegian Rat or the Bedbug. Or the plants, be it agricultural or ornamental, like the Traveller's Palm I'm looking at whilst writing this is Fiji - originally, endemic to Madagascar!

And recently and as always, mostly unwittingly, we've started meddling on a truly epic scale.
By building canals we've created highways for marine invasions between the Med and the Red Sea and between the Pacific and the Caribbean. By heating up the planet, tropical pests like disease-bearing Mosquitoes, Rodents and Fire Ants and pathogens are ever expanding (and check out this example of how anthropogenic marine invasions are affecting Great Britain) and according to the above mentioned paper, there's a risk that as the Arctic melts, it will lose its function as a barrier between the Atlantic and Pacific Oceans, with unknown consequences for those two ecosystems - as in: adios Deadliest Catch!

Anyway, I'm ranting as usual.
All I wanted to say is that it sure is complicated and always interconnected - and that we should never forget that Marine, and Shark Conservation are but one facet of a much bigger and alas, equally bleak picture.

OK, back to the Sharks.

Connected!

Have you read Predators as Prey?
If not, download it now!

Here's another very actual example from the Caribbean.

Sharks, barracuda and other large predatory fishes disappear on Caribbean coral reefs as human populations rise, endangering the region's marine food web and ultimately its reefs and fisheries, according to a sweeping study by researcher Chris Stallings of The Florida State University Coastal and Marine Laboratory.

“I examined 20 species of predators, including sharks, groupers, snappers, jacks, trumpetfish and barracuda, from 22 Caribbean nations,” said Stallings, a postdoctoral associate at the FSU Coastal and Marine Laboratory. “I found that nations with more people have reefs with far fewer large fish because as the number of people increases, so does demand for seafood. Fishermen typically go after the biggest fish first, but shift to smaller species once the bigger ones become depleted. In some areas with large human populations, my study revealed that only a few small predatory fish remain.”

“Large predatory fish such as groupers and sharks are vitally important in marine food webs,” Stallings said. “However, predicting the consequence of their loss is difficult because of the complexity of predator-prey interactions. You can't replace a 10-foot shark with a one-foot grouper and expect there to be no effect on reef communities. Shifts in abundance to smaller predators could therefore have surprising and unanticipated effects."

Surprising indeed!
Did you read the post over at Shark Diver about the Lionfish invasion of the Caribbean?
It proposed that one should start marketing them as food, a suggestion that ties in beautifully with centuries of Southern French cuisine where any self-respecting bouillabaisse contains a generous helping of delicious rascasse, or Mediterranean Scorpionfish.

Here's what the original paper (read it!) says.

Predicting the ecological consequences of changes to the structure of predator communities is difficult. Different sized predatory fishes may perform various functional roles and can have drastically different effects on the diversity and abundance of prey species. Furthermore, loss of functional roles can lead to decreased ecological stability and ecosystems can become both less resilient to catastrophic phenomena such as cyclones and less resistant to invasions by exotic species.

The recent invasion of Indo-Pacific lionfishes (Pterois volitans and P. miles) in the Caribbean may have been facilitated by overfishing large predators capable of controlling their rapid spread and population explosion and is alarming considering the strong predatory effects lionfish can have on native fishes.
Management of human impacts on entire functional groups may therefore be more important than targeting specific taxa but tests of functional redundancy among predatory marine fishes is sorely needed. In addition, incorporating the effects of environmental variation, multiple human stressors, and linkages in interaction webs with socioeconomic factors that lead to overfishing may improve management and conservation in coral reef systems.

There you have it: everything is connected.
Next time anybody asks you, tell them 'bout the Lionfish!