Fish Survival in Aquariums vs. the Ocean

[greenbean36191]

I also am not clear on exactly which herbivorous fishes were depleted by overfishing. Has this been established through systematic study?

Parrotfish and tangs mostly. Chubs and damsels to a lesser extent.

I'm far from an expert on this matter and most of the work on the subject is ancient, so I don't know the definitive studies on the issue of herbivore depletion.

However, Munroe collected tons of fisheries data from the 60s through the 80s. A lot of it can be found here: http://books.google.com/books?id=yu...resnum=1&ved=0CAwQ6AEwAA#v=onepage&q=&f=false
The bulk of it though is only available through the Jamaican government.

This paper also used traps to sample community composition over time at historically exploited vs. recently exploited reefs: http://www.int-res.com/articles/meps/43/m043p201.pdf

Browsing through the citations in Jeremy Jackson and John Pandolfi's work should also give you some leads but I don't have the time to scour them tonight.

 

[greenbean36191]

Oops, I thought I answered your question about the urchin plague, but I guess I left it off.

All that's really known about it is that it was first spotted in Panama in 1983 and from there moved clockwise around almost the whole Caribbean, which is the direction the currents flow. There was almost 100% mortality among infected urchins and by 1984 when the outbreak ended, more than 97% of of the urchins in the Caribbean had been wiped out. It's assumed some sort of pathogen was the causative agent, but since it swept through and moved on so rapidly no one was ever able to isolate or identify it.

It's not clear why some pockets survived. It may have just been due to local water flow that prevented the pathogen from getting to some locales or some populations may have been naturally resistant to it.

 

[ackee]

Thanks for the links and references. I muddled part way through Koslow, looking mostly at his data tables. Munroe I have, so I pulled it out and went through it with more care.
The interesting thing, though, is that neither source (I've also seen J'can fisheries data) address an issue which is of crucial importance to the overfishing theory. The sequence in that theory, as I undersatnd it, simplified and briefly outlined, is:


Large predators are fished out; fisherman catch an increased number of other fishes to maintain their catch volume; the removal of a significantly increased number of herbivorous fishes weakens the reef's algae removal potential. When the mysterious urchin plague strikes, and that remaining significant algae eater nearly vanishes, the fish that formerly had been an important part algae removal are, because of overfishing, no longer around in sufficient numbers to pick up the slack, consequently algae proliferates with all of its deleterious effects on corals.


The missing but absolutely vital element in what I've seen so far is data demonstrating that there was some measurably significant increase in the quantity of herbivorous fish caught by fisherman, with a demonstrable decrease in the numbers of these fishes on the reefs. I was not able to find this issue addressed in anything I've read. I've only seen it mentioned, as if it were Q.E.D.

Because the overfishing theory has little validity without this kind of comparative data, I'm confident that it must have been demonstrated conclusively in places I have not yet read. After all, a significantly decreased number of herbivorous fishes is a central assumption in establishing the sequence as described. Lists of catches made long ago have no real significance in that connection, especially when the comparative data in them is primarily locational and operational. In any case, the species lists mentioned in the stuff I waded through last night seem to slightly resemble the informal list I mentioned in another post.

I will certainly follow your suggestion to check references cited in the two papers you initially mentioned, and also to follow relevant citations I may discover in those papers, an endless but essential process with which I am quite familiar, though in another discipline.

Thanks again for your time and efforts. You are most generous.

 

[KarlBob]

Wow. This thread has come a long and winding way from

"Has anyone looked to compare survival rates of fish in the wild vs. captivity?"

through

"Reef collecting is a sham target, a comparatively harmless activity, used to deflect attention from {other} things."

to

"The missing ... element ... is data demonstrating that there was some ... increase in the quantity of herbivorous fish caught by fisherman."

The fact that this group has been able to cover that much territory without having the thread closed by the mods is a triumph of civil debate over the temptation to devolve into a frothing-at-the-mouth flamewar.

Note: My example quotes were taken from posts #1, 31 and 63 on a purely mathematical basis (beginning, middle, end), not because I agree or disagree with the quoted posts.

 

[cortez marine]

As in captivity and in the wild, survival rates depend on the quality of the environment the fish are in.
The discussion was all about quality of environments.

But, if the question were how long do fishes survive in captivity compared to the wild, how do you answer without the species by species reference?

What are we talking about here ?
Pinnatus batfish or porcupines?
Banded angels or passers?
Philippine bicolors or Tongan?
Many fish given the same quality care last a lot longer in captivity.
Others with more extreme dietary requirements may not.
Many fishes caught properly last a lot longer in captivity.
Others collected with extreme methods may not.
Fishes decompressed properly may live their age potential.
Fishes not decompressed properly may not.
and so forth...

All things being equal....some species live longer in captivity and...some species do not.
But, to take it seriously, the question is too broad in scope to illuminate the terrain in which we find ourselves deployed and as such cannot be taken seriously.
Such lack of definition in the original question allowed it to wander.

But, the thread was very educative and constructive nonetheless.
Steve

 

[skibum9884]

sorry for asking such a broad question. this thread certainly has wandered a lot, but has been extremely interesting and informative, and like Steve said, has been constructive!

 

[ackee]

I agree that the discourse has been, though heated at times, basically civil. This demonstrates a remarkable flexibility and insight from the site's administrators, and a professional approach by those involved, with the possible exception of myself.

I have seen and am aware of much academic research done for its own sake, in response to various professional pressures, and not simply in pursuit of the advancement of science. Many fields of study are dominated by 'big dog' researchers with the ability to direct research, affect the careers of graduate students, and in general impose their vision on junior researchers, along with occasional appropriations of their work. The cast of characters in these academic dramas changes as various paradigms wax and wane.

I certainly did not intend at any time to suggest that anyone participating in this discussion was less than absolutely honest. I would not, however, extend that assessment to the overall field of scientific research, which is as corrupt as most other fields of human activity. If I seemed a bit cutting at times, it was in response to what sounded like certainties regarding a field in which a great deal is completely unknown, and which has seen emphemeral theories come and go, with echos of things long abandoned surviving because their quondam champions continue to hold influential academic positions.

I have no idea if the current theories described by Greenbean are accurate. As I read more in this area, it seems that some elements may be a trifle flimsy. This is in part due to the difficulty of gathering data in areas that by their nature resist quantification, and in part because of my lack of expertise.

There are multiple theories regarding coral reef problems circulating in the world of scientific research. Some are complimentary, and some are not. One of the more interesting theories concerns the massive dust storms that arise in Africa and deposit fine dust particles all over the Caribbean. It has been demonstrated that this phenomena has existed for millins of years, but it has also been demonstrated (Shinn, Prospero, et al) that during the last 50 years these dust particles have become saturated with man-made toxins derived from chemicals used in agriculture and pest control, and that many problems, including the urchin plague, have occured during particularly heavy toxic dust clouds events.

My guess is that many of the various theories have at least partial validity, and that their convergences will illuminate phenomena still poorly understood. Natural systems are dauntingly complex, and resist easy explanations or descriptions.

 

[KarlBob]

My guess is that many of the various theories have at least partial validity, and that their convergences will illuminate phenomena still poorly understood. Natural systems are dauntingly complex, and resist easy explanations or descriptions.

I think this is the case more often than we know. Top-down forces caused by wiping out a high-level predator might cross paths with bottom-up forces caused by a problem very low in the food chain, and critters in the middle could be affected to a degree that seems all out of proportion to either of the potential causes. Some researchers may take sides and cheer for one explanation or the other, but it might take two or three theories at the same time to fully account for the end result.

Yes, it's true that science has its share of personality conflicts and dogmatic fights to the death, but in the end, the evidence usually outweighs the opinions. Sometimes the truth doesn't come out until long after the shouting's over, but that's just the way it goes.

I'd still rather be a biologist arguing with another biologist about the proper classification of a cave cricket than be a politician trying to change another politician's vote on a hot-button issue like abortion or tax policy.

 

[shroutk3]

I didn't read all the posts. But I can say that not all fish taken off of a reef are a loss. If survival in captivity is high, that fish will take the spot of another fish that would be removed. Similar to an altruistic action. That fish in captivity surviving means that another fish in the ocean won't likely be sought by that particular aquarist (lower demand should equal less harvest). If fish don't die, but do get traded between individuals a single fish may satisfy the desire of many aquarists over a 5-20 year lifespan.

 

[KarlBob]

I didn't read all the posts. But I can say that not all fish taken off of a reef are a loss. If survival in captivity is high, that fish will take the spot of another fish that would be removed. Similar to an altruistic action. That fish in captivity surviving means that another fish in the ocean won't likely be sought by that particular aquarist (lower demand should equal less harvest). If fish don't die, but do get traded between individuals a single fish may satisfy the desire of many aquarists over a 5-20 year lifespan.

If I read that correctly, you're saying that removing a "delicate" fish is worse for the reef than removing a "hardy"* fish, because many aquarists will keep replacing the dying fish, but they won't order replacements of the fish that lives.
* "Delicate" or "hardy" in captivity, that is.

I've seen some fish traded, but far less often than coral frags. I think that a single removed critter can satisfy more aquarists through reproduction (fragging of corals or captive breeding of fish) than through sequential trading.

I wonder if anyone has noticed a measurable decline in the number of a given species caught in the wild (Banggai cardinals, for instance) after captive breeding programs become well established.

 

[cortez marine]

I wonder if anyone has noticed a measurable decline in the number of a given species caught in the wild (Banggai cardinals, for instance) after captive breeding programs become well established

Zero diminished demand for wild ones.
Zero.
Wild ones have never been offered in such volume and so cheaply as now.
In fact, some wholesalers have offered them at lower prices then P.J. cardinals!
Steve

 

[KarlBob]

In fact, some wholesalers have offered them at lower prices then P.J. cardinals!
Steve

Wow. That sure hasn't trickled down to the retail level in my neck of the woods. The only ones I've seen for sale lately here in Phoenix are tank-bred, and they're definitely more expensive than pajamas.

 

[cortez marine]

Just because a store gets a deal doesn't mean he passes it down the line! :]

 

[shroutk3]

If I read that correctly, you're saying that removing a "delicate" fish is worse for the reef than removing a "hardy"* fish, because many aquarists will keep replacing the dying fish, but they won't order replacements of the fish that lives.
* "Delicate" or "hardy" in captivity, that is.

I've seen some fish traded, but far less often than coral frags. I think that a single removed critter can satisfy more aquarists through reproduction (fragging of corals or captive breeding of fish) than through sequential trading.

I would tend to stay away from hardy versus delicate. In most cases fish death is likely due to improper knowledge of their requirements. Any fish that has its needs met should be able to survive. Its the feasibility of a particular aquarist meeting a particular fishes needs that causes conflict. I do however agree that a desire for species whose needs aren't being met would lead to continual over harvesting.

My point was though that fish surviving in captivity could actually prevent the removal of more of their particular species. I have a scooter blenny in my tank. He does awesome. I don't need another one.

In the end though I'm skeptical of aquarium harvest having such a big impact. It seems that most techniques are fairly targeted and low numbers. I lived in the Galapagos Islands and the destructive fishing techniques used there involved unrestrained harvest because the consumers for those products didn't care about quality (they ate things). The aquarium trade has to be much better though. We want live fish (and most people want fish with requirements that can be met so they don't waste their money) which come from healthy reefs.

 

[KarlBob]

In the end though I'm skeptical of aquarium harvest having such a big impact. It seems that most techniques are fairly targeted and low numbers. I lived in the Galapagos Islands and the destructive fishing techniques used there involved unrestrained harvest because the consumers for those products didn't care about quality (they ate things). The aquarium trade has to be much better though. We want live fish (and most people want fish with requirements that can be met so they don't waste their money) which come from healthy reefs.

I tend to agree, in general. From what I've read, modern aquarium collecting seems to be aimed at snagging the fishes that customers want to buy, and leaving the rest in the ocean. It's expensive to haul around "junk" fish that nobody wants to buy, and that expense cuts into profits. Edit: There are people involved in this thread who have forgotten more than I've ever known about fish collection, and I'll defer to them 100% regarding the actual collection methods.

One problem that crops up is when some obscure fish that's only found in one square mile of reef near one island in the entire world becomes "this season's hot seller," like it was a trendy pair of sneakers or a designer handbag. When worldwide demand suddenly focuses on a tiny wild population, it can cause trouble. It's logical to assume that taking one adult fish out of a robust population will leave an ecological hole that will be filled by the next larval fish to drift into the unclaimed territory. Taking as many adults as you can find out of a severely limited population is a different matter, with different results.

Could people legitimately blame the aquarium hobby if "this season's hot seller" was hunted from a small, stable population to an endangered species? Yes. Is that the case with every reef fish that has gone through a population crash? Of course not.

A couple of examples: If, hypothetically speaking, reef-keeping demand were to drive the Banggai cardinal into extinction, that could be laid at our collective doorsteps. On the other hand, reef degradation off the coast of Haiti probably owes a lot more to poverty-driven overfishing, pesticides, lack of proper wastewater treatment, forest destruction, and mudslides than to aquarium collectors.

 

[greenbean36191]

The missing but absolutely vital element in what I've seen so far is data demonstrating that there was some measurably significant increase in the quantity of herbivorous fish caught by fisherman, with a demonstrable decrease in the numbers of these fishes on the reefs. I was not able to find this issue addressed in anything I've read. I've only seen it mentioned, as if it were Q.E.D.

Well you almost never get a 100% open and shut case with fisheries since usually no one bothers to monitor what's going on until they suspect there's a problem. There's usually no clear baseline. Plus, like I mentioned, these are probably not the definitive papers on Jamaica. However, especially given how old the problem is, these two papers alone make a pretty strong case.

They show that the landings in Jamaica were more than elsewhere in the Caribbean and far exceeded what fisheries models predicted as the sustainable production. They showed that catch per unit effort was declining, which is a classic indicator of overfishing. Based on life history data and trap sampling they also showed that too many fish that were being caught before they had a chance to reproduce to allow for a stable population. Not only that, parrotfish and tangs were among the top families of fish caught in the traps both by number and by weight- making up 40% of the catch along with grunts. There was also a decline in most of the target families that was correlated to change in fishing intensity across sites over time. In tangs in particular there was also a decrease in size with fishing intensity, another classic sign of overfishing.

So there are numerous bits of evidence pointing to a general overfishing problem, sampling indicating that two of the most important herbivore families were among the most caught, and reductions in abundance and size of those fish coincident with changes in fishing pressure. It's not an airtight case, but there aren't many other plausible explanations.

 

[ackee]

That there is and has been signifant overfishing I never questioned, and the effects have been many and varied. It may well be that overfishing is the cause of excessive algae growth and the consequent destruction of coral communities, but there are a few validating studies that, if not already part of the literature, ought to be.

Specifically, I think comparitive data must be developed between heavily overfished islands that have not experienced excessive development, and equally overfished islands that have experienced pollution caused by untreated effluent discharge from recently built seaside town, from construction, and tourist hotel and road development.

If it turns out that there are marked differences in algae growth between the two types of areas demonstrating much less algae growth in overfished but not overdeveloped islands,
(there are plenty of examples in both categories) then ascribing overfishing as the primary cause of choking algae overgrowth due to the sequences it theoretically engenders, should probably be reexamined, at least to explain the seeming inconsistencies. If, on the other hand, badly overfished but undeveloped islands show the same kind of algae growth due to missing herbivores (allowing for any differences in urchin population) then the overfishing theory is supported.

I'm not convinced that pollution alone is the cause, any more than I totally accept the overfishing explanation, and for similar reasons. I also do not presume to know in which directions research ought to go. I offer only my amatuerish opinions.

I'm also curious to know the current status of research regarding the African dust clouds that have grown increasingly toxic. The theory may have been abandoned, or simply fallen into disfavor. Perhaps it is still a player. If so, how do the various theories inform and affect one another?

I appreciate your most helpful efforts.

 

[KarlBob]

Specifically, I think comparitive data must be developed between heavily overfished islands that have not experienced excessive development, and equally overfished islands that have experienced pollution caused by untreated effluent discharge from recently built seaside town, from construction, and tourist hotel and road development.

If you really want to know the relative contributions of overfishing and development, you're halfway there. You also need to find two more examples: An island that has been developed but not overfished, and one that has been neither overfished nor developed. If you find an example of that last category, don't tell anyone where it is!

Comparing {X and Y} to {X but not Y} doesn't allow you to compare the severity of X vs. Y. A valid comparison also requires {Y but not X} and {neither X nor Y}. The full 4-way comparison is the only way to pick up synergistic effects. If X and Y reinforce each other, then {X and Y} minus {X but not Y} does not necessarily equal {Y but not X}.

 

[ackee]

It can be even more complicated, KarlBob. Your four conditions model assumes that there are no other major variables that affect what is being tested.
There are essential differences among islands due to their formation. Some are ancient volcanic projections from the sea floor, others are actually continental sections detached through land subsidence, and still others are primarily limestone reef based. Uninhabited islands are among the most heavily fished, and there is the issue of 'upstream' pollution from nearby islands and from the mainland. Still, I see the incompleteness in the dualistic comparative model I described. It does not address the many possible issues which your model might raise.

Its focus is only on observing the effects of overfishing in two comparable islands, one substantially affected by land based human activity, and one not. Naturally, time elements also need to be comparable, in that the overfishing would have to been present for a similar period.

 

[ezcompany]

not to mention, for every 10 fish collected for our aquarium, in my best guess, 4 would be lucky to make it all the way to our tanks, let alone survive in them.