Tang Police or Tang Nazis?

[asylumdown]

I would say that given that the aquarium trade removes about 1/1 millionth of the fish from the ocean that the commercial fishing industry does every year, and the damage we do to reefs by removing coral absolutely pales in comparison to the damage drag net fishing, or dynamite fishing, or cyanide fishing does to the reefs of the world, that the ethics of how damaging this hobby is to global ecosystems is a totally mute point if anyone here eats tuna.

Reefs in places that have something to gain from having a steady supply of healthy corals and fish to export to the aquarium trade and regulate it accordingly (Australia and Hawaii for starters) can actually benefit from an active aquarium trade. True not all places are like that, but that's why my elegance coral is Australian and not from the Philippines. Most species of fish on reefs reproduce in numbers greater than the niche market of the aquarium trade could really make a dent in, and in the cases where that's not true, it's usually the research that happens as a result of the aquarium trade that helps us find that out.

As for the ethics of keeping animals in glass boxes - that's always going to be a matter of opinion, but one would think that everyone here had to come to peace with that little conundrum by now.

[Aquattro]

Originally Posted by asylumdown

As for the ethics of keeping animals in glass boxes - that's always going to be a matter of opinion, but one would think that everyone here had to come to peace with that little conundrum by now.

Agreed. I guess my side of the fence feels that even though I've made peace with what I do, I'm not going to try and justify it with some story about research or saving fishies from sharks I am not a friend to the fish of the world (I eat tuna every day), but I'm ok with that.

[Youngster Dan]

Interesting read.

I only have one little issue with the article, with regards to measuring cortisol levels in the fish. It was stated that there wasn't really a difference in cortisol levels between captive fish (at various tank sizes) and fish in the "field". Now, I'm assuming you have to actually handle the fish to get a blood/cortisol sample?

Wouldn't the actual act of catching the fish induce stress (ie elevated cortisol) and so this stat is completely misleading? As every fish being tested is at an artificially elevated level of cortisol, and it being nearly impossible to take a baseline measurement?

[Aquattro]

Good catch Dan!

[asylumdown]

Originally Posted by Youngster Dan

Interesting read.

I only have one little issue with the article, with regards to measuring cortisol levels in the fish. It was stated that there wasn't really a difference in cortisol levels between captive fish (at various tank sizes) and fish in the "field". Now, I'm assuming you have to actually handle the fish to get a blood/cortisol sample?

Wouldn't the actual act of catching the fish induce stress (ie elevated cortisol) and so this stat is completely misleading? As every fish being tested is at an artificially elevated level of cortisol, and it being nearly impossible to take a baseline measurement?

I haven't read the article yet, but in my field (primate studies) we measure cortisol in feces and urine, with urine being the ideal source (try running through the forest with a giant funnel held over your head...). It's one of the easier hormones to study because of that fact actually. Not sure how they got their sample, but it seems to reason that they can probably get it passively

[daniella3d]

It may take a while before the cortisol level rise after a stress so they might have had plenty of time to take a sample without getting a stress response right away? could be.

then it could be that the fish returned to a normal level of stress after being handled so the stress hormones did not really rise. Maybe it take a constant amount of stress for this hormone to really show higher?

just my thoughts on it as I was wondering about the same thing when I read it.

Originally Posted by Youngster Dan

Interesting read.

I only have one little issue with the article, with regards to measuring cortisol levels in the fish. It was stated that there wasn't really a difference in cortisol levels between captive fish (at various tank sizes) and fish in the "field". Now, I'm assuming you have to actually handle the fish to get a blood/cortisol sample?

Wouldn't the actual act of catching the fish induce stress (ie elevated cortisol) and so this stat is completely misleading? As every fish being tested is at an artificially elevated level of cortisol, and it being nearly impossible to take a baseline measurement?

[don.ald]

Originally Posted by daniella3d

It may take a while before the cortisol level rise after a stress so they might have had plenty of time to take a sample without getting a stress response right away? could be.

then it could be that the fish returned to a normal level of stress after being handled so the stress hormones did not really rise. Maybe it take a constant amount of stress for this hormone to really show higher?

just my thoughts on it as I was wondering about the same thing when I read it.

statistics, well, they are just statistics! use them to create an argument/article and then defend it.
one can use this stat to show that fish are under constant stress...captive, in nature, or while being handled.
all i know is that the sale of tangs have increased dramatically since this thread was started

[shrimpchips]

http://www.reefmonitor.org/documents...rinol.%202.pdf

They do an assessment of cortisol and corticosterone levels from fecal matter, and find that baseline levels of aquarium acclimatized fish and reef dwelling parrotfish are not statistically different.

As for the testing of fecal matter vs direct (blood) measurement, they do both to validate the former method, and find that pooling fecal matter is an acceptable and useful metric for assessing stress hormone levels.

[Mandosh]

Originally Posted by daniella3d

It may take a while before the cortisol level rise after a stress so they might have had plenty of time to take a sample without getting a stress response right away? could be.

then it could be that the fish returned to a normal level of stress after being handled so the stress hormones did not really rise. Maybe it take a constant amount of stress for this hormone to really show higher?

just my thoughts on it as I was wondering about the same thing when I read it.

From what I know, cortisol levels in the average fish reach the highest levels around an hour after being stressed.

[shrimpchips]

Originally Posted by Youngster Dan

Wouldn't the actual act of catching the fish induce stress (ie elevated cortisol) and so this stat is completely misleading? As every fish being tested is at an artificially elevated level of cortisol, and it being nearly impossible to take a baseline measurement?

both fish are presumably caught and handled so that effect should not be a confound. If they can see a difference, and there's no change to their baseline measures (while they might not be true baselines), then it's a fine measure.


And the citation is more than likely to be generalizable to other fish - besides, it certainly isnt the biggest generalization of the literature. Assuming one large ref dwelling genus with a similar behavior acts and responds similarly with Tangs isn't a bad assumption.