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Old 05-07-2012, 07:55 PM   #51
jfjf
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Join Date: Oct 2003
Location: Palm Bch County
Posts: 11,256
Re: Goliath Jewfish Redux

Quote:
Originally Posted by Shaft'o'death View Post
I do agree with you Jim.. To assume that just because there are tons of other fish on the reef, swimming around, not being eaten, it does not mean that GG do not eat them at some point.

But, if that is the case, then the inverse must also be true.. Just because there is a lack of life on a ledge or wreck, other than GG, it does NOT mean that the GG ate them.. Correct?
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Yes of course. I'm not sure why my comments are categorized as inciteful and found to be hard to interpret.

If we are to believe the scientists (and I do)... the GG are eating LOW on the food chain. They are not eating high level predators like grouper and snapper. They are eating crustaceans (crabs and lobsters) but they are also eating fish other than the ones we are after (for the most part).

The studies examine the actual contents of the fish guts.. I myself have performed literally thousands of fish gut content examinations (although on much smaller fish than GG), these types of studies involve identifying prey items from simple visual observation.

However, other studies look at isotopic ratios in the tissue of the fish.

I would have to look it up, but basically the fish are what they eat, and this type of isotopic analysis does not tell exactly what they are eating, but gives sorta an average view of what level in the food chain they primarily derive food from. I'm too lazy to look up isotopic analysis methods, I'm sure I've butchered the explanation to a considerable extent, but it has been used by ecologists to study broad ecological (trophic) relationships for a long time.

I'm sure it varies on a lot of environmental factors and the size of the indivdual etc., but I have to believe them when they say the jewfish are not eating the predators (much). Kinda like when scientists say carbon dating says this or that... Either we believe the science (for the most part) or we just disregard it because it doesn't match our preconceived notion of reality. But few of us have the scientific background to question this stuff with any type of rigorous argument.

So if the scientists are mostly right and are not liars, then how come I have fish "stolen" from me when freediving all too frequently? There is absolutely no denying that these guys are stealing a lot of desirable fish from fisherman. How do we reconcile the glaring contradiction between what we see with our own eyes and what some scientists tell us?

I think the answer is simple really, they take top level predators off our lines and spears, because that is what WE target. They are opportunistic and will take cudas off the shaft too, but I doubt that they normally catch many 3-4 ft cuda in a natural setting. The fish are injured and compromised and struggling and the GG are turned on and take them, but..... on a global scale it does not constitute the primary diet of the jewfish... incidental take so to speak...our observations are not representative of the "natural" relationship.

To say that because we now see less gags and more jewfish on a reef is proof that this is a cause and effect relationship is not very scientific. Similarly, I have video of a bunch of black grouper and big snappers hanging around jewfish on a wreck (in close proximity to each other). This video does not prove they they never prey on the black grouper. These are just anecdotal observations that should not be taken out of context or extrapolated to a cause and effect.

OBVIOUSLY human fishing pressure has heavily impacted the snapper/grouper population, but I think we have to rely on the scientists to tell us that these are not the primary food source for the jewfish.

The reality of the situation is that GG are a major nuisance in some areas to fisherman. I don't support the idea that we need to "thin the heard" so we will have more gags next season.

I also don't support the idea that jewfish should be protected indefintely with zero take allowed by legitimate and legal fishing.

It seems that everyone agrees that the GG are being deliberately killed now to some considerable extent. My personal belief is that it makes more sense to work toward a future goal of developing a very small and sustainable (and legal) fishery rather than to forever resign ourselves to allowing only those who risk prosecution to take them.

I also think that many fisherman might be more willing to accept the nuisance interactions if they felt that the regulators would eventually re-open the fishery, if and when it can be sustained. If the prevailing thinking within the fishing community is that "the man" will NEVER allow them to be taken, no matter what density they attain... well then it is not hard to understand why some people will decide to "thin the herd now"...
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