Raising fish in the ocean in net pens?

Seahorsewisprer · #1 01/08/2006, 07:14 PM

Hi, guys! QWe are having a heated discussion in the seahorse forum. I want the opinion of the experts!

Are fish raised in the ocean, in net pens, less healthy than fish raised in artifical conditions?

spawner · #2 01/08/2006, 07:25 PM

Suzy,

That depends, are these fish raised in open ocean, near shore waters? Fed what type of food? They could more healthy but less suited for the aquarium market. Sure is cheaper than raising them in tanks. Guess it has to do with the pen culture of seahorses. Clownfish being raised this way are coming very soon.

andy

Seahorsewisprer · #3 01/08/2006, 07:30 PM

I don't know. Somewhere in Sir lanka?

Wouldn't they eat the copepods and amphopods that are in the ocean?

David M · #4 01/08/2006, 07:36 PM

Been in those "discussions" before, too many hairs to split

Is a floating pen really much different than a hatchery with an open water system? Suppose it's a closed water system using nsw? Suppose it's a closed water system using artificial seawater but harvesting wild plankton to feed ?? You can hurt your brain trying to draw lines, I stay out of it now

Seahorsewisprer · #5 01/08/2006, 07:41 PM

OK, let me rephrase it...

A net pen, or any type of system using natural seawater with the zooplanton and wild plankton

VS

A closed in-home system using artificial seawater and being fed newly hatched brine shrimp?

spawner · #6 01/08/2006, 07:43 PM

Well it really depends, near shore waters are normally have parasties around, now do the fish get parsites, that I don't know with out looking at them. Do fish reared in pens always have some type of parasite load, no but lots of times they will. Can fish reared in tanks have parasites, sure, but these can be different types/loads.

If I was rearing fish, say in the tropics, I would give pens a shot, no power needed, cheaper easier for villagers to use. You would have to feed them if they were reared at any density.

That said those coming out of pens are no comparison to those being reared in tanks (price or quaility). They could very well could be full of nematods or other parasites, as many wild seahorses and other fish normally have. Tank reared fish generally are more adapted to life in tanks, pened reared fish are going to be cheaper to produce. If someone takes the time to acclimate them tank life, de-worm them if needed etc. then I don't see a problem with it. The real question be comes are they truely cultured, do they capture wild males and hatch out and rear juv. up for a few months and then sell them or are using captive broodstock. This is the same issue as cultured corals in the wild and in tanks.

Either fish is better than buying a wild caught fish, if you have the money go for the tank reared ones or find some that are well acclimated.

As long as the people selling them are open with the sourse, pen cultured or tank cultured people can make a good decision.

Seahorsewisprer · #7 01/08/2006, 08:00 PM

But, if the fish had pathogenic parasites, wouldn't it die before it got to us? Or would it be the shipping stress that tips the balance of it's immune system? Would the stress cause it to be overcome by a opportunist infection?

Would the NSW fish have more immunities and antibodies than the fish raised in artificial conditions? If it was exposed to fish from the ocean in our tank?

spawner · #8 01/08/2006, 08:14 PM

Quote:

Originally posted by Seahorsewisprer
But, if the fish had pathogenic parasites, wouldn't it die before it got to us? Or would it be the shipping stress that tips the balance of it's immune system? Would the stress cause it to be overcome by a opportunist infection?

not always. Kind of think of them as wild fish, but not taken from the wild. They are exposed to similar pathagens as wild fish, in wild conditions, not in a tank for life.

Shipping is a huge issue. 40 hours in a bag or more is not a good thing, but if fish are in good shape they make it all the time.

I would suggest that NSW is much better than any ASW mixture, given it comes from a clean source and properly treated. You can't replace NSW for its benefits you can come close but its not the same.

Maybe Todd and Doug can enlight us a bit more with regards to seahorses.

Seahorsewisprer · #9 01/08/2006, 09:12 PM

Thanks, Andy. I'll inforn the seahorse guys they hit the nail on the head!

David M · #10 01/08/2006, 09:13 PM

Oh crap. My head hurts already.

Spawner hit it though, collecting pregnant male seahorses and growing out the fry is NOT a captive breeding program. As long as the "farmer" is upfront about how the fish are raised the market will set the value compared to actual captive BRED or tank raised fish. Brain really in pain now, I see new industry terms like "pen raised" and "ocean farmed" fish

How about "Free Range" clownfish

We had a similar thread on Seahorse.org a few years back. There is/was a guy (Elizier) in Matzatlan raising seahorses in above ground pools on the beach with a constant flow of nsw. Technically the locally collected wild caught horses were "captive" in the pools and he did feed them so the fry he raised were "captive bred". I belive the species was H. ingens . He was able to bring some into the US at MACNA and as far as I know they all went to knowledgable and experienced sh.org'ers. I believe they all perished in short order and there was great debate about why. Someone on the RC seahorse forum might remeber that and dig it up for the rest of you.