Global Warming from fishing and aquaculture

[anonposter]

I'm having trouble actually finding anything about how much global warming seafood production causes which seems to be quite a big gap in knowledge.

I'll just try to guess as best (or least worst) as I can.

For ordinary fishing I'd expect the diesel fuel used by the boat to catch them to be dominant as the growth of those fish is natural and so not counted among human caused additional emissions but that's just a guess (of course we are fishing at a rate beyond which the fish are being replaced).

For aquaculture you'd need to grow everything from the plankton up so an accounting similar to what you'd do with livestock would need to be done. I personally suspect it'd be less than livestock (I'm thinking less methane) but I can't really back that up.

Then there's the question of what we could do to reduce said emissions (personally I'd focus more on aquaculture as we're going to have to abandon large scale fishing, just as the vast majority of us no longer hunt).

[davidm]

It would seem to be self-evident that global warming is both a cause of the problems imparted to and effect from the fossil fuel etc. inputs associated with fishing and aquaculture, more the former. And of course the challenges attendant to wild harvesting and fish farming would to a large degree be driven by increased population demands. And this leads to international tensions. No small part of the piracy problem off the Somalia coast has to do with outside nations coming in and stripping them of their fish stocks.

Aquaculture involves a race between the problem of robbing Peter to pay Paul and real sustainable growth. I'd say the longer term jury remains out.

Today, nearly one-third of the fish we eat is not captured in the wild, but raised in a fish farm. However, as aquaculture gains importance in the modern food supply, there are growing concerns about the damage that it can cause to water quality, biodiversity, and ocean fish stocks.

I'm suspicious of one more techno-fix which accepts the sacrifice of the oceans and wild catch to be substituted more and more to fish and shellfish farming.

Here's just one example of an environmental problem.

In just 6 years, from 1987 to 1993, Thailand lost more than 17 percent of its mangrove forests to shrimp ponds (Holmes 1996:36). Destruction of mangroves leaves coastal areas exposed to erosion and flooding, and has altered natural drainage patterns, increased salt intrusion, and removed a critical habitat for many aquatic species (Iwama 1991:177-216). According to one estimate, for every kilogram of shrimp farmed in Thai shrimp ponds developed in mangroves, 400 g of fish and shrimp are lost from wild captured fisheries (Naylor et al. 2000:6).

[anonposter]

May 12, 2012 0:42:49 GMT 9.5 @davidm said:

It would seem to be self-evident that global warming is both a cause of the problems imparted to and effect from the fossil fuel etc. inputs associated with fishing and aquaculture, more the former.

That isn't quite clear.

May 12, 2012 0:42:49 GMT 9.5 @davidm said:

And of course the challenges attendant to wild harvesting and fish farming would to a large degree be driven by increased population demands.

Yes, if you have more people to feed then you do have to do things on a larger scale (and it seems that wild harvesting can't cope with the scale we'd need, it certainly isn't coping now).

May 12, 2012 0:42:49 GMT 9.5 @davidm said:

And this leads to international tensions. No small part of the piracy problem off the Somalia coast has to do with outside nations coming in and stripping them of their fish stocks.

It largely originated from that (and also dumping of toxic waste), whether solving that problem would make it go away is another matter.

May 12, 2012 0:42:49 GMT 9.5 @davidm said:

Aquaculture involves a race between the problem of robbing Peter to pay Paul and real sustainable growth. I'd say the longer term jury remains out.

Aquaculture can be done in a way which is environmentally destructive (everything can), certainly catching wild fish to feed the farmed ones is a bad idea (we grow all the grains we feed most livestock, I don't see why fish farms can't grow their own plankton).

Today, nearly one-third of the fish we eat is not captured in the wild, but raised in a fish farm. However, as aquaculture gains importance in the modern food supply, there are growing concerns about the damage that it can cause to water quality, biodiversity, and ocean fish stocks.

Those are likely issues which can be dealt with. For example we could try:

• Only feeding the fish what they need so that less excess nutrients end up in waste.
• Building treatment plants to clean up the waste water.
• Not feeding farmed wish wild fish.
• Genetically modifying farmed fish to be more productive (we haven't really selectively bred most of the seafood we eat to the degree we have crops and livestock so there's probably a lot of room for improvement here).
• Moving aquaculture to the middle of the ocean (e.g. a seastead).

May 12, 2012 0:42:49 GMT 9.5 @davidm said:

I'm suspicious of one more techno-fix which accepts the sacrifice of the oceans and wild catch to be substituted more and more to fish and shellfish farming.

I don't see any other option if we're to keep what fish are in the ocean from extinction (otherwise they'll be overfished to extinction, the fisherman will still be able to find the fish if they exist no matter whether or not they are endangered).

In just 6 years, from 1987 to 1993, Thailand lost more than 17 percent of its mangrove forests to shrimp ponds (Holmes 1996:36). Destruction of mangroves leaves coastal areas exposed to erosion and flooding, and has altered natural drainage patterns, increased salt intrusion, and removed a critical habitat for many aquatic species (Iwama 1991:177-216). According to one estimate, for every kilogram of shrimp farmed in Thai shrimp ponds developed in mangroves, 400 g of fish and shrimp are lost from wild captured fisheries (Naylor et al. 2000:6).

Land use is probably going to be the dominant environmental issue with aquaculture (then again, agriculture is the same).

[BNC Moderator]

Is sustainable aquaculture an oxymoron? Aquaculture can be a positive force in the marine environment

Appropriate for this thread?