Why Don't We Make More Fish ?

[mintyspilot]

The long running "Mass Plankton die-off" thread has raised some great idea and issues and one of the points was a documentary on the BBC about the state of fish in the oceans. The biologists on the documentary were generally upbeat.

This got me to wondering - why don't we simply make more fish?

Each fish lays thousands of eggs because only 1 out of a million (paraphrase) is expected to make it to being an adult fish. Most are eaten as eggs. Of those that hatch into fry another huge proportion get eaten.

Now it seems to me that humans can easily interfere here. If we simply lift some eggs, let them hatch and develop into fry and then put the fry back in the sea then we have bypassed the stage were most fish "lose their children". We could ensure that instead of 1 in a million, maybe one in a thousand eggs become a fish. I'm not talking fish farming in cages here - simply boosting the wild fish population.

If this was combined with marine reserves then it seems to me that we could restock the oceans quite quickly. So why are we not doing it?

[rakkor]

Some people are already doing this - Conserving Lobsters in Cornwall

National Lobster Hatchery

[anjou]

Its happening all round the world.
The Japanese eat more fish per capita than anyone and they understand the need to farm fish.

There is an epidemic of jellyfish north of Oz, but once the japanese find a recipie, even they will be endangered.
Several marine reserves which were set up only a short time ago have proved fish stocks can make it back from the brink if they are left alone.

[GordMay]

There are three basic types of fisheries enhancement (source: Bell et al., 2008):

Restocking — the release of cultured juveniles into wild population(s) to restore severely depleted spawning biomass to a level where it can once again provide regular, substantial yields. This may involve re-establishment of a species where it is locally extinct to rebuild a fishery, or for conservations purposes (i.e. conservation hatcheries).

Stock Enhancement — the release of cultured juveniles into wild population(s) to augment the natural supply of juveniles and optimize harvests by overcoming recruitment limitation.

Sea Ranching — the release of cultured juveniles into unenclosed marine and estuarine environments for harvest at a larger size in ‘put, grow, and take’ operations. Note that the released animals are not expected to contribute to spawning biomass, although this can occur when harvest size exceeds size at first maturity or when not all the released animals are harvested.

Stocking Cultured Organisms into the Sea ➥ History of marine stock enhancement

[Don1500]

Originally Posted by mintyspilot

The long running "Mass Plankton die-off" thread has raised some great idea and issues and one of the points was a documentary on the BBC about the state of fish in the oceans. The biologists on the documentary were generally upbeat.

This got me to wondering - why don't we simply make more fish?

I've noticed that they are doing this extensively with turtles (leatherbacks especially). They assure that the hatched young make it to the sea without the normal 90% loss to the Frigate birds. However this gain is made up in the greater ocean where the loss from other causes dramatically rises. In all the years that they have been doing this you would expect a huge increase in the number of adults, but the increase is slight. In order for there to be a larger gain in the adults the young would have to be nurtured for a longer period. This introduces other problems. Nature is very contrary to human design. The increase in turtle fry(?), while depriving the birds, just makes a bigger lunch for the aquatic predators.

The big problem is that there is no way of knowing if the program works at all. Without empirical data governments are loath to fund programs. And most programs are designed for the mechanics of hatching and growing the fry, not studying it.

An easy way to get data (to understand anyway) would be to create two genetic markers in eggs. One is passive and would not be passed along to future generations. This would show fish released from the hatchery. The other marker would be passed on, this would show descendants of released fish. But of course, any genetically altered fish would cause a stir in the environmental community if they were released into the general population. For every solution there is a problem.

[mintyspilot]

Originally Posted by Don1500

I've noticed that they are doing this extensively with turtles (leatherbacks especially). They assure that the hatched young make it to the sea without the normal 90% loss to the Frigate birds. However this gain is made up in the greater ocean where the loss from other causes dramatically rises. In all the years that they have been doing this you would expect a huge increase in the number of adults, but the increase is slight. In order for there to be a larger gain in the adults the young would have to be nurtured for a longer period, but this introduces other problems. Nature is very contrary to human design. The increase in turtle fry(?), while depriving the birds, just makes a bigger lunch for the aquatic predators.

I'm glad to see that people are at least trying. I find that encouraging in itself. I wonder if turtles are a "special" case since they are generally slower than fish whilst being quite obvious in size? Easy meat for predators.

Originally Posted by Don1500

The big problem is that there is no way of knowing if the program works at all ....... But of course, any genetically altered fish would cause a stir in the environmental community if they were released into the general population. For every solution there is a problem.

Indeed. Perhaps the baby turtles could be "chipped" before release in some way a bit like dogs or cats can have an encapsulated chip placed under their skin? Then at least some feedback might be possible.

[RiverRat]

We're raising/growing oysters off our dock. It's not creating more fish, but every little bit helps, right?

[MarkJ]

Originally Posted by mintyspilot

If this was combined with marine reserves then it seems to me that we could restock the oceans quite quickly. So why are we not doing it?

Aquaculture is not that easy.

Farmers in Australia have been pumping thousabds into making Blue Fin Tuna viable as a farmed fish because it would be worth millions. Yes, its being done sucessfully in smallish terms, but not big enough to restock... nor is it economically feasable now to do. If its difficult to make Blue Fin tuna pay, how much would it cost for restocking?

but in the near furture I agree with you.

Man will find a way.

Shrimp and salmon aquaculture, in particular, were indicted for depleting fisheries, disrupting coastal ecosystems, polluting the ocean with excess nutrients and pesticides, and using almost triple the quantity of wild-caught fish for "fish food" as the system produces in marketable shrimp or salmon.

http://www.sciencedaily.com/releases...1031180758.htm

[Don1500]

Originally Posted by mintyspilot

Indeed. Perhaps the baby turtles could be "chipped" before release in some way a bit like dogs or cats can have an encapsulated chip placed under their skin? Then at least some feedback might be possible.

Then there are two problems
1. Knowing if the "chipped" male turtles are reproducing. (The females could be checked when they lay eggs.)
B. Does the very act of "Chipping" the turtle reduce it's chances for survival? (this goes for any solution).

[captainKJ]

If everyone eats more beef then we do not need to worry about the fish,,,,

[MarkJ]

Originally Posted by Don1500

B. Does the very act of "Chipping" the turtle reduce it's chances for survival? (this goes for any solution).

Needs to be a small chip for this little bugger...

no, no... that me... look on my hand!

[mintyspilot]

Originally Posted by MarkJ

Aquaculture is not that easy.

Farmers in Australia have been pumping thousabds into making Blue Fin Tuna viable as a farmed fish because it would be worth millions.

Apparently the marine reserves that have been tried (no fishing allowed) have permitted many fish species to "bounce back". The UK has announced the world's biggest reserve around Diego Garcia in the Indian Ocean (probably to keep people away from the military base there) but it means that 500,000 km2 of ocean is now out of bounds

Originally Posted by MarkJ

Yes, its being done sucessfully in smallish terms, but not big enough to restock... nor is it economically feasable now to do. If its difficult to make Blue Fin tuna pay, how much would it cost for restocking?

I was not thinking of fish farming, more of interfering with the survival rate of fish eggs/larvae/fry and increasing their numbers 1000 or 10000 fold. Basically they would still be very, very small so a large number of them could be managed easily, but if the "turtle effect" (see above) comes into play then maybe all we are doing is moving the diet of other fish along a bit.

Originally Posted by MarkJ

but in the near furture I agree with you.

Man will find a way.

Let's hope so.

[GordMay]

“... Since the Pacific bluefin tuna (BFT) is one of the most expensive fish in Japan, the fish has received considerable attention as an important candidate for future aquaculture and stock enhancement. Spontaneous spawning of BFT in captivity was first recorded in 1979 at Kinki University, Wakayama, Japan (Kumai, 1997). Since then, the seed production of BFT has been attempted vigorously in some hatcheries. Although there remain many challenges before a rearing technique can be established, efforts are beginning to yield increased survival rates of BFT larvae and early juveniles...

... The first part of this paper briefly introduces the present state of larval rearing of BFT. Development of BFT larvae is summarized in the second part in terms of morphological, physiological and biochemical data (Kaji, 2000)...”

More ➥ http://ressources.ciheam.org/om/pdf/c60/03600100.pdf

***

“... researchers from Germany’s Heinrich Heine University used spearguns to deliver reproductive hormones to caged bluefins off Italy; within days, the fish spawned millions of fertilized eggs. The team is the latest to join a growing number of scientists and aquaculture farms around the world who are using such methods to get captive fish to breed—something that’s proved tricky in the past.

While breeding bluefins in captivity is controversial among both environmentalists and scientists, advocates say it’s an important step toward conserving the suffering swimmers. Bluefin populations have dropped by as much as 90 percent in some areas due to overfishing and the global demand for sushi.

“If we can develop bluefin tuna through marine aquaculture, this will definitely ease pressures on bluefin tuna in the wild,” says Zohar, who led the first successful hormone implantation project in bluefin tuna in July of 2005. “I expect it [hormone implantation] to be increasingly used and expanded for bluefin tuna as the hatchery technologies for this species are developed.” ...

... Still, some scientists are fearful that the method will hurt the world’s oceans more than it will help.”

More ➥ Farm-raised bluefin tuna spawn controversy | MNN - Mother Nature Network

[Don1500]

Originally Posted by MarkJ

Needs to be a small chip for this little bugger...

no, no... that me... look on my hand!

The chip is the size of a rice grain. It is not a long range sat-nav type transmitter. It is the type you put in a pet. Then when the turtle comes ashore to lay it's eggs you can check it to see where and when it was hatched.

[scook1]

what kind of seed do you need to plant for fish to come out of the ground?