Fish farmings future, and how microbes compete for space on our face

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Now we have staff writer eric. Stock said he wrote a feature on the modernisation of fish breeding in this week's issue. Hi eric a great to be back. Sarah great to have you so fish. Farming is modernizing and on the rise. What's the big picture here. The big picture if you go back to nineteen fifty. And you compare what's happened. Over the last seventy years you can see with with wild caught fish. The overall harvests flattened off in the last couple of decades but aquaculture's continuing to rise that production of farmed seafood. Nearly half the protein that we eat from aquatic organisms is grown on farms. Most of it is freshwater and in asia most of the farm fish in the world coming from the land. These are ponds with carpenter them up. Harp common carp to loppy right trout. Catfish there are a lot of these Aquaculture species would are being grown on land. I was surprised to learn. That fish are behind the times. Humans have been keeping fish to eat or at least a look at for thousands of years. But as you point out in your story fish haven't been altered through breeding like other livestock. How things been different. The big differences that most of the seafood that we're eating it is closer to being wild than the terrestrial livestock. Do you think just because the people who did this intensive breeding the people who were interested in tracing lineages of animals and getting the best from their cows. They just weren't that interested in fish farming or in seafood. Is it just a coincidence of history that the focus of all this intensive breeding has been terrestrial animals. If you're talking about the last century or the last one hundred and fifty years worth you're talking about thousands of years right about thousands of years of thousands of years right so over ten thousand years where humans first domesticated sheep goats cows and then lived with them and over that time. Pick the ones that had the traits that they liked they gave more milk. They had more meat on the bone. That's been happening for a longer time. We've had a longer stable relationship for the most part right. There are some exceptions here for the most part a longer relationship with those animals that walk around. Then with the ones specially no from the sea and the other is that over those thousands of years. the terrestrial livestock went through population bottlenecks that reduce their genetic diversity. It's like when you bring a few parents cows to a continent but nobody's bringing around a pond full of fish right. That's a great point. It is harder to bring those with you as your trucking across the continent there is some archaeological evidence for aquaculture. There's a lot of i inference. There is evidence in australia. Aboriginal people in six thousand years ago. Where building ponds to keep eels. But who knows you know to what extent they were selecting. If you can control the life cycle that's really the key thing with domestication and being able to have it reproduce in captivity right and then you really can pick the ones that you like and selectively breed. Those for continued improvements now. Researchers are jumping way ahead skipping centuries of painstaking documentation breeding line analysis and using modern technologies to get what they want from fish. Well what do we want from fish. Eric it depends on who you are right on the one hand. If you're a fish farmer their key things that you want the first one is fish to grow well or not just fish. They'll probably say fish a lot but we're really talking about a huge range of organisms right fish. Crustaceans molluscs really hugely different organisms. But no matter what you're growing you want creatures that grow. Well they have a lot of protein that you can sell to the grocery stores new consumers. You want bigger fatter oysters. Send you want large fillets you want them coming from animals that grow quickly so maybe you can do more generations right more cycles per year. So that's the first thing you want. The second thing you want. is hardy. Animals healthy animals ones that resist disease. And this is. It's a huge issue in aquaculture breaks of disease can really hamper an operation in shrimp farms. You could lose forty percent of your entire crop. In all of those cases having disease resistant animals is a real benefit. Fast and good growers diseases in animals. Anything else that you want out of your domesticated livestock. Once you've made progress with that. Breeders will turn to traits like in what does that fillet look like was salmond consumers really like reddish pink fillets so you can read salmon to have naturally redder flesh color around her fish right rather than a longer fish war color apparently in japan trout with a bluer color and fewer spots or spots. Just in the right place on the outside of the fish that's desirable so chilean breeders of optimize their trout that they export for those qualities. What technologies are fish. Farmers livestock breeders using to achieve these goals. You need to do as a breeder is. You need to be able to pick the fish that you want to propagate so four a faster growing fish. that's not hard right. You just need a ruler. In a scale you can. And when salmon breeding got underway in the late sixties early seventies. They were getting gains in growth rate of ten fifteen percent per generation. Right at wow. And put that in the context right. If you're a poultry breeder a few percent is a really good thing. Yeah so you can measure that but it's not always simple if you want to measure the color of the flay obviously you need to Sacrifice the fish right. So you can't use that fish for a hattrick because it's It's dead so what the breeders of done is the used. Something called family based approach where they have crosses between two parents and then the offspring hundreds thousands in a tank and they can test some of those but they'd have to use siblings for the actual production of the fish that go off to the farms. How do they know which sibling. Which family members carry those desirable traits. So the technology comes into this is using genetic markers where you can look for. Little changes in the in the genome that reveal whether a favourable lille of a gene is present us. Take a little clip of the fin. If it's a fish in you can sequence that tissue for the genetic markers that are in it so that allows you to really get much more accurate selection of fish for the next generation. We talking about fish for while here. Let's move to some of these invertebrates we have you talk a little bit about oysters. Triploid oysters what is that. And what does that accomplish. Oysters in the wild. They've got like us two copies of each chromosome. You call them diploid. If you took a human and you added an extra copy of chromosome. They wouldn't survive. That moisture is our of stuffing with one voice to reader. Who know asked him. Why did you get interested. Your genetic trained as a geneticist. Why did you get interested in oysters. And he said there so tolerant of genetic abuse. Neka really manip- manipulate their genes. And they'll survive right so you can give them a whole half extra genome and they're fine or double it you can make them tetsuo -ployed and the really has a tremendous impact for improving the production of the oysters. If you make triploid waster it becomes sterile. It's healthy. it's normal. It might be hardier. More disease resistant to they. Mature faster you harvest them sooner and in some places that means you pull them out of the water. E four the disease outbreaks in the hotter warmer conditions. The next nother advantage of triplet wasters. Because they're sterile. they're not putting much energy into reproducing. Why bother so. They don't develop the same mass of sperm or eggs. That affirmative oyster does. There's more meat on them. So the real advantages to making a triploid bicester.

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