If I was to eat a fish I caught, it would need to come from "reasonably" clean water.
I would not eat fish from say Cherry Lake or TNA, which have putrid water.
I don't know if I'd eat fish from the Yarra, Maribyrnong or Docklands.
The bottom of these waterways are a treasure trove of heavy metals (mercury,lead etc).
Umpteen years ago they said "PPB flathead contained acceptable amounts of mercury".
Has there been any toxicity tests done on the fish from these areas ???.
Can't find anything on the DEDJTR website.
Maybe Broomstick, GTS hoon or someone else can help.
Lest we forget
Gra
Are fish toxic ??
Re: Are fish toxic ??
I think the whole thing about eating fish from "clean water" confuses a lot of people. How do you know when water is "clean"? Many people won't eat bream from the Yarra - largely because of perceptions about how the water looks, despite the fact that the official EPA advice says that it is safe to eat fish from the river, with an advisory to limit your meals to four serves per month (unless pregnant): http://www.shipmate.com.au/news/YarraRi ... erdredging
On the other hand, many people would happily eat bream caught in the "clean" waters of the Werribee River, which is often very clear and even has coral growing on the bottom in some areas. They forget that the fish caught there are potentially exactly the same fish caught in the Yarra, since bream not only can, but do regularly swim between the systems, as we now know: http://vro.agriculture.vic.gov.au/dpi/v ... arra_river
This is likely (almost certainly, I would say) true of mulloway, mullet, pinkies, flathead and so on in the northern part of Port Phillip Bay at least.
Researcher, Lauren Veale is currently trying to answer that question on the mulloway, and we should see some results in a year or two (if I can bloody catch one or two locally this season!): http://catchmore.fish/Articles/Display/ ... n-Victoria
To my mind, what this says is that people fishing in the local Melbourne and bay estuaries are probably over cautious with eating their fish, and people fishing in the top half of the bay are probably over optimistic about the heavy metal and PCB contamination in their catches. If you've ever caught and eaten a mulloway from the bay, for instance, you've almost certainly eaten a big fish that has spent a lot of time in the Yarra or Maribyrnong. It's a numbers game, though, so the risks are small unless you encounter one of those freak days where you're catching (and not releasing) multiple mulloway. On the other hand, pinkies come and go from the Yarra system all the time (especially in from late summer to winter). I've caught snapper way upstream, in all size ranges (my brother's PB from the river is 7.5kg) - who knows how long they stay, and what they eat while they do, but it's a safe bet that the number of days they spend in the system is small compared with bream.
And then there's the final question mark - all that "dirty" water from the Yarra has been flowing into Port Phillip Bay and despositing out as sediment for over 150 years. So the top section of the bay is, in some ways, just as contaminated as the river bed itself. Fortunately, with time the sediment is naturally "capped" with fresh sediment, making it slightly less exposed to entering the food chain, although the migration route of certain heavy metals and other chemicals into the food chain is still not fully understood.
On the upside, we are very lucky that our river systems are considered "safe" to eat from in 2017 - many parts of the world don't have this luxury. If you want to take home a meal of bream or snapper from the river, you can be assured that the amount of contaminant you are consuming on average is no worse than what would pass as safe for human consumption at the Vic. Market and in supermarkets around the country. This isn't to say that you won't be getting a higher level of contaminant load from your Yarra catch, but there will be fish at the market with just as high a load that do pass testing. And some farm grown fish at the market will be from the "dirty" heavy metals contaminated waters of Tasmanian estuaries (e.g. the Huon River), and have a load of anit-biotic to boot!
Other places are not so lucky - go to Europe or as mentioned, the "pristine" Tasmania, and you find that many of their urban rivers are so bad that the health advisories recommend strict catch and release policies: http://dpipwe.tas.gov.au/sea-fishing-aq ... for-eating
So, at the end of the day, we have some decent scientific information about our local fisheries, with more on the way soon -using this, you really have to rationally evaluate the risk yourself. Almost all our food is "contaminated" with something we wouldn't want to ingest a large amount of, it's just a question of how much, and how often you ingest it.
http://www.abc.net.au/science/articles/ ... 490350.htm
On the other hand, many people would happily eat bream caught in the "clean" waters of the Werribee River, which is often very clear and even has coral growing on the bottom in some areas. They forget that the fish caught there are potentially exactly the same fish caught in the Yarra, since bream not only can, but do regularly swim between the systems, as we now know: http://vro.agriculture.vic.gov.au/dpi/v ... arra_river
This is likely (almost certainly, I would say) true of mulloway, mullet, pinkies, flathead and so on in the northern part of Port Phillip Bay at least.
Researcher, Lauren Veale is currently trying to answer that question on the mulloway, and we should see some results in a year or two (if I can bloody catch one or two locally this season!): http://catchmore.fish/Articles/Display/ ... n-Victoria
To my mind, what this says is that people fishing in the local Melbourne and bay estuaries are probably over cautious with eating their fish, and people fishing in the top half of the bay are probably over optimistic about the heavy metal and PCB contamination in their catches. If you've ever caught and eaten a mulloway from the bay, for instance, you've almost certainly eaten a big fish that has spent a lot of time in the Yarra or Maribyrnong. It's a numbers game, though, so the risks are small unless you encounter one of those freak days where you're catching (and not releasing) multiple mulloway. On the other hand, pinkies come and go from the Yarra system all the time (especially in from late summer to winter). I've caught snapper way upstream, in all size ranges (my brother's PB from the river is 7.5kg) - who knows how long they stay, and what they eat while they do, but it's a safe bet that the number of days they spend in the system is small compared with bream.
And then there's the final question mark - all that "dirty" water from the Yarra has been flowing into Port Phillip Bay and despositing out as sediment for over 150 years. So the top section of the bay is, in some ways, just as contaminated as the river bed itself. Fortunately, with time the sediment is naturally "capped" with fresh sediment, making it slightly less exposed to entering the food chain, although the migration route of certain heavy metals and other chemicals into the food chain is still not fully understood.
On the upside, we are very lucky that our river systems are considered "safe" to eat from in 2017 - many parts of the world don't have this luxury. If you want to take home a meal of bream or snapper from the river, you can be assured that the amount of contaminant you are consuming on average is no worse than what would pass as safe for human consumption at the Vic. Market and in supermarkets around the country. This isn't to say that you won't be getting a higher level of contaminant load from your Yarra catch, but there will be fish at the market with just as high a load that do pass testing. And some farm grown fish at the market will be from the "dirty" heavy metals contaminated waters of Tasmanian estuaries (e.g. the Huon River), and have a load of anit-biotic to boot!
Other places are not so lucky - go to Europe or as mentioned, the "pristine" Tasmania, and you find that many of their urban rivers are so bad that the health advisories recommend strict catch and release policies: http://dpipwe.tas.gov.au/sea-fishing-aq ... for-eating
So, at the end of the day, we have some decent scientific information about our local fisheries, with more on the way soon -using this, you really have to rationally evaluate the risk yourself. Almost all our food is "contaminated" with something we wouldn't want to ingest a large amount of, it's just a question of how much, and how often you ingest it.
http://www.abc.net.au/science/articles/ ... 490350.htm
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Sinsemilla
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Re: Are fish toxic ??
How good can the fish out of the yarra be for you though if you shouldn't have more than a serve a week?
Anth
Anth
Re: Are fish toxic ??
So, the answer to that question depends on your perception of risk. That's what I was trying to say, (sorry about the long post!) - you can't apply your usual understanding of "risk" by looking at whether the water is dirty, or even at a health advisory, without understanding what you are comparing it to.
For example, everyone is happy to eat flathead, calamari, whiting, snapper and gummy shark from the bay. Why? It is fed by the Yarra and has been subject to heavy environmental pollution for 150 years (less so now thanks to the EPA and relevant environmental laws).
The answer might be something like, "I assume it is fine because no one says otherwise, whereas there is a health advisory for the Yarra". Well, that's true, but lack of evidence is not a good basis for decision making.
The more interesting question is this: how different is the government health advisory on eating fish more generally? I.e. - any fish, from anywhere?
Here's your answer, (but who ever bothers to read health advisories on food we all eat all the time and just assume is fine because it is available for sale in shops and markets?):
http://www.foodstandards.gov.au/consume ... fault.aspx
In other words, the reality (uncomfortable though it might be) is that a gummy shark caught off beautiful Portsea backbeach, or in the clear waters off Sorrento in the bay, is considered just as "toxic" as any fish (apart from eel) from the Yarra estuary - eat no more than 1 serve per week.
Does that mean gummy shark is "unhealthy"? I don't think so. The government advisories are deliberately conservative. But if you want to be on the safe side, it makes sense to follow them.
So, no fish is considered "clean" by scientists, if by clean you mean "uncontaminated" with heavy metals, etc. It is more a question of how contaminated your fish is. And in the case of the Yarra, the answer is, by urban standards around the world, not very!
For example, everyone is happy to eat flathead, calamari, whiting, snapper and gummy shark from the bay. Why? It is fed by the Yarra and has been subject to heavy environmental pollution for 150 years (less so now thanks to the EPA and relevant environmental laws).
The answer might be something like, "I assume it is fine because no one says otherwise, whereas there is a health advisory for the Yarra". Well, that's true, but lack of evidence is not a good basis for decision making.
The more interesting question is this: how different is the government health advisory on eating fish more generally? I.e. - any fish, from anywhere?
Here's your answer, (but who ever bothers to read health advisories on food we all eat all the time and just assume is fine because it is available for sale in shops and markets?):
http://www.foodstandards.gov.au/consume ... fault.aspx
In other words, the reality (uncomfortable though it might be) is that a gummy shark caught off beautiful Portsea backbeach, or in the clear waters off Sorrento in the bay, is considered just as "toxic" as any fish (apart from eel) from the Yarra estuary - eat no more than 1 serve per week.
Does that mean gummy shark is "unhealthy"? I don't think so. The government advisories are deliberately conservative. But if you want to be on the safe side, it makes sense to follow them.
So, no fish is considered "clean" by scientists, if by clean you mean "uncontaminated" with heavy metals, etc. It is more a question of how contaminated your fish is. And in the case of the Yarra, the answer is, by urban standards around the world, not very!
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Sinsemilla
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Re: Are fish toxic ??
Makes sense. Thanks for the reply.
Wouldn't a fish caught off a back beach in portsea be less "toxic" than lets say a fish that spends a lot of its life around the yarra or northern part of the bay?
Wouldn't a fish caught off a back beach in portsea be less "toxic" than lets say a fish that spends a lot of its life around the yarra or northern part of the bay?
Re: Are fish toxic ??
Probably. But the amounts of chemical load we are talking about are tiny, so it's like describing the difference between getting an electric shock of say 1ma and 0.5ma (i.e. neither are dangerous, nor could you detect much difference - https://www.sparkfun.com/news/1385).
Keep in mind, though, that even fish from "pristine" environments have naturally occurring levels of heavy metals (i.e. this is part of seawater), but human made industrial pollutants like PCBs can be found more commonly in urban areas (because that's where the polluting factories and other sources were, historically).
Again, the EPA has issued reports on this, and has not upgraded its health advisory, so things aren't too bad in old Melbourne town. I do feel sorry for Hobart, though - the Derwent looks stunning, but its seafood is basically inedible due to heavy industrial contamination after failure upon failure of successive governments to protect this natural asset. Tasmania actually needed a few more "greenies" back in the day when they really could have made a difference.
Keep in mind, though, that even fish from "pristine" environments have naturally occurring levels of heavy metals (i.e. this is part of seawater), but human made industrial pollutants like PCBs can be found more commonly in urban areas (because that's where the polluting factories and other sources were, historically).
Again, the EPA has issued reports on this, and has not upgraded its health advisory, so things aren't too bad in old Melbourne town. I do feel sorry for Hobart, though - the Derwent looks stunning, but its seafood is basically inedible due to heavy industrial contamination after failure upon failure of successive governments to protect this natural asset. Tasmania actually needed a few more "greenies" back in the day when they really could have made a difference.