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Blue Fin Tuna


ditchman
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16 hours ago, Old farrier said:

But that’s not the North Sea it’s miles they could just have been frightened by the oil rigs 

It's not about pressures in the North Sea, it's about the pressures on breeding fish numbers meted out further south. ABT breed in the Med (where the water's warmer) and then move out of there for the rest of the year to hunt the baitfish on which they predate. Their historical ranges included the North Sea, but their journey as fish always begins further south. Prior to the mid 00's ABT were heavily fished - both legally and illegally - with many fish not making it to breeding age. Fewer fish spawning means fewer tuna. But breeding stock fish are the more highly prized ones, so both small and big tuna were being hammered. As you move away from a concentrated population centre, density decreases. So: fewer fish make it out of the Med, fewer make to Cornwall's waters, even fewer make it up and around the channel and so fewer still make it to the North Sea. 

The North Sea represents the extent of ABT's traditional range because the water's cooler. But it still should be able to support them if spawning numbers are high enough. 

With warming sea temperatures, this will help to improve stock numbers in the North Sea, but rising sea temperatures are only an added bonus. The AMO will certainly be having an effect, but what it doesn't account for is the suddenness of the recovery. The real saving grace was the massive tightening of the fishing market of ABT, but it conveniently coincided with the AMO being in a warm cycle. This graphic from ICAAT shows just how dramatic the recovery has been.
image.png.2f00211154b8eb5789e2248e700ad336.png

AMO alone would account for a more gradual increase, because the rising sea temps give gradually improving breeding conditions. What ABT saw was a population explosion, centred on the tightening of the ABT fishing industry.

Edited by chrisjpainter
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ABT were fished for by rod and line off Scarborough until well into the 1960s. “The Tunny Club” building is now… you guessed it, a chippy! 
l read zoology and marine biology at Liverpool graduating in 1991 and I remember a lecture on this. I was born in Hull in the 60s so this was common knowledge but when the lecturer asked if anyone knew what the largest species landed by rod and line in the North Sea was, and I shouted “tuna”, everyone laughed at me!!

Once herring stocks had been fished out, the tuna moved on, in much the same way as many other big migratory predators have done. Ironically, that also includes most of the haddock and cod fishermen.

Chris is doing a good job of summarising the current science and applying a good deal of balance to the evidence I think.

GG

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20 minutes ago, general grievous said:

ABT were fished for by rod and line off Scarborough until well into the 1960s. “The Tunny Club” building is now… you guessed it, a chippy! 
l read zoology and marine biology at Liverpool graduating in 1991 and I remember a lecture on this. I was born in Hull in the 60s so this was common knowledge but when the lecturer asked if anyone knew what the largest species landed by rod and line in the North Sea was, and I shouted “tuna”, everyone laughed at me!!

Once herring stocks had been fished out, the tuna moved on, in much the same way as many other big migratory predators have done. Ironically, that also includes most of the haddock and cod fishermen.

Chris is doing a good job of summarising the current science and applying a good deal of balance to the evidence I think.

GG

Our Cod and Haddock are overfished not moved on. in my lifetime Ive witnessed once common species disappear...... that is deeply worrying

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13 hours ago, old man said:

Not this again surely, the planet has warmed  and cooled many times in the past?

Sadly he is probably responsible for more climate damage than the average pleb?

I'm sorry but do you realise what you have said? You infer that global warming is a natural thing and then say Attenborough is more responsible than the average person for climate damage.

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5 hours ago, henry d said:

I'm sorry but do you realise what you have said? You infer that global warming is a natural thing and then say Attenborough is more responsible than the average person for climate damage.

Said in jest Henry. 

Lots of money and names made from it? The lunacy of electric vehicles? Volcanic activity? Smoke and mirrors?

Global warming maybe a response to the evolution of mankind ever exploiting resource and expanding economies?

I'm afraid it's no good battering us here on this tiny island with impossible targets of reduction which will ruin our economy when China and India are ever increasing their footprint?

As to Dave, he has more air miles than everyone except Andy maybe, but he is curtailed now? 😀

Anyway, off out now to cause more mayhem.

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14 minutes ago, old man said:

Said in jest Henry. 

Lots of money and names made from it? The lunacy of electric vehicles? Volcanic activity? Smoke and mirrors?

Global warming maybe a response to the evolution of mankind ever exploiting resource and expanding economies?

I'm afraid it's no good battering us here on this tiny island with impossible targets of reduction which will ruin our economy when China and India are ever increasing their footprint?

As to Dave, he has more air miles than everyone except Andy maybe, but he is curtailed now? 😀

Anyway, off out now to cause more mayhem.

you're not going bloody Tuna  fishing again...............thats the 4th time this week:mad:

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On 22/09/2021 at 21:03, islandgun said:

Our Cod and Haddock are overfished not moved on. in my lifetime Ive witnessed once common species disappear...... that is deeply worrying

Agreed, and that’s exactly what I’m implying.

I remember going on a 4 hour trip out of Brid when I was 10 and everyone caught. My mum lived off Hessle road in Hull, right next to the fish dock and when she saw my catch she said they were all “chats” and laughed. I watched a boat landing in Whitby this summer and only one young girl got off with any fish.

GG

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On 22/09/2021 at 21:03, islandgun said:

Our Cod and Haddock are overfished not moved on. in my lifetime Ive witnessed once common species disappear...... that is deeply worrying

While I would agree that some areas have been over fished, the Clyde for example, the problem is much more complex.

When the herring fishery started to collapse their was a sudden explosion of gaddids, cod Pollock etc, which is against the logical idea of herring fry being a big part of their diet, however large herring (and mackerel) eat gaddid fry, so a lack of large herring meant more gaddid fry maturing, however the herring fleet had nothing to catch so it had to adapt, so the cod etc were scooped up. Wind the clock on and we have sandeel being scooped up for feed and oil so it gets further complicated, herring stocks are now increasing, mackerel are decreasing in some areas and increasing hugely in areas they were not really fished for, further complicating things, the seas are complex systems and I hope that the increase in ABT is a sign of good things happening and an increase of straps, whiting, octopus etc not a sign of bad things.

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3 hours ago, henry d said:

While I would agree that some areas have been over fished, the Clyde for example, the problem is much more complex.

When the herring fishery started to collapse their was a sudden explosion of gaddids, cod Pollock etc, which is against the logical idea of herring fry being a big part of their diet, however large herring (and mackerel) eat gaddid fry, so a lack of large herring meant more gaddid fry maturing, however the herring fleet had nothing to catch so it had to adapt, so the cod etc were scooped up. Wind the clock on and we have sandeel being scooped up for feed and oil so it gets further complicated, herring stocks are now increasing, mackerel are decreasing in some areas and increasing hugely in areas they were not really fished for, further complicating things, the seas are complex systems and I hope that the increase in ABT is a sign of good things happening and an increase of straps, whiting, octopus etc not a sign of bad things.

The single biggest factor affecting UK fish stock is without doubt EU over fishing in our waters and it still goes on today. The sooner we boot them out the better as we'd see a recovery in no time at all. 

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5 hours ago, 12gauge82 said:

The single biggest factor affecting UK fish stock is without doubt EU over fishing in our waters and it still goes on today. The sooner we boot them out the better as we'd see a recovery in no time at all. 

I'm afraid we don;t have the ability or gonads required.

As with most of our essentials we have simply sold the asset to others?

Now we have  no control of anything of value or benefit to the nation?  Fantastic!

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5 hours ago, Jim Neal said:

https://www.bbc.co.uk/news/46401558

Not sure if the details in this have been superseded or not..

Why on earth do the EU and UK government think they have any right at all to our fish? Do we demand Saudi share their oil with us or Germany give us there coal, nickel and lignite, or Italys Mercury and zinc. Its crazy, we've left the EU allowing the to enter our waters and plunder our fish is like allowing the school bully to take a percentage of you paycheck as an adult. 

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12 hours ago, 12gauge82 said:

Why on earth do the EU and UK government think they have any right at all to our fish? Do we demand Saudi share their oil with us or Germany give us there coal, nickel and lignite, or Italys Mercury and zinc. Its crazy, we've left the EU allowing the to enter our waters and plunder our fish is like allowing the school bully to take a percentage of you paycheck as an adult. 

Correct me if i'm wrong but weren't the licences sold to the highest bidders?

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18 minutes ago, old man said:

Correct me if i'm wrong but weren't the licences sold to the highest bidders?

While we were in the EU our entire fish stock was allowed to be plundered by the entire eu, in effect we had 1 27th share of our own fish or something like that. When we left we took some of it back but not much, our own share will increase over the next few years and in 5 years we can theoreticaly have it all back. I'm no expert on the fish situation and I'm sure there's others far more knowledgeable than me on on here. But I believe it's something along those lines, it's definitely outrageous though. 

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