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Discussion Starter #1
We left Cheshunt at 5.25am for the Hundred mile drive to Newhaven with some of us having reservations on the day ahead.
Looking at the previous posts from last week we saw the "Bloom" had started, I was concerned at the size of the tide, all in all lot's of negative vibes.
Then Terry phoned to say he was running late, was it all going horribly wrong?

We arrived at the Coral Cafe at 7.15am had a great breakfast and boarded Sea Leopard at around 8am.

The sun was shining, the sea was flat calm but still the niggling doubts.
I then unpacked my sunglasses to find them broken, extreem doubts now.

As we cleared Newhaven John opened up Sea Leopard to her cruising speed, we chatted about our prospects for the day and asked about the bloom.
John re-assured us and said we were going further to try and get out of it, he was reasonably happy with the size of the tide, our doubts started turning to optimism. I lookedat the plotter to see 30.2 miles to go, and thought to go that far John must be confident.

We arrived at our destination around 9.45am a variety of lures were sent to the sea bed, Jelly worms favorite at the stern, and a mix of Twin tails and Red Gills down the sides.

First drift and the shout of fish on came from Dave, and seconds later Chris, me too. The first two fish were both Pollack not huge but reasonable at around 6lb
The jelly worms then became the main bait, taking fish after fish with none to any other bait, most of us changed to jelly worms with differing success. I managed 4 pouting and one Pollack, but everywhere else all Pollack, Chris next to me was still catching on a blue and white red gill.
Rob then produced what was to be the only Cod of the day, a nice one in double figures.
Chris caught a Red Gurnard of about 1lb on a red gill, and returned it.
Once the tide died the fishing slowed, but we were still getting the odd fish. The tide started running and the fish returned. Then it was as if a switch had been thrown the jellies stopped producing and a few fish came on the gills.
Again a change in the tide and it did not seem to matter what we put down the fish were hitting them, Terry, Kevin and Rob all bringing in better specimens.
As the day went on we had several more changes of baits as some seemed to out fish the others.

I put a black leadhead shad on, it only hit the bottom then bang Pollack straight away, let down again same thing. Terry seeing these results also put one on bang a 5lb Bass. Soon there were 4 black shads on.

Meanwhile John "Bully" produced his first fish, closely followed by his second, It must have been frustrating waiting that long to land one.

Kevin caught a small Pollack at around 2.45pm we decided we had got enough fish so called it a day, Kevin then said he had heard that if you nick the swim bladder with a hook point the fish would survive if returned, we decided as the fish was effectively dead anyway we would give it a try.
We put a small pin ***** in the swim bladder, waited until it reduced in size and returned the fish.
It took a while for the fish to twitch and swim about, but then two short bursts and it shot off to the depths again.

I would be interested if anyone knows if this is proven to work, it certainly appeared to.

A peek into the fish boxes and the reality of the day we had just had sank in.
We had fourty one Pollack, one Cod and one Bass, returned two Gurnards four pout and one Pollack. Christ now we have got to fillet all of them.
This was done on the journey back to Newhaven, just.

Thanks for a great day John.


5,980 Posts
Great day again Gary, happy to see the weather was kind as well. Much better than anti fouling and maintenance.

3,652 Posts
Glad you had a better day than we had out the other Sunday when the bloom killed off the fishing.You got further out than we did which probably helped.
Some nice pollack caught, not sure about bursting the swim bladder :g:
Seen it done a few times and the fish do seem to swim away, how they get on after is anyones guess.


890 Posts
some good fish there mate.:clap3:
what i have found when i get pollack up from any depth is their stomach hanging out of their mouth.because if you gut them immediately you will notice the swim bladder is still in place and their stomach has been turned inside out.probably due to the pressure change in the swim bladder.
also if the water is clear and you can see the fish coming up near the surface they seem to through up their last dinner with what i think is their stomach following.
your thoughts guys?
15,082 Posts
some good fish there mate.:clap3:
what i have found when i get pollack up from any depth is their stomach hanging out of their mouth.because if you gut them immediately you will notice the swim bladder is still in place and their stomach has been turned inside out.probably due to the pressure change in the swim bladder.
also if the water is clear and you can see the fish coming up near the surface they seem to through up their last dinner with what i think is their stomach following.
your thoughts guys?
Its called ''The Bends''! Much the same as a diver would get if he was roped up a bit lively from 200ft :)


1,284 Posts
Glad you had a good day.Im out from Eastbourne sunday would like to try and get some of those black shads any idea of the make.Ive got every colour going but no true black ones .


1,173 Posts
Something else I found
Thank you for your enquiry regarding our cod tagging programme.

Our electronic tagging programme began in March 1999, and we have released 380 cod in a number of locations in the North Sea since then, with plans to release 250 to 300 more over the next couple of years. To date we have had 108 tags returned to the lab.

Our tagging procedures are very strict. All of our tagging staff ('taggers') are trained and qualified to tag fish, and do so under a personal licence from the UK Home Office. We do not tag cod unless
they are in excellent condition after capture, and all fish are handled extremely carefully during their time on the tagging vessel.

We ensure that contact between the taggers and the fish is minimal, that taggers wear latex gloves for when the fish needs to be handled during tag surgery, and that fish are brought aboard and released from the tagging vessel with great care. Fish are returned to the location of capture within 2 hours of being caught, and are never out of the water for more than a couple of minutes.

The biggest problem with cod caught in water deeper than ten metres is the expansion of the swimbladder, a gas filled organ responsible for buoyancy control in cod. Cod control the volume of gas in the swimbladder by either secreting gas into it through a special gland, or absorbing gas into the blood stream. Absorbtion occurs relatively quickly.

The size of this organ is pressure dependent, and as an example, a fish brought to the surface (1 atmosphere of pressure) very quickly from ten metres (2 atmospheres of pressure) will experience a reduction in pressure of 50% and the swimbladder will expand.

Each 10 metres depth of water exerts a pressure of 1 atmosphere, so a fish at 40 metres will be under a pressure of 5 atmospheres, at 6 atmospheres at 50 metres and so on. With respect to the seriousness of the expansion of the swimbladder, any water deeper than 30 metres can be considered 'deep'.

Two things can happen to the swimbladder when it expands. First, it can remain intact and exert outward pressure on the internal organs and the body wall.

These organs are compressible to some extent, and the body wall can expand outwards, but if the increase in size of the swimbladder is very large the stomach can be forced out through the mouth. I'm sure you have seen this phenomenon.

Alternatively, small holes can form in the swimbladder wall (these repair within a few hours or days), allowing gas to escape into the body cavity.

This gas can often escape from the body cavity, but in some cases will remain inside and prevent the fish from exhibiting normal posture and buoyancy. This gas can be vented to the atmosphere with minor surgery.

Rod and line caught cod can usually be brought to the surface in good condition, unless the fish has been foul hooked in which case the chances of survival are very slim, and can therefore be returned to the water with a good chance of survival.

We bring cod to the surface at as slow a rate as possible (several minutes in water> 40 metres) to minimise the effort expended by the fish when it fights against the line and to maximise the amount of swimbladder gas that the fish can absorb as its depth is decreasing.

This therefore minimises the increase in size of the swimbladder. On arrival at the surface, all fish are checked for evidence of buoyancy failure and swimbladder expansion by placing them immediately into a large holding tank.

Those requiring' deflation' are operated on and returned to the water, as they are unsuitable for tagging. Of the remaining fish, those in the best condition are tagged and returned carefully to the sea.

The longer the cod spends on the tagging vessel prior to tagging, the more closely it has adjusted its buoyancy to atmospheric pressure because it will absorbs excess gas from the swimbladder into its bloodstream all the time.

On release therefore, the cod will find itself much less buoyant than when it was caught. Cod therefore often show a characteristic post-tagging behaviour related to re-inflation of their swimbladders (see chart).

This is characterised by a declining average daily depth and occasional rapid ascents or descents that may be interpreted as the fish 'exploring' the limits of its buoyancy.

After a few days, cod have usually regained the correct buoyancy for their capture depth, and then behave normally once more. CEF AS have had great success in tagging cod from water as deep as 90 metres, but we collaborate with fisheries institutes in Norway and Iceland where cod captured at more than 200 metres have been successfully tagged and subsequently returned to scientists many months later.

You asked what were the chances of a cod caught in deep water surviving on release, so that anglers could judge the worth of releasing surplus deep water cod.

Cod are very robust fish and our data show that after the initial post-tagging behaviour, tagged cod have lived perfectly normal (and we hope happy!) lives, and have migrated to feeding and spawning grounds as they would be expected to.

This is borne out by the increase in weight and length offish (when we receive these details).

When we have the opportunity to talk to fishermen who have returned cod tags, we invariably hear that the fish were in good condition when captured.

I would therefore be optimistic that anglers could return cod to the water provided they were not foul hooked, they were brought to the surface relatively slowly, they were handled minimally and with care, and they were returned to the sea as quickly as possible.

I'm afraid I cannot comment on the chances of survival of other species.

David Righton

Fish Behaviour Team Leader
Fisheries Biology Section
CEFAS Lowestoft

9 August 2005

Cod has an 'incredible ability' for fixing its swim bladder if it swells & cracks

A recent study by Norwegian scientists has shown that cod shows 'an incredible ability for restoration' when and if its swim bladder swells and cracks when the groundfish is brought back to surface quickly.

This has implications both in animal welfare terms and for the wild harvest of cod destined to be 'ranched' or farmed.

For the first time, tests have shown how the cod itself repairs the damages when its swim bladder cracks.

"The cod has an incredible ability for restoration", says Senior Scientist Kjell Midling at Fiskeriforskning, the Norwegian Institute of Fisheries and Aquaculture Research.

The difference between the pressure down in the sea and the surface causes the swim bladder to swell and crack before the cod is taken on board the fishing vessel.

A new study carried out by Veterinary Surgeon Christian Koren and Scientist Kjell Midling at Fiskeriforskning shows that the cod itself is capable of fixing the damages that occur.

On the inside of the gas bladder is a thin elastic membrane.

This membrane lies close to the bladder until this cracks.

When the gas bladder then collapses, this thin membrane slides such that the hole in the bladder is blocked.

The cod can then refill the bladder without the air seeping out.

"With that, the cod has a new bladder that functions immediately after the normal swim bladder has cracked, until the wound in the bladder wall has grown.

Almost like a self-repairing car tyre," says Midling.

He continues, "We have acquired more knowledge about the cod's biology and ability to cope with the handling during catching and live storage.

This knowledge is useful in connection with catch-based aquaculture and how this industry can be responsibly developed also with consideration to the welfare of the fish."
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