Cod not feeling the heat

[Ian Burrett]

http://www.cefas.co.uk/news/2006/news2006-04-10.htm

[Norm B]

http://www.cefas.co.uk/news/2006/news2006-04-10.htm

I have been led to believe that temperature does affect spawning, hatch and survival rates though, or will this be disproved also? If so, does global warming pose a threat at all?

[wurzel]

When it's cold we catch cod when it's hot we don't, every time we have a colder winter we get more baby cod, when it's a very mild winter we don't.

[Ken Davison South Wales]

Hi Wurzle,

 

Can you explain why we should catch summer cod of the south coast wrecking?

 

Most fish have an optimum breeding temperature and I can state that from personal experience with the breeding of tropical and cold water fish.

 

Take the zebra danio, keep it at 79 to 80 degrees and feed well with white worm for two weeks, then drop the temperature by adding cold water to give the fish the idea the snow is melting giving more oxygen and subsequent more food in the water and they start spawning. Left full of spawn without the right conditions and they become egg bound on most occasions and die.

 

Will fish migrate to find ideal conditions for spawning? I would have to guess yes, they have been around for a lot longer than us.

[wurzel]

Hello Ken

 

Do you catch cod on the wrecks all summer?

 

In this area as the sea warms up the cod seem to move from the closer in shore wrecks to the further off deeper wrecks, by August they even disappear from these, but then they some times start to show up on the inshore rocky ground in september and early October when the sea is about as warm as it gets, which cofirms what they are saying, some like hot, but the bulk don't turn up untill the end of October, these days more like the end of November.

 

dIt's the reproduction that the tempreature effects, Cod defiantly don't breed well or the fry don't survive, I'm not sure which, in warmer sea tempreatures. In this area the cod have not had a succesfull spawn for 12 years now and that was nothing compared to the ones they had in the early 60 and 70's. A good year class always with out fail follows a hard winter, this years is looking better, only time will tell just how good.

As you suggest some fish probaby do migrate to find better conditions to breed in, if conditions are right and the food souce is there they probably stay there, boosting the stocks in that area and further depleteing the stock in the area they moved from, It's been going on for millions of years, I doubt we have as much effect on it as people think.

[Ian Burrett]

In this area the cod have not had a succesfull spawn for 12 years now and that was nothing compared to the ones they had in the early 60 and 70's.

Hi Wurzel

 

This isn't going to happen as the breeding stock is no longer there. Well according to everyone else except commercial fishermen

[slackline]

Hi Wurzle,

 

Can you explain why we should catch summer cod of the south coast wrecking?

 

Most fish have an optimum breeding temperature and I can state that from personal experience with the breeding of tropical and cold water fish.

 

Take the zebra danio, keep it at 79 to 80 degrees and feed well with white worm for two weeks, then drop the temperature by adding cold water to give the fish the idea the snow is melting giving more oxygen and subsequent more food in the water and they start spawning. Left full of spawn without the right conditions and they become egg bound on most occasions and die.

 

Will fish migrate to find ideal conditions for spawning? I would have to guess yes, they have been around for a lot longer than us.

 

May be its due to the gulf stream coming around the top of scotland and forcing the cooler water south and fish with it. Does the south east get the same amount of lionsmane jelly fish that the north east get in summer

[dillydangler]

we were catching codling in october on the taw/torridge estuary when the sea temp was about 16 celsius.and that is warm.possibly in for the last major peel and the small hardbacks that there guts are always full of.

 

didnt get much of a spring run though when the water was 8 celsius.maybe their out spawning? will find out this october if they come back.

[wurzel]

Hi Wurzel

 

This isn't going to happen as the breeding stock is no longer there. Well according to everyone else except commercial fishermen

 

 

I am certain there are plenty enough breeding stock if conditions became favourable, I don't think you need as large a breeding stock as you might think, the cod explosion of the early 60's came from next to nothing, same as the 1999 year class of North sea haddock, but then you would need a bass recovery plan, because whats favourable for cod is not for bass.

 

 

Hello Slackline

 

Quote

Does the south east get the same amount of lionsmane jelly fish that the north east get in summer

 

No thank goodness, I can remember only one year and that was after a very mild winter about 15 years ago when we had alot here and that was only off shore in the clear water.

[adambroadley]

http://www.cefas.co.uk/news/2006/news2006-04-10.htm

In the past months it has been cold in Whitby and i was catching plenty of codling but i went down fishing when it was sunny and didn't catch anything! Maybe cod like to stay deep down out of the sun and like coming up in the cold??? who knows????