European Sea Bass migration and spawning question

[jhcabs]

I've been reading up at lot during the last few weeks to help get me excited about the upcoming season. Marine eco systems are definitely not a strong area of mine. While i did learn a bit there was one or two things in particular that i couldn't get my head around. I was hoping someone might be able to help me out, plus hoping this turns out to be an interesting thread discussion.

To shorten the tonnes of material i found, basically bass stocks have been tagged and tracked in the past to learn more about there movements. The study was conducted around the coasts of Ireland, England, France and Whales. In part of the conclusion the study decided to view Irelands Bass stocks as being separate to that of the UK and France. I also didn't realise how much irish anglers esepcially Jim H from SEAI has helped pretect our beloved bass. I only knew half the storey and i must say your a legend

The main spawning areas for the UK and france seems to be offshore cornwell and the bay of biscay. The bass then move to their summer feeding grounds quite widely spread throughout the regions. they also move inshore during srping to spawn too (the confusing part for me) the study shows that they were generally recaptured 16km from their release point during the spring and summer season and up t 80km south to south west during the autumn migration.

Thats the seriously shortened version of what i was able to gather. so my main two questions are;

If they spawn during the winter out at sea why do they then spawn again in spring inshore. how many times do they spawn and why the mix of locations? why do they bother?

Why is the irish stock concidered seperate? do they not mix, do they not share the same spawning grounds? If this is the case where are the irish spawning grounds? if they tend to migrate during winter to deeper water south or south west my guess is offshore kerry.

[roger de dodger]

yes you can guess this bad weather has you diong alot of thinking i suppose it will be down the south as the water temp would be alot more pleasant ,also with kerry having bass prob 12 months of the year its a good bet its down that neck of the woods?

[jhcabs]

yes you can guess this bad weather has you diong alot of thinking i suppose it will be down the south as the water temp would be alot more pleasant ,also with kerry having Bass prob 12 months of the year its a good bet its down that neck of the woods?

Hey Rodger, Hope your keeping well mate. We'll have to get out for some smoothie sessions soon enough

Thats exactly what i was thinking to about kerry, but there was no mention of it in the study. If it was south uk or France then you'd expect different patterns than what we have in ireland and like you said, there would be no bass in Kerry late Autumn. All i can think about since the start of march is fish, hense all the reading. Happens every year to me, although i must say it started early this year.

The spawning twice a year is the bit that is confusing me most. i thought they only spawn inshore around may - june when we have our ban. If they also spawn offshore during winter then surely they are being commercially exploited during those times. so, ok they spawn twice a year, but you'd think they'd spawn twice around the same type of area right?

Is deeper water in winter actually warmer than inshore waters during winter?

[JimH]

JH

I'm no biologist or similar and am without that type of qualification- there are a lot of big questions in the above posts - I can make some of it clearer to you during your visit here but to address all of the issues above would take some time. There are however qualified people on here who may have more actual information.

As far as I can determine bass may spawn 'fractionally', not every year and sometimes on a start stop cycle - generally the physiological condition of fish for breeding is achieved during November / December / January - and fish are 'ready' to spawn at this time. They will choose when to do so based on light levels, water temp, food prevalence etc - this is a movable feast i.e it could be early it could be late - it may in fact be twice or indeed for some fish not at all - generally from mid Feb to June could be the window. Its not specifically done twice and its done inshore.



There are many contributory and impactful influences that have effects here too - heres a quick summary http://jimhendrick.com/2012/02/01/testing/

I have included a small collection of white papers from various people on my website http://www.scribd.com/collections/37347 ... -Data-Bass which mya be helpful (and at times confusing) - see Fahys paper amongst others on bass regarding breeding and distribution etc - bear in mind the year of publication for each

hope it helps a bit and see you in Spring

[jhcabs]

JH

I'm no biologist or similar and am without that type of qualification- there are a lot of big questions in the above posts - I can make some of it clearer to you during your visit here but to address all of the issues above would take some time. There are however qualified people on here who may have more actual information.

As far as I can determine Bass may spawn 'fractionally', not every year and sometimes on a start stop cycle - generally the physiological condition of fish for breeding is achieved during November / December / January - and fish are 'ready' to spawn at this time. They will choose when to do so based on light levels, water temp, food prevalence etc - this is a movable feast i.e it could be early it could be late - it may in fact be twice or indeed for some fish not at all - generally from mid Feb to June could be the window. Its not specifically done twice and its done inshore.



There are many contributory and impactful influences that have effects here too - heres a quick summary http://jimhendrick.com/2012/02/01/testing/

I have included a small collection of white papers from various people on my website http://www.scribd.com/collections/37347 ... -Data-Bass which mya be helpful (and at times confusing) - see Fahys paper amongst others on Bass regarding breeding and distribution etc - bear in mind the year of publication for each

hope it helps a bit and see you in Spring

Thanks for that Jim.

The above really helped fill in a lot of gaps for me. One could guesstimate then that the lack of sport during the autumn/spring north easterly is mainly due to the low water temperatures which keeps the fish offshore, but once the water temperature rises slightly (from what i gather 9 - 11c) then the instinct trigger to spawn starts. this would also trigger crabs to peel, and the sandeel would be on the move. days would also be longer (this wouldn't be a measure of light levels i'd imagine though, plus one would argue that darkness brings them closer to shore anyway). Would i be right in saying that after they spawn they would stay around inshore until the autumn/winter migration out to their "breeding grounds, gonad development, growth" (thanks for clearing that one up)

This would also make sense why an easterly wind during the summer can be so productive on the east coast, because the water temperature is already high enough for the bass to be taking up residence near by. the surf would trigger them to feed for bait food dislodged.

I'd still be very interested in discussing light levels, and tidal effects with you at some stage. when will your guiding season be in full swing?

[JimH]

JH - go here http://www.probassfisher.com/2012/05/season.html - busy trying new flies for seatrout at the moment -