Flounder - populations on isolated beach/strand

Two strands that I started fishing 8 to 9 years ago initially produced flounder that made 2 pounds and a few ounzes with plenty in the 1lb 12oz range. This might not sound too big to estuary men but these were open western beaches where the available food resources can't compare with estuaries. Each trip would throw up two or three of these good fish.

Since those initial trips the flounder size has plummeted and I haven't seen a fish over 1lb since. There have been lots of small fish but the bigger ones have dissappeared completely. Shamefully looking back we did keep a number of those flounder for the table but it wasn't bin-bag stuff just a few for the tea. The beaches in question where not huge but they were fairly isolated in the sense that they were bound by rocky headlands and rough ground. What I am beginning to fear is that the flounder populations in a lot of those beaches are very susceptible to overfishing and that there is very little migration from outside stocks into the beach population. So that the big fish we killed simply haven't been replaced in time.

I know this might sound a bit long winded and mere speculation but I'd be interested does anybody have any experience or opinions on this subject or anything on flounder pop's and migration.

Pete

Hi Pete

A slightly different explanation would be that the fish you took were very old, close to the 7-10 years expected for the species, having grown far more slowly due to the relative shortage of food, in which case, you did little or no harm in that the fish would have died from old age anyhow!

... although you would have expected some of them to reach the same size in the intervening period.

Another observed feature (especially in freshwater) is that the loss of the bigger fish in a species from a location leads to an explosion in the number of smaller fish (particularly true for pike and perch) who no longer have to compete with larger fish for the same food. Could be this happened too...

It could also be that other factors like dredging or similar have affected the supply of food, or that other species have moved in to fill the gap left by the missing flounder - that's a theory proposed to me by some anglers in the SE concerning the availability of smuts - their arguement (which I find hard to agree with) is that the lack of bass has left a gap in the local ecology and that the smuts have moved in to take advantage of this...

As for migration patterns, haven't a clue but I will bounce it off a few of the marine biologists and see what they say...

Anyone seen similar changes in size pattern in other locations?

Kieran,
It really is quite difficult to ascertain what exactly happened to those big flounder when there could be so many variables at play. Although I thought that was an interesting point you raised, and one I often forget about, is that fish really have quite short lifespans. Maybe they were fish of a particularly good year class that simply died out through old age.

You would have thought though that some larger ones would have started to show again. The strands in question would be very similar to Mulranny and Keem down your way, you noticed any patterns or trends on those?

Trawling doesn't come into the equation because the trawlers would find it difficult to get into the ground, rocky in patches and all.

What was an interesting thing about the bigger flounders was that they were all feeding on sandeel, in so much as thay when cleaned this was what dominated the stomach contents. These were big sandeels too, not the finger size ones. Could it be that declines in these sandeel populations have had some influence on the growth potential of the flounder. Still in the spring of 2003 there were massive amounts of sandeel shoaling on alot of the shore marks we fished. Its really hard to figure out whats going on but then again thats one of the things that makes sea angling so interesting and unpredictable.

Pete

Hi Pete

Sadly I have had very little fishing of late, either at Keel or Mulranny (Keel is better for the flatties but you need a dry and calm spell otherwise the bog water turns the water almost black instead of its standard pelucid green).

There are loads of storm beaches around Mayo with lots of small flatfish, either flounder, dab or turbot, and its a struggle to find a decent fish amongst them - the entire north coast from Ballina west to Belmullet.

I never use anything smaller than a 2/0 now and even with that the smaller buggers still manage to impale themselves...

It is very interesting to find that the big flounder were stuffed full of the big sandeels - not what I would have expected. It might be worth taking a few bags out of the freezer to see if we can coax a big flattie out... In the past I have had my best flatfish on big lugworm and squid baits that had been sent out looking in vain for codling. Them and the damned dogs...

Where abouts are you fishing pete (no need to be specific, a county will do)?

Kieran,
Donegal mate. Yeah it was quite strange to see such big sandeels crammed in their gut, the only large one that had anything different was an individual that was heaving with sandhoppers. Not a sign of any crab in their stomachs although I'd say densities of crab would be low on those types of beach in the first place.

Still they all fell to the rather humble mackerel strip. Cross Strand on the Mullet always struck me as a place where any bigger flounders would have access to sandeels. There is a smaller beach at the very south of the Mullet (don't know the name) that looked right aswell, have you tried it? I can imagine any patterns prevalent in Donegal might also apply to Mayo being so geographically similar, at least you would think.

Pete

Don't know if it's relevant but the size of pearch cycles, mostly there is a plague of small ones but every few years they get much much bigger. Maybe the population reduces for some reason leaving more food for the survivors.