Progress With Perch

[Vagabond]

Just a couple of recent perch from Deerdrink Dam - compare the shape of the two heads. One long and zander-like, t'other short and blunt.

 

Many years ago Fred J Taylor drew attention to two forms of perch from the Great Ouse - it was thought then that the two forms night pursue different life styles. Ie one was thought to eat fish with t'other being a bottom feeder - more likely to take worms or crayfish.

 

However, both these perch took fish baits. In fact all the seven larger (2 lb plus) perch I have taken from this venue since September took fish baits, and although I've had stacks of perch on worm from the same swim, they have all been small (one solitary half-pounder and all the others an ounce or two).

 

I'm getting a bit mystified as to the make-up of this population. It is a very tiny water (just about an acre and a half,) so I would not expect more than a dozen big perch present. If that were so then by now I should be getting repeat captures, but despite close examination of all the photos I can't see any likenesses between them . Perhaps there are more big perch there than I thought. Any thoughts on numbers Steve ?

 

Certainly there is one perch that had a wipe at one of my baits which looked rather bigger than any I've caught so far, and there is a tale of a huge fish two years ago. (I'm not telling you the alleged weight 'cos I don't believe it either!)

 

A little piece of the jigsaw has fallen into place - remember my comment on the perch coming out from under the roots and seizing the live bait, then making off for open water ? They all did that. I wondered why they did not return to their hidey-hole.

 

Having spent a long time motionless and head -down over the dam watching my livebaits, I think I have now solved this problem. As soon as the perch comes in sight, the bait bolts for the roots. The perch does not always catch it first time, and abandons the chase when the bait gets into roots. At that point I cautiously ease the bait free again and then sometimes the perch comes back for another go. As soon as the bait is successfully grabbed, the perch goes for open water.

 

The penny has dropped. The perch wants its prey in open water so it can easily grab it again if it escapes whilst being turned. It doesn't want it dashing into nearby roots.

 

When I was eight years old I did precisely the same thing with my first good fish (2lb Crucian) I waded in, scooped it ashore, picked it up and ran twenty yards away from the water before putting it down!

 

HELP ! Thought I could paste in a couple of piccys but can't get it to work - someone please explain how to do that - I have converted them to jpg and copied, but can't get "paste" to work.

[Steve Burke]

Congrats on the specimens! I remember Fred J's theories about the 2 types of perch from the Gt. Ouse - "Angling in Earnest" wasn't it? Seems to make sense although I've not come across this on my own waters.

 

I wouldn't like to guess at the numbers present but there seems to be a fair few doesn't there? At the moment perch populations are very high as there's been no major outbreaks of perch disease since the mid 80s.

 

I find that fish baits often score well in the more coloured stillwaters, worm in the clearer ones. However, this is a very broad generalisation. It may just be that the coloured waters are like that purely due to the numbers of bottom feeding fish of course, many of which are food for the perch. The best bait can also vary from season to season. I suspect it's down to availability of food and the predator/prey balance more than anything else. See my piece on perch baits in the articles section for more on this subject.

[Vagabond]

quote:

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Originally posted by Steve Burke:

 

I find that fish baits often score well in the more coloured stillwaters, worm in the clearer ones. However, this is a very broad generalisation. It may just be that the coloured waters are like that purely due to the numbers of bottom feeding fish of course, many of which are food for the perch.

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[Vagabond]

Yes, this water (Deerdrink) is surprisingly clear though, despite the presence of bream, roach-bream hybrids, and a lot of carp up to 10/12 lb. Will press on with these perch until end of season, and after some trouting hope to tackle the Wingham tench.

 

New ball game there - no doubt I will struggle as most of my tenching has been on estate lakes.

[Kappa]

This sort of thing is well studied in the stickle back. I can't find a link for the origianl work by Dolph Schluter. But this this gives the general gist. Or I could email you the original paper! Basically it different forms of the same species occupy different ecological niches in the same water.

 

Sorry for the science attack by the way! But this is probably why you get different shaped fish.

[poledark]

Vagabond, email the pics to me and I will put them on my website and you can post a link to them,

 

Den

[Newt]

Richard Capper:

... Basically it different forms of the same species ...

Interesting paper Richard. It does open some questions though.

 

The studied fish seems to have specialized in body shape, etc. in response to very different needs based on diet choice and living conditions forced by the diet choice. And with the very short term study, it makes sense that the fish weren't very likely to breed with another body shape. Anti-survival to do so.

 

This sort of thing seems more likely to occur in a large body of water with dramatic variations in habitat existing in the one water though. Not normally the case in the UK waters I've read about.

 

Also, my strong suspicion is that if the vaired body types of the same (well, pretty much the same) species were placed into a water that had more homogeneous conditions, you would see a lessening of the "breed with my own shape by preference" behavior. Thus more and more hybreds and eventually a blending of the various phenotypes until you would a population of similar appearing fish.

 

Is there a hole in my thinking somewhere?

[Kappa]

Yes you are right Newt. If these fish are put in a more homogeneous they tend to be a intermediate body shape. However what I really wanted to illustrate (but can't put a link to the paper) is that if you put the intrmediates in a lake with both conditions/diet choices then they start to divurge. It is the idea that this leads to speciation. However it is important to note they don't change their body shape but instead there is a different survivial rate for different body shapes. Thus leading to a general shift in body shape over several generations.

 

My feeling about this Perch one is that it is to do with feeding.

 

Every now and then (as always happens in sexual repsroduction) a Perch hatches that has a body shape/mouth shape different to the others which allows it to hunt a certain food source more effectively. However the lake can't support lots of these larger fish as it would decimate the prey stocks.

 

Thus this is a self contolling process where by too many alternative mouth shape perch cause a decrease in the prey which means less food whcih means less successsful breeding which means less larger perch next year. Whilst they may mate together just because they inhabit a different micro habitat, most of the time I guess they two forms will interbreed but only the extreme types survive. After all a female Perch lay 10,000-200,000 eggs so there has to be some sort of differential survival rates.

[Vagabond]

Very interesting Richard, and it sent me back to look at all the photos of perch I've taken from Deerdrink since September. Remember, these all took fish baits.

 

These break down to 5 "blunt-nosed" fish (Weights 2-12,2-12,2-14, 3-0 and 3-1) and 3 "zander-nosed (Weights 1-12, 2-0 and 2-4)

 

At first sight it is tempting to say that as there is a bimodal distribution of weights against head shape, then the head shape changes as the fish gets older/bigger, rather like human males growing in body length up to age 18, after which they only increase in girth!

 

However it may be more subtle than that - Lets say for the sake of argument, that both a proportion of longnosed, and a proportion of bluntnosed fish develop the habit of eating fish rather than invertebrates.

 

What these catches MIGHT show, is that blunt nosed fish are more efficient than longnosed fish at catching small fish, and therefore grow bigger.

 

What is surprising is the lack of any intermediate-sized perch. I've caught a couple of hundred tiny perch on maggot whilst roach-fishing, and some more tiny ones on worm.

 

Only ONE intermediate sized fish taken (half-pound on worm) - and almost all the perch, big and small, came from the same swim.

 

Until I start getting repeat captures I can't estimate how many big perch might be present - but commonsense suggests something between 12 and 20 - its a small water.

 

Lack of repeats MIGHT indicate that once caught, these perch learn to leave livebait rigs alone - but if this were so, then the catch rate would decline - but not yet it hasn't, had another on Sunday at 2-14. However, no big perch today - just roach up to 13 oz.

[Steve Burke]

I agree it could be that most of the big perch are currently fish eaters, with the blunt-nosed ones being more successful.

 

The lack of medium-sized perch gives weight to this idea. The big perch have put on a growth spurt on changing to a predominenly fish diet, whilst the large numbers of small perch are competing for a limited amount of invertebrate food. This growth spurt has been well-documented by biologists, and I summarised a paper by LeCren in one of my pieces in the articles section here on AN.

 

[ 05 March 2002, 11:46 PM: Message edited by: Steve Burke ]