The case for pike

Pike have lived in our waters for millions of years, largely unchanged. They can be found in river systems, lakes and small ponds. In many cases, the same population of Pike has probably occupied the same enclosed area of water, almost ever since the water has been there. Perhaps for many thousands of years, always living in a perfect natural balance with their prey. The hungry ravenous Pike of myth, consuming several times it own weight of prey per day, wouldn’t be able to do that!

Ah! says the non-pike angler, I dont care about that. Fewer pike means more fish for me to catch right?

Well in the short term maybe, but certainly not in the long term, and I’ll guarantee that you will have far fewer problems in managing a fishery with pike in situ, compared to one practising a pike control policy.

Er?

Given a natural state of affairs, pike will occupy around 10% of the biomass of fish, in any given water. That’s the way nature intends it.  Try to change that balance and your troubles could be just about to begin.

The 10% biomass of pike is organised into a structure, lets call it a pyramid hierarchy.

A few huge pike, with other pike as part of their diet, at the top.  A large number of middle size ones, eating some smaller pike, and lots of nuisance jacks at the bottom (eating even smaller pike).

The mechanism by which pike keep their numbers in balance with their prey is by cannibalism of the smaller pike by larger pike. When other prey is scarce, the larger  pike eat a greater proportion of the smaller pike, maintaining the ratio of pike to other species.

The message has begun to get through that removing the biggies only leads to an explosion of ravenous jacks.

For a short while, after the removal of big fish, the total biomass of pike actually increases (and so does the predation on other species) as the number of jacks increases.

If cull policy is continued, then this situation continues. You are now on an expensive and time consuming tread mill.

Pound for pound jacks eat a lot more of other species than big pike do, and being small themselves, they don’t eat to many other pike either.  They need to pack on weight, and grow big before they themselves are eaten, if nature gives them the chance.

Fishery owners, adopting a pike removal policy, often find that they thought they had a pike problem before, they certainly have now. And each year it gets worse!

Not has only the total weight of pike biomass increased, but there a lot more individual pike. They may have a smaller average size, but they make up for that by eating more.

Even if the water management cease culling pike, it will take several seasons of inaction before things return to ‘normal’ and that’s several seasons of the members complaining increasingly bitterly that the pike are getting out of hand and demanding more action from the committee. But the more action the committee takes the worse it is likely to get.

So the answer is to remove the small fish. say everything under 10lb, and leave the biggies alone, to do their job of helping to reduce the number of jacks, Right?

Well such a policy may not be quite so disastrous, but it brings it’s own problems.

Remember that nature will fight you every inch of the way, trying to re-establish that balance, 10% biomass of pike, distributed in a pyramid hierarchy, by weight of individual fish. Take out fish of under 10lbs and you’ll see an increase in numbers of very small jacks ( less than a pound say) and it’s not to long before they become medium size jacks.

And you’ve probably forgotten that all male pike are under 10lbs!

By concentrating on removing fish under 10lbs, as well as young females, you are targeting 100% of male fish, unbalancing the female to male ratio. A lot of those big girls which you need to retain to keep the smaller pike in check are going to end up spawn bound and dead. By culling the under 10lbers you will still, in effect, be extending your cull to the larger fish, only you’ll be taking longer to do it. Having removed a considerable number of smaller pike, have you thought about what the larger pike are going to feed on?

Ok but if I remove all the bloody pike I don’t have a problem right?

Well yes you do,

Firstly it’s damn near impossible to rid a water of all pike, certainly from a water of appreciable size. Can you be sure you eliminated every last fry from the margins; blocked every source of a new pike population moving in; feeder streams, over flowing rivers, maybe illegal stockings (pike have remarkable of turning up in waters where they are said not to exist). If you can’t be sure, you are pretty soon likely to have a water famous for jacks!

Secondly Pike have a purpose.

As a lure fisherman I sometimes find it perplexing that, in a lake with many thousand of bait fish, I expect my lure to be taken several times in a session, even on those days when other piker’s are blanking. Yet most of those bait fish will remain untouched during their whole lives. It’s my opinion that pike have an instinct to target anything that seems not quite right, and none of my lures look quite right, believe me.

Land locked and living for generation after generation, in balance with it’s prey it would be a disaster for pike, if their food source were to be devastated by disease, perhaps introduce by an alien species turning up in the water. Unknowingly nature has equipped pike with attack triggers that ensure any fish that’s likely to spread disease into its larder is taken out. Although it’s well known that pike will go for the slowest and weakest fish, we can only surmise at the number of potentially disastrous epidemics that pike have nipped in the bud. Pike will readily take dead fish to: again removing as source of disease. Thirdly if you do succeed in removing all of the pike from your water you are probably going to end up with a lake full of stunted fish, prone to disease, and to fish kills in hot or thundery weather.

Pike as pollution control

Pike have another role to play in keeping a fishery healthy. Nutrients coming into water, cause excessive phytoplankton growth, (excessive nutrient levels often arrive courtesy of farm run off, via a feeder stream, or perhaps via the water table sustaining a lake). Unrestricted phytoplankton growth can cause a crash in the waters night time oxygen levels, causing fish and weed to die off, and leading to eutrophication, when bacteria feeding on the black, stinking, dead mess at the bottom of the lake, starve the water of all oxygen and render it lifeless. Normally zooplankton feed on the phytoplankton preventing this situation arising. This mechanism, protecting the water from such disaster, suffers when the planktivorous fish life, their numbers swelled by so much available food, and unchecked by natural pike predation, reduces the amount of zooplankton below the threshold necessary to keep the phytoplankton growth in check. A healthy balanced population of pike keeping down the numbers of smaller planktivorous fish prevents this happening.

On more than one occasion, fisheries have discovered this aspect of unbalancing their prey/ predator ratio to their great cost, Having spent their members cash culling pike, and boosting stocking levels of ‘desirous’ species they have ended up loosing much of their stock, and have had to spend even more money re- introducing pike to get  the water back into balance. Even where the situation is not so disasterous, the introduction of pike can in turn limit the amount of phytoplankton in a water, making more nutrients available to plant life and increasing the amount of insect life, and therefore food supply for the fish, leading to larger and more healthy fish of all species.

Moving Pike

I’ve argued the case against culling pike until I’m blue in the face, but the committee remains adamant. At least I’ve got them to agree to moving the pike to another water”

Personally, I’m very uneasy about moving pike, remember the 10% biomass, and the hierarchy which nature fights so hard to keep in balance aswell as working hard to get pike numbers back up to the natural balance you can be sure that nature will work just as hard if the balance goes the other way.

By moving pike from one water to another, all you are doing is unbalancing two waters instead of just one.

A pike that has lived in one water, and has reached any size, has successfully adapted to the unique conditions in that particular water. Perhaps establishing a territory of it’s own and a place in the waters hierarchy.  Perhaps it becomes a specialist, feeding on dead winter kill rainbows, introduce that pike to another water, and it’s got problems, and so have the resident pike.  What studies there have been, all seem to show that relocated pike do not usually do well. Instead of a quick death the pike may suffer a lingering battle, trying to establish itself in what to it is a totally alien world. In my opinion, the only exception, which I believe, warrants the moving of pike, is where the receiving water needs to have its balance of pike restored.  Perhaps in recognition that a previous policy of pike culling has only damaged the water, now full of nuisance jacks, or stunted and disease prone fish.

Trout Waters

My members pay to catch trout, not vermin, its hard enough to balance the books as it is, without feeding vermin, and losing anglers to waters where pike aren’t a problem.

Hmmm! You might not have noticed, but attitudes are changing fast.

Trout fishing is no longer the elitist sport it once was, and fly fishers are tiring of fishing for obliging rainbows all the time. They are looking for new experiences.

Pike fishing and lure fishing in particular, are becoming very popular pastimes. There is a lot of money to be made from good pike fishing. And Trout fisheries can make good pike fisheries. It’s known that on waters, regularly stocked with rainbows that fall to over winter, the habit of pike  in mopping up many of the casualties which would otherwise rot on the bottom, leads to improved water quality, when compared to such fisheries were pike are not present. And Pike grown big and fat on winter killed rainbows, are prized by specimen hunters, many who are willing to pay a lot of money for the privilege of landing and releasing such big fish.

Try not to think of the pike eating your stock, Think more along the lines of pike anglers willing to pay good money to catch and return your ‘water guardians’ The revenue you get from pike fisherman should more than compensate you for the number of rainbows taken during the season – stock a few more as pike food, and get a good return on the additional investment. Let the pike anglers pay for the rainbows, which the pike eat (and perhaps make a bob or two on top, to keep the Trout anglers membership down too).

You may not have noticed, but Game Fishing magazines, have long ago caught onto the fact that pike offer good sport, when taken on the fly. And a lot of your members are probably sneaking off to have a go at flinging fluff amongst the Lilly pads, in the nearby river, not to your rival’s pike free trout water after all ( not that they will ever admit that to you ).

You might find the information I’ve written in a previous article (Pike-The Basics) see www.anglersnet.co.uk

 

Leon Roskilly

 

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