The Omnivorous Carp – Jon Wood

For a change, a guest article by Jon Wood, author of the recently published book, Carp Fishing Science. It’s a remarkably complex and detailed read that will pretty much tell you everything you might ever have wanted to know about how a carp works. Indeed you can read a more detailed summary of it here.

Meanwhile, here are Jon’s views on attraction, energy and digestion…

The Omnivorous Carp

One of the biggest problems any angler has to face is bait selection. In the case of carp this is particularly complicated due to their omnivorous nature.

For many years now, the carp fishing world has tried thousands of different alternatives with the obvious intention that of finding one to beat the rest and, depending on your fishing objective, whether that be the one elusive monster or simply trying to catch more than the rest, anglers end up developing their own preferences with varying degrees of success.

During my research I looked at many of these choices with varying degrees of probability regarding their true pulling power. However, the one factor that is commonplace among the alternatives and something which can be seen throughout all areas of angling for every species of interest is that “if they’re having it, they are having it and if not, well, they’re not.” The other thing you have to do is be in the right place at the right time, although that can be easier said than done.

And whereas many areas of elaborated bait preparation are calculable (for example the percentage of protein or lipid in a diet), it is this unknown factor, that of the fish’s reaction to the bait, which is more or less incalculable.

Why is that?

Carp behave differently both at different times of the day and during different period of the year. Any angler, independently of his or her experience can make that observation. There are good days and bad days and also preferred hours. Some lakes are more productive at night and others in the afternoon. This is often related to such environmental variables as oxygen and temperature and of course light intensity and the differences may also be due to factors still unknown such as the strain of the carp present and their genetics.

Carp activity is dependent on temperature but this is not directly proportional to feeding. We can see a clear difference between summer and winter regarding the ease with which a carp will feed and catch rates show this, but as temperatures become very high, carp will usually become inactive and often very difficult to catch. This is because as the temperature peaks, the optimum range for the carp’s metabolic functions is surpassed and the fish is left outside what we could call its “comfort zone”.

So how does this affect the angler?

We can of course learn when the best times to fish are on any water by experience and watching others and their catch rates but we will always come back to the same question of bait selection at any time of the day or year and even when it seems that they are willing to eat whatever you throw at them – people will always want to catch more or bigger carp.

Omnivory is a problem since if a fish is willing to eat anything, what happens when everything becomes available? Well, that situation is present particularly in summer when invertebrate diversity is high and we also have plant growth including algae, plant leaves and roots which can be ingested and utilised by the carp (although inefficiently in some cases) but still provide an alternative food source. Invertebrate choice may stretch to hundreds of species in a lake and as well as that, carp are able to eat small fish and even nuts and berries. So with all that food in the water and all those different choices, how can we possible attract a carp to our bait?

Well, catches in summer show that despite the bonanza of food items available, carp fishing is maybe at its most productive at that time of year, so we must be doing something right.

It is my belief that the key to beating carp when alternatives are plentiful is down to three things:

  1. Attraction
  2. Energy
  3. Digestion

All three of these considerations are related to temperature and therefore the activity of the carp. In the case of attraction, many of the low molecular mass soluble attractants such as syrups and low density oils diffuse faster through the water column and over greater distances at higher temperatures. You also have to consider that some substances are more likely to solidify at lower temperatures and not diffuse at all. Animal fats are a good example.

On the majority of waters, you are fishing against other anglers, albeit involuntarily and they are trying to catch the same fish as you. Therefore, improved attraction is a good way to get the edge and particularly on waters with high angling pressure, any confidence boost caused by using a more attractive bait is always welcome.

For me, the most important consideration is the energy provided by the bait, which again is related in some way to temperature. Almost all fish are poikilothermic. This means that their body temperature is dependent of the temperature of their surroundings. As the temperature increase, so does the fish’s metabolism up to a point. Therefore, in order to satisfy the requirement imposed on the carp by the higher temperature it has to eat more.

But it can’t eat more of just anything. At higher temperatures, the carp requires more energy and therefore it’s preferential that the fish consume those items higher in energy; fats and carbohydrates. Whether the fish is able to detect a food source with a specific amount of a certain food substance is doubtful. However, what we do know is that the carp possesses a memory and is able to differentiate between something beneficial and something disadvantageous. So, it’s possible to suggest that a carp can remember something that it has eaten that it can associate with satisfying a high energy requirement.

If you consider the amount of energy that an invertebrate such as a bloodworm provides, then it may well be very similar to that of your boilie on a calories per gram basis. However, the great benefit of elaborated baits such as boilies and pellets is that they are relatively large and more importantly are energy efficient food items. The carp must expend energy to feed (to open and close that big vacuum cleaner mouth), to digest the food, to swim and locate food and also to maintain and repair tissues. All those processes require energy and if we compare the energy expended in locating three grams of bloodworm with the same for three grams of boilies (which may in fact be just one bait) then there is a big difference. It therefore makes sense that an important reason why a carp would prefer a bait over natural food items is to satisfy dietary needs with minimum energy expenditure.

The third consideration is digestion, a topic discussed in carp circles as frequently as any. Again, with increased temperature, this factor increases proportionally since, as stated before, the fish’s biological processes function more quickly at higher temperature, which need to be so in order to provide the substances required for growth, maintenance and energy use more quickly.

Digestion efficiency is how easily food mass is converted to usable substances and growth. Lower temperature reduces the efficiency of digestion and the rapid availability of those substances. For that reason, carp anglers frequently discuss the changes that need to be made to a “winter bait” using partially or wholly digested ingredients.

This is applicable to homemade baits in particular because for the time being, the ingredients of frozen and shelf-life baits still remain as big a mystery as ever.

All the best,

Jon Wood

You may care to visit Jon’s web site, to see a sample chapter or to download a digital copy. Copies of the book can be ordered from the fishingbooksender price £19.99 plus £2.95 P&P.

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