HOME | CONTENTS NEWS UPDATES FISHING TIPS ARTICLES PUBLICATIONS GALLERY LINKS | JOIN HERE | |||||
ABOUT PACREGIONSFEEDBACKEVENTS NEWS FEEDABOUT PIKESEARCH | |||||||
The relationship between any fish predator and it's prey is perhaps best described by the comprehensive experiments reported by 'Swingle 1950'. These involved the study of predator prey relationships in 89 separate ponds, containing fish populations that had been established for between 2 and 30 years. In his definition of balance, Swingle concludes that this implies a combination of species. Including at least one piscivorous (carnivorous) species. The
studies on the status of the ponds 'balanced or unbalanced' revealed that the
predator prey ratio, by weight of balanced ponds was between 1:1.4 to 1:10;
77% of the best 'balanced' populations had ratios of between 1:3 and 1:6. Conversely,
'unbalanced' populations had ratios of between 1:0.06 and 1:63; most unbalanced
populations had a relatively small weight of predators in relation to the weight
of prey. The most exhaustive work undertaken in Britain has taken place on Lake Windermere, where pike have been removed for scientific purposes since the 1940s. The results are complex, but can be summarised, see the following: There was an initial drop in the NUMBERS of pike but these have remained relatively stable for many years. The average size of the pike has fallen. Their speed of growth has increased. Food availability (rather than the size or species of prey) controls diet. The only species in the lake to show unequivocal upturn in its numbers is Char. This species is particularly vulnerable to pike predation when seasonal shoals are formed. Pike cannibalism is reported as 'rare' with individuals of less than 16" normally being taken. Other studies reveal a higher incidence of cannibalism Toner (1969) records that small pike formed 25% - 32% of the food of other small pike. Otto
(1979) studied the effect of pike removal on a Swedish lake, defining three phases: It is worth reporting that the weight of pike present did not change markedly. Other studies relating to pike removal shed few new facts. There appears to be NO reports of studies on the effect of removing only large pike or indeed, returning only large pike. It is interesting that many studies on pike have been conducted into the best methods of conserving /stocking this species. Bouquet (1979), records ways in which Dutch fishery management work focuses on maintaining high levels of pike and zander in their fisheries carryout annual stockings to maintain their numbers. Several other facts are worthy of note: 1. There are no reported instances where pike have reduced the levels of prey fish to unacceptable proportions. 2.
Pike are an indigenous species in Britain (not Ireland) and have been living in
balance with their food for as long as they have been present many thousands of
years. 4. Evidence from countries where pike and fish-eating birds like Ospreys etc are present, does not suggest that such birds were ever a major controlling factor of pike numbers. 5. It is very difficult to totally
eradicate pike from any water. Generally this is biologically only desirable when
prey species do not breed successfully i.e. trout and some carp, Stillwater fisheries
or where other forms of prey control can be successfully practised. 6.
In order to increase the numbers of non-predatory fish present in a water, effort
and resources would be better expended on increasing water fertility and habitat
diversity rather than haphazard pike removal. Indeed if the survival of prey species
is paramount, it would be wise to radically improve methods of fish handling,
unhooking and retention, which often produce high mortalities. 7. Pike are and can be demonstrated to be a popular and valuable asset in many fisheries. Demand for pike fishing of good quality is great, and pike anglers make a significant contribution to the budgets of water authorities and angling clubs. If the pike fishing is poor, pike anglers will go elsewhere taking their valuable financial contribution with them. 8. There has not been a single reported instance whereby the use of live or deadbait legally obtained from elsewhere has caused the spread of an infection or resulted in fish mortalities. Click here to download this page in Acrobat Reader format. |
HOME | CONTENTS NEWS UPDATES FISHING TIPS ARTICLES PUBLICATIONS GALLERY LINKS | JOIN HERE | |||||
ABOUT PACREGIONSFEEDBACKEVENTS NEWS FEEDABOUT PIKESEARCH | |||||||