The longevity and size allegedly achieved by the pike were, as is their voracity, the subject of many guesses tinged with fantasy. The most popular was the story of the 'imperial' giant, the length of which was to reach 6 m, and the weight 250 kg. A copper ring with a proclaiming inscription was found there, that he was personally admitted to one of the lakes of Württemberg by Frederick II of the year 1230, on 267 years before being re-caught. The credibility of the event was confirmed by the skeleton of the monster kept in the Mannheim Cathedral. Only at the beginning of the 20th century, more detailed studies showed, that this peculiarity contains a greater number of vertebrae than one pike is entitled to and is the work of skilful osteological assembly.
Keeping reasonable proportions, however, the pike must be included among our largest freshwater fish. It is not possible today to define the age and size limit, because intensive fishing practically excludes the chance of survival until natural death. Specimens over a dozen kilograms are not rare in our lakes - especially the great ones.
W 1962 In the year, a measuring specimen was caught in Lake Pluszne in Masuria 125 cm and weighing 24,6 kg (Korzynek, 1962). Older sources raise the maximum weight to 30-35 kg (Walther, 1921), which, with some caution, can be considered the upper limit of probability.
The age of the pike is read from the scales or bones of the gill cap. Every year, in connection with seasonal changes in the physiological state of the body, two zones with a diversified fine structure are formed on the scales, concentrically running uplifts called sclers. During the period of intensive growth, the fish lay slightly further apart, while with stunted growth, in winter and early spring, thicken to form darker strands. Outside the zone of concentrated sclerites, on its edge, there is a generally distinct annual ring (figure — A), which in pike from the lakes of our geographical region is established in April (Ciepielowski, 1970) or in May (Załachowski, 1965). The annual ring formation was confirmed by marking experiments (Frost, Kipling, 1959; Anwand, 1969).
Drawing. Pike scales: A - aged 2+, B - aged 1+ with fry ring (photo. C. Bends).
However, it can be difficult to read your age correctly, because sudden changes in environmental conditions sometimes complicate the scale structure due to the formation of supplemental rings. The most common is the so-called. fry ring, visible in some pikes at the edge of a dark field of sclerites closed around the center (figure — B). It may arise in the fall of the first year of life, if only then the young predator starts to eat fish and this change of food causes a significant acceleration of growth. The other supplementary rings are usually distinguished from the annual ones after that, that they do not run around the entire scale. In large individuals, the annual increments are significantly reduced, which makes it difficult to distinguish between closely spaced rings. Frost i Kipling (1959) then they recommend using the bones of the gill cap, in which narrow stripes of a darker substance correspond to the annual rings of the scales. In many lakes, however, the clarity of the drawing of the bones is not sufficient.
The correlation between the growth of the fish and the scales or bones of the gill cap makes it possible not only to determine the age, but also a reverse calculation of the rate of growth in subsequent years of life; this can be done according to the following pattern:
ln = (L · rn) / R
where: ln - fish length in any year, rn - distance between the center and the corresponding annual ring, L - length of the fish at the time it is caught, R - the total radius of the scale or bone.