Hecht, The northern pike, Esox lucius

Hecht (Northern pike)
The northern pike (Esox lucius) is a species of carnivorous fish of the genus Esox (the pikes). They are typical of brackish and fresh waters of the Northern Hemisphere (i.e. holarctic in distribution).

Pike can grow to a relatively large size: the average length is about 40–55 cm, with maximum recorded lengths of up to 150 cm and published weights of 28.4 kg. The IGFA currently recognizes a 25 kg pike caught by Lothar Louis on Greffern Lake, Germany, on 16 October 1986, as the all-tackle world-record northern pike. Northern pike grow to larger sizes in Eurasia than in North America, and typically grow to larger sizes in coastal than inland regions of Eurasia.

Northern Pike typically live to 10–15 years, but sometimes up to 25 years.

Pike are found in sluggish streams and shallow, weedy places in lakes and reservoirs, as well as in cold, clear, rocky waters. They are typical ambush predators; they lie in wait for prey, holding perfectly still for long periods, and then exhibit remarkable acceleration as they strike. They inhabit any water body that contains fish, but suitable places for spawning are also essential. Because of their cannibalistic nature, young pike need places where they can take shelter between plants so they are not eaten. In both cases, rich submerged vegetation is needed. Pike are seldom found in brackish water, except for the Baltic Sea area, here they can be found spending time both in the mouths of rivers and in the open brackish waters of the Baltic Sea. It is normal for pike to return to fresh water after a period in these brackish waters. They seem to prefer water with less turbidity, but that is likely related to their dependence on the presence of vegetation.

Aggression
The northern pike is a relatively aggressive species, especially with regard to feeding. For example, when food sources are scarce, cannibalism develops, starting around five weeks in a small percentage of populations. This cannibalism occurs when the ratio of predator to prey is two to one. One can expect this because when food is scarce, Northern pike fight for survival, such as turning on smaller pike to feed; this is seen in other species such as tiger salamanders. Usually, pike tend to feed on smaller fish, such as the banded killifish. However, when pike exceed 700 mm long, they feed on larger fish.
Because of cannibalism when food is short, pike suffer a fairly high young mortality rate. Cannibalism is more prevalent in cool summers, as the upcoming pike have slow growth rates in that season and might not be able to reach a size to deter the larger pike. Cannibalism is likely to arise in low growth and low food conditions. Pike do not discriminate siblings well, so cannibalism between siblings is likely.
Aggression also arises from a need for space. Young pike tend to have their food stolen by larger pike. Pike are aggressive if not given enough space because they are territorial. They use a form of foraging known as ambush foraging. Unlike species such as perch, pike undergo bursts of energy instead of actively chasing down prey. As such, a fair amount of inactive time occurs until they find prey. Hunting efficiency decreases with competition; the larger the pike, the larger the area controlled by that particular pike. An inverse relation to vegetation density and pike size exists, which is due to the possibility of cannibalism from the largest pike. This makes sense, as the smaller pike need more vegetation to avoid being eaten. Large pike do not have this worry and can afford the luxury of a large line of sight. They prefer a tree structure habitat.

Physical behavioural traits
Pike are capable of "fast start" movements, which are sudden high-energy bursts of unsteady swimming. Many other fish exhibit this movement as well. Most fish use this mechanism to avoid life-threatening situations. For the pike, however, it is a tool used to capture prey from their sedentary positions. They flash out in such bursts and capture their prey. These fast starts terminate when the pike has reached terminal velocity.

25.09.2021, Stechlinsee, Germany