Pike

(Esox lucius)

Order: Esociformes Family: Esocidae

Description: The many sharp teeth of the pike distinguish it as a predator. Other characteristics are the long pointed snout and large eyes. The dorsal and anal fins are located near the tail, and the greenish sides are covered with yellowish spots.

Origin and distribution: The pike is widely distributed throughout the cold and temperate zones of the Northern hemisphere, and occurs almost everywhere in Europe. Together with the perch, it is one of Finland’s most common fish species and has been estimated to inhabit 80─90 per cent of Finnish lakes. The abundance of a local pike stock is largely dependent on suitable spawning and nursery grounds.

Reproduction: The male pike normally reaches sexual maturity in about 2─4 years, and the female in about 3─4 years. In lakes, pike spawn soon after the ice cover has melted, and the spawning season usually lasts one or two weeks. In the sea area, the spawning season may begin as early as mid-April and continue until June, especially in the outer archipelago. In lakes, pike spawn in shallow flooding shores; in the sea, in shallow vegetated shores, stream and river estuaries, and in lakes and ponds connected to the sea. After hatching, the 8─9-mm-long larvae attach themselves to the plant material for a couple of days where they are nourished by their yolk sac, after which they start exogenous feeding and soon they bear a closer resemblance to adult fish.

Diet, growth and migrations: After hatching, pike larvae first feed on zooplankton and then switch to insect larvae. At a length of about 3 cm, they start to feed on fish larvae. Pike may already prey on their own species during their first summer (cannibalism). Large pike also eat frogs, moles and young water-fowl. Pike grow fast, usually reaching a length of 8─15 cm, sometimes even 20 cm, in their first year of life. They reach a length of 50 cm at 5─6 years, and one meter 6─10 years later. The adult female grows clearly faster than the male, and any really big pike (10─20 kg) will be a female. As a species, the pike is very local and does not migrate far.

Fishing and catches: Being common, large in size and relatively easy to catch, pike were an important addition to the diet of Finns in olden times. Today, the pike is one of the most common catch species for recreational fishermen: in 2006, recreational fishery accounted for 92% of the total annual pike catch in the sea area, and for over 98% in inland waters. The total pike catch has decreased recently, being 10 million kg in 2006. Pike are caught with lures, flies, gill nets, baited hooks, long lines and trap nets.

Vulnerability, threats and management: Pike stocks have diminished in both inland waters and marine estuaries due to lake regulation, dredging of rivers for log floating, bog drainage, building of flood banks, obliteration of shores due to eutrophication, and excavation of aluminium- and sulphur-rich soils. Pike stocks have also decreased locally in coastal areas, the islands of the outer archipelago and the Åland Islands. The reasons for the decrease are not always known, but environmental change is thought to be the most likely culprit.

Previously, over 30 million newly hatched larvae of pike were released in Finland every year. During the last decades, however, such releases have declined, and today 5-cm-long juveniles are used instead. Owing to the extent of stocking, it is often difficult to know whether a pike stock in a specific locality is indigenous or not. The stocking material has often originated from brood fish caught in other watersheds. It has also been common to release freshwater larvae into sea areas. As a whole the pike is a least concern species in Finland and most populations are self-sustaining.

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