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A brief review is provided in some advances in understanding the ecology of pike Esox lucius Linnaeus over the last 10 years. Based on longterm studies and manipulative, often short-term experiments (laboratory, field and mesocosms) several established theories have been supported, as well as new concepts developed. Despite their wide distribution pike show low levels of polymorphism and divergence indicative of a recent common ancestral population. Recent genetic studies, however, indicate a single refugium in North America compared to several refugia in Europe. Pike are found in rivers, lakes and weakly saline waters. Variables such as growth and mortality are mainly affected by factors such as temperature, water transparency, productivity, availability of prey and density of pike and other predators. In choice of habitat pike have been shown to support the ideal free-distribution theory. The importance of macrophyte habitat in the life history of pike has been reconfirmed and pike have been shown to be flexible in response to water clarity. Pike are extremely 'plastic' in choice of prey types, prey size and in response to prey behaviour (e.g. they are unaffected by shoal size). Predation by pike not only affects abundance and biomass of prey (including younger and smaller pike through cannibalism which plays a major role in population dynamics, other fishes and invertebrates) but also evolution and adaptation of their morphology (in particular body shape) and behaviours. There appears to be no relationship between stock and recruitment. Recruitment is influenced by several abiotic factors in lakes and rivers. Pike play a major role in structuring freshwater communities and have been used in stocking programmes to improve water quality (biomanipulation). Many new concepts have been developed in pike behaviour in maximizing these stocking programmes both in biomanipulation and fisheries management. Despite many recent advances in understanding the ecology of pike, particularly at the individual level, developments in quantifying and modelling the role of pike as a top predator in large ecosystems have been limited, probably due to the difficulties of sampling natural populations.

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The theoretical limits of net reproduction rates for perch, Perca,fluviarilis L. and pike, Esox /ucius L., have been estimated from the upper and lower limits of fecundity, growth, mortality, age of maturity and biomass of parental stock, observed in Windermere over 40 years. Differences in egg numbers due to changes in fecundity were for perch x 1.5, for pike x2. Assuming the same mortality, a fast growing cohort would produce more eggs during its lifespan than a slow growing, for perch x2, for pike x9. Changes in mortality from high to low resulted in more eggs, for perch x 7, and for pike (where high mortality includes natural and fishing mortality) x 10. Change in age at first maturity from 3 to 2 years was unimportant. Biomass of parental stock varied by x 6 for perch and x 3 for pike, and number of eggs laid varied by x 2 for perch and x5 for pike. The number of recruits at age 2 years varied by x 300 for perch and x 7 for pike. It was concluded that temperature in the first summer of life and predation were of major importance in regulating the number of recruits. Ricker recruitment curves and a simple model showed that perch, but not pike, could produce maximum recruitment from minimum parental stock. For perch, but not pike, compensatory density dependent mortality increased with increased parental stock. It was concluded that responses by the perch and pike populations to a changing environment cannot be of sufficient magnitude to prevent wide fluctuations in recruitment.