Biological plasticity of non-native European perch (Perca fluviatilis) populations and the implications for management in northern New Zealand

Abstract

Size and age structure, longevity, growth, and reproductive activity of European perch (Perca fluviatilis) were studied at Lake Wainamu in March 2012 and 2013 as part of an introduced species eradication programme. Size and age structure of P. fluviatilis were dominated by smaller and younger individuals, while maximum age was estimated at 6 and 5 years for both years, respectively. Initial growth by the end of first year was faster when compared with selected studies in Europe, but size-at-equivalent age thereafter was smaller at Lake Wainamu. Oocyte atresia, asynchronous gonad development and vitellogenic oocytes were prevalent in ovaries at time of sampling in later summer, which warrant further investigation of P. fluviatilis as an iteroparous spring-spawning species in northern New Zealand. Our findings imply that the population dynamics of P. fluviatilis are highly plastic and may be influenced by local biogeographical factors. This has strong implications for the management of P. fluviatilis in New Zealand freshwater systems.