Latitudinal gradients in onset date, onset temperature and duration of spawning of roach J. LAPPALAINEN*† AND A. S. TARKAN‡ *Department of Biological and Environmental Sciences, P. O. Box 65, FIN-00014 University of Helsinki, Finland and ‡Istanbul University, Faculty of Fisheries, Ordu Cad. No: 200, 34470, Laleli, Istanbul, Turkey (Received 20 January 2006, Accepted 28 September 2006) Onset date, onset temperature and duration of spawning of roach Rutilus rutilus were related to latitude (40–66° N) and altitude (1–825 m) based on data from the literature over the whole geographic distribution of roach. Onset date was positively and duration was negatively correlated with latitude, while no correlation was found between onset temperature and latitude. No significant correlations were found between any of the analysed variables of spawning and altitude, probably because most of the analysed populations were below 300 m altitude. # 2007 The Authors Journal compilation # 2007 The Fisheries Society of the British Isles Key words: altitude; latitudinal gradient; roach; spawning; temperature. INTRODUCTION Roach Rutilus rutilus (L.) is a widespread, commonly occurring and often abun- dant cyprinid species in Europe, where it occurs in rivers, lakes, reservoirs and in brackish waters (Holcik, 1967; Peczalska, 1968; Kozlovskiy, 1992; Lappalainen et al., 2005; No˜ ges & Ja¨rvet, 2005). Typical habitats for roach are slow-flowing or still, muddy waters (Hellawell, 1972; Vostradovsky, 1973). It spawns gener- ally on vegetation, but it can spawn also on the remnants of vegetation, other debris or even on stones (Sva¨rdson, 1951; Holcik & Hruska, 1966; Goldspink, 1977; Mills, 1981; Kozlovskiy, 1992). The onset of spawning is synchronized by photoperiod, and water temperature is important in regulating the intensity and duration of spawning (Worthington et al., 1982; Jafri, 1990; No˜ges & Ja¨rvet, 2005). Spawning usually takes place in water temperatures between 8 and 17° C (Sva¨rdson, 1951; Holcik, 1967; Peczalska, 1968; Papadopol, 1970; Goldspink, 1979; Papageorgiou, 1979; No˜ges & Ja¨rvet, 2005). Vøllestad & L’Abe´e-Lund (1987) found, however, a lower onset temperature (7  4° C) of spawning for roach, which they suggested to be an adaptation to the colder climate in Norway. A fish species in the northern hemisphere with a wide distribution range has to adapt to a simultaneous decrease in the length of the first growing season †Author to whom correspondence should be addressed. Tel.: þ358 9 19158470; fax: þ358 9 19158257; email: jyrki.t.lappalainen@helsinki.fi Journal of Fish Biology (2007) 70, 441–450 doi:10.1111/j.1095-8649.2007.01315.x, available online at http://www.blackwell-synergy.com 441 # 2007 The Authors Journal compilation # 2007 The Fisheries Society of the British Isles