Mar Biol (2007) 152:201–212 DOI 10.1007/s00227-007-0674-4 123 RESEARCH ARTICLE Sardine (Sardina pilchardus) spawning seasonality in European waters of the northeast Atlantic Yorgos Stratoudakis · Stephen Coombs · Ana Lago de Lanzós · Nicholas Halliday · Gersom Costas · Bruno Caneco · Concha Franco · David Conway · M. Begoña Santos · Alexandra Silva · Miguel Bernal Received: 11 July 2006 / Accepted: 9 March 2007 / Published online: 3 April 2007  Springer-Verlag 2007 Abstract Egg data from ichthyoplankton monitoring sites in the western English Channel (1988–2003) and northern Spain (1990–2000) and macroscopic maturity data from biological samples of purse seine landings in western and southern Iberia (1980–2004) are used to describe the spawning seasonality of sardine (Sardina pilchardus) in European waters of the northeast Atlantic using generalised additive models. The Wtted models reveal a double peak in spawning activity during early summer and autumn in the western Channel, a wider spring peak oV northern Spain and a broad winter season in the western and southern Ibe- rian Peninsula. At all sites, a high probability of spawning activity was observed over at least 3 months of the year, with the duration of the season increasing with both decreasing latitude and increasing Wsh size. OV western and southern Iberia there are indications that the spawning sea- son has been of longer duration in recent years for all size classes (reaching in some cases 8 months of the year for large Wsh). These patterns are in general agreement with existing literature and theoretical expectations of sardine spawning being driven locally by the seasonal cycle of water temperature, assuming preferences for spawning at 14 –15°C and avoidance for temperatures below 12°C and above 16°C. Regional quotient plots indicated that spawn- ing tolerance to higher temperatures increases progres- sively with decreasing latitude. Despite the weak evidence for geographical diVerences in temperature tolerance that may have some genetic origin, the degree of spatio-tempo- ral overlap in sardine-spawning activity within Atlantic European waters is unlikely to promote any reproductive isolation in that area. Introduction Sardine (Sardina pilchardus) is distributed from the north- ern North Sea to Mauritania/Senegal and from the Azores to the eastern Mediterranean, with the biggest populations and most important Wsheries concentrated in the Atlantic coasts of north Africa and Europe (Parrish et al. 1989). Within the northeast Atlantic (NEA) margin, sardine spawns from the Celtic Sea and the southern North Sea to Mauritania, over a wide range of temperatures and in most months of the year. Synoptic ichthyoplankton surveys have shown that during local peak spawning, sardine eggs and larvae are widely distributed within the continental shelf of Morocco (Furnestin and Furnestin 1959; Ettahiri et al. 2003), southern and western Iberia (Stratoudakis et al. 2003; Baldó et al. 2006), Cantabrian Sea, Bay of Biscay and Celtic plateau (Petitgas et al. 2006; Ibaibarriaga et al. Communicated by S.A. Poulet. Y. Stratoudakis (&) · B. Caneco · A. Silva INRB/IPIMAR, Avenida de Brasilia s/n, 1449-006 Lisbon, Portugal e-mail: yorgos@ipimar.pt S. Coombs · N. Halliday · D. Conway Marine Biological Association, The Laboratory, Citadel Hill, PL1 2PB Plymouth, UK A. L. de Lanzós · C. Franco IEO, Servicios Centrales, Corazón de Maria 8, 28002 Madrid, Spain G. Costas · M. B. Santos IEO, Centro Costero de Vigo, Cabo Estai, Canido, 36200 Vigo, Spain M. Bernal IEO, Centro Costero de Cádiz, Centro Andaluz de Ciencia y Tecnología Marina, Poligono del Río San Pedro s/n, 11519 Puerto Real, Cádiz, Spain