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The spawning habitats of many large marine pelagic predators are poorly known. This lack of knowledge hampers conservation efforts that are aimed at identifying critical habitats for the spawning of these species. We hypothesized that phylogenetically related species show different adaptations and respond differently to environmental and geographical cues for when and where to spawn. We tested this hypothesis on a 5 yr data set (2001 to 2005) from the Balearic Islands region (Mediterranean Sea), targeting the early larval stage of 3 abundant species of tuna: bluefin tuna Thunnus thynnus, a large migratory oceanic species; albacore T. alalunga, a smaller species; and bullet tuna Auxis rochei, often found closer to coastal areas. The spatial distribution of spawning locations at the regional scale differed for the 3 tuna species. Bluefin tuna relied heavily on environmental signals, and therefore their spawning habitats can vary depending on the environment. In contrast, the spawning habitat of albacore and bullet tuna was driven mostly by geography and was less variable over contrasting environmental conditions. These regional adaptations for spawning habitats among the 3 tuna species may play a critical role in offspring survival and species interactions, and should be taken into account when establishing conservation practices.KEY WORDS: Spawning strategy · Spawning habitat · Regional scale · Spatial distribution · Large predators · Migratory strategy · Mediterranean · Tuna Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 463: [273][274][275][276][277][278][279][280][281][282][283][284] 2012 ted dispersal abilities and complete their life cycle in relatively closed spatial areas. It is possible that within similar geographical ranges, species with different life history traits can reproduce and thrive, but also show adaptations to local spawning habitats at smaller spatial scales.The cues and clues that fish respond to in their decisions regarding when and where to spawn can be geographically and environmentally based (Bailey et al. 2004, Ciannelli et al. 2007). Some species may adapt to spawn in geographic areas where the environment tends to be more stable, and where habitat characteristics are optimal for the survival of later larval and juvenile stages. Other species may adapt toward a more opportunistic strategy and spawn within specific environmental ranges of a larger geographic area. Depending on the physical tolerances of the species, the 2 strategies can show any degree of mixing. At a regional spatial scale (e.g. around the Balearic Islands), the prevalence of one or the other spawning strategy can be correlated with specific life history traits. The important question then is how species' life history traits and spawning strategies are linked. Providing an answer to this question would allow us to generate hypotheses on how spawning strategies are regulated across a wide range of species, and thus to determine their importance in fisheries...

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[1] Different works appearing during the last decade show that the western Mediterranean has suffered a temperature and salinity increase during the 20th century. Most of these works analyze long-term trends in Levantine Intermediate Water (LIW) and Western Mediterranean Deep Water (WMDW); those dealing with changes in shallow and coastal waters are very scarce. It is still an open question whether these changes are due to meteorological factors occurring in the western Mediterranean or if they are caused by the salinity increase of the water masses contributing to deep water formation. In this work we analyze the data obtained in the last decade of the 20th century (and longer time series in some cases) within the frame of six projects aimed at the systematic collection of hydrographic data at fixed stations in the northern sector of the western Mediterranean (mainly in coastal areas). We detect strong warming trends in those stations located in the continental shelf (and probably with no influence of the LIW). This result could indicate that changes observed in the WMDW cannot be explained only on the basis of changes imported from the eastern basin. Another striking result is that these trends are an order of magnitude higher than those reported for the rest of the century, indicating that the 1990s have been an exceptionally warm decade. On the other hand, time series affected by the LIW show a salinity increase, and in some cases this is not accompanied by the corresponding temperature increment, indicating that the LIW salinity increase could also be a factor to be taken into account.