Life-history traits of the endangered river blenny Salaria fluviatilis (Asso) and their implications for conservation D. VINYOLES* AND A. DE SOSTOA Departament de Biologia Animal (Vertebrats), Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain (Received 31 July 2005, Accepted 9 November 2006) The life-history characteristics of the river blenny Salaria fluviatilis in a Mediterranean stream in north-east Spain have been studied. The maximum age observed was 4þ years in both sexes, although only age groups 0þ and 1þ years were well represented. For both sexes, growth was rapid between April and June (before the summer drought) and in October. The instantaneous rate of monthly growth (April to October) was positively correlated with water depth. All fish attained sexual maturity during their first year of life. Females spawned multiple times. Spawning occurred mainly from June to August, although older females (2þ years old) began in May. The relationship between fecundity and total length recorded for older females in the spring was not significantly different from that obtained for 1 year-old females in the summer. The mean diameter of ripe oocytes, however, was greater in older females. Larger eggs that were laid during a period of good food supply (spring) might have a higher probability of survival. The results suggest that female fecundity is affected by environmental conditions. The species is characterized by fast growth, early maturity, multiple spawning and limited longevity. This may be a good life-history strategy for small fish species in unstable environments, where adult mortality is high, variable or unpredictable. Some life-history traits of the river blenny suggest that this species might be vulnerable to more severe drought conditions than those associated with the Mediterranean climate. # 2007 The Fisheries Society of the British Isles Key words: age and growth; Blennius fluviatilis; fluctuating streams; fresh water; Mediterranean- type climate; reproduction. INTRODUCTION Many freshwater animal species are in sharp decline (Richter et al., 1997; Ricciardi & Rasmussen, 1999). Freshwater fishes, in particular, may be one of the most threatened groups of vertebrates (Bruton, 1995). The decline of freshwater fishes due to anthropogenic action is currently a matter of concern (Williams & Miller, 1990; Cambray & Bianco, 1998). In Europe, more than half of freshwater fish species are threatened, and actions to ensure their con- servation are required at all levels. Familiarity with the life-history patterns of *Author to whom correspondence should be addressed. Tel.: þ34 934021448; fax: þ34 934035740; email: d.vinyoles@ub.edu Journal of Fish Biology (2007) 70, 1088–1108 doi:10.1111/j.1095-8649.2007.01371.x, available online at http://www.blackwell-synergy.com 1088 # 2007 The Fisheries Society of the British Isles