Atlantic salmonSalmo salarL., brown troutSalmo truttaL. and Arctic charrSalvelinus alpinus(L.): a review of aspects of their life histories

Abstract

-Among the species in the family Salmonidae, those represented by the genera Salmo, Salvelinus, and Oncorhynchus (subfamily Salmoninae) are the most studied. Here, various aspects of phenotypic and life-history variation of Atlantic salmon Salmo salar L., brown trout Salmo trutta L., and Arctic charr Salvelinus alpinus (L.) are reviewed. While many strategies and tactics are commonly used by these species, there are also differences in their ecology and population dynamics that result in a variety of interesting and diverse topics that are challenging for future research. Atlantic salmon display considerable phenotypic plasticity and variability in life-history characters ranging from fully freshwater resident forms, where females can mature at approximately 10 cm in length, to anadromous populations characterised by 3-5 sea-winter (5SW) salmon. Even within simple 1SW populations, 20 or more spawning life-history types can be identified. Juveniles in freshwater can use both fluvial and lacustrine habitats for rearing, and while most smolts migrate to sea during the spring, fall migrations occur in some populations. At sea, some salmon undertake extensive oceanic migrations while other populations stay within the geographical confines of areas such as the Baltic Sea. At the other extreme are those that reside in estuaries and return to freshwater to spawn after spending only a few months at sea. The review of information on the diversity of life-history forms is related to conservation aspects associated with Atlantic salmon populations and current trends in abundance and survival. Brown trout is indigenous to Europe, North Africa and western Asia, but was introduced into at least 24 countries outside Europe and now has a world-wide distribution. It exploits both fresh and salt waters for feeding and spawning (brackish), and populations are often partially migratory. One part of the population leaves and feeds elsewhere, while another part stays as residents. In large, complex systems, the species is polymorphic with different size morphs in the various parts of the habitat. Brown trout feed close to the surface and near shore, but large individuals may move far offshore. The species exhibits ontogenetic niche shifts partly related to size and partly to developmental rate. They switch when the amount of surplus energy available for growth becomes small with fast growers being younger and smaller fish than slow growers. Brown trout is an opportunistic carnivore, but individuals specialise at least temporarily on particular food items; insect larvae are important for the young in 1 Un resumen en espan˜ol se incluye detra´s del texto principal de este artı´culo. Introduction''There is no group or family of fishes that supplies better materials for the study of the effects of geographic or physiologic isolation, or which presents more curious and interesting facts in their life histories than do the various species of Salmonidae.'' (Evermann 1925) The salmonid subfamily Salmoninae comprises about 30 species ...

Life-history plasticity in female threespine stickleback

“…As opposed to reproductive effort, clutch size is relatively easily defined, and relatively easily quantified if done so just before reproduction. Plasticity for clutch size has been documented in a wide array of poikilotherms (Roff et al, 1999: Klemetsen et al, 2003, including numerous fish (Kennedy et al, 2008;Evans et al, 2010). Little clutch-to-clutch size fluctuation is reported in ectotherms, but there is evidence for long-term plasticity cued by energy acquisition during the prespawning period when the gonads are developing.…”

Marine migrations in anadromous brown trout (Salmo trutta). Fjord residency as a possible alternative in the continuum of migration to the open sea

“…Partial migrations are observed in trout (Salmo trutta L.) populations, with sea trout individuals performing repeated seasonal movements between freshwater and the sea (Elliott 1994, Klemetsen et al, 2003. This behaviour is referred to as non-breeding partial migration in Chapman et al, (2012).…”

Adaptive winter survival strategies: defended energy levels in juvenile Atlantic salmon along a latitudinal gradient

“…Atlantic salmon is a teleost fish that spawns in rivers or freshwater streams, where juveniles typically live from one to five years before migrating to sea (Klemetsen et al 2003). After one to three years at sea, they usually return to their natal river to spawn.…”