Circannual Cycle of Seawater Adaptability in Oncorhynchus nerka: Genetic Differences between Sympatric Sockeye Salmon and Kokanee

Abstract

1992. Circannual cycle of seawater c3daptability in Oncorhynchus nerka: genetic differences between syrnpatric sockeye salmon and kokanee. Can. J. Fish. Aquat. Sci. 49: 99-109.Anadromous sockeye salmon and nonanadromous kokanee (Oncorhynchus nerka) spawn syrnpatrically in locc3-tions across British Columbia, yet remain genetically distinct. To investigate the possibility that these differences are maintained by selection against hybrids of the two forms owing to differences in seawater adaptability, we raised pure and reciprocal crosses of Shuswap River sockeye and kokanee in controlled hatchery conditions and tested their seawater adaptabilities nine times over 2 yr. Sockeye, kokanee, and reciprocal hybrids all showed a seasonal cycle in their seawater adaptability, which was lowest in midwinter and highest in the spring. However, clear differences were evident among cross-types in the spring s f their second year. Sockeye were the first to show increased seawater adaptabilities, hybrid groups next, and kokanee last. The observed differences could not be attributed to tank effects, or to differences in sine, sex, or state s f maturity. Le saurnon nerka anadrome et sa forme non anadrome, le kokani (Oncorhynchus nerka), fraient de facon sympatrique en plusieerrs lieux de la Colombie-Britannique, mais demeurent genktiquernent distincts. Afin d'etudier la possibiliak que ces differences soient maintenues par une selection s'exer~ant 21 ['encontre des hybrides des deux formes, pour des raisons d'adaptation a I'eau de mer, nsus avons eleve en pisciculture et dans des conditions contr8lees des produits de croisements purs et r6ciproques de saumons nerkas et kokanis de la rivi6re Shuswap et vkrifik leurs capacitks $'adaptation A l'eau de mer a neuf reprises au cours d'uns periode de 2 aws. Les saumons nerkas et kskanis de meme que leurs hybrides rkciproques ont tous prksente u n cycle saisonnier d'adaptation a I'eau de mer qgli etait le moins kleve au milieu de I'hiver et le plus eleve au printernps. Des diffkrences nettes etaient cependant evidentes entre les poissons de types de croisement differents au cours de la deuxieme annee.Les nerkas ont 6t4 les premiers a presenter une capacitk accrue d'adaptation a I'eau de mer, venaient ensuite les hybrides et, en dernier, les kokanis. Les kcarts observes ne pouvaient @tre attribues 2 des effets lies aux cuves csu a des differences de taille, de sexe ou de stade de maturite.

Aspects of parr-smolt transformation in anadromous and resident forms of brown trout (Salmo trutta) in comparison with Atlantic salmon (Salmo salar)

“…In fact, salinity tolerance improves with size in all salmonids (McCormick and Saunders, 1987 ). Development of salinity tolerance, independent of Parr-smolt transformation, exists naturally in non-anadromous salmonids, such as Salvelinus fontinalis (McCormick et al, 1985 ), and can be stimulated by seawater transfer in landlocked forms, such as kokanee salmon, Oncorhynchus nerka (Foote et al, 1992), and resident brown trout (Quillet et al, 1986; this study).…”

Vertical Movements of a Mekong Giant Catfish (Pangasianodon gigas) in Mae Peum Reservoir, Northern Thailand, Monitored by a Multi-Sensor Micro Data Logger

“…Generally, organisms have various biological rhythms (e.g., circadian, circalunar, circatidal, and circannual rhythms) for reproduction, migration, and feeding (Baggerman, 1985;Boujard and Leatherland, 1992;Foote et al, 1992;Gwinner, 1986Gwinner, , 1996Heilman and Spieler, 1999;Mizushima et al, 2000;Satoh et al, 2008;Wikelski et al, 2009;Takemura et al, 2010). Seasonal feeding rhythms usually involve a fasting period; such a pattern has been identified in various organisms, especially in avian and mammalian species (Hissa, 1997;Piersma et al, 2008).…”

The Genetic Basis of Smoltification-Related Traits in Oncorhynchus mykiss

“…The inheritance of nonmigratory and migratory lifehistory types and associated traits has been examined in several salmonid species (Refstie et al 1977;Clarke et al 1992Clarke et al , 1994Foote et al 1992;Johnsson et al 1994;Thrower et al 2004;Duston et al 2005). Although plasticity exists within and across populations (Quinn and Myers 2004;McPhee et al 2007), inheritance studies suggest that both timing of and propensity for smoltification are also under genetic control.…”

“…In crosses between life-history variants of Chinook salmon that differ in smoltification timing, Clarke et al (1994) found that early smolting (smolting during the first year of life, also called ''ocean type'') was dominant and apparently controlled by few genetic loci; the authors used body morphology and coloration to discriminate between dark, stream-dwelling individuals and silvery, premigratory smolts to determine if Chinook salmon in their study were smolting in their first or second year of life. In species for which both freshwater resident and migratory forms exist, studies evaluating smoltification in intercrosses between resident and anadromous forms indicate that there is also a genetic basis for the propensity to undergo smoltification (Foote et al 1992;Johnsson et al 1994). In these studies, hybrid progeny were made from crosses between anadromous sockeye salmon and freshwater resident kokanee (O. nerka) (Foote et al 1992) and between anadromous steelhead and freshwater resident rainbow trout (O. mykiss) (Johnsson et al 1994); in both studies, hybrids were intermediate between freshwater and migratory forms in their ability to hypo-osmoregulate in seawater, suggesting that propensity for smoltification is under additive rather than dominant genetic control in these species.…”

“…In species for which both freshwater resident and migratory forms exist, studies evaluating smoltification in intercrosses between resident and anadromous forms indicate that there is also a genetic basis for the propensity to undergo smoltification (Foote et al 1992;Johnsson et al 1994). In these studies, hybrid progeny were made from crosses between anadromous sockeye salmon and freshwater resident kokanee (O. nerka) (Foote et al 1992) and between anadromous steelhead and freshwater resident rainbow trout (O. mykiss) (Johnsson et al 1994); in both studies, hybrids were intermediate between freshwater and migratory forms in their ability to hypo-osmoregulate in seawater, suggesting that propensity for smoltification is under additive rather than dominant genetic control in these species.…”