The influence of habitat complexity and fish size on over-winter survival and growth of individually marked juvenile coho salmon (Oncorhynchus kisutch) in Big Beef Creek, Washington

Abstract

Wild juvenile coho salmon (Oncorhynchus kisutch) were individually marked in October 1990 and 1991 to evaluate the effects of habitat complexity and fish size on over-winter survival in Big Beef Creek, Washington. Habitat complexity was quantified for the habitat unit where the fish were collected and, in 1991, also for the 500-m reach downstream from the collection site. Survival, estimated from recovery of marked smolts at the stream's mouth, differed between years (25.4 and 46.2%) and also varied among habitat units and reaches within years. Survival was at most weakly correlated with complexity of the habitat units but was strongly correlated with the quantity of woody debris and density of habitat units in the 500-m reach, and distance from the estuary. Because distance covaried with habitat complexity, we could not ascertain which factor had the primary influence on survival. In addition, larger fish generally survived at a higher rate than smaller individuals. However, fish tagged above William Symington Lake were smaller in the fall but larger as smolts and had higher survival rates than those tagged below the lake. Taken together, these results reveal complex relationships between size, habitat, and growth that may affect over-winter survival and subsequent life-history events. Résumé : Nous avons marqué individuellement des juvéniles de saumon coho (Oncorhynchus kisutch) sauvage, en octobre 1990 et 1991, pour évaluer les effets de la complexité de l'habitat et de la taille des poissons sur la survie hivernale dans le Big Beef Creek (Washington). Nous avons quantifié la complexité de l'habitat dans l'unité d'habitat où les poissons ont été prélevés et, en 1991, nous l'avons fait également dans le tronçon de 500 m situé en aval du lieu de prélèvement. La survie, estimée d'après la récupération de smolts marqués à l'embouchure du cours d'eau, différait d'une année à l'autre (25,4 et 46,2%) et variait aussi selon les unités d'habitat et les tronçons une même année. Le taux de survie était au moins faiblement corrélé à la complexité des unités d'habitat, et était fortement corrélé à la quantité de débris de bois et à la densité des unités d'habitat dans le tronçon de 500 m, et avec la distance par rapport à l'estuaire. Étant donné que la distance variait avec la complexité de l'habitat, nous n'avons pas pu établir quel facteur avait l'influence la plus forte sur la survie. De plus, les poissons de grande taille survivaient généralement en plus grande proportion que les individus de petite taille. Toutefois, les poissons marqués au-dessus du lac William Symington étaient plus petits à l'automne mais plus grands au stade du smolt, et présentaient des taux de survie plus élevés, que ceux marqués au-dessous du lac. Considérés ensemble, ces résultats révèlent des relations complexes entre la taille, l'habitat et la croissance, relations qui peuvent affecter la survie hivernale et les événements subséquents du cycle biologique. [Traduit par la Rédaction]

Nature and Functions of Cover for Riverine Fish.

“…But these growth benefits are known to be rapidly offset by a reduction in the amount of critical overwintering instream cover and increasing fish mortality . BUSTARD and NARVER, 1975;RIMMER et al, 1983) and recruitment or early survival of some salmonid species (MORTENSEN, 1977;QUINN and PETERSON, 1996). Some authors have also reported the importance of cover in lowering the dispersal patterns and the extent of habitat range of fish populations (LEWIS, 1969;BJORNN, 1971;APARICIO and DE SOSTOA, 1999;HARVEY et al, 1999;RONI and QUINN, 2001a) reinforcing the hypothesis that the degree of structuring of habitats influences movement rates (BAADE and FREDRICH, 1998).…”

“…Rarely were abundances of benthic and drifting invertebrates jointly undertaken (ANGERMEIER and KARR, 1984;ELLIOT, 1986). Since the measure of fish density cannot account for the significance of cover for population dynamics, at least for territorial species such as salmonids, some authors have also marked individuals and used Capture-Marking-Recapture (CMR) for addressing the demographic mechanisms (growth, survival, or immigration) responsible for changes in population abundance or biomass with changes in cover structures (GOWAN and FAUSCH, 1996;QUINN and PETERSON, 1996;HARVEY 1998). In many instances, visual observation from the banks (BACHMAN, 1984) and by snorkelling (FAUSCH and WHITE, 1981;GRIFFITH and SMITH, 1993), or radiotelemetry (TODD and RABENI, 1989;YOUNG, 1995;ALLOUCHE et al, 1999;HARVEY et al, 1999) has allowed either counts or behavioural records.…”

Personality Traits in Dumpling Squid (Euprymna tasmanica) : Context-Specific Traits and Their Correlation With Biological Characteristics.

“…Increased boldness is correlated with body size in fish (Magnhagen & Staffan, 2003) and may result in increased growth (Sundström et al, 2004;Ward et al, 2004). Body size also has consequences for an individual's survival and fitness (Quinn & Peterson, 1996;Werner & Gilliam, 1984), explaining why larger bold feeders are observed in some populations. However, there are costs as well as benefits associated with being larger and bolder.…”

Quantitative trait locus analysis of hatch timing, weight, length and growth rate in coho salmon, Oncorhynchus kisutch

“…Rapidly developing embryos may have more access to resources, because they emerge from the gravel first and have more opportunity for feeding early in the season, resulting in larger size as fry (Beacham et al, 1988;Einum and Fleming, 2000). Greater size at the fry stage is positively correlated with freshwater overwintering survival (Quinn and Peterson, 1996). However, when predation is density dependent, early development and corresponding high growth rates as fry may increase an individual's exposure to predation risk and result in lower fitness (Sundstrom et al, 2005).…”