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Salmonid fishes have complex life cycles involving major changes in habitat requirements at different stages in their life history. Effects of changes in flow and flow regime on salmonids are therefore highly stage-specific. Successful management requires consideration of stage-specific influences and integration of these effects over the entire life history to predict ultimate impacts on abundance and population viability. The state of science regarding stage-specific influences of flow regime on juvenile salmonids and their habitats, referring specifically to fundamental attributes of natural regimes and to characteristic alterations of these regimes associated with water management, is reviewed. It appears that a key consideration in integrating the stage-specific impacts of flow is the extent to which flow-related losses or gains early in ontogeny can be compensated by increased growth or survival later in juvenile life history. Further, fundamental interactions between flow and water temperature must be incorporated into the robust models ultimately required for science-based management. In the absence of such models and data, the current state of science may be sufficient to target specific aspects of flow regimes that are critical to multiple life-history stages, which can then serve as a basis for interim flow prescriptions and subsequent adaptive management. [ABSTRACT FROM AUTHOR]

ABSTRACT In-channel large woody debris (LWD) promotes quality aquatic habitat through sediment sorting, pool scouring and in-stream nutrient retention and transport. LWD recruitment occurs by numerous ecological and geomorphic mechanisms including channel migration, mass wasting and natural tree fall, yet LWD sourcing on the watershed scale remains poorly constrained. We developed a rapid and spatially extensive method for using light detection and ranging data to do the following: (i) estimate tree height and recruitable tree abundance throughout a watershed; (ii) determine the likelihood for the stream to recruit channel-spanning trees at reach scales and assess whether mass wasting or channel migration is a dominant recruitment mechanism; and (iii) understand the contemporary and future distribution of LWD at a watershed scale. We utilized this method on the 78-km-long Narraguagus River in coastal Maine and found that potential channel-spanning LWD composes approximately 6% of the valley area over the course of the river and is concentrated in spatially discrete reaches along the stream, with 5 km of the river valley accounting for 50% of the total potential LWD found in the system. We also determined that 83% of all potential LWD is located on valley sides, as opposed to 17% on floodplain and terrace surfaces. Approximately 3% of channel-spanning vegetation along the river is located within one channel width of the stream. By examining topographic and morphologic variables (valley width, channel sinuosity, valley-side slope) over the length of the stream, we evaluated the dominant recruitment processes along the river and often found a spatial disconnect between the location of potential channel-spanning LWD and recruitment mechanisms, which likely explains the low levels of LWD currently found in the system. This rapid method for identification of LWD sources is extendable to other basins and may prove valuable in locating future restoration projects aimed at increasing habitat quality through wood additions. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

GONe is a user-friendly, Windows-based program for estimating effective size ( N e) in populations with overlapping generations. It uses the Jorde-Ryman modification to the temporal method to account for age structure in populations. This method requires estimates of age-specific survival and birth rate and allele frequencies measured in two or more consecutive cohorts. Allele frequencies are acquired by reading in genotypic data from files formatted for either GENEPOP or TEMPOFS. For each interval between consecutive cohorts, N e is estimated at each locus and over all loci. Furthermore, N e estimates are output for three different genetic drift estimators ( F s, F c and F k). Confidence intervals are derived from a chi-square distribution with degrees of freedom equal to the number of independent alleles. GONe has been validated over a wide range of N e values, and for scenarios where survival and birth rates differ between sexes, sex ratios are unequal and reproductive variances differ. GONe is freely available for download at . [ABSTRACT FROM AUTHOR]

1. Empirical studies show that average growth of stream-dwelling salmon and trout often declines with increasing density in a characteristic concave relationship. However, the mechanisms that generate negative density–growth relationships in populations in natural streams are not certain. 2. In a recent study, Imre, Grant & Cunjak (2005; Journal of Animal Ecology, 74, 508–516) argue that density-dependent growth due to exploitative competition for prey causes the negative density–growth relationships for stream salmonids. They argue that the concave shape of empirical density–growth relationships is consistent with a simple model of exploitative competition and not consistent with interference competition for space. 3. We use a simple model to show that competition for space can yield concave density–growth relationships consistent with the empirical pattern when individuals compete for foraging sites that vary spatially in quality and lower-quality sites predominate. Thus, the predictions of the exploitative competition and spatial competition models overlap. 4. The shape of the density–growth relationship does not differentiate between candidate mechanisms underlying density-dependent growth for stream salmonids. Our results highlight the general problem with determining the mechanism driving an ecological process from patterns in observational data within the context of linking population demographics to habitat structure and animal behaviour. [ABSTRACT FROM AUTHOR]