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For an estuarine restoration project to be successful it must reverse anthropogenic effects and restore lost ecosystem functions. Restoration projects that aim to rehabilitate endangered species populations make project success even more important, because if misjudged damage to already weakened populations may result. Determining project success depends on our ability to assess the functional state or "performance" and the trajectory of ecosystem development. Mature system structure is often the desired "end point" of restoration and is assumed to provide maximum benefit for target species; however, few studies have measured linkages between structure and function and possible benefits available from early recovery stages. The Salmon River estuary, Oregon, U.S.A., offers a unique opportunity to simultaneously evaluate several estua-rine restoration projects and the response of the marsh community while making comparisons with a concurring undiked portion of the estuary. Dikes installed in three locations in the estuary during the early 1960s were removed in 1978, 1987, and 1996, creating a "spacefor-time substitution" chronosequence. Analysis of the marsh community responses enables us to use the development state of the three recovering marshes to determine a trajectory of estuarine recovery over 23 years and to make comparisons with a reference marsh. We assessed the rate and pattern of juvenile salmon habitat development in terms of fish density, available prey resources, and diet composition of wild juvenile Oncorhynchus tshawytscha (chinook salmon). Results from the outmigration of 1998 and 1999 show differences in fish densities, prey resources, and diet composition among the four sites. Peaks in chinook salmon densities were greatest in the reference site in 1998 and in the youngest (1996) site in 1999. The 1996 marsh had higher densities of chironomids (insects; average 864/m 2 ) and lower densities of amphipods (crustaceans; average 8/m 3 ) when compared with the other sites. Fauna differences were reflected in the diets of juvenile chinook with those occupying the 1978 and 1996 marshes based on insects (especially chironomids), whereas those from the 1987 and reference marshes were based on crustaceans (especially amphipods). Tracking the development of recovering emergent marsh ecosystems in the Salmon River estuary reveals significant fish and invertebrate response in the first 2 to 3 years after marsh restoration. This pulse of productivity in newly restored systems is part of the trajectory of development and indicates some level of early functionality and the efficacy of restoring estuarine marshes for juvenile salmon habitat. However, to truly know the benefits consumers experience in recovering systems requires further analysis that we will present in forthcoming publications.

Chinook salmon is an anadromous species that varies in size at freshwater emigration, which is hypothesized to increase population resiliency under variable environmental regimes. In California's Central Valley (USA), the majority of naturally spawned juveniles emigrate in 2 pulses: small juveniles (referred to as fry), typically ≤55 mm fork length (FL), emigrate from natal streams in February-March, whereas larger juveniles (smolts), typically > 75 mm FL, emigrate in mid-AprilMay. In some river systems, there is a smaller pulse of emigrants of intermediate size (parr), typically 56 to 75 mm FL. Although the relative contribution of these migratory phenotypes to the adult population is unknown, management activities focus on survival of larger emigrants and most artificially produced fish (98%) are released from hatcheries at parr and smolt sizes. We reconstructed individual length at freshwater emigration for a sample of adult Central Valley Chinook salmon from 2 emigration years using chemical (Sr:Ca and Ba:Ca) and structural otolith analyses. The adult sample was comprised of individuals that emigrated as parr (mean = 48%), followed by smolts (32%) and fry (20%). Fry-sized emigrants likely represent natural production because fish ≤55 mm FL comprise < 2% of the hatchery production. The distribution of migratory phenotypes represented in the adult sample was similar in both years despite apparent interannual variation in juvenile production, providing evidence for the contribution of diverse migratory phenotypes to the adult population. The contribution of all 3 migratory phenotypes to the adult population indicates that management and recovery efforts should focus on maintenance of life-history variation rather than the promotion of a particular phenotype. KEY WORDS: Chinook salmon · Migratory phenotype · Otolith chemistry Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 408: [227][228][229][230][231][232][233][234][235][236][237][238][239][240] 2010 logistic and interpretive limitations. Chemical and structural analyses of fish otoliths, which hold a record of aspects of an individual's environment, provide an alternative approach to generating empirical data on the contribution of migratory phenotypes without the need to recapture individuals (Campana 1999, Campana & Thorrold 2001.Extensive agricultural land use conversion and water development within California's Central Valley (USA) (Fig. 1) have impacted the region's fall Chinook salmon (Moyle 2002), which are listed as a species of concern under the Endangered Species Act (Good et al. 2005). The majority of naturally spawned juveniles emigrate in 2 pulses: small juveniles (referred to as fry), typically ≤55 mm fork length (FL), emigrate from natal streams in February-March, whereas larger juveniles (smolts), typically > 75 mm FL, emigrate in mid-April-May (Brandes & McLain 2001) (Fig. 2a-f). In some river systems, there is a smaller pulse of emigrants of intermediate size (parr), typically 56 t...

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