10/20/2023 0 Comments Coastal flats salmonWithin what remains of the Fraser River estuarine environment, there are three habitats used by salmonoids and other migrating fish: seagrass, marsh, and sand flats, which together form a ‘seascape’. Over 70% of the Fraser River estuarine habitat has been lost or disconnected due to habitat degradation, shoreline modification, alteration of hydrology, nutrient and waste runoff, and noise pollution from industrial, agricultural, and urban development. The estuary’s lower reaches serve as crucial habitat for over 50 fish species, including those found in freshwater, estuarine, and marine environments. It supplies essential terrestrial nutrients that support the fish communities and influences the migration routes of emigrating salmon and it governs the nutrient cycling processes of the surrounding Salish Sea. The Fraser River, where the study was conducted, is a primary source of freshwater and significantly impacts the marine ecosystem surrounding it. To compound the issue, each species using an estuary has a unique life-cycle pattern. An estuary is subject to daily tidal variations and fluctuations from seasonal changes in temperature and hydrology. Therefore, the abundance and quality of the habitat in estuaries greatly impacts salmon survival rates.ĭetermining the significance of estuarine habitats is complex. All Pacific salmon species use estuarine habitats during their downstream migrations, with some residing there for days to months. As they leave rivers, salmon enter and stay in estuaries before migrating to the ocean. The article Habitat use by juvenile salmon, other migratory fish, and resident fish species underscores the importance of estuarine habitat mosaics contends that limited and degraded estuarine environments pose a large obstacle to salmon survival.
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