The Importance of Estuarine Environments for Pacific Salmon
Pink Salmon (Oncorhynchus gorbuscha) – E. Jones
There are 8 unique and 11 shared species in marsh, 15 unique and 22 shared species in eelgrass, and 1 unique and 21 shared species in sand flat habitat.
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. As they leave rivers, salmon enter and stay in estuaries before migrating to the ocean. All Pacific salmon species use these habitats during their downstream migrations, with some residing there for days to months. Therefore, the abundance and quality of the habitat in estuarine environments greatly impacts salmon survival rates.
Determining the significance of estuarine habitats is complex. An estuary is subject to daily tidal variations and fluctuations from seasonal changes in temperature and hydrology. To compound the issue, each species using an estuary has a unique life-cycle pattern.
The Fraser River, where the study was conducted, is a primary source of freshwater and significantly impacts the marine ecosystem surrounding it. 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 estuary’s lower reaches serve as a crucial habitat for over 50 fish species, including those found in freshwater, estuarine, and marine environments.
Over 70% of the Fraser River Estuary has been permanantly transformed by industrial, agricultural, and urban development leading to reduced connectivity between habitat patches. Examples of this transformation include habitat degradation and shoreline modification, alteration of hydrology, nutrient and waste runoff, and noise pollution.
Within this estuarine environment, there are three habitats used by salmonoids and other migrating fish: seagrass, marsh, and sand flats, which together form a ‘seascape’. The article found that in terms of estuarine fish species richness and abundance, eelgrass made the largest contribution and exhibited the greatest seasonal variation. While marsh habitat supported the fewest species, it supported more distinct species as compared to sand flat and was particularly preferred by juveniles of the five commercially significant Pacific salmon species. In the Fraser River estuary, marsh was found to be the most used habitat by migrating salmon.
Concerning Pacific salmon species in the Fraser River Estuary, the authors of the study concluded that concentrating exclusively on eelgrass habitat remediation could exacerbate the reduction in salmon populations by depriving them of the remaining marsh. This highlights the idea that interconnected seascapes comprising various habitat types support higher biodiversity and productivity.
Chalifour L, Scott DC, MacDuffee M, Iacarella JC, Martin TG, Baum JK (2019) Habitat use by juvenile salmon, other migratory fish, and resident fish species underscores the importance of estuarine habitat mosaics. Mar Ecol Prog Ser 625:145-162.
EElgrass (Zostera marina) is a seagrass that grow to create vast underwater meadows, commonly referred to as eelgrass beds.
Regularly disturbed by wave action and tidal fluctuation and lacking vegitation.
A type of wetland that is dominated by herbaceous species. They form a transition between the aquatic and terrestrial ecosystems.
Kus-kus-sum Site History
Pre-European Contact there was a First Nation village located roughly where the present-day Courtenay Airpark is now. The village was called Kus-kus-sum and is the namesake for the present day Kus-kus-sum site. The term Kus-sum means slippery and Kus-kus-sum, means...
Forage Fish Surveying Summary
Wow 40 plus amazing, citizen scientists supported the forage fish project this season. They covered almost 30 beaches between Hornby Island, the Comox Valley, Campbell River, and Cortes Island.
Kus-kus-sum Project History
Below is an interactive timeline of the events regarding the gensis of Project Watershed's Kus-kus-sum Project. Hover over each salmon icon to learn more about what happened that year.Related Posts
Citizen Science Seal Monitoring for Kus-kus-sum
Your contribution is greatly appreciated, thank you for participating!Make a donation to celebrate a special someone and they receive a gift card.Welcome to our pinniped observation guide and data submission page! "Pinniped" is a Latin word meaning "fin-footed," and...
We got a first look at how a restored Kus-kus-sum will operate during storms and king tides this winter. It was exciting to see the high tides move over the steel wall and inundate the site.
The three main partners of the Kus-kus-sum project are the K'ómoks First Nation, City of Courtenay, and Project Watershed. Each of these partners has an important role to play in the purchase, restoration and long-term maintenance of the Kus-kus-sum site. In 2018, a...