Abstract Title

Session S-01D: Pelagic Ecology in the Salish Sea I

Proposed Abstract Title

Distribution of epipelagic biomass in Puget Sound over the summer

Keywords

Species and Food Webs

Location

Room 6C

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Description

Fishes often utilize multiple habitats over the course of their estuarine residence. Puget Sound, WA, provides epipelagic habitat to a variety of species, including declining populations of (Pacific herring, Clupea pallasi) and Endangered Species Act-listed Pacific salmon (Oncorhynchus spp). Currently, little is known about epipelagic habitat use by the fish community in Puget Sound. We used surface townetting, midwater trawling, and hydroacoustic data to characterize epipelagic fish distribution from April through October, 2011 in four basins of Puget Sound. Seasonal and spatial variability was evident in epipelagic biomass (fish and jellyfish). Biomass generally increased progressively during the summer and shifted to deeper depths. Biomass was observed more often in the offshore zone than in shelf and transition zones. Net catches indicated that herring and juvenile salmon species dominated the epipelagic fish community and exhibited considerable spatial and temporal overlap with one another. Spatial and temporal patterns in fish biomass sampled by surface townets generally reflected the patterns measured below the surface by acoustics. In July and September, when midwater trawl data were also available, acoustics and midwater trawls produced closer relative estimates to one another than to the surface townets. The spatial-temporal overlap among species and increase in biomass over the summer period create increased potential for species interactions, especially in the offshore zone.

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May 1st, 5:00 PM May 1st, 6:30 PM

Distribution of epipelagic biomass in Puget Sound over the summer

Room 6C

Fishes often utilize multiple habitats over the course of their estuarine residence. Puget Sound, WA, provides epipelagic habitat to a variety of species, including declining populations of (Pacific herring, Clupea pallasi) and Endangered Species Act-listed Pacific salmon (Oncorhynchus spp). Currently, little is known about epipelagic habitat use by the fish community in Puget Sound. We used surface townetting, midwater trawling, and hydroacoustic data to characterize epipelagic fish distribution from April through October, 2011 in four basins of Puget Sound. Seasonal and spatial variability was evident in epipelagic biomass (fish and jellyfish). Biomass generally increased progressively during the summer and shifted to deeper depths. Biomass was observed more often in the offshore zone than in shelf and transition zones. Net catches indicated that herring and juvenile salmon species dominated the epipelagic fish community and exhibited considerable spatial and temporal overlap with one another. Spatial and temporal patterns in fish biomass sampled by surface townets generally reflected the patterns measured below the surface by acoustics. In July and September, when midwater trawl data were also available, acoustics and midwater trawls produced closer relative estimates to one another than to the surface townets. The spatial-temporal overlap among species and increase in biomass over the summer period create increased potential for species interactions, especially in the offshore zone.