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Long River Ichthyoplankton Survey (LRS)
Overview of the LRS, a survey component of the HRBMP
Historical Photo Gallery
Photos taken during the early days of the LRS in the 1970s.
Survey Specifics
Why
This survey was designed to estimate the relative abundance, spatiotemporal distribution, and growth rates of key species (Striped bass, White perch, Atlantic tomcod, and Atlantic shad) at different life stages (eggs, larvae, and juveniles). Although the LRS targeted a few key species, information on all species caught were collected and recorded.
Where
Initially, the LRS covered the spatial area from the George Washington Bridge (RM 12) to RM 140. After 1987, this program covered the entire river from Battery Park (RM 1) to the Troy Dam (RM 152).
How
Two different types of gear were used for comprehensive coverage. A Tucker trawl with a 1-meter (m) square mouth with an attached 8-m long, 500 micrometer (μm) mesh net was used to sample the channel. An epibenthic sled with a 1-m square mouth with an attached 8-m long, 500 μm mesh net was used to sample the shoals and bottom. Samples collected were randomly subsampled for identification and analysis in the laboratory.
When
1974-2017; sampling occurred biweekly February through October and weekly mid-April through June using a stratified random sampling design.
Distribution Maps
Heatmaps of standardized density of fish at different life stages, showing spatial variation of fish population density from 1974 to 2017. Values on the heatmaps are standardized deviations (YSL = yolk sac larvae, PYSL = post yolk sac larvae, YOY = young of year).