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Researchers using acoustic telemetry to track PIT-tagged salmon in the Penobscot River. Photo courtesy of Joseph ZydlewskiWater quality monitoring by the Water Resources Program of the Penobscot Indian Nation. Photo: C DaigleAssessing riverbed characteristics through geomorphology. Photo: CHarlie BaederElectrofishing the Penobscot River to survey fish communities. Photo: Charlie Baeder

Penobscot River Restoration - River Science & Monitoring

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The National Oceanic and Atmospheric Administration (NOAA) invested $7.3 million through the American Recovery and Reinvestment Act (ARRA) to help rebuild the sea-run fisheries of Maine's Penobscot River. This award to the Penobscot River Restoration Trust funded removal of the Great Works dam, completed in 2012. It also initiated a scientific baseline monitoring program to track physical, chemical and biological changes in the river following the removal of Great Works and Veazie dams, and the decommissioning and bypass of the Howland Dam. Here we summarize preliminary findings from the baseline phase, and highlight the enormous opportunity provided by the Penobscot Project for fisheries agencies, academia, and the general public to better understand some of the ecological responses to large scale dam removals.

JANUARY 2013 PENOBSCOT RIVER SCIENCE NEWSLETTER (pdf) scroll down for summaries

This baseline (pre-dam removal) assessment began in 2009.  Work completed in 2012 and planned for 2013 is being conducted during the transition phase of the project while the dams are being removed.  Monitoring planned for 2014 and 2015 will collect data on the early effects of dam removal on the restoration of fisheries, and on changes in geomorphology, water quality, wetlands, and marine nutrients.

Gathering data on riverbed characteristics pre-dam removal. Photo: Charlie Baeder

Geomorphology: Researchers are photographing the river, conducting bathymetry and seismology studies, and analyzing grain size data. Over the two-year monitoring period, few changes were noted in river bathymetry or bank characteristics. Channel sediment characterization revealed that, within the study area, the Penobscot River channel in both flowing and impounded reaches is dominated by coarse sediment with a predominately sand matrix. This is in striking contrast to fine-grained sediment storage noted in many impoundments.

Geological Survey work underway on the Penobscot ... watch the VIDEO describing how this is done.

Rock baskets used to determine insect diversity and abundance and water quality parameters. Photo courtesy Penobscot Indian Nation

Water Quality/Insect Diversity: The Penobscot Indian Nation Water Resources Program monitored aquatic benthic macroinvertebrates from seven locations associated within the impoundment and tailwater areas of the Great Works and Veazie dams, as well as the tailwater area of the Milford Dam. To characterize water quality conditions prior to dam removal we collected water samples and measurements from 10 sites within the Great Works and Veazie dams project areas. Water quality parameters collected included dissolved oxygen, temperature, conductivity, BOD, bacteria, turbidity, secchi transparency, total suspended solids, pH, chlorophyll, and total phosphorous.

Researchers collect data on nutrients moving through the river system. Photo: Charlie Baeder

Nutrient Transfer: Researchers collect samples throughout the system that are used for stable isotope studies. The studies can be compared to provide information on nutrient cycling and feeding habits of the various species at different places and times throughout the system. Stable isotope studies are based on the idea that "you are what you eat" because isotope signatures of consumers reflect the isotope values of their prey, which in turn can be used to infer food chain level and habitat associations (in this case marine vs. freshwater). Pre-dam removal data collected in 2009-2011 shows strong isotopic distinctions between the freshwater and marine food webs.

Atlantic salmon at the Veazie fish trap

PIT detection:  Atlantic salmon adults and other tagged fish are being tracked as they move past dams on their upstream migration. Antennas (loops of wire a tagged fish must swim through to be read) are located near the entrances and exits of fishways ... to determine if a fish entered a fishway, and, if so, was it successful in passing upstream ... the use of PIT tag technology allowed large numbers of fish to be tracked. This research will continue throughout the dam removal period.

Inserting an acoustic tag into a salmon smolt that was then released and tracked on it's migration route. Photo courtesy Joseph Zydlewski

Smolt telemetry:  Atlantic salmon smolt, both hatchery and wild, are being tagged and tracked as they descend the river, passing over and through dams, to the Atlantic. Several years of results indicate that in the Penobscot River, migrating salmon move more quickly through areas without dams than those with dams. Survival is markedly higher in river reaches without dams.

Shortnose sturgeon caught, tagged, and released in the Penobscot River.

Shortnose Sturgeon:  Researchers are catching sturgeon, tagging them and seeing if they spawn in the Penobscot River.  The presence of reproductive females and suitable spawning habitat in the upper river has been documented. Reproductive females from the Penobscot River have been tracked moving to the Kennebec River, potentially indicating a complex reproductive migration pattern.

Check out our spotlight on sturgeon page, which includes photos and video of ongoing sturgeon research in the Penobscot River.

Hyrdoacoustic monitoring on the Penobscot River. Photo: C Daigle

Hydroacoustics: SONAR systems are used to monitor fish presence, abundance and movements in rivers, estuaries, and oceans. Our goal is to measure and understand changes in fish populations before and after the Penobscot River Restoration Project. We have been developing a standardized approach for long-term SONAR monitoring, and collecting pre-restoration data that will be the baseline for comparison in subsequent years following restoration activities. When correlated with other data, it is hoped that hydroacoustics will provide accurate estimates not only of biomass, but also of fish species.  

Hydroacoustic Monitoring Video

Electrofishing the Penobscot River to study fish communities. Photo courtesy of Steve Coghlan

Fish Community: Researchers are  electrofishing throughout the Penobscot, providing detailed information on total fish biomass, abundance, and species. Findings show that many diadromous fishes were restricted to tidal waters below Veazie Dam, although Atlantic salmon, sea lamprey, and American eel were captured or observed upstream. Species richness was relatively high below Veazie Dam ... These data indicate that the restoration of connectivity through dam removal will likely result in predictable shifts in fish assemblages

Meet the Scientist!: Steve Coghlan describes the impact of dam removal on sea-run fish and his work investigating fish communities pre-dam removal.

Wetlands:  Researchers are collecting data on wetlands, rare plants, and invasive plants.


Diadromous Species Restoration Research Network (DSRRN)

Maine Interagency Stream Connectivity Work Group 2009-2010 (Year One) Summary and Recommendations.

Penobscot River Science and Monitoring Archives

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