Geology topics

Erin Peterson

Publications and source records attributed to Erin Peterson.

4 recordsLinked to original sources

USGS2023

Adult Sea Lamprey approach and passage at the Milford Dam fishway, Penobscot River, Maine, United States

Objective Sea Lamprey Petromyzon marinus provide important ecological services within their native range, such as nutrient cycling, and can also act as a prey source for other species. Adult Sea Lamprey must access freshwater rivers to spawn, and because of this they are susceptible to changes in river connectivity. Human-made structures, such as dams, can exclude them from usable habitat. Sea Lamprey dam passage has not been extensively studied in Maine, despite Maine being within the native range of this species. The goals of this study were to evaluate upstream passage efficiency at the Milford Dam on the Penobscot River, Maine, and to provide comprehensive information about adult Sea Lamprey passage at five other dams throughout the Penobscot River watershed. Methods In 2020–2021 we captured and tagged 150 Sea Lamprey at the Milford Dam, the lowest dam in the Penobscot River, Maine, and displaced them downstream to assess passage efficiency at this dam and five upstream dams. In 2020, 50 Sea Lamprey were released on the east shore of the river downstream of Milford Dam; in 2021, the east shore release was repeated with an additional 50 fish and another 50 fish were released on the west shore. Result Between 70–82% of Sea Lamprey were observed passing Milford Dam again after mean delay times of 9–11 days. The release location did not affect dam passage success or the amount of time that was required to locate and use the passage structures. Sea Lampreys from both release groups were equally likely to approach the entrance to the fishway upon returning to Milford Dam, despite the fishway being located against the eastern shore of the river. However, high flows shortly after release may have resulted in higher attraction to the fishway in 2020. Passage success at dams upstream of Milford was highly variable. All Sea Lamprey were able to successfully navigate past West Enfield Dam (100% passage, n = 63), whereas Brownsmill Dam apparently acted as a complete barrier to further migration (0% passage, n = 7). Fish from all years and release groups together had a median upstream migration distance of 38.8 km after fish had passed Milford Dam, and a maximum observed upstream travel distance of approximately 100 km, indicating that most tagged Sea Lamprey ended their migration in the vicinity of a dam. Conclusion The results of this study indicate that Sea Lamprey have high passage efficiency at the Milford Dam and highlight areas within the Penobscot River basin—such as the Brownsmill Dam—where passage facilities are currently inadequate for Sea Lamprey.

Maine↗

USGS2022

Adult Atlantic salmon (Salmo salar) delayed below dams rapidly deplete energy stores

Atlantic salmon ( Salmo salar ) return to rivers in spring for an energetically costly upstream migration for spawning. These fish are often delayed in the lower river below dams, subjecting them to warmer waters than occur in upstream sections of river, that may increase metabolic costs. We sought to quantify the energetic cost of dam-mediated delays in migrating adults in the Penobscot and Kennebec rivers, ME. We radio-tagged fish at the lower most dams, released them downstream (18 and 14 km), and tracked their movements back upstream. We used a Distell Fish Fatmeter as a noninvasive measurement of full-body energy at tagging and then again after re-ascending the fish-way at the dams. We found that adults ( n = 99) experienced average delays of 16–23 days at dams, losing 11%–22% of initial fat reserves. Using linear regressions, we showed thermal experience as a strong predictor of fat loss. Delay time was also a contributing factor. Extensive delays at dams expose migrating Atlantic salmon to warmer temperatures and increase the depletion rate of energy reserves required for spawning and post-spawn survival.

Maine↗

USGS2021

Scale growth rates and scale circulus deposition rates of marine-stage Atlantic salmon Salmo salar raised under semi-natural conditions

Scale circuli yield valuable information about the life history, age, and growth of a fish. However, because circuli formation is influenced by somatic growth, the rate at which circuli are formed and the factors influencing these rates must be taken into account for the given life stage of the study species. Scales were collected from Atlantic salmon raised in marine net pens off of the coast of Maine in order to characterize the formation of scale circuli and the growth of scales during the ocean phase, and to relate circulus deposition and scale growth rate to water temperature. Fish were sampled 13 times over a period of 25 months. Neither circulus deposition rate nor growth rate were constant through time and the same trend held when circulus deposition and growth were related to thermal experience. Both rates decreased over the course of the study, presumably related to the fish reaching sexual maturity. The results of this study indicate that the pattern of circulus deposition and scale growth of Atlantic salmon vary greatly during the early marine phase, and this dynamic should be taken into account when assessing growth, especially over short time periods.

Newfoundland↗

USGS2021

Movement, survival, and delays of Atlantic Salmon smolts in the Piscataquis River, Maine, USA

Movement, delays, and survival of hatchery Atlantic Salmon Salmo salar smolts were evaluated through the Piscataquis River, a tributary of the Penobscot River in Maine, USA. We explored the effects of the river’s four dams (Guilford, Dover, Browns Mill, and Howland dams) from 2005 to 2019. During this period, the downstream-most dam (Howland Dam) transitioned from full hydropower generation to seasonal turbine shutdowns and later was decommissioned with the construction of a nature-like fish bypass in 2016. We estimated survival through open-river reaches and at each dam using acoustic telemetry ( n = 1,611). Dams decreased survival, with per-river-kilometer (rkm) apparent survival averages of 0.972, 0.951, and 0.990 for Guilford, Dover, and Browns Mill dams compared to a per-rkm survival of 0.999 for open-river reaches. Turbine shutdowns increased survival at Howland Dam (to around 0.95), which was further increased by the nature-like fish bypass (0.99). We used radiotelemetry in 2019 ( n = 75) and demonstrated that approximately one-third of the fish used the bypass, while the remaining fish used alternative routes. Smolts successfully passing the three upstream dams had lower apparent survival through Howland Dam than smolts that were released upstream of Howland Dam. Although smolts passing Browns Mill Dam had high survival, the dam caused extended delays, with median delay times surpassing 48 h in most years. Most of the delays caused by Browns Mill Dam occurred after fish had passed the dam and may indicate a sublethal effect of passage. Overall, while survival through Howland Dam has improved, passage and delays at the three upstream dams in aggregate represent a critical impediment to the effective use of the high-quality spawning habitat found upstream.

Maine↗