DOI: 10.5061/dryad.qbzkh18v4
title: Data from: Smallmouth bass (Micropterus dolomieu) and chain pickerel (Esox niger) identified as Atlantic salmon (Salmo salar) smolt predators in a reservoir system

description: Reservoir predation has been identified as a leading mortality source for
 smolts migrating through impounded river systems. We investigated smolt
 predation risk for an endangered Atlantic salmon (Salmo salar) population
 in the Weldon Dam reservoir in the Penobscot River, Maine, USA. In spring
 2022, we characterized the fates of 390 tethered smolts. Smolts were
 exclusively predated by two predator species not native to the study area:
 chain pickerel (Esox niger, n=43) and smallmouth bass (Micropterus
 dolomieu, n=42). Using Cox-proportional hazard analysis, we estimated that
 23% (95% CI = 15–29%) of tethered smolts were expected to be predated
 within a one-hour deployment. Water temperature was the primary driver of
 predation risk as predation probability increased from 10% to 33% when
 temperature increased from 5°C to 15°C. Smolts also incurred above-average
 predation risk when they were within 40 m of shore. We demonstrate that
 non-native fish predation may drive patterns of high impoundment mortality
 and that risk is spatially and temporally heterogeneous within these
 systems. Collectively, this study offers direct evidence of
 species-specific predation on Atlantic salmon smolts and illuminates
 potential strategies to mitigate predation risk during reservoir
 migration.
description: # Smallmouth bass (*Micropterus dolomieu*) and chain pickerel (*Esox
 niger*) identified as Atlantic salmon (*Salmo salar*) smolt predators in a
 reservoir system
 [https://doi.org/10.5061/dryad.qbzkh18v4](https://doi.org/10.5061/dryad.qbzkh18v4) ## Description of the data and file structure We used Predation Event Recorders to characterize predation risk for Atlantic salmon (*Salmo salar*) smolts in the Penobscot River, Maine from April-May, 2022. ### Files and variables #### File: per\_2022\_hobo\_20250224.csv **Description:** Data from HOBO Pendant Temperature/Light Data Loggers attached to each Predation Event Recorder (PER). ##### Variables * dep: a unique ID assigned to each PER deployment. * start: the start of the deployment in local time. * end: the end of the deployment in local time. * pred: whether the smolt was predated (1) or not (0) during the deployment. * top: the time of the predation event in local time. NA = no predation event.  * per: the PER ID used in the deployment. * timestamp: the time recorded on the HOBO logger in local time. * temp: the temperature (°C) recorded by the HOBO logger at the corresponding timestamp. * light: the relative light level (lux) recorded by the HOBO logger at the corresponding timestamp. * obs: the observation number of each HOBO logger reading within the deployment. #### File: per\_2022\_deployments\_20250224.csv **Description:** Data associated with each Predation Event Recorder (PER) deployment. ##### Variables * dep: a unique ID assigned to each PER deployment. * date: the date of the PER deployment. * area: the area of the Weldon Headpond that the PER was deployed. * per: the PER ID used in the deployment. * fork: the fork length (mm) of the smolt tethered to the PER. * start: the start of the deployment in local time. * end: the end of the deployment in local time. * pred: whether the smolt was predated (1) or not (0) during the deployment. * species: the predator species (smb = smallmouth bass, chp = chain pickerel, NA = no predation event). * top: the local time of the predation event. NA = no predation event. * xtime: short for "exposure time". Defined as the time from the start of the deployment until either the predation event occurred (i.e., for predated smolts) or the PER was retrieved (i.e., for non predated smolts). * temp: the median water temperature recorded by the HOBO logger during the deployment (°C). * lite: the median light intensity (lux) recorded by the HOBO logger within the exposure time of each deployment.  * rate: the mean PER drift rate (m/s) during the exposure time of each deployment. NA = drift rate was not available.  * sunr: the time (in hours) since/until local sunrise. * day: the ordinal date of the deployment. * shor: the distance from shoreline (m) at the time of the predation event (i.e., for predated smolts) or averaged across the exposure time (i.e, for non-predated smolts). NA = distance was not available. ## Code/software These data can be processed using the attached R Script (per_predation_analysis_20250224.R) which was developed in Program R version 4.4.0