Data from: Evaluating the potential for pre-zygotic isolation and hybridization between landlocked and anadromous alewife (Alosa pseudoharengus) following secondary contact

The recent increase of river restoration projects is altering habitat connectivity for many aquatic species, increasing the chance that previously isolated populations will come into secondary contact. Anadromous and landlocked alewife (Alosa pseudoharengus) are currently undergoing secondary contact as a result of a fishway installation at Rogers Lake in Old Lyme, Connecticut. To determine the degree of pre-zygotic isolation and potential for hybridization between alewife life history forms, we constructed spawning time distributions for two anadromous and three landlocked alewife populations using otolith derived age estimates. In addition, we analyzed long-term data from anadromous alewife migratory spawning runs to look for trends in arrival date and spawning time. Our results indicated that anadromous alewife spawned earlier and over a shorter duration than landlocked alewife, but 3% to 13% of landlocked alewife spawning overlapped with the anadromous alewife spawning period. The degree of spawning time overlap was primarily driven by annual and population level variation in the timing of spawning by landlocked alewife, whereas the timing and duration of spawning for anadromous alewife was found to be relatively invariant among years in our study system. For alewife and many other anadromous fish species, the increase in fish passage river restoration projects in the coming decades will re-establish habitat connectivity and may bring isolated populations into contact. Hybridization between life history forms may occur when pre-zygotic isolating mechanisms are minimal, leading to potentially rapid ecological and evolutionary changes in restored habitats

Dryad - Rangewide blueback microsatellite data

This tab-delimited text file contains the raw microsatellite data (15 loci) for blueback herring (A. aestivalis) used by Palkovacs et al. (2013) 'Combining genetic and demographic information to prioritize conservation efforts for anadromous alewife and blueback herring' to examine genetic population structure, and by Hasselman et al. (2014) 'Human disturbance causes the formation of a hybrid swarm between two naturally sympatric fish species' to examine rangewide frequency of hybridization in river herrings

Data from: Combining genetic and demographic information to prioritize conservation efforts for anadromous alewife and blueback herring

A major challenge in conservation biology is the need to broadly prioritize conservation efforts when demographic data are limited. One method to address this challenge is to use population genetic data to define groups of populations linked by migration and then use demographic information from monitored populations to draw inferences about the status of unmonitored populations within those groups. We applied this method to anadromous alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis), species for which long-term demographic data are limited. Recent decades have seen dramatic declines in these species, which are an important ecological component of coastal ecosystems and once represented an important fishery resource. Results show that most populations comprise genetically distinguishable units, which are nested geographically within genetically distinct clusters or stocks. We identified three distinct stocks in alewife and four stocks in blueback herring. Analysis of available time series data for spawning adult abundance and body size indicate declines across the US ranges of both species, with the most severe declines having occurred for populations belonging to the Southern New England and the Mid-Atlantic Stocks. While all alewife and blueback herring populations deserve conservation attention, those belonging to these genetic stocks warrant the highest conservation prioritization

Dryad - Rangewide alewife microsatellite data

This tab-delimited text file contains the raw microsatellite data (15 loci) for alewife (A. pseudoharengus) used by Palkovacs et al. (2013) 'Combining genetic and demographic information to prioritize conservation efforts for anadromous alewife and blueback herring' to examine genetic population structure, and by Hasselman et al. (2014) 'Human disturbance causes the formation of a hybrid swarm between two naturally sympatric fish species' to examine rangewide frequency of hybridization in river herrings

gpiper_0.1.tar

gpiper is an R package that is required to run the program gsi_sim used in the study. Please see the Readme file for instructions

herring_0.0.1.tar

'Herring' is an R package that contains all the data and the code required for reproduction of the results in the study

Table S2 - Individual bycatch mixtures

This is a MS Excel spreadsheet that contains posterior mean estimated mixing proportions for each individual in the mixture sample (i.e., the bycatch). These estimates were calculated using gsi_sim