Abstract
Maximum densities of juvenile river herring (Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis) vary among freshwater lakes, likely due to densities of adult spawners. Differences in habitat availability and lake water quality may also contribute to variation in juvenile river herring productivity between populations, yet these relationships have not been tested across a large geographic scope. In this study we investigated relationships between juvenile river herring densities and (1) spawning adult river herring densities, (2) lake habitat availability, and (3) lake water quality in 29 freshwater lakes in the northeastern USA. Purse seines were used at night to sample juvenile river herring monthly in June–August 2014 and 2015, with concurrent collection of lake-specific physical (e.g., lake surface area, mean depth, depth to thermocline), chemical (e.g., nitrogen, phosphorus, dissolved organic carbon [DOC]), and biological (chlorophyll a, adult spawning density) data. Spawning adult density (number of adults per surface area of lake) explained 66.6% of the variation in juvenile densities using a generalized additive model. Juvenile densities increased with increasing adult density, peaking at roughly 1,000 adults/ha, and then declined at higher adult densities, suggesting a limit to carrying capacity in juvenile production. Linear mixed-effects models revealed that differences in water quality and habitat across lakes explained additional variation in juvenile densities. Specifically, DOC was negatively related to juvenile densities, suggesting that DOC limits the amount of suitable, well-oxygenated epilimnion habitat available to juvenile river herring in late summer. Our results can be used to help understand expected juvenile production based on adult density within a lake, to inform expectations about juvenile growth and survival, and to understand the mechanisms for how changes in habitat availability and water quality affect river herring populations.
| Original language | English |
|---|---|
| Pages (from-to) | 207-221 |
| Number of pages | 15 |
| Journal | Transactions of the American Fisheries Society |
| Volume | 150 |
| Issue number | 2 |
| DOIs | |
| State | Published - Mar 2021 |
Funding
We thank the many University of Massachusetts undergraduate students who contributed to fieldwork and sample collection. We thank employees from the Connecticut Department of Energy and Environmental Protection, Rhode Island Department of Environmental Management, Massachusetts Division of Marine Fisheries, New Hampshire Department of Fish and Game, and Maine Department of Marine Resources for providing technical support and guidance on site selection. We are grateful to many local residents and lake associations for site access, field assistance, and data sharing. This research was supported through funding from the University of Massachusetts, Massachusetts Division of Marine Fisheries, National Fish and Wildlife Foundation, and Atlantic States Marine Fisheries Commission. The experimental protocol was approved by the University of Massachusetts Institutional Animal Care and Use Committee (IACUC number 2013-0047). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service. There is no conflict of interest declared in this article.
| Funders | Funder number |
|---|---|
| Atlantic States Marine Fisheries Commission | 2013-0047 |
| Massachusetts Division of Marine Fisheries | |
| University of Massachusetts Boston | |