Using Larval Fish Community Structure to Guide Long-Term Monitoring of Fish Spawning Activity

Abstract

Larval fishes provide a direct indication of spawning activity and may therefore be useful for long-term monitoring efforts in relation to spawning habitat restoration. However, larval fish sampling can be time intensive and costly. We sought to understand the spatial and temporal structure of larval fish communities in the St. Clair–Detroit River system, Michigan–Ontario, to determine whether targeted larval fish sampling can be made more efficient for long-term monitoring. We found that larval fish communities were highly nested, with lower river segments and late-spring samples containing the highest genus richness of larval fish. We created four sampling scenarios for each river system: (1) using all available data, (2) limiting temporal sampling to late spring, (3) limiting spatial sampling to lower river segments only, and (4) limiting both spatial and temporal sampling. By limiting the spatial extent of sampling to lower river sites and/or limiting the temporal extent to the late-spring period, we found that effort could be reduced by more than 50% while maintaining over 75% of the observed and estimated total genus richness. Similarly, limiting the sampling effort to lower river sites and/or the late-spring period maintained between 65% and 93% of the observed richness of lithophilic-spawning genera and invasive genera. In general, community composition remained consistent among sampling scenarios. Targeted sampling offers a lower-cost alternative to exhaustive spatial and temporal sampling and may be more readily incorporated into long-term monitoring.

Received August 14, 2014; accepted November 28, 2014

ACKNOWLEDGMENTS

This work would not have been possible without the support of Nick Arend, David Bennion, Emily Bouckaert, Dustin Bowser, Nelson Cordero, Jaquie Craig, Ellen George, Darryl Hondorp, Robert Hunter, Stacey Ireland, Christina Jovanovic, Greg Kennedy, Kelsey Lincoln, Maureen Lynch, Bruce Manny, Darrin McCullough, Erik McDonald, Matthew McLean, Tim O'Brien, Stacy Provo, Lismar Rodriguez, Jenny Sutherland, and Patricia Thompson. This work was supported by the Great Lakes Restoration Initiative Project Number 70 (Fish Habitat Enhancement Strategies for the Huron-Erie Corridor). This is Contribution Number 1895 of the U.S. Geological Survey, Great Lakes Science Center. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.