Abstract
Despite aquatic invasive species (AIS) being a widely recognized threat to native biodiversity in streams on subtropical and tropical oceanic islands across the Pacific, AIS management has been constrained by concerns that methods of removal could result in more harm than good. In this study, we assessed the effectiveness and outcomes of combining hand-netting and streamside sequestration of native species with AIS removal via three-pass electrofishing tailored for Hawaiian Island watersheds. Removals were conducted in 13 watersheds on the island of O‘ahu following a before-after, control-impact design to assess how AIS removal and post-removal community reassembly varied by surface flow and target species of interest. We found that removals resulted in a sharp reduction in AIS densities without altering native species densities. Removal efficacy was greatest in streams with intermediate mean discharge irrespective of target group or pre-removal AIS densities. Long-term monitoring demonstrated that removals led to persistent shifts in community composition reflecting sustained reductions in AIS densities. These findings indicate that electrofishing can be a valuable tool for AIS management in Hawaiian and other subtropical Pacific island streams, so long as steps are taken to minimize potential harm to at-risk and culturally important native species.
| Original language | English |
|---|---|
| Pages (from-to) | 1739-1763 |
| Number of pages | 25 |
| Journal | Biological Invasions |
| Volume | 23 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 2021 |
Funding
We would like to thank James Gilliam for contributing to the design of this study, Roderick Gagne for logistical guidance, and Ellen Hamann for assistance with flow data collection and post-removal organismal processing, as well as Aiyzah Javaid, and Will Rosenthal. We are thankful to Kauaoa Fraiola, Annessa Musgrove, Christine Hayes, Hannah Wilson, John Morgan, Alexandra Del Favero, Jayson Gallatin, and Susannah Halbrook for their long-term monitoring and AIS removal efforts, as well as Rebecca Hazen, and Jennifer Summers for assistance with AIS removals. We thank the members of the Hawai\u2018i Division of Aquatic Resources for supporting AIS removal efforts. We would particularly like to thank Glenn Higashi and Cathy Gewecke for guiding and supporting AIS removals. Additionally, we would like to thank Kamehameha Schools, Bayview Golf Course, Laurent Pool at Waimea Valley, the Fraiola family, the Hawai\u2018i Department of Transportation, Bart Potter, Gordon Smith, Pharris Eggelton, Christopher Zarka of Empela Place, Papahana Kualoa, Anne and Richard Stack, and Joby Rohrer who generously provided access to the watersheds examined in this study and John T. King for providing storage and office space. Funding for this study was made available from the Department of Defense Strategic Environmental Research and Development Program (SERDP) through project RC-2447 and from the Tulane University ByWater Institute. This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).
Keywords
- Amphidromy
- Aquatic invasive species
- Conservation
- Electrofishing
- Gobies