Modeling control of Common Carp (Cyprinus carpio) in a shallow lake– wetland system James Pearson, Jason Dunham, J. Ryan Bellmore & Don Lyons Wetlands Ecology and Management ISSN 0923-4861 Wetlands Ecol Manage DOI 10.1007/s11273-019-09685-0 1 23 Your article is protected by copyright and all rights are held exclusively by This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply. This e-offprint is for personal use only and shall not be self- archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”. 1 23 Author's personal copy Wetlands Ecol Manage https://doi.org/10.1007/s11273-019-09685-0 (0123456789().,-volV)( 0123456789().,-volV) ORIGINAL PAPER Modeling control of Common Carp (Cyprinus carpio) in a shallow lake–wetland system James Pearson . Jason Dunham . J. Ryan Bellmore . Don Lyons Received: 18 April 2018 / Accepted: 1 August 2019 Ó This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2019 Abstract The introduction of Common Carp (Cypri- Results from CarpMOD suggest that no single active nus carpio) into North American waterways has led to removal method would decrease Common Carp widespread alteration of aquatic ecosystems. Control biomass below the targeted 50 kg/ha threshold. Com- of this invader has proven extremely difficult due to its binations of two or all three active removal methods capacity for rapid population growth. To help under- could, however, reduce biomass below the desired stand how Common Carp can potentially be controlled threshold due to cumulative mortality on multiple life we developed a population dynamics model (Carp- stages. CarpMOD simulations suggest that the level of MOD) to explore the efficacy of active and passive carp removal necessary to reach the desired biomass control measures that impose mortality on multiple threshold is approximately 40% at each life-stage, life stages (embryos, juveniles and adults). We applied which may be unrealistic to maintain over longer time CarpMOD to Common Carp in Malheur Lake, a large scales. Passive removal via avian predation may also shallow lake in Southeast Oregon, USA. Simulated contribute to suppression of Common Carp, but was control measures included commercial harvest of not sufficient in isolation to reduce biomass below the adults, trapping of juveniles, embryo electroshocking, desired threshold. Collectively, our results indicate and passive removal imposed via avian predation. control of Common Carp as a sole means of ecosystem restoration is unlikely to be effective in the system we modeled. This suggests additional means of restora- J. Pearson (&) U.S. Fish and Wildlife Service, Malheur National Wildlife tion may be warranted, perhaps in combination with Refuge, Princeton, OR 97721, USA control of Common Carp, or development of more e-mail: [email protected] effective control measures. J. Dunham U.S. Geological Survey, Forest and Rangeland Ecosystem Keywords Common Carp Á Pest control Á Wetland Science Center, Corvallis, OR 97331, USA management Á Commercial harvest Á Embryo e-mail: [email protected] electroshocking Á Juvenile harvest Á Ecological modeling J. Ryan Bellmore USDA Forest Service, Pacific Northwest Research Station, Juneau, AK 99801, USA e-mail: [email protected] D. Lyons Oregon State University, Corvallis, OR 97331, USA e-mail: [email protected] 123 Author's personal copy Wetlands Ecol Manage Introduction of aquatic vegetation (Weber et al. 2011). This positive feedback process can transform shallow lakes Shallow lakes and wetland ecosystems are among from a clear state to a highly turbid state (Bajer et al. some of the most important habitats on Earth due to 2009; Vilizzi et al. 2015). Carp biomass must be their numerous ecological functions, such as ground- substantially decreased to reduce these impacts and water recharge, water purification, flood protection, return the aquatic ecosystem to previous conditions and habitat for a varied collection of aquatic and (Bajer et al. 2009). Control of carp can be extremely terrestrial species (Jeppesen et al. 1997). These difficult, however, due to their high capacity for ecosystems frequently exist in two alternative states population growth and expansion, survival in habitat (clear or turbid), with the clear state defined by the refugia, and ability to modify their environment to presence of aquatic macrophytes and zooplankton, as their own advantage (Brown and Walker 2004). well as low water column nutrients, and decreased Carp populations exhibit compensatory density phytoplankton biomass, whereas the turbid state is dependence (Weber et al. 2016), in which demo- defined by the opposite (Scheffer 1990, 1993;Gu¨ner- graphic rates (i.e. mortality and recruitment) shift in alp and Barlas 2003). A shift from a clear to a turbid response to variation in the population’s overall state can be induced by several factors (e.g., climatic density (Rose et al. 2001). Thus, even if carp are change, loading of nutrients), and these same factors removed in large numbers, the species can rebound can increase the system’s resistance to a shift back to quickly (biomass doubling time of 2.7 years; Colvin the clear state (Gu¨neralp and Barlas 2003; Hargeby et al. 2012b). Although it is known that carp popula- et al. 2004). Nonnative species, in particular, have tions are generally resilient to a wide range of been shown to facilitate shifts in water clarity in perturbations, predicting the specific effects of alter- wetland and lake ecosystems, with cascading effects native control measures is difficult because there are on ecosystem services (Van Duin et al. 2001; Scheffer many processes in play. This complexity has led et al. 2001). researchers to develop population models to evaluate In the United States, approximately 50,000 nonna- carp control measures prior to their implementation tive species have established populations outside of (Weber and Brown 2009; Bajer et al. 2015). their natural range, causing an estimated $120 billion Modeling has performed a crucial role in the in environmental damages each year (Pimentel et al. advancement of carp control due to the ability to 2005). Many of these species were introduced delib- quickly and effectively investigate alternative control erately, such as the Common Carp (Cyprinus carpio), measures (e.g., commercial harvest, separation cages, which were distributed by the US Fish Commission cyprinid herpesvirus, daughterless carp, pheromone throughout the United States to serve as an alternative lures, and spawning sabotage). These modeling efforts food source for rural Americans from 1889–1897 suggest that successful carp control may require (& 2.4 million individual carp; Smiley 1886, 1896; control strategies that target multiple life stages Cole 1905; Nico and Fuller 1999). The Common Carp (Brown and Walker 2004; Weber and Brown 2009; (hereafter ‘‘carp’’) is the eighth most prevalent non- Colvin et al. 2012b; Brown and Gilligan 2014; Bajer native invader in the world (Lowe et al. 2000), often et al. 2015). For example, a previous modeling project reaching high levels of abundance ([ 1000 kg/ha) due determined that commercial harvest was unsuccessful to their ability to tolerate a range of abiotic conditions when targeting one life stage (adults), however the (Bajer et al. 2009; Weber and Brown 2009; Bajer and targeting of two or more life stages (adults and Sorensen 2010; Bajer et al. 2011). juveniles) resulted in a reduction of carp below the Once a population of carp becomes established, target biomass (\ 100 kg/ha; Lechelt and Bajer 2016). their activity and mode of feeding can degrade aquatic Although imposing mortality on two or more life ecosystems (Koehn 2004; Kloskowski 2011; Pietsch stages of carp can hypothetically result in effective and Hirsch 2015). Benthic foraging uproots aquatic control, in practice, carp control is challenging vegetation while simultaneously suspending sediment because most of the developed removal methods are in the water column, which increases turbidity and focused on adults (Weber et al. 2011), with minimal diminishes light penetration (Weber and Brown 2009). impact on other life stages (e.g., embryo to juvenile). In turn, this can further inhibit growth and recruitment Thus, there is not only a need to identify new removal 123 Author's personal copy Wetlands Ecol Manage methods that target juvenile carp and carp embryos imposed by avian predation or juvenile trapping) and (Carl et al. 2016; Simpson et al. 2018; Poole et al. larval (e.g., as imposed by embryo electroshocking) 2018), but also to examine how these novel life stages. We applied this model to Malheur Lake approaches perform in combination with adult (Oregon, USA), a large lake–wetland ecosystem with removal methods. To address this issue, we evaluated a 65-year legacy of efforts to control invasive carp four different control measures that span three distinct (Ivey et al. 1998). Specifically, we simulated the life-stages and represent both active and passive individual and interactive effects of adult commercial removal methods: (1) commercial harvest of adults harvest, embryo electroshocking, juvenile trapping, (active), (2) embryo electroshocking of larvae in and the individual effects of bird predation on carp spawning areas (active), (3) trapping of juveniles via population dynamics. Results of this effort provide fyke nets (active), and (4) increased avian predation of novel insights into interactions among multiple factors juveniles (passive). that drive the success or failure of carp control within Additional consideration of avian predation and lakes and associated wetlands.