International Journal of Aquaculture, 2024, Vol.14, No.4, 174-183 http://www.aquapublisher.com/index.php/ija 179 6 Management and Control Strategies 6.1 Physical removal and habitat modification Physical removal and habitat modification are common strategies employed to manage invasive common carp populations. Techniques such as netting, electrofishing, and trapping are frequently used to physically remove carp from aquatic ecosystems. For instance, targeting winter aggregations of adult carp for removal has been identified as an effective strategy (Bajer et al., 2019). Habitat modification, such as altering water levels or modifying substrates, can also reduce carp populations by disrupting their breeding and feeding habitats (Coulter et al., 2018). However, these methods often require continuous effort and can be labor-intensive. 6.2 Biological control methods 6.2.1 Use of predators and competitors Biological control through the introduction or enhancement of natural predators and competitors is another strategy. Native predators, such as certain fish species, can help control carp populations by preying on their eggs and larvae (Busst and Britton, 2017). For example, stocking native predators has been successful in controlling juvenile invasive species like the rusty crayfish. However, the effectiveness of this method can vary depending on the specific ecosystem and the presence of suitable predator species. 6.2.2 Sterilization and genetic approaches Sterilization and genetic approaches are emerging as promising methods for controlling invasive carp populations (Feng, 2024). Techniques such as the release of sterilized males or the use of genetic modifications to reduce reproductive success are being explored. In Australia, there are ongoing investigations into the use of a virus to control carp populations. These methods aim to reduce the reproductive capacity of carp, thereby gradually decreasing their numbers over time. 6.2.3 Environmental manipulation Environmental manipulation involves altering the conditions of the habitat to make it less favorable for carp. This can include changes in water quality, such as increasing turbidity or altering nutrient levels, which can negatively impact carp while benefiting native species (Cupp et al., 2021). For example, increasing water turbidity has been shown to reduce carp abundance by disrupting their feeding and breeding behaviors. However, these methods must be carefully managed to avoid unintended consequences on the broader ecosystem. 6.3 Policy and regulatory frameworks Effective management of invasive carp also requires robust policy and regulatory frameworks. These frameworks can include regulations on the transport and release of carp, as well as policies that support the implementation of control measures. Integrated pest management (IPM) plans, which combine multiple control strategies, are being developed by natural resource agencies to address the complex challenges posed by invasive carp (Figure 3) (Kulhanek et al., 2011). Additionally, international cooperation and consistent enforcement of regulations are crucial for preventing the spread of carp across borders and ensuring the success of management efforts (Rytwinski et al., 2019). 7 Ecological and Environmental Considerations 7.1 Long-term ecological effects The long-term ecological effects of common carp (Cyprinus carpio) invasions are profound and multifaceted. Invasive species like common carp can cause significant shifts in ecosystem structure and function. For instance, common carp have been shown to increase water turbidity and nutrient levels, leading to eutrophication and a decline in water quality (Gallardo et al., 2016). These changes can result in stable-state shifts from clear water, macrophyte-dominated systems to turbid, phytoplankton-dominated systems, which are less hospitable to native species. Additionally, the presence of common carp can lead to a reduction in the abundance of benthic macroinvertebrates and submerged macrophytes, further altering the ecosystem. Over time, these changes can lead to a decrease in native fish biomass and biodiversity, as seen in Australian dryland rivers where carp monopolize food resources (Marshall et al., 2019).
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