Awareness and behavior change campaigns are key tools in efforts to manage environmental problems, including the unwanted impacts of aquatic invasive species (AIS). Stop Aquatic Hitchhikers! and Clean Drain Dry are two common, nationally recognized brands used to target recreational boaters with an AIS-prevention messages within the United States. Despite how often these AIS awareness brands are used, though, there is limited evidence that these brands are associated with boaters performing AIS-prevention behaviors. To investigate the impact of these brands, we used data from a national survey to determine factors that are related to boaters' self-reported frequency of performing AIS-prevention behaviors. Of the measured factors, overall awareness of AIS and awareness of Stop Aquatic Hitchhikers! and Clean Drain Dry were the most significant variables in predicting performance of AIS-prevention behaviors. This suggests that awareness of these commonly used brands is having a desirable impact on recreational boaters performing AISprevention actions and leveraging these brands and associated outreach materials is an effective method of outreach.
Numerous control methods are in use and under development to manage invasive carps in the United States. Commercial harvest, electric deterrents, and chemical toxicants, among other methods, are most efficient at targeting larger individuals. Research on methods to control recruitment of juvenile invasive carps has been limited. Our primary objective was to assess the vulnerability of juvenile invasive carp and common native forage species, gizzard shad (Dorosoma cepedianum) to native fish predators. Eighteen two-week long experiments, from April-October in 2015 and 2016, were conducted in experimental ponds with differing habitats (structure, vegetation, or open), simulating backwater habitats that are commonly used by juvenile invasive carps. Bowfin (Amia calva), channel catfish (Icatalurus punctatus), shortnose gar (Lepisosteus platostomus), hybrid striped bass (Morone saxatilis & times; Morone chrysops), largemouth bass (Micropterus salmoides), blue catfish (Ictalurus furcatus), flathead catfish (Pylodictis olivaris), walleye (Sander vitreus), northern pike (Esox lucius), and smallmouth bass (Micropterus dolomieu) were tested as predators of bighead carp (Hypophthalmichthys nobilis), silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon idella), and gizzard shad. We observed prey survival rates across seasons, habitats, and predator species. Invasive carp odds of survival varied from those of native gizzard shad between years. Hybrid striped bass, largemouth bass, smallmouth bass, and northern pike were effective predators of all tested prey species. Largemouth bass and smallmouth bass consumed bighead carp and silver carp over gizzard shad and grass carp (log OR < 0.5). Our results demonstrate the importance of habitat and cover availability, and that predator management may be a potential control method for juvenile invasive carps. Future research may consider effective predator densities, as well as studies in natural habitats.
Common carp (Cyprinus carpio) is one of the world's most widely distributed invasive fishes. Their high abundance and destructive feeding habits often lead to eutrophication, high water turbidity, and decimation of aquatic macrophytes. A relatively new control method for carp uses pop-up net systems ("box nets") and bait placed within the net. Carp can quickly learn the bait location, which is often carp-specific, and form feeding aggregations, allowing large numbers of carp to be removed without significantly impacting native fish. However, the efficacy of box nets depends on the size and synchronization of carp feeding aggregations. Here, we investigated if acoustic conditioning might be used to enhance bait-induced carp feeding aggregations in a lake. Two study sites were established in Harrisons Bay, Lake Minnetonka, Minnesota, USA, in which 142 carp were tagged with passive integrated transponder (PIT) tags. Each site was subjected to sound-plus-bait, bait-only, sound-only, and no-stimuli treatments over the summer while the presence of carp visiting each site was continuously monitored using PIT antennas. While the carp did not respond significantly to the acoustic cue alone, pairing it with bait seemed to contribute to more synchronized feeding aggregations, resulting in faster and greater recruitment of carp to the sites after bait was dispensed. Specifically, the sound-plus-bait treatment was expected to recruit, on average, 11% more carp than the bait-only treatment. Further, the time to recruit 90% of the nightly tags decreased by 28% when bait was administered with the acoustic cue vs. alone. These findings suggest that adding an acoustic cue to bait applications might enhance the efficiency of bait-and-removal strategies and accelerate control of common carp populations.
Biological invasions, driven by the spread of non-native species, have become a critical global issue because of their far-reaching ecological and socioeconomic impacts. Effective communication of the risks of biological invasions is essential for implementing robust policy and legislation and gaining public support for conservation efforts. However, current policies often suffer from fragmentation and ineffectiveness, largely due to inadequate risk communication and complex multi-level governance. To address this challenge, we develop a global framework designed to enhance clearer communication about biological invasion risks. The framework contextualizes key terms across three domains in invasion science: species invasiveness, risk analysis, and decision support tools. Using both diffusion-of-English and ecology-of-language paradigms, and following a three-step process involving preliminary consensus, AI querying, and ground-truthing with final consensus, we validate the framework in 70 non-English languages which, together with English, have official status in at least one country and collectively cover all 195 countries worldwide. Our findings reveal that while terminology for risk analysis is well established, terminology for species invasiveness and, especially, for decision support tools remains underdeveloped in many languages, hindering effective communication and policy implementation. Our framework underscores the importance of cultural and political neutrality. By promoting clearer risk communication among scientists, policymakers, and the public globally, we aim to reduce policy fragmentation and foster enhanced collaboration in risk mitigation. We recommend expanding multilingual decision support tools to include the full risk analysis process: risk identification, risk assessment, and risk management. This will support intergovernmental mitigation efforts and promote a unified global response to biological invasions.
Managing non-indigenous species (NIS) is a key priority for natural resources managers, particularly as climate change increases the risk of these species becoming invasive. The lionfish (Pterois miles), an invasive NIS in the eastern Mediterranean and southern Aegean seas of T & uuml;rkiye, has become a target for small-scale fishers (SSF) due to declining native fish stocks and NIS control efforts. A market-based approach to exploiting lionfish is a promising strategy, given the challenge of complete eradication in marine ecosystems-even though its commodification may carry unintended ecological and socio-economic risks in the long term. In T & uuml;rkiye, despite market demand, fishers hesitate to supply lionfish due to potential gear damage and safe handling. This study examines the size selectivity and catch efficiency of thick trammel nets (TTNs), commonly used by SSF in T & uuml;rkiye to overcome this barrier. Fishing trials from 2022 to 2024 mainly in the summer using TTNs with varying mesh sizes in the southern Aegean Sea caught 771 lionfish (18.2-42.7 cm total length). Results showed significant differences in mean total lengths across mesh sizes, with optimal model lengths exceeding the species' first maturity length (L50). Larger mesh sizes may meet market demand but are insufficient for population control, while smaller mesh sizes have an increased risk of bycatch of native species. Nevertheless, since TTNs generally have limited bottom contact compared to more destructive gear types such as trawlers and purse seiners, defining an optimal mesh size targeting lionfish has been the main aim of this study to inform decision-makers and SSF on best means available to tackle lionfish invasion in a collaborative way.
The economic and environmental impacts associated with aquatic invasive species (AIS) introductions continue to rise, despite ongoing prevention measures. Education and outreach messages are foundational to prevention and the most effective messaging targets both specific behaviors and audiences. Most often, message development relies on self-reported behaviors which, while informative, can also be inflated due to social desirability or recall issues. Thus, obtaining objective behavioral information is essential to understand the situational context and what prevention behaviors are actually performed. Such knowledge can inform messages for specific behaviors and, theoretically, improve the likelihood of their completion. To that end, we observed boating anglers as they left select public water accesses in Minnesota to inform message development among an important segment of the boating community. Of particular interest were behaviors that complied with required and recommended actions such as removing vegetation from the boat, trailer, and equipment, removing the drain plug, cleaning equipment, and draining water from boat compartments and bait buckets. Across the summer of 2023, we observed 193 vessels at four accesses selected due to their comparability in design, traffic, and similarity in size and boating/angling resource. The majority of observed boating anglers took at least some of the required and/or recommended behaviors to prevent the spread of AIS. However, fewer than 50% comprehensively completed all required behaviors in accordance with Minnesota AIS prevention laws before leaving the public launch area. This gap represents an opportunity to improve prevention, education, and outreach among boating anglers to further limit the spread of AIS.
Zebra mussels (Dreissena polymorpha Pallas, 1771) are an invasive mollusk that cause severe ecological and economic impacts on North American water resources. More information is needed on viable operational management options to control this invader and restore water use and ecology. This study evaluates the effectiveness of a chelated copper molluscicide (Natrix (R)) for controlling adult zebra mussels under in situ mesocosm conditions in Lake Minnetonka, Minnesota. Zebra mussel mortality and impacts to nontarget invertebrates were assessed in response to sustained free copper exposures of 0.5 and 1.0 mg Cu/L formulated as copper ethanolamine complexes. Copper concentrations, water temperature, pH, dissolved oxygen, and specific conductance were routinely monitored throughout all mesocosms. Results demonstrated a concentration and duration-related response, with 100% mortality of zebra mussels achieved at 0.5 mg Cu/L after 72 hours of exposure and 100% mortality achieved after 48 hours of exposure at 1.0 mg Cu/L. Water quality analyses revealed that environmental conditions were compatible with zebra mussel requirements and did not impact treatment outcomes. Non-target effects on benthic invertebrates showed no differences in the low-dose treatment, though there was a decrease in the numbers of invertebrates, but not taxa richness, in the high-dose treatment. This research provides valuable information to water resource managers on a chelated copper molluscicide to better inform zebra mussel management decisions.
