高体鳑鲏化学预警响应与“个性”行为的关联

化学通讯是水生动物最原始、最普遍和最主要的通讯方式之一。对捕食风险源的回避可以使猎物减少被捕食风险,但如果出现的化学信息并不代表真正的威胁,那么就会导致猎物减少觅食或求偶的机会,从而降低适合度。因此基于能量代价-生态收益的权衡可能导致动物行为决策与化学通讯模式的分化。"个性"行为（Personality）已被证实与动物的行为决定有关,然而,有关鱼类化学预警通讯与"个性"行为关联的研究至今鲜见报道。推测："个性"行为是鱼类的化学通讯模式多样化的重要内因。采捕了广泛分布于我国淡水水域的野生高体鳑鲏（Rhodeus ocellatus）并于半自然状态下探究了：（1）实验鱼对不同化学信息（池水对照组、柠檬新奇信息组、高浓度和低浓度化学预警信息（Chemical alarm cues,CAC）组）的行为响应,（2）实验鱼在新异环境（被转入新栖息地）、新异刺激（新异物理刺激）、新异食物资源下的"个性"行为及其与化学预警响应的关联。结果发现：（1）不同溶液化学信息对实验鱼静止时间与爆发游泳的变化以及摄食个体的比例等参数均有显著影响（P < 0.05）。其中,柠檬组（未知"假风险"）与对照组相比无显著差异（P > 0.05）,实验鱼对不同浓度CAC（已知"真风险"）表现出不同程度的行为响应,高浓度和低浓度CAC均导致摄食个体比例下降（P < 0.05）,但只有高浓度CAC导致静止时间和爆发游泳的变化增加（P < 0.05）。可见,实验鱼对外源化学信息有准确高效的行为应答。（2）实验鱼静止时间比对不同溶液化学预警响应的变化与新异刺激下的活跃性显著负相关（P < 0.05）,但与新异环境下的活跃性无关（P > 0.05）,提示"个性"行为与化学预警响应有关但这种关联可能又有一定的环境依赖性（例如测试环境的稳定性与可预测性）。     

繁殖期高体鳑鲏对化学预警信息的行为响应及其与生理状态的关联

对化学预警信息(Chemical alarm cues,CAC)的识别与应答体现了鱼类在特定生理状态和特定环境下的生态策略,与动物的生存适合度密切相关。由于化学预警通讯和繁殖均为高能耗的生命活动,繁殖期鱼类的CAC通讯是否表现出基于能量代价-收益(Cost-benefit)的权衡成为值得关注的科学问题。本研究以具有特殊繁殖方式的高体鳑鲏(Rhodeus ocellatus)为实验对象,测定了繁殖IV期不同性别实验鱼对CAC的行为响应,并探究了实验鱼化学预警行为与其繁殖生理状态的关系。结果发现:(1)高体鳑鲏空间分布状态(底栖时间)和活跃状态(静止时间、运动距离、身体不重合度)均对CAC表现出明显的行为应答(P0.05),但逃逸行为(高速运动时间)不受CAC的影响(P0.05);(2)高体鳑鲏对CAC的响应无性别差异;(3)高体鳑鲏预警行为的变化与繁殖生理状态(性腺指数、产卵管长度、肥满度)无显著相关性(P0.05)。结果表明,繁殖期高体鳑鲏依然对CAC展现出一定程度的行为应答,然而其行为响应程度并不受繁殖生理状态以及性别的影响,这可能主要与该物种特殊的繁殖对策有关。     

基于稳定同位素技术的长湖鱼类营养结构研究

本研究应用碳、氮稳定同位素技术分析了2017年秋季（10月）和2018年春季（3月）湖北省荆州长湖鱼类营养结构特征,构建了δ¹³C和δ¹⁵N稳定同位素双位图,并计算了7个相关的量化指标。结果显示：所采集的16种鱼类,δ¹³C均值范围为（-27.7±0.8）‰~（-24.8±0.1）‰,δ¹⁵N的均值范围为（11.4±0.3）‰~（16.6±0.5）‰。营养生态位分析显示,长湖鱼类以偏肉食性鱼类黄颡鱼的营养级最高（3.28±0.2）,草鱼的营养级最低（1.74±0.1）。稳定同位素的量化指标表明,长湖春季鱼类群落核心生态位空间（standard ellipse area, SEA）、生态位总空间（total area, TA）和基础食物来源（δ¹³C range, CR）均高于秋季,两个季度的营养多样性（centrifugal distance, CD）和鱼类群落的整体密度（mean nearest neighbor distance, MNND）相似,但春季的营养长度（δ¹⁵N range, NR）和鱼类群落营养生态位分布范围（standard deviation of nearest neighbor distance, SDNND）值低于秋季。说明春季长湖的生态位总空间（TA上升）和基础食物来源（CR上升）较为丰富,但因鱼类种类的食性相近,其群落的总食物链降低（NR下降）。该研究可为分析拆围后长湖鱼类群落结构特征积累基础数据,也为长湖的渔业管理策略提供依据。     

鲢鲴混养对水体环境的影响

为评估鱼类混养及其排泄物对水体环境的潜在影响,采用室内受控实验研究了鲢（Hypophthalmichthys molitrix）和黄尾鲴（Xenocypris davidi）混养对水体鱼腥藻和水质的影响。实验设置鲢投放组、鲢鲴组合投放组和空白对照组,实验周期14 d。结果发现,鱼类的放养增加了实验水体的营养负荷,有鱼实验组水体中总氮、总磷、氨氮和高锰酸盐指数均高于对照组,且实验后期鲢组的营养盐浓度均高于鲢鲴组;有鱼实验组水体中叶绿素a浓度和藻密度均降低,且鲢鲴组较鲢组降低更为明显;黄尾鲴的加入可以减少水体中鱼类排泄物的积累,鲢鲴组鱼类生物量较鲢组多,但排泄物重量却低于鲢组;鲢鲴组对鱼腥藻的消化率更高,实验结束时达到79.33%,极显著高于鲢组（P<0.01）。即在鲢控藻的基础上,混养黄尾鲴可以减少鲢摄食鱼腥藻后的排泄物重量,减少因鱼类排泄物造成的二次污染。     

铜陵淡水豚国家级自然保护区半自然水域鱼类群落结构研究

2021年5月采用多网目复合刺网和抛网相结合的方法,对铜陵淡水豚国家级自然保护区半自然水域夹江鱼类群落进行了调查。共采集到鱼类30种,隶属于5目7科27属。相对重要性指数显示鲢（Hypophthalmichthys molitrix）、贝氏?（Hemiculter bleekeri）、似鳊（Pseudobrama simoni）、团头鲂（Megalobrama amblycephala）、鳊（Parabramis pekinensis）和翘嘴鲌（Culter alburnus）为群落优势种。与长江江豚（Neophocaena asiaeorientalis）争夺饵料资源的凶猛性鱼类比例达到2.4%,体长分布显示夹江中存在大量长江江豚无法摄食的大个体鱼类（17.5%）。夹江鱼类群落的Shannon-Weiner指数、Simpson指数、Margalef指数和Pielou均匀度指数依次分别为1.955~2.181,0.794~0.820,2.952~3.856和0.705~0.730。空间生态位宽度指数、平均拥挤度和生态位重叠指数表明,夹江优势种鱼类可能存在较为激烈的种间竞争。建议清理鳡（Elopichthys bambusa）、翘嘴鲌、达氏鲌（Culter dabryi）和乌鳢（Channa argus）等凶猛性鱼类及其他与长江江豚争夺饵料的鱼类,及时捕捞全长超过25 cm的鱼类,补充投放鲢、似鳊、银鲴（Xenocypris argentea）等长江江豚偏好摄食鱼类。     

澜沧江西双版纳段鱼类组成和物种多样性

根据2018-2020年澜沧江西双版纳段5次鱼类资源调查数据,结合相关文献资料,对该流域鱼类组成及物种多样性进行了分析。结果显示：澜沧江西双版纳段此次共调查到鱼类119种,隶属于11目28科79属,而历史记录鱼类共179种,隶属于12目34科106属。随着调查的不断深入,土著鱼类种数逐渐增多,但占比却逐渐下降,外来鱼类种数逐渐增多,占比也逐渐升高;本次调查到土著鱼类92种,占鱼类种数的77.31%,占比进一步下降;外来鱼类27种,占鱼类种数的22.69%,占比进一步升高。该区域鱼类优势种为云南吻孔鲃Poropuntius huangchuchieni和少鳞舟齿鱼Scaphiodonichthys acanthopterus,常见种为长臀鲃Mystacoleucus marginatus和宽额鳢Channa gachua。有《国家重点保护野生动物名录》（2021年）鱼类5种,《中国生物多样性红色名录脊椎动物卷》（2015年）受威胁鱼类8种。相对于我国其他江河,澜沧江西双版纳段有极高水平的鱼类物种多样性,其中澜沧江干流鱼类物种多样性相对于左、右岸支流较低,左岸支流鱼类多样性高于右岸,罗梭江鱼类多样性高于其他一级支流。虽然澜沧江西双版纳段鱼类物种多样性维持在较高水平,但土著鱼类占比下降趋势明显,仍面临着严重威胁,本文分析了受威胁因素,并提出了保护建议。     

西藏双须叶须鱼年龄与生长特点研究

双须叶须鱼（Ptychobarbus dipogon Regan）隶属裂腹鱼亚科（Schizothoracinae）叶须鱼属（Ptychobarbus）,是西藏特有经济鱼类,2016年被列入中国脊椎动物红色名录,必须加快推动该鱼的养护工作。2013年2~3月份及2014年2~6月份,在雅鲁藏布江谢通门段与支流拉萨河上游段采集1 030尾双须叶须鱼样本,以脊椎骨作为年龄鉴定材料进行年龄与生长特点研究,以期分析和评价该类群鱼类资源情况。研究结果如下：双须叶须鱼样本中最大年龄为49龄,最小年龄为4龄;体重与体长关系是样本总体W=4.4×10^-5?SL^2.7688、雌鱼W_♀=5.0×10^-4?SL^2.3474、雄鱼W_♂=2.8×10^-5?SL^2.8414;体长生长方程为雌鱼L_t（♀）=431.8［1-e^-0.19（t+1.19）］,渐进体长L∞_（♀）=431.8 mm,拐点年龄为3.3龄,雄鱼L_t（♂）=367.6［1-e^-0.42（t+3.37）］,渐进体长L∞_（♂）=367.7 mm;体重生长方程为雌鱼W_t（♀）=767.40［1-e^-0.19（t+1.19）］^2.3474,雄鱼W_t（♂）=545.02［1-e^-0.42（t+3.37）］^2.8414;群体异速生长指数b=2.768 8与匀速生长指数3存在显著性差异,即P<0.05。研究表明双须叶须鱼体趋向低龄化,应当予以充分关注。     

东太湖鱼类群落结构特征及其与环境因子的关系

基于2019年4月、7月和10月的调查数据,用多元分析方法研究了围网拆除后东太湖鱼类群落结构的变化,及其与主要环境因子的关系。共调查到鱼类4目10科31属39种,其中鲤形目鱼类占69.23%。按不同生态类型东太湖鱼类主要为定居性鱼类、中上层鱼类以及肉食性和杂食性鱼类。优势种为鲫（Carassius auratus）、大鳍鱊（Acheilognathus macropterus）和（Hemiculter leucisculus）等。鱼类的种类数、渔获量、丰富度指数和多样性指数在监测月份间均差异显著（P＜0.05）,均为4月 > 7月 > 10月。鱼类个体呈现小型化,鱼类物种多样性处在一般水平。等级聚类分析（Cluster）结果表明,除10月份的1号点和3号点外,各样方间的相似度在46.75%以上。单因子相似性分析（ANOSIM）和相似性百分比分析（SIMPER）也表明,4月和10月的鱼类群落物种组成差异显著,平均相异性为59.41%。丰度/生物量曲线（ABC）分析表明,东太湖鱼类群落结构处于中度干扰状态。冗余分析（RDA）表明,总磷对主要鱼类变化的解释量为21.0%,是重要的解释因子（蒙特卡罗检验P＝0.036）。而总磷、pH、溶解氧等是目前影响东太湖鱼类群落的主要环境因子。     

长江江豚重要栖息地清节洲水域鱼类群落结构

长江清节洲水域是长江江豚的重要栖息地之一,为了解该水域鱼类群落结构特征,于2017年4月、7月、10月和2018年2月对该水域鱼类群落进行了季节性调查。调查共采集鱼类38种,隶属于5目8科29属,其中鲤科鱼类占优势,占总种类数的68.4%。相对重要性指数结果显示鱼类群落优势种为贝氏?（Hemiculter bleekeri）、似鳊（Pseudobrama simony）、银鲴（Xenocypris argentea）和刀鲚（Coilia nasus）。按生活习性划分,定居性鱼类占绝对优势,占总种数的78.9%;在空间上,中上、中下和底层鱼类分布较为均衡,占总种数的比例依次为36.8%,28.9%和34.2%;从食性上划分,杂食性和肉食性鱼类较多,分别占总种数的44.7%和39.5%。Shannon-Weiner指数、Simpson指数、Margalef指数和Pielou均匀度指数依次分别为0.820~1.711,0.601~0.981,1.640~3.423和0.249~0.592。单因素方差分析表明,除春夏季与秋冬季的Margalef指数存在显著性差异（P<0.05）,各指数在时间和空间均无显著性差异（P>0.05）。与历史资料相比,该区域鱼类群落呈现物种多样性降低和群落结构小型化的趋势。因此,建议加强该水域鱼类资源的监测和保护,以维护长江生态系统的稳定与江豚栖息地的适合度。     

海南岛陵水河流域淡水鱼类群落结构及历史变化研究

根据2019年4月至2021年3月的调查数据,对海南岛陵水河流域淡水鱼类群落结构、多样性及其历史变化进行了研究。共调查到鱼类47种,隶属于6目19科,其中海南特有种7种,陵水河流域历史未记录种21种。鲤形目（Cypriniformes）鱼类种类最多,为23种,占物种总数的49%。Shannon-Wiener多样性指数（H′）为3.12、物种丰富度（D）为6.10、均匀度指数（J''）为0.81、优势度（λ）为0.06。与历史资料相比陵水河流域土著鱼类缺失种类达16种,其中受威胁鱼类种类锐减明显,同时外来鱼类种类显著增加。本研究结果为陵水河流域淡水鱼类多样性保护策略制定提供科技支撑,同时为海南省热带淡水鱼类多样性保护研究积累基础数据。     

The reproductive biology of an endemic cyprinid,Zacco pachycephalus,in Taiwan

Synopsis Reproductive parameters including body weight-length relationship, condition factor, gonadosomatic index (GSI) and fecundity of an endemic cyprinid,Zacco pachycephalus, were studied from October 1991 to January 1993. Although the condition factor was similar between both sexes, GSI values of female (3.72 to 14.24%) were significantly larger than that of males (0.21 to 2.23%) during the major breeding season. The number of yolky eggs per fish ranged from 459 to 2059. Ovum size distribution, annual GSI value, and recruitment of juvenile fish indicated thatZ. pachycephalus conducted two major spawning activities in spring (February to April) and summer (June to August). The larger GSI value and number of yolky eggs in spring compared to those in summer implies thatZ. pachycephalus has evolved a reproductive style by investing more energy in spring to avoid the damage of summer freshet on its recruitment success. The mating behavior ofZ. pachycephalus is similar to that of otherZacco fishes.     

Discrimination among Fish Models by Hawaiian Eleotris sandwicensis (Eleotridae)1

I examined behavioral responses of the benthic fish Eleotris sandwicensis to painted models (dummies) of fish that Eleotris typically encounter in Hawaii. Eleotris sandwicensis were associated with coarse substrates where their mean (±SE) density was 1.5 (±0.30) fish/m². I hypothesised that Eleotris would retreat from all models in open areas, but not when they were present in shelters. The five models represented Stenogobius hawaiiensis, Awaous guamensis, E. sandwicensis (female coloration), a male E. sandwicensis in breeding colors (black), and a 12 cm block of wood (control). Whether or not Eleotris held its position or retreated was not a function of body size. Differences among the responses of Eleotris to models depended on whether or not the fish was hidden or exposed on substrates. More retreats in response to models occurred when Eleotris were exposed on substrates than when fish were hidden. There were no significant differences in the response of E. sandwicensis to models when fish were exposed on substrates. In contrast, responses of E. sandwicensis to the models were not random for fish that were hidden, indicating that Eleotris discriminated among the models. The basis for discrimination among models was most likely visual. Although Eleotris are typically secretive, their presence on exposed substrates at this study site may be attributed to die lack of benthivorous fishes and few avian predators. The ability of Eleotris to distinguish among fishes when hidden as well as their tendency to retreat in response to all intruders whenever exposed on substrate surfaces could reduce potential interactions between Eleotris and other native and nonindigenous fishes.     

Underwater Video Reveals Strong Avoidance of Chemical Alarm Cues by Prey Fishes

A diversity of fishes release chemical cues upon being attacked by a predator. These cues, commonly termed alarm cues, act as sources of public information warning conspecifics of predation risk. Species which are members of the same prey guild (i.e. syntopic and share predators) often respond to one another's alarm cues. The purpose of this study was to discriminate avoidance responses of fishes to conspecific alarm cues and cues of other prey guild members from responses to unknown damaged fish odours and novel odours. We used underwater video to measure avoidance responses of freshwater littoral species, namely fathead minnows (Pimephales promelas), finescale dace (Chrosomus neogaeus), and brook stickleback (Culaea inconstans), to both injured fish cues and novel non‐fish odours. The cyprinids (minnows and dace) showed significant avoidance of minnow cues over swordtail cues, morpholine, and the control of distilled water and tended to avoid fathead cues over cues of known prey guild members (stickleback). Cyprinids also significantly avoided cues of stickleback over unknown heterospecific cues (swordtail) and tended to avoid stickleback cues over morpholine and the distilled water control. Stickleback significantly avoided fathead minnow extract over the distilled water and tended to avoid stickleback and swordtail over distilled water. We conclude that fishes in their natural environment can show dramatic changes in behaviour upon exposure to alarm cues from conspecifics and prey guild members. These responses do not represent avoidance of cues of any injured fish or any novel odour.     

Trade‐offs between salinity preference and antipredator behaviour in the euryhaline sailfin molly Poecilia latipinna

Salinity preference and responses to predatory chemical cues were examined both separately and simultaneously in freshwater (FW) and saltwater (SW)‐acclimated sailfin mollies Poecilia latipinna, a euryhaline species. It was hypothesized that P. latipinna would prefer FW over SW, move away from chemical cues from a crayfish predator, and favour predator avoidance over osmoregulation when presented with both demands. Both FW and SW‐acclimated P. latipinna preferred FW and actively avoided predator cues. When presented with FW plus predator cues v. SW with no cues, P. latipinna were more often found in FW plus predator cues. These results raise questions pertaining to the potential osmoregulatory stress of salinity transitions in euryhaline fishes relative to the potential fitness benefits and whether euryhalinity is utilized for predator avoidance. This study sheds light on the potential benefits and consequences of being salt tolerant or intolerant and complicates the understanding of the selection pressures that have favoured the different osmoregulatory mechanisms among fishes.     

Which Factors Affect Sex Ratio of Spined Loach (genus Cobitis) in Lake Müggelsee?

The distribution and extent of chemical alarm signaling systems among some families of fishes, including the Cottidae, remains unclear. In laboratory experiments, we tested whether reticulate sculpins, Cottus perplexus, respond to chemical alarm signals released by injured conspecifics. Sculpins decreased movement following exposure to skin extracts from conspecifics, but did not respond to cues of syntopic speckled dace, Rhinichthyes osculus, or allotopic swordtails, Xiphophorous helleri. Additional tests demonstrated that the responses of sculpins to alarm cues were dependent on the hunger level of the test fish. Sculpins deprived of food for 2 days failed to respond to conspecific alarm cues, however, the same individuals fed to satiation did respond to alarm cues.     

Predation risk assessment by olfactory and visual cues in a coral reef fish

Assessment of predation risk is vital for the success of an individual. Primary cues for the assessment include visual and olfactory stimuli, but the relative importance of these sources of information for risk assessment has seldom been assessed for marine fishes. This study examined the importance of visual and chemical cues in assessing risk for the star goby, Asterropteryx semipunctatus. Visual and chemical cue intensities were used that were indicative of a high threat situation. The behavioural response elicited by both the visual cues of a predator (the rock cod, Cephalopholis boenak) and the chemical alarm cues from conspecifics were similar in magnitude, with responses including a decrease in feeding strikes and moves. A bobbing behaviour was exhibited when the predator was visible and not when only exposed to the chemical alarm cue. When visual and chemical cues were presented together they yielded a stronger antipredator response than when gobies were exposed solely to conspecific alarm cues. This suggests additivity of risk assessment information at the levels of threat used, however, the goby’s response is also likely to depend on the environmental and social context of the predator–prey encounter. This study highlights the importance of chemical cues in the assessment of predation risk for a coral reef fish.     

Sexual and seasonal plasticity in the emission of social electric signals. Behavioral approach and neural bases

Behavior in electric fish includes modulations of a stereotyped electric organ discharge (EOD) in addition to locomotor displays. Gymnotiformes can modulate the EOD rate to produce signals that participate in different behaviors. We studied the reproductive behavior of Brachyhypopomus pinnicaudatus both in the wild and laboratory settings. During the breeding season, fish produce sexually dimorphic social electric signals (SES): males emit three types of chirps (distinguished by their duration and internal structure), and accelerations, whereas females interrupt their EOD. Since these SES imply EOD frequency modulations, the pacemaker nucleus (PN) is involved in their generation and constitutes the main target organ to explore seasonal and sexual plasticity of the CNS. The PN has two types of neurons, pacemakers and relays, which receive modulatory inputs from pre-pacemaker structures. These neurons show an anisotropic rostro-caudal and dorso-ventral distribution that is paralleled by different field potential waveforms in distinct portions of the PN. In vivo glutamate injections in different areas of the PN provoke different kinds of EOD rate modulations. Ventral injections produce chirp-like responses in breeding males and EOD interruptions in breeding females, whereas dorsal injections provoke EOD frequency rises in both sexes. In the non-breeding season, males and females respond with interruptions when stimulated ventrally and frequency rises when injected dorsally. Our results show that changes of glutamate effects in the PN could explain the seasonal and sexual differences in the generation of SES. By means of behavioral recordings both in the wild and in laboratory settings, and by electrophysiological and pharmacological experiments, we have identified sexual and seasonal plasticity of the CNS and explored its underlying mechanisms.     

Innate responses to conspecific and heterospecific alarm cues in the endangered eastern cape redfin Pseudobarbus afer

We examined innate responses to conspecific and heterospecific alarm cues in a small cyprinid minnow, the Eastern Cape redfin Pseudobarbus afer. We found that redfins respond to conspecific skin extract, which contains alarm chemicals, and showed that their preferred response is to hide in refugia. Redfins also respond to skin extract from an allopatric, distantly related minnow species, the chubbyhead barb Enteromius anoplus indicating that neither sympatry nor close phylogenetic relationships are necessary for recognition of heterospecific alarm cues. Although both conspecific and heterospecific alarm cues induced similar responses, the response to heterospecific cues was less intense. This may be explained by a trade-off between selection to maximise threat recognition and selection to avoid the costs of responding to irrelevant cues, or by differences in chemical structures of alarm cues between species. These findings have implications for the conservation of this Endangered fish species and for freshwater fishes throughout Africa.     

Habitat Restoration as a Means of Controlling Non-Native Fish in a Mojave Desert Oasis

Non‐native fish generally cause native fish decline, and once non‐natives are established, control or elimination is usually problematic. Because non‐native fish colonization has been greatest in anthropogenically altered habitats, restoring habitat similar to predisturbance conditions may offer a viable means of non‐native fish control. In this investigation we identified habitats favoring native over non‐native fish in a Mojave Desert oasis (Ash Meadows) and used this information to restore one of its major warm water spring systems (Kings Pool Spring). Prior to restoration, native fishes predominated in warm water (25–32°C) stream and spring‐pool habitat, whereas non‐natives predominated in cool water (≤23°C) spring‐pool and marsh/slack water habitat. Native Amargosa pupfish (Cyprinodon nevadensis) and Ash Meadows speckled dace (Rhinichthys osculus nevadensis) inhabited significantly faster mean water column velocities (MWCV) and greater total depth (TD) than non‐native Sailfin molly (Poecilia latipinna) and Mosquitofish (Gambusia affinis) in warm water stream habitat, and Ash Meadows speckled dace inhabited significantly faster water than non‐natives in cool water stream habitat. Modification of the outflow of Kings Pool Spring from marsh to warm water stream, with MWCV, TD, and temperature favoring native fish, changed the fish composition from predominantly non‐native Sailfin molly and Mosquitofish to predominantly Ash Meadows pupfish. This result supports the hypothesis that restoring spring systems to a semblance of predisturbance conditions would promote recolonization of native fishes and deter non‐native fish invasion and proliferation.