长江中游典型草型湖泊与藻型湖泊鲫种群结构和生长比较(英文)

浅水湖泊牛山湖和月湖均位于长江中游武汉市境内,前者水质清澈、沉水植物茂盛,属典型的草型湖泊;后者长期受生活污水和工业废水排放的影响,水质恶劣、沉水植物稀少,属典型的藻型湖泊。文章选择这两个湖泊的共同优势鱼类——鲫(Carassius auratus)作为研究对象,通过比较两类不同湖泊环境条件下鲫种群结构和生长上的差异,评估人类活动引起的水环境改变对鱼类种群生存状况的影响。2006年春季(3—5月),于牛山湖和月湖各采集鲫种群样本713尾和641尾,研究结果表明:(1)牛山湖和月湖鲫种群的全长频数分布经kolmogorov-Smirnov检验均符合正态分布,但前者的分布范围(63—271 mm)大于后者(72—191 mm),前者的全长峰值(190 mm)亦大于后者(110 mm);(2)牛山湖鲫种群的年龄组成(6个年龄组)较月湖(仅3个年龄组)完整,但月湖各龄鲫的全长均显著大于牛山湖(P<0.05);(3)两个湖泊性成熟鲫的雌、雄鱼比均随全长的增长而增加,即小个体性成熟鲫以雄鱼为主,大个体性成熟鲫以雌鱼为主,该现象在月湖更为明显;(4)牛山湖和月湖鲫全长–体重回归关系(W=a Lb)分别为W=0.00001 L3.060(R2=0.989)和W=0.000006 L3.246(R2=0.971),协方差分析表明两个湖泊鲫种群的b值差异极显著(P<0.01);另一方面,月湖鲫种群各全长组雌、雄鱼的肥满度均显著大于牛山湖(P<0.05)。作者认为影响牛山湖和月湖鲫生长和种群结构的主要因素是两个湖泊饵料组成和捕捞压力等方面的差异。     

太湖五里湖生态修复示范区水质改善效果分析

鱼类清除和沉水植被恢复常是富营养化浅水湖泊生态系统修复的重要手段。为探讨这种生态系统修复方式对亚热带富营养化浅水湖泊太湖五里湖水质的改善效果,论文研究了五里湖生态修复区与未进行任何修复的对照湖区为期6个月(2010年7～12月)的水质监测数据。数据分析结果表明,生态修复区总氮(TN)、总磷(TP)、叶绿素-a(Chl-a)以及悬浮质(TSS)浓度显著降低,分别比对照区低43.4%、48.3%、65.5%和78.9%,透明度则明显升高,约为对照区的3倍。本研究表明以鱼类清除和沉水植被恢复为主要手段的生态系统修复措施能够有效改善亚热带富营养化浅水湖泊水体的水质。     

大型浅水湖泊太湖藻类浊度与非藻类浊度的变异规律

为探究大型浅水湖泊中沉水植物对浊度的影响, 对大型浅水湖泊——太湖(有草区和无草区)进行了为期1年的野外调查, 将浊度分为藻类浊度(Turb_Alg)和非藻类浊度(Turb_NonAlg), 分析其变异规律及其对总浊度(Turb_Tot)贡献率的差异。结果显示: (1) 太湖水体中Turb_NonAlg(年均值为2.45/m)为主要的浊度组分, 占总浊度(2.88/m)的83%, 春季时高达89%; (2) 有草区Turb_NonAlg(2.52/m)和无草区的(2.37/m)差异不显著(P>0.05); (3) 在相同TP范围内, 有草区Turb_Alg (0.21/m)和无草区的(0.32/m)无明显差异(P>0.05), 在夏季时甚至略高于后者。研究表明, 在大型浅水湖泊中, 沉水植物对水体浊度的抑制效果有限, 对非藻类浊度和藻类浊度均未起到有效的控制作用。因此, 在相同营养条件下, 大型浅水湖泊更易发生稳态转换, 且发生转换后恢复原始状态的难度也可能更大。     

不同捕食者暴露对鲫幼鱼行为、运动和形态特征的影响

自然界中鱼类的捕食者种类繁多,为验证猎物鱼针对不同捕食者是否会做出相异的反捕食策略选择,选取鲫（Carassius auratus）幼鱼为猎物鱼,乌鳢（Channa argus）和胡子鲶（Clarias fuscus）为捕食者,将鲫幼鱼分别暴露于空白（对照）、乌鳢、胡子鲶和双捕食者（同时存在乌鳢和胡子鲶）环境中持续2个月,随后考查不同组鲫幼鱼的生长、行为特征、形态和运动能力等指标之间的差异。结果表明：经过2个月的捕食胁迫处理,鲫幼鱼的自发运动、隐蔽场所利用率和勇敢性等行为指标在4个组之间均未表现出显著性差异。相比对照组,乌鳢、胡子鲶和双捕食者暴露组鲫幼鱼的快速启动反应时滞显著缩短（P<0.05）;但所有处理组中仅乌鳢暴露组鲫幼鱼的快速启动120ms移动距离（S_120ms）和体高（BD）显著高于对照组（P<0.05）。另外鲫幼鱼的临界游泳速度（U_crit）和活跃代谢率（M_O2active）在各组之间也未表现出显著差异。乌鳢暴露组鲫幼鱼快速启动能力的提升可能与形态上体高的提高有关;另外相比临界游泳能力,快速启动能力可能在鱼类逃避捕食者过程中更为关键;鲫幼鱼表现出对乌鳢的反应最为明显,可能与乌鳢口裂较大,给鲫幼鱼带来的威胁更大有关。整体而言,应对捕食胁迫时,鲫幼鱼仅表现出形态和快速启动能力的反捕食响应,其行为特征的保守性可能是对生长作出的妥协,这对于鱼类适应生境中长期存在的捕食胁迫十分关键。     

背角无齿蚌(Anodonta woodiana)、苦草(Vallisneria natans)及其共存对水质的影响

滤食性贝类与沉水植物是水生态系统的重要组成部分,对浅水湖泊生态系统的结构、功能和过程具有重要影响,但两者共存产生的生态环境效应尚不明确。本文以背角无齿蚌(Anodonta woodiana)及沉水植物苦草(Vallisneria natans)为对象,通过构建中型水生态系统(对照组、蚌处理组、草处理组、蚌草共存组),研究了背角无齿蚌、苦草及其共存对水质的影响。结果表明:背角无齿蚌可显著降低浮游藻类生物量(Chl-a,P0.05);苦草显著降低了总氮(TN)、硝态氮(NO3--N)、总磷(TP)、溶解性总磷(TDP)及浮游藻类Chl-a(P0.05);蚌草共存显著降低了氮、磷营养盐水平及浮游藻类Chl-a(P0.05);背角无齿蚌对苦草的生长起促进作用,实验结束时蚌草共存组的苦草干重及株高显著高于草处理组(P0.05)。     

人工骨表面覆盖口腔修复膜对颌骨囊性缺损人工骨植入术患者植入腔感染的预防作用

目的:探讨人工骨表面覆盖口腔修复膜对颌骨囊性缺损人工骨植入术患者植入腔感染的预防作用。方法:将我院2012年4月～2016年2月收治的78例颌骨囊性缺损患者按治疗时间分为对照组38例与观察组40例,均行开窗人工骨植入术,其中对照组采取常规抗感染,观察组采取人工骨表面覆盖口腔修复膜。比较两组的囊腔体积、面积缩减率、人工骨植入量、骨厚度及植入腔感染率。结果:两组的囊腔体积、面积缩减率及人工骨植入量比较差异无统计学意义(P0.05)。但观察组的骨厚度明显大于对照组(P0.05),植入腔感染率明显低于对照组(P0.05)。结论:在开窗人工骨植入术的基础上使用口腔修复膜不仅能引导骨组织再生,而且能够显著降低植入腔的感染率。     

银鲫apelin基因的克隆、组织表达谱和摄食关系的初步研究

apelin是一种参与哺乳动物和鱼类摄食调控的重要神经肽。为了更好地研究apelin在银鲫(Carassius auratus gibelio)上的摄食调控作用,本试验采用RACE技术首次获得了银鲫apelin的cDNA全长序列,并通过实时荧光定量PCR(RT-PCR)技术检测了apelin基因在各组织的表达情况以及餐前餐后和禁食对其表达量的影响。结果显示银鲫apelin全长cDNA序列长度为1082 bp,其中5’非编码区(5’-UTR)的长度为114 bp,3’非编码区(3’-UTR)的长度为734 bp,开放阅读框(open reading frame,ORF)的长度为234 bp。银鲫apelin基因的ORF区编码77个氨基酸,前22个氨基酸为信号肽。apelin基因在银鲫21个组织中普遍表达,特别是在下丘脑中表达量最高。在餐前餐后的试验中,银鲫下丘脑apelin基因在餐后表达量显著下降(p<0.05);在禁食试验中,禁食组下丘脑apelin基因的表达量在第5天显著升高(p<0.05),第7天极显著升高(p<0.01),复投喂后,apelin基因的表达量在第9天、第11天、第14天极显著降低(p<0.01)。综上所述,apelin基因可能是银鲫的诱食因子,在其摄食调控起到一定的作用。     

浅水湖泊稳态转换预警识别方法局限与展望

浅水湖泊水体底泥交换强烈,极易受人类活动干扰,超过一定阈值即可能发生灾难性的稳态转换,对其有效识别有助于湖泊富营养化的及时防控与修复。浅水湖泊稳态转换可通过系统关键变量(叶绿素、溶解氧、浮游动物、鱼类等)的时间序列(判别不同稳态)、预警信号及阈值等进行识别,其中预警识别可为湖泊生态系统稳态转换提供预判信息,有利于早预警早行动。目前,浅水湖泊稳态转换预警识别因子(方差及自相关性等)主要用于"临界慢化"现象,但在强大外力作用、强烈随机扰动及极端事件下,这些"临界慢化"因子则可能出现误用或错用。基于浅水湖泊基本特征,针对稳态转换的不同驱动机制,探讨"临界慢化"因子的适用性与局限性,并展望其未来发展方向,旨在为湖泊生态系统稳态转换预警识别提供科学参考。     

在太湖中栽种沉水植物能使水变清吗？

浅水湖泊富营养化修复是环境科学领域的前沿研究.在富营养化的太湖中栽种沉水植物能使水变清,进而"向后跃变"为"草型湖泊"吗?回答是几乎不可能.原因在于藻类和沉水植物之间存在着竞争.在湖泊中决定沉水植物能否生长的关键是水体的光照条件.在富营养化的湖泊中,藻类对沉水植物有明显的"遮光效应",从而降低了它的竞争能力.另一种情况,枝角类的消失或者数量减少对藻类有利."下行效应"在浅水湖泊中可能更为重要,因此浅水湖泊中滤食性鱼类对浮游动物的捕食控制可能更强,导致枝角类几乎不可能通过牧食控制藻类的生长.在这样的状况下,沉水植物的恢复几乎是不可能的.如果沉水植物再遭受其它的损害或者恶劣的天气,就会突然一下子全部消失.因此在富营养化的湖泊中栽种沉水植物的成活率是很低的.这与浅水湖泊二种替代性稳定状态概念是相一致的.     

不同饵料对稀有鲫生长和繁殖的影响

饵料对鱼类生长发育和繁殖具有重要影响。为了筛选稀有鲫(Gobiocypris rarus)幼鱼和成鱼阶段最适投喂方式, 实验将出膜5周末(日龄为35 day after hatching)的幼鱼随机分为5个组: A组投喂丰年虫; B组每周前6d (days)投喂丰年虫, 后1d投喂商业化微颗粒S3饲料; C组每周前3.5d投喂丰年虫, 后3.5d投喂饲料; D组每周前1d投喂丰年虫, 后6d投喂饲料; E组一直投喂饲料; 各组均采用饱食投喂策略。每2周统计生长、存活指标, 直至第21周(147 dah), 在17周(119 dah)取材用于观察性腺发育程度。在产卵后统计各组产卵量、孵化率和子代畸形率。结果显示: (1)E组存活率和特定生长率显著低于其他组(P<0.05); (2)从产卵量、孵化率和子代畸形率上看, B组产卵量显著高于其他组(P<0.05); (3)从性腺组织学上看, 不同投喂方法对精巢的成熟度无显著影响, 但投喂过丰年虫的稀有鲫卵巢发育成熟度显著优于E组。研究结果提示:适量加入丰年虫比单一投喂活饵或饲料更有利于稀有鲫的生长和繁殖。建议在标准化养殖过程中, 幼鱼和成鱼期的稀有鲫采取丰年虫与饲料投喂频次比值为6﹕1的方式最佳。     

洪泽湖鱼类资源现状、历史变动和渔业管理策略

研究于2010年秋季和2011年夏季对南水北调东线工程最大调蓄湖泊洪泽湖的鱼类资源进行了调查,结合历史资料分析该湖鱼类资源变动情况,以期为渔业管理和生物多样性保护提供依据。自20世纪60年代以来,洪泽湖累计记录鱼类88种,本研究发现63种,其中新记录6种,分别为:点纹银 、彩副 、方氏鳑鲏、鲻、大眼鳜和波氏吻虾虎鱼;与历史记录比较,湖泊定居性鱼类所占比例由59%上升78%,而喜流水性鱼类和河海洄游性鱼类分别由22%和7%下降到3%和3%;未采集到的25种鱼类中,流水性鱼类计17种,占68%。网簖和丝网的渔获物分析表明,鲫、黄颡鱼、刀鲚和红鳍原鲌等小型鱼类具有较高的IRI值（相对重要性指数,Index of Relative Importance）,是鱼类群落的优势种,大型鱼类除鲤外,IRI值均不高,在群落中不占优势。20102011年洪泽湖渔业年产量为2200104 kg,以刀鲚和鲫为主的小型鱼类产量达1967104 kg,占89.4%;四大家鱼产量96104 kg,占4.4%;鳜、翘嘴鲌、乌鳢和鲇等大型食鱼性鱼类合计仅占0.89%。文章分析江湖阻隔、过度捕捞和生境破坏对洪泽湖鱼类资源的影响,提出相应的渔业管理策略,并初步预测南水北调东线工程对该湖鱼类和渔业的潜在影响。       

Retention of loop,monel, and passive integrated transponder tags by wild,free‐ranging Lake Sturgeon (Acipenser fulvescens Rafinesque, 1817)

Tagging or marking of fish is instrumental to fisheries biologists and managers seeking to distinguish groups of fish, track movement or migration patterns, and monitor population characteristics. However, tag loss can inhibit the ability of biologists and managers to reach these objectives. The ability of Lake Sturgeon to live for long periods of time and reach large sizes, in combination with their dynamic spawning activity, requires tags to be retained under a variety of environmental and physically demanding conditions. This study evaluated tag retention of loop, monel, and passive integrated transponder (PIT) tags on wild, free‐ranging Lake Sturgeon in Lake Huron and the St. Clair – Detroit River System. Lake Sturgeon in this study were double‐tagged with both a PIT tag under one of the three anterior‐most dorsal scutes and an external tag (loop or monel) at the base of the dorsal fin. Fish were at large for up to 16 years. Overall, tag loss for PIT tags was 1% followed by monel tags at 12% and loop tags at 36%. Tag loss for loop tags was higher when the initial length of Lake Sturgeon tagged was smaller. Tag loss for monel tags increased with time at large but was not related to length at initial tagging. Monel tags left behind abrasion marks when attached to smaller Lake Sturgeon. PIT tag retention was higher than reported in previous studies that tagged other sturgeon species in different body locations. Monel tag retention was higher than other external tag types evaluated in previous studies while loop tags had similar retention rates to external tag types. Most previous studies on tag retention of sturgeon species were of shorter duration and conducted in laboratory settings, therefore loop tags may have performed more favorably during studies under short term laboratory settings. Results of this study suggest that PIT tags inserted below dorsal scutes represent a viable option for long‐term tracking of Lake Sturgeon. Monel tags attached at the base of the dorsal fin also seem to be a viable option relative to other external tag types, but should be limited to larger sturgeon as they can leave behind abrasion marks.     

Mobile receivers: releasing the mooring to ‘see’ where fish go

Much has been learned from the large scale deployment of acoustic tags on aquatic species and associated networks of riverine and marine receivers. While effective in the linear environment of river systems, marine systems limit the ability to provide spatial information on fish movements and distributions due to a combination of costs, logistics, and lack of off-shore technology. At the same time, each year millions of dollars worth of tags are being released into the aquatic environment with extended battery/transmission life, yet detections are limited to coastal arrays. Here we explore new methods of tracking acoustically tagged species in the marine environment. A new miniaturized acoustic receiver, the Vemco Mobile Transceiver (VMT) can be carried by large marine organisms. In combination with satellite and archival tag technology, VMTs were deployed on northern elephant seals to monitor acoustic tags encountered during their migrations across the Northeast Pacific. Early results include acoustic detections of tagged great white sharks, salmon sharks, Chinook salmon, steelhead, lingcod, green sturgeon and other elephant seals. We also propose several alternative directions for future effort: 1) analyzing the growing number of passive acoustic survey recordings made from hydrophone arrays for acoustic tag detections, 2) working with acoustic technology providers to develop hull-mounted receiver systems for the thousands of ocean going vessels around the world and 3) integrating acoustic receiver technology into the thousands of moored and drifting oceanographic buoy arrays.     

Methods for estimating detection efficiency and tracking acoustic tags with mobile transect surveys

Mobile transect surveys were conducted for 5 years in a deep fjord looking for weak acoustic tags, most of which were in dead fishes lying on the seabed. Detection efficiencies were quantified because inferences about fish presence were made from tag detection data but a considerable proportion of tags were not detected. Methods for assessing transect widths using cumulative probabilities of measured perpendicular distances from blind transect lines to triangulated tag locations are described. Three methods for estimating detection efficiencies are presented: fitting attenuation functions to perpendicular distance data, simultaneous use of two receiver systems and test tag surveys. Several factors that influenced these detection efficiencies and ranges are shown, including boat speed, depth of tag, tag type, different hydrophone–receiver systems and variation among individual hydrophones and receivers of the same model. The trade‐off between detection efficiency per unit area and area swept is discussed, which is largely based on boat speed during transects. Finally, several methods are suggested for increasing decoding efficiencies in mobile tracking studies when tags are heard but are difficult to decode.     

四种鲤科鱼类对捕食胁迫行为响应的种间比较

为了比较早期捕食胁迫经历和当前环境中存在的捕食者对鱼类行为的影响, 并考查这些影响是否存在种间差异, 研究分别考查了测定环境(有、无捕食者存在)对有、无捕食胁迫经历的鳊(Parabramis pekinensis)、草鱼(Ctenopharyngodon idellus)、鲫(Carassius auratus)和中华倒刺鲃(Spinibarbus sinensis)等4种鲤科鱼类探索性、活跃性和勇敢性的影响。结果发现: 早期捕食胁迫经历与当前环境条件对鱼类行为产生截然不同的影响, 且存在较大的种间差异。无捕食胁迫经历的鳊、草鱼和中华倒刺鲃均会对陌生的捕食者乌鳢(Channa argus)做出行为响应, 提示这3种鱼可能对陌生捕食者具有一定的识别能力, 但这种识别与猎物鱼通过捕食胁迫经历获得的识别仍具有一定差距; 具有捕食胁迫经历的鳊和中华倒刺鲃在空白环境中未表现出反捕食行为, 可能是节约能量的一种策略。总体而言, 草鱼对捕食胁迫经历和测定环境处理反应更为敏感, 而中华倒刺鲃的反应则相对保守。但当周围环境中存在捕食者时, 4种鲤科鱼类均会通过维持较高运动状态的方式来应对捕食者。维持这种应激状态可能对猎物鱼保持与捕食者的距离, 并随时保持警惕较为关键。     

铜镉联合胁迫处理对鲫体内重金属和组织病理的影响

采用半静态铜镉联合胁迫处理鲫(Carassius auratus), 研究铜和镉在鱼体各组织的富集以及对各组织的病理损伤。结果表明, 在鲫的肝脏、鳃丝、肠道和肌肉中均可富集铜和镉, 且铜的蓄积比镉显著。在鲫各组织中镉含量随着铜、镉浓度的增加逐渐增加, 而铜含量则呈下降趋势, 可能是镉抑制了机体对铜的吸收。在0.15 mg/L铜联合0.20 mg/L镉处理鲫14d后, 其肌肉中镉含量为0.13 mg/kg, 超出了行业标准的阈值(0.10 mg/kg)。在铜镉联合处理鲫后, 其肝组织出现血细胞聚集、脂沉积、细胞空化等症状; 鳃丝组织上皮增生、水肿和黏膜肿胀; 在肠组织中杯状细胞肿胀、柱状细胞增生、固有层出现液泡、肠黏膜糜烂、肠绒毛脱落坏死; 在肌组织中肌纤维断裂、聚集、崩溃、溶解, 同时肌纤维间隙增大。研究结果表明, 铜和镉不仅能在鲫体内富集, 而且能够对鲫各组织产生病理损伤, 且浓度越高、损伤越严重, 这主要是由于鲫体内镉浓度的升高所导致。研究可为重金属污染对鲫生长状况和食用安全性的影响分析提供数据支撑。     

Using PIT-tags and portable antennas for quantification of fish movement and survival in streams under different environmental conditions

While PIT-tag tracking using mobile antennas is being increasingly used to study fish movement and survival in streams, little is known about the limitations of the method, especially over longer periods of time and under different environmental settings. We used 6 years of data combining tagging, mobile antenna tracking and recaptures of Salmo trutta in multiple small streams in the Lake Lucerne drainage area in Switzerland to evaluate the relative importance of different environmental and intrinsic factors affecting the efficiency of the method. Our study system and experimental design allowed us to accurately verify the continuous presence and survival of recaptured fish in the stream after tracking, which meant that we could estimate detection probability with high confidence. The mean detection probability of tagged trout was 43%, but we found that fish length had a strong negative effect on detection probability, especially in males. Multivariate axes of stream environmental features did not predict efficiency but stream width alone was significantly positively correlated with efficiency. Additionally, stream temperature when tracking had a positive effect on fish detectability. Tag loss at recapture was globally rare (<8%) but common in large postspawn females (>30%). Based on the escape response of fish after detection, we could estimate the proportion of ghost tags, which reached a plateau of around 80% 2 years after tagging. We finally showed that our models of tag loss, fish detection and escape response are needed to interpret detection events. Our results highlight that individual variation in detection probability and tag loss is high and has to be considered for analysis.     

The fate of dead fish tagged with biotelemetry transmitters in an urban stream

Mortality is a key factor in understanding the population dynamics of fish. For studies using biotelemetry, missing individuals pose a challenge since the ultimate fate of both the animal and the tag are unknown. In this study, we document three releases of carcasses in a simulated small-scale summer fish kill in a small urban stream using juvenile white sucker (Catostomus commersonii). Passive integrated transponder (PIT) and radio tags were affixed to carcasses that were tracked to determine the fate of both the dead fish and the tags. Mean daily dispersal distances ranged from 0.0 to 7.6 m day^?1 and included downstream and lateral dispersal. Of the 44 radio-tagged carcasses, 26 tags (and presumably carcasses) were consumed by scavengers; the majority were consumed by snapping turtles (Chelydra serpentina) with fewer carcasses scavenged by great blue heron (Ardea herodias), raccoon (Procyon lotor) and muskrat (Ondatra zibethicus). We also contrasted the decomposition rates of in-stream carcasses with those experimentally placed on the riverbank and found that while there was no significant difference in the time to carcass evisceration, the rate of decomposition was more rapid in-stream compared to on-shore. Radio tag loss during the decomposition study was moderate (one of three lost); PIT tag loss occurred when carcasses became eviscerated, typically by invertebrates. By examining the role of scavengers, dispersal and decomposition, it is possible to understand the fate of dead fish, the fate of tags and role of mortality in tagging experiments and the connections between stream and riparian habitats and organisms. This information will help inform the interpretation of potential mortalities in fish tracking studies and improve fish kill investigations.     

海口地区集贸市场淡水鱼华枝睾吸虫囊蚴感染调查

用直接压片法和人工消化法检查了海口集贸市场上5种淡水色(鲫色、罗非鱼、鲤鱼、土鲮色、白鲳)感染华枝睾吸虫囊蚴情况。结果表明：5种淡水色的总感染率为53．66％。其中,鲤鱼、土鲮色、鲫鱼、罗非鱼、白鲳的感染率分别为68．75％、58．82％、58．06％、48．57％和36．67％;平均每克鱼肉含囊蚴数最高的是鲫鱼(9．47个／g),平均每尾阳性鱼含囊蚴数最高的是土鲮鱼(43个／尾)。     

Long-term retention of acoustic telemetry transmitters in temperate predators revealed by predation tags implanted in wild prey fish

Bloater Coregonus hoyi (n = 48) were implanted with V9DT-2x predation transmitters and monitored on 105 acoustic receivers in eastern Lake Ontario for >6 months. Twenty-three predation events were observed, with predator retention of tags ranging from ≤1 to ≥194 days and 30% of retentions lasting >150 days. Long tag retention times raise concerns for acoustic telemetry analysis and the health of piscivorous predators retaining tags.