Anadromous Waters Cataloging and Fish Inventories in subbasins of the Copper and Bering rivers 2023 and 2024

***Funded by the Alaska Sustainable Salmon Fund #56012, a part of the Pacific Coastal Salmon Recovery Fund Synopsis During the summers and falls of 2023-24, staff from the Alaska Department of Fish and Game (ADF&G), Division of Sport Fish, Alaska Freshwater Fish Inventory (AFFI) program will conduct a rapid, systematic inventory of anadromous and resident fish distribution and associated aquatic and riparian habitat in select drainages of the Copper and Bering rivers. This proposal addresses a critical area in Alaska - adjacent to or within land units such as Wrangell-St. Elias National Park & Preserve and the Chugach National Forest - that supports significant sport, commercial, personal use, and subsistence fisheries within expansive glacial fed watersheds that are experiencing glacial retreat, potentially leading to increased stream habitat available to migratory and resident fishes. AFFI program staff will identify and survey streams most likely to expand coverage of the State of Alaska's Catalog of Waters Important for the Spawning, Rearing or Migration of Anadromous Fishes (AWC) and when anadromous fish are observed, AFFI staff will nominate those waterbodies to the AWC. Introduction In Alaska habitats that support migrating, spawning, or rearing anadromous fish are protected under state, federal, and local administrative jurisdictions. Alaska Statute (AS) 16.05.871 (the Anadromous Fish Act) is the keystone statutory protection for freshwater habitats of anadromous fish in Alaska, requiring the ADF&G to "specify the various rivers, lakes, and streams or parts of them" of the state that are important to the spawning, rearing, or migration of anadromous fish in the Anadromous Waters Catalog (AWC) and Atlas. It is important that water bodies used by anadromous fish are listed in the AWC because only listed water bodies are protected from potentially harmful activities. To be listed in the AWC, water bodies require site-specific, direct, unambiguous observations of anadromous fish by a qualified observer (Giefer and Blossom 2021a). Anadromous fish habitat protection and management in Alaska are predicated on explicit knowledge of the distribution of species and life stages. Although the AWC currently lists 20,846 total water bodies (18,772 streams, 2,074 lakes) as being important for the spawning, rearing, or migration of anadromous fish, the documented extent of these waters and their tributaries as critical habitat to anadromous life histories is far from complete. Based on current areas surveyed, this number of AWC-listed water bodies likely represents a small proportion of the total number of streams, rivers, and lakes used by anadromous species statewide. Until these habitats are inventoried, they will not be protected under Alaska’s Anadromous Fish Act. Further, as landscapes respond to climate change and glaciers retreat, the AWC may increasingly underestimate salmon habitat without focused sampling of sensitive glacial watersheds such as those draining into the Gulf of Alaska or Prince William Sound (Pitman et al. 2021). Knowing where, and when anadromous fishes and resident species use habitats in Alaska, is crucial to respond to natural or manmade disturbances, manage fisheries, mitigate development, and understand regional ecology. Without this knowledge, managers have limited ability to respond to potential shifts in species use of habitat such as those in response to glacial retreat associated with climate change. Predicted near-term impacts of glacial retreat on salmon and fish habitat may manifest in at least two major ways (Ogden 2018; Pitman et al. 2021): 1) increased upstream access for salmon populations that already use glacier-fed rivers; 2) fish community shifts whereby some streams previously devoid of fish may start supporting one or more species of salmon that stray or colonize the streams exposed and lengthened by glacial retreat. However, long-term effects of glacial retreat are less predictable to fish populations that may be affected by more dynamic hydrography in the absence of stable summer glacier-fueled flows. Additionally, mining, and other land uses in or along currently glaciated streams may also exploit newly exposed resources. In the Copper River basin and other watersheds draining into the Gulf of Alaska, salmon distributions are predicted to gain 1,000 km of accessible waters due to glacial retreat – an increase in stream habitat greater than other glaciated drainages in the Pacific Northwest (Pitman et al. 2021). Therefore, the time is ripe to establish where salmon distributions have changed in the Copper and Bering rivers within both a contemporary timeframe (e.g., comparing this study’s findings to previous extents of AWC waters from historical sampling) as well as providing a current baseline of extents for reference to future predictions of shrunken glacial coverage in the region. The knowledge provided by this research would be integral into putting glacial retreat into a regulatory context protecting significant subsistence, commercial, personal use, and sport fisheries while also providing a metric that could assess accuracy of current and future predictions of how glacial retreat will affect Alaskan salmon populations. Knowing contemporary distributions of anadromous and resident fishes is especially critical to current and future management of glacial areas such as the Copper River basin and the Bering River These watersheds support subsistence and commercial fisheries for chum, Chinook, coho, pink and sockeye salmon amid intensifying effects of climate change including permafrost or glacial thawing that has associated hydrological changes in streams. Despite cultural, ecological, and economical interest in this climate-sensitive region, the Copper River basin not been investigated for anadromous and freshwater fishes at a landscape level and consequently, current AWC coverage may underestimate salmon habitat (Bidlack et a. 2014; Giefer and Blossom 2021a). From July 20-August 1, 2023 and 2024 AFFI staff will sample fish communities using AFFI protocols in selected tributaries of lower Copper River. Sampling target survey sites will include backpack electrofishing wadeable smaller headwater streams and raft-mounted electrofishing un-wadeable medium-sized streams. This timing will maximize the ability to detect juvenile and spawning or migrating Chinook and sockeye salmon in upstream areas as well as spawning or migrating pink and chum salmon in lower reaches. Then, depending on run timing based on data from Division of Commercial Fisheries, AFFI staff will sample fish communities using aerial surveys and AFFI protocols in selected streams of the Copper and Bering rivers during late-August, September, or early October. The timing of these late-season sampling events is to maximize encounters of spawning and migrating coho salmon. Location(s) Sampling will be performed in select drainages of the Copper River with base camps enhancing access longitudinally throughout the basin (from downstream to upstream): · Cordova (60.541053, -145.757522) · Glenallen (62.108639, -145.527079) Objectives Objective 1: To maximize the spatial increase of documented anadromous fish habitats depicted in the AWC within the study area (annually sampling a minimum 72 headwater target streams, and 8 un-wadeable target streams) to reach 144 headwater site visits and 16 un-wadeable stream site visits in total across two years (160 sites total). Objective 2: To record characteristics, using established protocols, of aquatic habitats (including riparian zone) at each sampling location. Objective 3: To provide the fish distribution and associated aquatic habitat information to State & Federal agencies, participating communities, and the public. Study area selection The long-term goal of the AFFI program is to complete a statewide baseline inventory of fish assemblages and associated aquatic and riparian habitats. At its inception, the AFFI program developed a systematic approach to rank and prioritize Alaska’s 139 subbasin level hydrologic units. Subbasins were chosen because they most closely match the scale of the project study area of a typical helicopter-supported, regional baseline fish inventory. A survey priority index (SPI) of the subbasins was then developed based on; amount of past survey effort in the subbasin, removing lands considered to have adequate protection from anthropogenic degradation such as National Parks & Preserves, the ratio of current AWC coverage to the total length of all mapped streams within the subbasin, and a Human Activity Index (HAI) created by The Nature Conservancy (Feirer et al. 2006), assessing 4 types of human activities that could impact Alaska ecosystems. At the time of this proposal, the AFFI program has surveyed 91 of the 139 subbasins that were originally prioritized. This prioritization method has been documented by AFFI staff in an unpublished internal document that is available upon request. The Copper River study area drains 67,480 km2, including four subbasins (HUC8 level). The Bering River drains an additional 1,991 km2 of glaciated lands. This proposed study would add 5 subbasins to the total sampled by the AFFI program. Target stream selection This project is guided by the AFFI program’s survey site selection protocol, which uses a Geographic Information System (GIS) to rank potential survey sites across the study area based on upstream catchment area and potential mileage to be added to the AWC. Target stream selection will be initially carried out using the AFFI published method of using GIS to identify previously unsampled (or not rigorously sampled) streams that can be safely accessed and effectively electrofished while maximizing potential additions to the AWC (e.g., Giefer and Cathcart 2019). Based on past AFFI projects, it is estimated that a minimum of 72 headwater and 8 un-wadeable streams could be sampled annually by a two-person field staff during helicopter-assisted efforts in July-August (12 field days) and late August, September, or October (6 field days). However, these estimates of total sites are conservative (e.g., this equates to only 4 headwater sites per day) and contingent upon no weather or logistical problems preventing sampling. Additionally, opportunistic sampling via the road systems will be done as able. The number of headwater streams in the study area will exceed the project’s limited sampling effort capacity; therefore, a subset of mapped streams, comprising the longest stream segments not listed in the AWC will be selected as targets. The headwater team will sample on average four streams per day and, when operating, the raft or riverboat team(s) will float and sample one to two un-wadeable streams per day. Sites will be prioritized according to logistics (i.e., fuel and time needed to reach location) and potential for addition to the AWC. Further, sites within the study area that have the highest potential for habitat degradation will be identified and prioritized after consultation with local land owners (e.g., native communities), the ADF&G Habitat Section and federal land managers and biologists. Sampling methods Fish surveys using methods that can target a broad range of fish species, both anadromous and resident, are useful to identify critical habitat supporting important fish populations. Following ADF&G's AFFI protocols (Giefer and Cathcart 2019), crews will use a helicopter or boat to access streams and sample their fish communities during at least 20 days annually in 2025 and 2026. Target survey sites will include wadeable headwater streams sampled with a backpack electrofisher, and un-wadeable streams (including mainstem rivers) sampled with a raft-mounted electrofisher. At all target streams, a length of stream (referred to as a reach) standardized by stream width (i.e., 40 or 120 wetted-channel-widths in wadeable and un-wadeable target streams, respectively), will be sampled to include all aquatic habitat types within that reach. Collected fish will be identified to species, tallied, fork length measured, and examined for external abnormalities. At selected reaches, the fish community will be sampled with standardized methods and effort, according to AFFI protocols. Fish will typically be collected by single-pass electrofishing. Electrofishing is the principal fish collection gear because it is recognized as the most comprehensive and effective method for collecting fish in lotic systems. Opportunistic sampling with gillnets (especially for subsistence targeted species that have demonstrated catchability with gillnets), angling, minnow trapping and other gears will be performed as needed, such as if conditions prohibit safe or effective electrofishing. Additionally, standard water chemistry, channel morphology, and riparian habitat parameters will be recorded at each sample site. To enhance data quality and completeness and data entry efficiency, all collected data will be entered each day into an integrated database installed on a notebook computer.本项目由太平洋沿岸三文鱼恢复基金（Pacific Coastal Salmon Recovery Fund）下设的阿拉斯加可持续三文鱼基金（Alaska Sustainable Salmon Fund）第56012号项目资助。 项目概要 2023至2024年的夏季与秋季期间，阿拉斯加鱼类与野生动物部（Alaska Department of Fish and Game, ADF&G）游钓鱼类分部下属的阿拉斯加淡水鱼类调查项目（Alaska Freshwater Fish Inventory, AFFI）团队，将对铜河与白令河的选定流域开展溯河洄游鱼类及定居性鱼类分布，以及相关水生与河岸生境的快速系统性调查。本项目聚焦阿拉斯加一处关键区域——毗邻或隶属于兰格尔-圣伊莱亚斯国家公园及保护区（Wrangell-St. Elias National Park & Preserve）与楚加奇国家森林（Chugach National Forest）的区域，该区域的冰川补给型流域内拥有规模可观的游钓、商业、自用及生计渔业。区域内广袤的冰川补给型流域正经历冰川消退，这可能会为洄游与定居鱼类带来更多的溪流生境。AFFI项目团队将识别并调查最有可能补充纳入《阿拉斯加州溯河洄游鱼类产卵、育幼与洄游重要水域目录》（Catalog of Waters Important for the Spawning, Rearing or Migration of Anadromous Fishes, AWC）的溪流；若观测到溯河洄游鱼类，团队将把对应水体提名纳入该目录。 引言 在阿拉斯加，支撑溯河洄游鱼类洄游、产卵与育幼的生境受州级、联邦及地方行政管辖的保护。《阿拉斯加州法》（Alaska Statute, AS）第16.05.871条（即《溯河鱼类法》）是阿拉斯加溯河洄游鱼类淡水生境的核心法定保护依据，要求ADF&G在《溯河洄游重要水域目录与图集》（Anadromous Waters Catalog, AWC）中明确标注本州内对溯河洄游鱼类产卵、育幼或洄游具有重要意义的各类河流、湖泊及溪流或其区段。将溯河洄游鱼类所使用的水体纳入AWC名录至关重要，因为只有列入名录的水体才能免受潜在有害活动的破坏。水体若要纳入AWC名录，需由合格观察者针对该点位开展直接、明确的溯河洄游鱼类观测（Giefer与Blossom，2021a）。 阿拉斯加溯河洄游鱼类生境的保护与管理，依赖于对鱼类物种及生活史阶段分布的精准认知。尽管当前AWC名录已收录20846处重要水体（其中溪流18772条、湖泊2074个），但这些水体及其支流作为溯河洄游鱼类生活史关键生境的已记录覆盖范围仍远未完整。根据现有调查区域推算，AWC收录的水体数量仅占全州范围内溯河洄游鱼类所使用的溪流、河流与湖泊总数的极小一部分。这些生境若未完成调查，将无法受到《阿拉斯加溯河鱼类法》的保护。此外，随着景观响应气候变化与冰川消退，若不对阿拉斯加湾或威廉王子湾沿岸等敏感冰川流域开展针对性采样，AWC名录对三文鱼生境的覆盖范围可能会持续低估（Pitman等，2021）。 掌握阿拉斯加溯河洄游鱼类与定居性鱼类的生境利用位置与时机，对于应对自然或人为干扰、开展渔业管理、减缓开发活动影响以及理解区域生态系统均至关重要。若缺乏此类数据，管理者对物种生境利用的潜在变化（如响应气候变化引发的冰川消退所带来的变化）的应对能力将十分有限。冰川消退对三文鱼及鱼类生境的近期影响预计至少体现在两个主要方面（Ogden，2018；Pitman等，2021）：1）已利用冰川补给河流的三文鱼种群将获得更多的上游栖息空间；2）鱼类群落结构发生转变，此前无鱼栖息的部分溪流可能会迎来因冰川消退而暴露、延长的流域，并被洄游或定居的三文鱼物种占据。但冰川消退的长期影响则更难预测，因为在夏季冰川补给径流不再稳定的情况下，鱼类种群可能会受到水文动态变化的显著影响。此外，当前冰川覆盖溪流内或沿岸的采矿及其他土地开发活动，也可能会利用新暴露的资源。在铜河流域及其他注入阿拉斯加湾的流域内，预计冰川消退将使三文鱼的可栖息水域增加1000公里，溪流生境的增幅超过太平洋西北其他冰川流域（Pitman等，2021）。因此，当前正处于适当时机，可明确铜河与白令河流域内三文鱼分布的变化情况：一方面可在当代时间尺度上将本研究结果与历史采样得到的AWC名录水体覆盖范围进行对比，另一方面可建立当前的生境范围基线，为该区域未来冰川覆盖缩减的相关预测提供参考。本研究获取的相关数据，可将冰川消退纳入监管框架，以保护规模可观的生计、商业、自用及游钓渔业；同时也可提供一项评估指标，用于验证当前及未来关于冰川消退如何影响阿拉斯加三文鱼种群的预测准确性。掌握溯河洄游与定居性鱼类的当代分布，对铜河流域、白令河等冰川区域的当前及未来管理尤为关键。这些流域支撑着大麻哈鱼（chum salmon）、奇努克三文鱼（Chinook salmon）、银大麻哈鱼（coho salmon）、粉三文鱼（pink salmon）与红大麻哈鱼（sockeye salmon）的生计与商业渔业，而气候变化的影响正不断加剧，包括永久冻土或冰川融化引发的溪流水文变化。尽管这片对气候敏感的区域具有重要的文化、生态与经济价值，但铜河流域尚未在景观尺度上开展过溯河洄游鱼类与淡水鱼类的系统性调查，因此当前AWC名录对三文鱼生境的覆盖范围可能存在低估（Bidlack等，2014；Giefer与Blossom，2021a）。 2023年与2024年的7月20日至8月1日期间，AFFI团队将按照AFFI标准规程，对铜河下游的选定支流开展鱼类群落调查。本次调查的目标点位包括：使用背包式电捕鱼器（backpack electrofisher）采样可涉水的小型源头溪流，以及使用筏载式电捕鱼器（raft-mounted electrofisher）采样不可涉水的中等规模溪流。该采样时段可最大化上游区域幼鱼、产卵或洄游的奇努克三文鱼与红大麻哈鱼，以及下游区域产卵或洄游的粉三文鱼与大麻哈鱼的检测概率。随后，根据商业渔业分部提供的洄游时间数据，团队将在8月下旬、9月或10月初，通过航空调查并遵循AFFI规程，对铜河与白令河的选定溪流开展鱼类群落调查。这些季末采样时段的设置，旨在最大化观测产卵与洄游银大麻哈鱼的概率。 调查点位 本次调查将在铜河的选定流域开展，团队将设立营地以提升全流域（从下游到上游）的纵向通行便利性： · Cordova（科尔多瓦，坐标60.541053, -145.757522） · Glenallen（格伦艾伦，坐标62.108639, -145.527079） 调查目标 目标1：在研究区域内，最大化《AWC名录》已记录的溯河洄游鱼类生境的空间覆盖范围（每年至少采样72处源头溪流目标点位与8处不可涉水溪流目标点位），计划在两年内累计完成144处源头溪流点位与16处不可涉水溪流点位的调查，总计160个点位。 目标2：按照既定规程，记录每个调查点位的水生生境（包括河岸带）特征。 目标3：向州级与联邦机构、参与社区及公众提供鱼类分布与相关水生生境的调查数据。 研究区域遴选 AFFI项目的长期目标是完成全州范围内鱼类群落及相关水生与河岸生境的基线调查。项目启动之初，AFFI团队便建立了一套系统性方法，对阿拉斯加139个亚流域级水文单元进行分级与优先级排序。选择亚流域作为研究单元，是因为其尺度与典型直升机支援的区域基线鱼类调查项目的研究区域高度匹配。随后，团队基于以下指标构建了亚流域调查优先级指数（Survey Priority Index, SPI）：亚流域既往调查投入量、剔除已获得充分保护免受人为破坏的区域（如国家公园及保护区）、当前AWC名录覆盖范围与亚流域内所有已测绘溪流总长度的比值，以及由大自然保护协会创建的人类活动指数（Human Activity Index, HAI）——该指数用于评估4类可能影响阿拉斯加生态系统的人类活动（Feirer等，2006）。截至本提案提交时，AFFI团队已完成原优先级排序中的139个亚流域中的91个的调查。该优先级排序方法已由AFFI团队记录在一份未公开的内部文档中，可应要求提供。 铜河研究区域的流域面积达67480平方公里，包含4个HUC8级亚流域。白令河的流域面积另有1991平方公里，均为冰川覆盖区域。本拟开展的调查将为AFFI项目的已采样亚流域总数新增5个。 目标溪流遴选 本项目遵循AFFI项目的调查点位遴选规程，该规程通过地理信息系统（Geographic Information System, GIS），基于上游集水区面积与潜在可新增至AWC名录的溪流长度，对研究区域内的潜在调查点位进行分级。 目标溪流的初步遴选将采用AFFI已发表的方法：通过GIS识别此前未被采样（或未被严格采样）、可安全通行且能有效开展电捕鱼调查的溪流，同时最大化其新增至AWC名录的潜力（例如Giefer与Cathcart，2019）。根据过往AFFI项目的经验，预计在直升机支援下，两名野外工作人员可在7月至8月（12个野外工作日）以及8月下旬、9月或10月（6个野外工作日）期间，每年至少采样72处源头溪流与8处不可涉水溪流。不过，该点位总量估算较为保守（例如仅相当于每天采样4处源头溪流），且需确保无天气或后勤问题阻碍调查。此外，团队还将视情况依托道路系统开展机会性采样。 研究区域内的源头溪流数量远超本项目有限的采样能力，因此将从已测绘溪流中选取未纳入AWC名录的最长河段作为目标点位。源头溪流调查团队平均每天可采样4处溪流，而筏船或内河船调查团队在作业期间，每天可漂流采样1至2处不可涉水溪流。 点位优先级将根据通行便利性（即抵达点位所需的燃料与时间）以及新增纳入AWC名录的潜力进行排序。此外，研究区域内生境退化风险最高的点位，将在与当地土地所有者（如原住民社区）、ADF&G生境分部及联邦土地管理者与生物学家磋商后，予以优先识别与排序。 调查方法 采用可覆盖多种溯河洄游与定居性鱼类的调查方法，有助于识别支撑重要鱼类种群的关键生境。 遵循ADF&G的AFFI规程（Giefer与Cathcart，2019），团队将在2025年与2026年每年至少开展20天的野外调查，通过直升机或船只抵达溪流点位，开展鱼类群落采样。目标调查点位包括：使用背包式电捕鱼器采样可涉水源头溪流，以及使用筏载式电捕鱼器采样不可涉水溪流（包括干流河道）。 在所有目标溪流中，将以溪流宽度为标准划定调查河段（即：可涉水点位采样40倍湿道宽度，不可涉水点位采样120倍湿道宽度），覆盖该河段内的所有水生生境类型。采集的鱼类将被鉴定至物种水平、计数、测量叉长，并检查外部异常情况。 在选定河段，团队将按照AFFI规程，采用标准化方法与采样强度开展鱼类群落调查。鱼类样本通常通过单趟电捕鱼采集。电捕鱼是主要的鱼类采集工具，因为其被公认为河川生态系统中最全面、高效的鱼类采集方法。若条件不允许安全或有效开展电捕鱼，将根据需要采用刺网（尤其针对已证明可通过刺网捕获的生计渔业目标物种）、垂钓、迷你陷阱网及其他工具开展机会性采样。 此外，每个调查点位将记录标准水质参数、河道形态参数与河岸生境参数。为提升数据质量、完整性与录入效率，所有采集的数据将在每日结束时录入安装于笔记本电脑的集成数据库中。