DOI: 10.5281/zenodo.13994276
title: Anadromous Waters Cataloging and Fish Inventories in Subbasins of the Koyukuk and Kobuk Rivers - 2022

description:  Synopsis

During the summers and falls of 2022 and 2023, 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 fish distribution and associated aquatic and riparian habitat in select drainages of the Kanuti River and upper Kobuk River. AFFI program staff will identify and select target streams most likely to fill gaps in coverage of the State of Alaska's Catalog of Waters Important for the Spawning, Rearing or Migration of Anadromous Fishes (AWC); for each water body in which anadromous fish are observed, nominations to the AWC will be submitted.

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 a 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. The resulting product is known as the Anadromous Waters Catalog (AWC) and Atlas which are adopted as regulation under 5 AAC 95.011. Under the Anadromous Fish Act, activities and uses conducted in or otherwise affecting water bodies specified in the AWC require a permit from the ADF&G Habitat Section.

Many other federal, state, and local government policies specify additional protections for anadromous fish habitat in Alaska. Like the ADF&G Habitat Section, these agencies apply protections only to those water bodies where anadromous fish use is explicitly documented, typically by reference to the AWC. It is important that water bodies used by anadromous fish are listed in the AWC because only listed water bodies are afforded protection. To be listed in the AWC, water bodies must have site-specific, drect, unambiguous observations of anadromous fish by a qualified observer. 

 The various anadromous fish habitat management tools in Alaska are predicated on explicit knowledge of the distribution of individual anadromous fish species and life stages. However, Alaska has over 3,000 streams totaling over a half a million kilometers (km) in length, > three million lakes, and > 10,000 km of coastline. These represent critical habitats for many fish species and the communities that depend upon them. But in the vastness of Alaska, only a fraction of extant anadromous fish freshwater habitats has been documented. The AWC currently lists nearly 20,000 streams, rivers, or lakes around the state, which have been specified as being important for the spawning, rearing, or migration of anadromous fish. Based on current areas surveyed, this number likely represents a small proportion of the streams, rivers, and lakes used by anadromous species. Until these habitats are inventoried, they will not be protected under Alaska’s Anadromous Fish Act.

 The long-term goal of the AFFI program is to complete a statewide baseline inventory of fish assemblages and associated aquatic and riparian habitats. Knowing foundational aspects of biology, such as where and when anadromous fishes (and resident species) use habitats in Alaska, is crucial to respond to natural disturbances, manage fisheries, mitigate (or approve, deny, or plan) development, and understand regional ecology. However, due to the remoteness and multitudes of Alaska’s waterbodies, much remains to be learned about basic information of fishes in the state. This foundational knowledge is especially critical to areas such as western and interior Alaska (e.g., waters draining the Brooks Range), where subsistence and commercial fisheries for chum, Chinook, and sockeye salmon (and anadromous whitefishes and Dolly Varden) exist among ongoing and planned development (e.g., mining, road building) in addition to intensifying effects of climate change (permafrost thawing, hydrological changes). The proposed Ambler Road, a 340-km long road to assist mining development, would connect the Dalton Highway to the mining district north of the community of Kobuk by crossing several tributaries of the Koyukuk and Kobuk rivers. 

 The Koyukuk and Kobuk rivers are both critical watersheds to local communities for subsistence harvests in addition to supporting regional communities through commercial fisheries in Kotzebue Sound or the Yukon River drainage. Summer chum salmon are the biggest contributor to Koyukuk River basin harvests, with the Koyukuk River being the largest single contributor to the summer chum salmon run in the Yukon River drainage. Chum salmon are the largest contributor to commercial and subsistence harvests in Kotzebue Sound and the Kobuk River. However, all species of Pacific salmon are harvested to some degree by these areas’ commercial and subsistence fisheries. 

The various communities, resources, fisheries, and land uses allow for multiple stewardship roles in this region, including those performed by native communities, native corporations, private enterprises, the National Park Service (NPS), the Bureau of Land Management (BLM), and the U.S. Fish & Wildlife Service (USFWS). Accordingly, accurately depicting the distributions and timing of fish species in the AWC can simultaneously inform responsible decisions and support the needs (or goals) of stakeholders across a landscape. However, despite cultural, ecological, and economic interest in this region, the upper Kobuk and Koyukuk rivers (and Ambler Road corridor) had not been investigated for anadromous and freshwater fishes at a landscape level prior to 2018.

Prior to 2018, there was minimal data available on fish species assemblage and habitat use, generally limited to a few main waterbodies across the region. In 2017, an NPS wildlife biologist alerted ADF&G staff in the AWC and AFFI programs that GPS-collared grizzly bears had been observed eating salmon in streams that were not currently documented in the AWC. This represents a significant ecological link between marine and inland Alaska ecosystems, and presented an opportunity for AFFI biologists to use this knowledge to inform and plan a landscape-scale AFFI investigation which began in the summer of 2018.  

When ADF&G habitat biologists surveyed the upper Kobuk and Koyukuk river systems in 2018 and 2019, they found numerous previously unlisted waters that support anadromous and resident fishes. These efforts added 972 km of stream to the AWC among 68 different waterbodies, notably for (in order of highest to lowest contribution of added AWC length): chum salmon, Chinook salmon, sockeye salmon, pink salmon, and Dolly Varden. However, these efforts were plagued by several days of work lost to mechanical issues with helicopters, leaving large areas and potentially important fish habitat unexplored and undocumented. Accordingly, ADF&G staff will return through this project to fill in remaining knowledge gaps of this region. 

 From July 25-August 2, 2022, one 2-person crew (plus helicopter pilot) will sample fish communities using AFFI protocols in selected tributaries of the Kanuti River watershed and middle Koyukuk 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 salmon as well as spawning or migrating summer chum salmon. Then, from August 25-September 2, 2022, one 2-person crew (plus helicopter pilot) will sample fish communities using AFFI protocols in selected streams of the Kobuk River basin. This timing is to maximize encounters of spawning and migrating chum salmon but could also include coho salmon. In 2023, crews based in Kiana and the Kobuk River sampled fishes from August 20-September 1.

3.      Locations: 

Sampling will be performed in select drainages of the Koyukuk and Kobuk rivers with a base camp in Bettles, AK (66.91938, -151.52536) for the Koyukuk River basin field season and a base camp in Kobuk (66.90218, -156.87492) for the Kobuk River basin field season. The approximate region would include an area bounded to the west by the community of Kiana (66.96914, -160.44455) and to the east by the Dalton Highway (67.15459, -150.35730), e.g., 66.864255, -156.87492 (e.g., Pick River: 66.618510, -156.724571 ).

 Objectives

·         I    Increase documented anadromous fish habitats in the AWC within the study area. Record aquatic habitat characteristics (including riparian zone) at each sampling          location.

II.                Methods

Study area selection

The 131,785 square kilometer study area includes subbasins of the Koyukuk and Kobuk rivers. This includes target streams that were not sampled due to logistical constraints in 2018 (e.g., helicopter mechanical troubles leading to multiple lost days of work). Specifically, areas that were not explored include the Kanuti River in the Koyukuk River basin as well as tributaries of the Kobuk River near Walker Lake and the Pick River. This study area is critical to management and potential mitigation of the proposed Ambler Road.

 Target stream selection

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. Based on past AFFI projects, it is estimated that a minimum of 72 headwater and 4 un-wadeable streams could be sampled during efforts in July-August (9 field days) and August-September (9 field days). However, these estimates are contingent upon no weather or logistical problems preventing sampling. 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 four to six headwater streams per day and, when operating, the raft or riverboat team will float and sample one un-wadeable stream per day, including a reach from all mainstem rivers in the study area.

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 the ADF&G Habitat Section and federal land managers and biologists.

Sampling methods

Following ADF&G's AFFI protocols (Giefer and Cathcart 2019), crews will typically use a helicopter to access streams and sample their fish communities during at least 18 days in 2022 and at least 5 days in 2023. 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. Onset Hobo temperature data loggers may be deployed at the beginning of the sampling effort in pre-selected reference streams in the study area to document the full range of water temperatures during the field season. 

III.             Benefits

Updated and more comprehensive AWC coverage will be the primary benefit of this project toward sustaining salmon habitat. Only anadromous fish habitat listed in the AWC receives protection under the Anadromous Fish Act and various other policies that provide additional protections to specified anadromous fish habitat. Providing more complete and accessible fish community and habitat information will help ADF&G and other federal, state, and local resource agencies better implement their respective fish habitat management, protection, and research missions. Together, better protection and management of salmon habitat will benefit subsistence salmon fisheries and the communities they sustain by safeguarding critical salmon habitat, thereby ensuring the long-term productivity of habitats and salmon populations. Enhanced communication and partnerships with tribal communities will be established through community outreach prior to and after the field work.