The Kobuk Selawik Estuarine System

Published Date: 02 Nov 2017

A Management Plan for Sheefish in the Kobuk-Selawik Estuarine System

Abstract

Sheefish, a large gray fish from the whitefish family, are crucial to the lives of Alaskan Native peoples. These fish are common in northwest Alaska in the Kobuk-Selawik Estuary (KSE) and spend the majority of their lives within this estuary. With upcoming development and climate change, the need for a management plan is essential to maintain current or increased harvest levels. The management plan will describe the actions required and costs involved. This will be achieved through a series of baseline studies, followed by monitoring programs that track the health of the estuary and its resident sheefish.

Contents

Introduction 1

Background 1

Location 1

Harvest 2

Life History 3

Feeding 3

Migration 3

Spawning 3

Known vs. Unknown 4

Estuary Comparison 5

Management Plan 5

Introduction 5

Baseline 6

Monitoring 7

Final Phase 7

Budget 8

Narrative-Baseline Studies 8

Narrative-Monitoring Studies 9

Conclusion 10

Tables and Figures 11

Literature Cited 17

Introduction

The goal of our research team is to develop a management plan that maintains the Kobuk-Selawik estuary (KSE) ecosystem at a level that ensures sustainable subsistence harvests of sheefish (Stenodus leucichthys). Sheefish, (or inconnu which means ‘unknown’ in Old French), have been a crucial part of the subsistence lifestyle for Native people in Northwest Alaska for over 10,000 years and are a cornerstone of their diet and traditions. Currently, the KSE is healthy and productive, creating the ideal environment for the Kobuk-Selawik sheefish which spend the vast majority of their lifespan in the KSE region. Baseline knowledge of this untouched ecosystem, before the advent of any development and further climate change, is needed for the preservation of the KSE. The key piece to the proposed plan is the recognition that the KSE is a pristine ecosystem and sheefish within the system are an indicator species of the ecosystem’s health.

Background

Location

The KSE system is located just inside the coastal waters of Northwest Alaska [Figure 1]. The KSE region includes Hotham Inlet, Selawik Lake, and the lower reaches of the tributaries draining into them. The Kobuk and Selawik tributaries drain 32,000 and 11,700 km2,respectively. The lake and inlet cover 1,046 and 2,560 km2, respectively. The estuarine habitat

consists of relatively shallow brackish waters with a combination of sandy, silty, and rocky bottoms. A variety of small shrubs and trees coupled with grasses and tundra surround the majority of the inlet and lake. Aquatic vegetation is fairly consistent throughout the area and includes eelgrass, lichens, pondlilly, pondweeds, and sphagnum mosses. The KSE is home to

sheefish, Arctic char and Arctic grayling, burbot, chum, lake trout, northern pike, and whitefish. The estuary and surrounding tundra also support the Western Arctic Caribou Herd.

Harvest

In the northwest region, Native Alaskans rely heavily on the subsistence harvest of sheefish for cultural and economic reasons. For example, every year the average annual subsistence harvest in six communities is over 25,000 fish (J. Savereide, personal communication, November 12, 2012). The subsistence harvest has huge economic importance as a supplement to their diet. In addition, fishing traditions and knowledge are passed down to ensure future generations will be able to utilize this resource. Sheefish are harvested in winter and summer subsistence and sport fisheries. Subsistence fishermen use gill nets, beach seines, and hook and line to capture sheefish during their annual migrations in and out of the KSE. Sport fishermen use hook and line in the summer and winter. The majority of the sheefish harvest occurs in the Kotzebue District, which includes the KSE and the Kobuk and Selawik rivers [Figure 1].

Life History

The life history of sheefish is complex and varies throughout Alaska. The sheefish is a large silver colored fish that belongs to the whitefish subfamily Coregoninae. Mature females are typically larger than male sheefish [Figure 2]. Sheefish in the KSE are considered estuarine anadromous or amphidromous, meaning they spawn in freshwater and overwinter in brackish water (Alt 1987). Unlike salmon, which are semelparous, sheefish are iteroparous, which means they can spawn multiple times. Sheefish throughout Alaska and Russia mature around age seven

and typically spawn in non-consecutive years; however, consecutive year spawning has been documented on several rivers in Alaska including the Kobuk River (Berg 1948, Brown 2000, Taube and Wuttig 1998, Stuby In press, Savereide In prep).

Feeding

Sheefish spend their winters and the majority of their summers in the KSE feeding on juvenile salmon and sheefish, herring, shrimp, and smelt (Alt 1965). Juvenile sheefish feed mainly on insects or plankton, but sheefish in their first year have been observed feeding on other young fish (Alt 1967). Sheefish throughout Alaska typically utilize the same areas every year to feed, which is known as site fidelity (Brown 2000, Stuby In press). Kirilov (1962) noted that some sheefish continue to feed during their upriver spawning ground migration, but Nikolski (1954) and Vork (1948) reported a feeding cessation until after spawning. During recent studies on the Kobuk River, stomachs of spawning sheefish were sampled and juvenile lamprey, pike, and grayling were found (Savereide personal communication).

Spawning

Studies have shown that upriver migrations to their spawning grounds are protracted and span from early June until late August or early September, whereas their downstream migration is rapid and only spans a few weeks [Figure 3, Stuby In press, Brown 2000, Savereide In prep]. The Kobuk River spawning area spans approximately 96 km from an area called Kalla upstream to the Reed River. The Selawik River spawning grounds are smaller and found in two areas within the drainage: a small section on the Tagagawik River and a ten kilometer section between Ekiek and Ingruksukruk Creeks [Figure 4]. Recent spawning abundance estimates range from

25,000 to 40,000 on the Kobuk River and 23,000 to 46,000 on the Selawik River (Taube and Wuttig 1998, Hander et al. 2008).

The Kobuk-Selawik sheefish spawning areas share similar habitat characteristics. Both areas have moderately swift currents that keep the bottom silt-free, which is important because the eggs need interstitial space under the gravel to survive (Alt 1987). Sheefish are broadcast spawners, meaning their eggs are dispersed by females directly into the water column while the trailing males disperse the milt (Alt 1987). Peak spawning occurs at temperatures between 2.6 and 3.2 degrees Celsius in water depths between 1.5 and 1.8 m. Spawning occurs along the cut bank and in the center of the channel, but never over gravel bars or on the inside curve of the river (Alt 1987). Optimum spawning substrate is composed of differently sized coarse gravel (25 to 100 mm) with some sand but no silt present (Alt 1967). This variety of gravel size ensures the fertilized eggs will lodge into the interstitial spaces where they will develop throughout the winter (Alt 1987, Hander et al. 2008). There is no information available on juvenile emergence in Alaska, but Russian studies have documented a 182-day incubation period, which puts emergence around mid-April (Vork 1948).

Known vs. Unknown

There is ample information about adult sheefish in the KSE but there is very little known about juvenile fish. The KSE is a large area that encompasses a variety of habitat types, but summer and winter migration studies have shown the majority of adult sheefish overwinter and feed in the northern portion of Hotham Inlet and Selawik Lake [Figure 5, Smith In prep]. In addition, Alt (1987) has demonstrated that adult sheefish typically enter the lower section of the

tributaries to feed during early summer, but only migrate further upriver if they are going to spawn. Even though these areas are known there have been no habitat studies to determine why they spend the majority of their time in these areas. Like adults, juvenile sheefish spend most of their lives in the KSE (Alt 1987), but in contrast, the habitats utilized while rearing and the seasonal migrations within the KSE are not known. In fact, other than a little information about their diet, the only information we have about juveniles is their entrance timing into the KSE after emergence, which is dictated by high spring flows due to thawing ice and snow.

Estuary Comparison

Southwest England is home to the Tamar complex of estuaries. The Tamar complex contains many species of national importance, similar to the cultural importance of inconnu in the KSE. This region, historically, has been adversely affected by human development, including industrial and sewage discharge, overfishing of shellfish, and building development. Much of this occurred long before significant research and monitoring of this estuarine system was in place and as such, there is no baseline that shows how this system behaves when it is perfectly healthy. This has led to complicated and expensive plans involving habitat enhancement, which even then is only possible on the small scale (Our South West 1999).

Management Plan

Introduction

Based on the previous evidence, a management plan that ensures sustainable subsistence harvest of sheefish by protecting the KSE is needed before effects of development and climate change threaten the subsistence lifestyle that has thrived for thousands of years. There are a

number of ways to develop and maintain a management plan, but in this situation the most appropriate first step is to identify any data gaps or information that are needed to manage the area. Our research team has identified the following gaps: background studies on juvenile sheefish and habitat studies based on adult and juvenile migrations. The methods, logistics, and monies needed to carry out an adult sheefish monitoring program are already known. The combination of the current and new knowledge will be used to institute a monitoring program that will allow our team to make management decisions.

Baseline

The baseline studies will be broken down into two categories: juvenile sheefish assessments and habitat assessments [Table 1]. The juvenile sheefish studies will include: mark- recapture (M-R) experiments to estimate the abundance of juvenile sheefish, and a concurrent genetic study that will allow us to determine abundance estimates by stock (Kobuk and Selawik). Another aspect of juvenile sheefish life history is the migrations they undergo while rearing in the estuary. To determine these patterns, an intensive acoustic tagging program, similar to Smith et al. (In prep), will be conducted, with an array of sonar buoys placed throughout the KSE.

The habitat assessments will concentrate on the areas where juvenile and adult sheefish have been observed during rearing, feeding, and spawning. These studies will examine the physicochemical properties of the water (pH, turbidity, hardness, and flow) as well as the physical characteristics of the area (substrate, vegetation, and presence of species).

Monitoring

Upon completion of the baseline studies, monitoring studies will be conducted at regular intervals to track the ecosystem health of the KSE and subsistence harvest of sheefish [Table 1]. These studies are important as they are the only way to gauge the effects of any development and/or climate change. Monitoring the subsistence harvest is also important to ensure sustainable harvests and ecosystem health. Unmet harvest levels will influence our management team decisions. For this reason, annual subsistence harvest reports for sheefish will be required for all subsistence fishermen in the area. Adult abundance studies will be conducted every three years with sonar technology, which is less invasive and less expensive than an M-R experiment. M-R experiments will be used for juvenile abundance studies every three years, because sonar techniques are ineffective. Adult and juvenile migration studies are the most intensive and expensive projects to conduct, so they will be performed every five years. It is important to continue the migration studies because their habitat use patterns may change over time. These differences will likely be due to a change in the ecosystem, which may be connected to development or climate change. Finally, habitat assessments of the spawning grounds and estuary, which are relatively inexpensive, will be conducted every three years to monitor the health of the ecosystem.

Final Phase

The final phase of our management plan details the actions the team would take to ensure our goal of sustainable sheefish subsistence harvests. Essentially, if the subsistence harvests remain stable or improve, there will be no additional action beyond monitoring the system. If the subsistence harvests are declining and/or fishermen have to expend more effort to harvest, the

analysis of the monitoring program can identify possible reasons for the decline. If the decline is strictly sheefish-related, then targeted fishing restrictions will be used to limit the harvest to ensure a sustainable spawning abundance. If the decline is an outcome of a measurable habitat condition, such as heavy metal discharge or loss of rearing areas, then a combination of actions will be introduced. These could include fishing restrictions, habitat enhancement, and development regulations used to limit harvest, improve the quality of habitat, and ensure sustainable spawning abundance.

Budget

All costs for each particular project are detailed by category over a 15 year timeline [Table 1]. These costs will be borne by numerous stakeholders, including Federal, State, and Non-Governmental agencies such as Fish and Wildlife, Fish and Game, NANA Incorporated.

Narrative - Baseline Studies

Habitat studies for juveniles and adults will be completed with one crew of three people, using a combination of large and small skiffs equipped with pertinent sampling equipment. These studies can be conducted concurrently over a one- to two-year period.

The initial phase of juvenile abundance studies will assess a variety of capture techniques. Then the M-R experiments, using the most appropriate gear, will be carried out on the lower Selawik and Kobuk rivers. From experience, these studies are much more intensive and will involve two crews of three people per river. Crew members will use large and small

skiffs to capture and tag juvenile sheefish during early June. Attempts to recapture these tagged fish will take place in early August.

Juvenile migration studies will replicate Smith et al. (In prep) and attempt to tag juveniles with acoustic tags to track their movements throughout the KSE. The capture and tagging portion of the study can concur with the juvenile abundance project (the same is true for the adult migration studies). In addition, an array of acoustic buoys will be anchored in the water throughout the estuary. These buoys will record the date, time, and depth of tagged fish as they migrate through the ensonified area. These type of studies are less intensive but quite costly because of the acoustic tags and array of sonar buoys.

Narrative - Monitoring Studies

Monitoring studies are broken down into five categories: harvest surveys, spawning abundance, juvenile abundance, migration, and habitat assessments. Once all baseline studies are finished, harvest surveys will be conducted annually to ensure that all subsistence needs are being met. These studies will be completed on different timelines depending on need, cost, and level of difficulty. Abundance studies will be conducted every three years because of their cost and the fact that any alarming decrease in stock size can be easily detected during this timeframe. Migration studies are expensive and the information provided by these does not need to be updated quite so often. Instead, these projects will be conducted every five years unless subsistence needs are not being met. Habitat studies are relatively inexpensive and will be conducted every three years unless a substantial decrease in sheefish harvest is observed.

Conclusion

The sheefish of the KSE region are of monumental cultural and economic importance to the Native Alaskans of the region, necessitating the creation and implementation of a management plan to ensure that, regardless of human development and environmental change, sheefish are there to stay. The management plan begins by addressing the fact that many properties of the KSE and the habits of the sheefish within are, as of yet, unknown. Once these information gaps have been filled the KSE will be better understood under pristine conditions. This will provide a baseline from which to compare the results of subsequent migration, stock, and habitat studies, securing our ability to maintain sustainable subsistence harvest of sheefish

Figure 1.- A map of the Kobuk-Selawik Estuary (shaded) including the Kobuk and Selawik River drainages, Hotham Inlet, Selawik Lake, and surrounding communities.

Figure 2.- A map of the Kobuk and Selawik River drainages demarcating the documented spawning areas (shaded).

18

16 2008

Number of sheefish14

12 Males

10 Females

8

6

4

2

0

675 725 775 825 875 925 975 1025

Length Categories (mm)

25

2009

20

Number of sheefishMales

15

Females

10

5

0

675 725 775 825 875 925 975 1025 1075

Length Categories (mm)

Figure 3.- Length distributions of mature sheefish that were radiotagged in 2008 and 2009.

1.00

0.90

0.80

0.70

Cumulative proportion0.60

0.50

2008

2009

2011

0.40

0.30

0.20

0.10

0.00

30-Aug 9-Sep 19-Sep 29-Sep 9-Oct 19-Oct 29-Oct

Downstream migration date past tracking stations

Figure 4.- Downstream migration timing of radiotagged sheefish near Kobuk village in 2008, 2009, and 2011.

Figure 5.- Monthly distribution maps for Selawik River (top,red) and Kobuk River (bottom, blue) sheefish in the 2010/2011 winter. A larger circle indicates higher monthly usage.

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Table 1.- Management plan budget break down by project type, category, and year.

Project

Personnel

Travel

Contractual

Commodities

Total

Harvest Surveys

10,000

1,500

10,000

8,000

29,500

Habitat Assessments

10,000

5,000

20,000

20,000

55,000

Juvenile Abundance

40,000

18,000

-

50,000

108,000

Juvenile Migration

7,500

3,000

10,000

5,000

25,500

Spawning Abundance

20,000

5,000

-

15,000

40,000

Adult Migration

7,500

3,000

10,000

5,000

75,500

Project Type

Personnel

Travel

Contractual

Commodities

Equipment

Harvest

1 person, 3 months

1 RT ticket, R&B

survey distribution

desktop, laptop

-

Habitat

3 people, 3 weeks

3 RT tickets, R&B

lab analysis

food, gas, gear

4 boats

Juvenile Abundance

6 people, 2 months

12 RT tickets, R&B

-

food, gas, gear

-

Juvenile Migration

1 person, 2 months

2 RT tickets, R&B

aerial surveys

food, gas, gear

sonars, acoustic tags

Spawning Abundance

4 people, 1 month

4 RT tickets, R&B

-

food, gas, gear

-

Adult Migration

1 person, 2 months

2 RT tickets, R&B

aerial surveys

food, gas, gear

acoustic tags

Years

Harvest Surveys

Habitat Assessments

Abundancea

Migrationa

Total

2013-2015

88,500

55,000

148,000

51,000

342,500

2016-2018

88,500

55,000

148,000

51,000

342,500

2019-2021

88,500

55,000

148,000

51,000

342,500

2022-2024

88,500

55,000

148,000

51,000

342,500

2025-2027

88,500

55,000

148,000

51,000

342,500

Project

Equipment

400,000

Total All Years

$ 2,112,500

a Abundance and migration studies include the totals for adult and juveniles combined.

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Literature Cited

Alt, K. T. 1965. Food habits of inconnu in Alaska. Transactions of the American Fisheries Society, 94(3):272-274.

Alt, K. T. 1967. Taxonomy and ecology of the inconnu, Stenodus leucichthys nelma, in Alaska.

M.S. Thesis University of Alaska, Fairbanks.

Alt, K. T. 1987. Review of inconnu Stenodus leucichthys studies in Alaska. Alaska Department of Fish and Game, Federal Aid in Fish Restoration, Fishery Manuscript No. 3, Juneau.

Berg, L. S. 1948. The fish of the fresh waters of the U.S.S.R. and contiguous countries. 3rd Edition. Publication of the All Union Institute of the Lake and River Fisheries. Leningrad. P 191- 195.

Brown, R. J. 2000. Migratory patterns of Yukon River inconnu as determined with otolith microchemistry and radio telemetry. M. S. Thesis, University of Alaska, Fairbanks.

Hander, R. F., R. J. Brown, and T. J. Underwood. 2008. Comparison of inconnu spawning abundance estimates in the Selawik River, 1994, 2004, and 2005, Selawik National Wildlife Refuge. U.S. Fish and Wildlife Service, Alaska Fisheries Technical Report Number 99.

Kirilov, F. N. 1962. Fauna of fish and invertebrates from the basin of the Vilvui River. Isdat.

Akad. Nauk. USSR. Moskva. 163 p.

Nikol’skii, G. V. 1954. Chastnaya ikhtiologiya (Special Ichthyology) Gosudarslvennoe Izdatel. "Sovetskaya nauka" Moskva 538 pp. Translated be Israel Program for Scientific Translations, Jerusalem, 1961).

Our South West Millennium Archive. OurSouthwest, n.d. Web. 30 Nov. 2012.

<http://www.oursouthwest.com/Wild_Hab/Coast%20and%20Marine/Estuaries/estuaries.htm>.

Savereide, J. W. In prep. Spawning location, run timing, and spawning frequency of Kobuk River sheefish. Alaska Department of Fish and Game, Fishery Data Series, Anchorage.

Smith, N. J., T. M. Sutton, C. E. Zimmerman, R. F. Hander, A. Whiting, and C. Moran. In prep. Winter movement patterns and habitat use of Kotzebue region inconnu. M.S. Thesis University of Alaska, Fairbanks.

Stuby, J. W. In press. Spawning locations, seasonal distribution, and migratory timing of Kuskokwim River sheefish using radiotelemetry, 2007-2011. Alaska Department of Fish and Game, Fishery Data Series, Anchorage.

Taube, T. T. and K. G. Wuttig. 1998. Abundance and composition of sheefish in the Kobuk River, 1997. Alaska Department of Fish and Game, Fishery Manuscript Number 98-3, Anchorage.

Vork, F. I. 1948. The Yenisei Stenodus leucichthys nelma. Transactions Siberia Otd. V. Sesoyuznogo Nauchno-usledovatel’skogo Inst. Ozernogo I Rechnogo Ryb. Khoz., T. 7, No. 2.