Habitat Restoration |
Introduction
The Alaska National Interest Lands Conservation Act (ANILCA) of 1980 directs
that fish populations and their habitats be maintained in their natural
abundance and diversity within the 16 national wildlife refuges in Alaska.
This branch works closely with in season federal subsistence fishery managers
and the nine refuges in the region to satisfy these mandates by conducting
a variety of assessment and monitoring projects that provide information
critical to management of northern Alaska fish and their habitats.
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A biologist uses a seine and dip net to collect spawning whitefish.
Photo Credit: USFWS |
Salmon Enumeration Weir Projects
The salmon stocks in the Chandalar River are an important resource of the Yukon Flats National Wildlife Refuge, and support subsistence and commercial fisheries in the Yukon
River drainage. The fall chum salmon population in the Chandalar is recognized as the largest stock of fall chum salmon in the Yukon River drainage. For more Information (pdf)
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“A DIDSON image showing fish passing through at 4 to 7 meters. Photo Credit: USFWS |
Chandalar Sonar Project
The Fairbanks Fish & Wildlife Field Office uses resistance board weirs in several important drainages to gather accurate information about spawning salmon stocks. Weirs allow biologists to determine the escapement and run timing of salmon stocks, as well as determining their sex and size composition. For more Information (pdf) |
Resistance board weirs like this one are an important tool to determine salmon run timing and total numbers of spawning fish.
Photo Credit: USFWS |
Yukon River Video Project
Fish wheels are commonly used as a capture method to determine relative
abundance and run timing of Yukon River salmon. These “test wheel” catch rates are used by fishery managers to assess the in-season salmon runs on a daily basis. The wheels use live boxes to store fish until they are counted by dip netting. Recent studies on Yukon River fall chum salmon suggest that holding time and crowding in live boxes may affect the ability of fish to travel upstream to spawning streams. This is of particular concern during years of low salmon abundance.For more Information (pdf)
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This video system continuously records fish passing through the fishwheel and captures the information on a laptop for later analysis.
Photo Credit: USFWS |
Video systems attached to fish wheels obtain chinook and chum
salmon passage rates and timing without the need to handle or
hold fish. These systems reduce operational costs and provide
a permanent visual record of all fish captured.
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Sophisticated computer programs and video equipment are now used in some places to count fish migrating up the Yukon River. Photo Credit: USFWS |
Several projects also provide information about species other
than salmon (like this longnose sucker). Projects are located in
freshwater and nearshore environments throughout the nine refuges.
These projects generally provide the first information available
about a species and provide a baseline for future comparison.
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The long-nosed sucker can be identified by it's mottled brownish back, lighter belly, and round mouth with fleshy lips on the under side of the head. Long-nosed suckers mostly eat insects and algae found on the bottom of lakes and streams. Photo Credit: USFWS |
The wire exiting the belly of this broad whitefish is the antenna
from a surgically implanted radio transmitter. Radio telemetry is
one example of research methods that yield new information about
species that will be used for more effective management of the population
and its habitats. These techniques and the interpretation of the
data they provide, allow fish in northern Alaska to be managed for
the future enjoyment of all.
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This broad whitefish carries a surgically implanted transmitter to track its movements. The wire antenna can be seen below its belly. Photo Credit: USFWS |
Permafrost Thaw Impacts to Sheefish Spawning Habitat in the Selawik River -
One of the biggest concerns of climate change is the increased rate of thawing permafrost and the changes it causes to the hydrological regimes and habitat conditions of river systems. Studies are underway to learn the effects of a large retrogressive thaw slump that occurred in the spring of 2004 in the upper Selawik River drainage on sheefish, which supports the primary subsistence fishery in the village of Selawik.
For more information (pdf)
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A retrogressive thaw slump that occurred in 2004 continues to expand from its initial estimated size of 350 m. diameter and 50m. deep.. Photo Credit: USFWS |
Kaktovik Project -
Information to evaluate the stock status and trends of Arctic cisco and Dolly Varden in lagoons adjacent to the village of Kaktovik in Arctic Refuge was collected during 2003-2005. Objectives of the study were to measure relative abundance, determine length and weight characteristics, and compare current data with baseline data from 1988-1991. Fyke nets were set at four stations in Kaktovik and Jago lagoons. Approximately 1,500 Arctic cisco and 1,000 Dolly Varden were captured and released. Numbers of incidental species ranged from 600 Arctic cod, 200 saffron cod, 200 fourhorn sculpin, and smaller numbers of Arctic sculpin, threespine stickleback, and least cisco. Lengths and weights were measured for Arctic cisco and Dolly Varden to compare to historic values. A final report will completed in 2006.
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Dolly Varden can be identified by the red spots on their sides. They inhabit coastal lagoons on Alaska's North Slope. Photo Credit: USFWS
Biologists on Alaska's North Slope set traps in coastal lagoons to study Dolly Varden and Arctic cisco. Photo Credit: USFWS
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Feasibility of enumerating Dolly Varden Using Dual Frequency IDentification SONar (DIDSON)
Dolly Varden char Salvelinus malma, an important subsistence resource on the North Slope of Alaska, are currently monitored by aerial survey of various rivers. A more accurate method of estimating abundance of stocks is important to sustain the Dolly Varden fisheries. A dual frequency identification sonar (DIDSON) has been proposed as a method to improve stock estimates. This study aims to evaluate the feasibility and usefulness of using a DIDSON to estimate Dolly Varden stock abundance in the Hulahula River near Kaktovik, Alaska.
The Hulahula River was chosen as the site for this work because it lies within the Arctic National Wildlife Refuge (ANWR), is used for subsistence fishing by Kaktovik residents, is relatively easy to access, and appears to contain suitable locations for sonar operations below Dolly Varden char spawning areas.
The DIDSON sonar is a relatively recent technology that is becoming widely used within Alaska for fish enumeration which may, for the first time, allow accurate abundance estimation of Dolly Varden in North Slope Rivers. The DIDSON creates an image from sound waves that are reflected off of objects in the water. Fish targets are then counted from these images. This technique has been tested on Chinook and sockeye salmon throughout Alaska, as well as with chum salmon on the Chandalar River in the Yukon Flats Refuge. An appropriate site to use DIDSON on the Hulahula River was identified in 2004. Operations in 2005 began on July 7 and continued until September 19. During the 2005 season the crew counted more than 11,000 fish moving upstream. Several fish that were in the DIDSON beam close to shore were captured by hook and line and identified as Dolly Varden. The sonar count will be repeated in 2006 and a final report will be completed in 2007.
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DIDSON sonar on river-bank
and installed in Hulahula River. Photo Credit: USFWS
DIDSON sonar animation showing fish passing upriver. Blobs in background are rocks. Photo Credit: USFWS
A biologist holds a Dolly Varden in spawning colors. Photo Credit: USFWS
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Sheefish Studies in the Nowitna River
The U.S. Fish and Wildlife Service is collaborating with other agencies on a radio telemetry project to learn more about sheefish in the Nowitna River drainage. The study will document the sheefish spawning frequency, identify the geographic bounds of the spawning area in the Sulukna River, and search for other possible spawning areas in the Nowitna River drainage.
To related projects supported by the Service, BLM and University of Alaska Fairbanks (UAF) are describing the habitat features of the Sulukna River spawning habitat, and estimating the abundance of the spawning population by using sonar to count the post-spawning out-migration of sheefish from the Sulukna River.
For more information. (pdf)
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A sheefish with implanted radio tag is ready for release. Photo Credit: ADF&G |
Aquabase
A user-friendly, map-based reference system, AQUABASE, is being developed to compile the plethora of aquatic literature on the north slope of the Arctic National Wildlife Refuge in a useful, concise form so land managers, biologists, and project planners can access all the pertinent data relating to their individual needs.
For more information (pdf)
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Aquabase GIS-based map display. Yellow colored water bodies have biological and hydrological linked data, blue colored waterbodies have not had previous data collected. |
