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Data Types Much data are collected during the course of managing salmon
fisheries or operating stock assessment and research in AYK. We have attempted
to categorize related data into “types” allowing them to reside in separate
databases which can accommodate their different data structure (Table 1). Not
all data “types” have been added to our DBMS. Currently we include ASL, CPUE,
Escapement Counts, and Survey Counts as data types. This is in contrast to data
relating to radio telemetry locations of salmon (Tag/Mark data), environmental
measurements (temperature, water depth, velocity, etc.) or juvenile salmon data
which could be added at a later time. We have also not been able to link to
other databases in which reside commercial and subsistence harvest data (Harvest
Age, sex, and length data are collected annually from sampled
commercial and subsistence harvests, escapement, run timing and abundance
monitoring projects in the AYK Region. Scales are collected primarily to
determine the age of fish, but may also be examined for growth patterns.
ASL data have been collected in the Yukon Area since 1960, in the Kuskokwim Area
since 1961, in the Norton Sound-Port Clarence Area and Kotzebue Areas since
1962. All salmon species have been sampled but the emphasis has been on chum and
Chinook salmon. Scales collected from salmon are stored on gum cards along with
an acetate impression used to determine age. Both are organized into files by
year, species, and project and stored in cabinets located in the Anchorage ADF&G
This data type consists of biological measurements of individual salmon
sampled from fishery harvests, stock assessment, or research projects.
Biological measurements consist of length in mm generally mid-eye to fork of
tail, age in European notation as judged from a scale or bony structure, and sex
of the fish determined from external characteristics or internal inspection of
sex organs. The location of capture for the sampled salmon consists of the
general location of the harvest area or more specific location code for the
project (weir, tower, test fishery, etc.). Capture gear type may also be
included in the data record and should correspond to the method type filter on
the web site.
Data are generally collected as a sample from a larger population
with the intent that the sample’s age, length, or sex composition will be
representative of the larger population. Examples are the age composition of a
harvest from an area, time, and gear combination or the estimation of the age
composition of a run of salmon to a specific river.
ASL sampling methods follow
standard procedures throughout AYK which were documented by Kohler (2003) for
the Kotzebue and Norton Sound-Port Clarence areas, by DuBois and Molyneaux
(2000) for the Kuskokwim Area and ADF&G (2004) for the Yukon Area. Three scales
were removed from the preferred area of each Chinook, sockeye, and coho salmon,
and from one to three scales from chum salmon. Scales were then mounted on gum
cards (INPFC 1963). Length was generally measured to the nearest millimeter from
mid-eye to the fork-of-the-tail using a meter stick or tape. The type of length
measurement is noted in the database and very old data may represent total
length. Sex is determined by visually examining external morphological
characteristics such as development of the kype, roundness of the belly, the
presence or absence of an ovipositor, and overall size or by internal inspection
of sex organs. Data are recorded on computer mark-sense forms, field notebooks
or logged electronically on a computerized fish measuring board or hand held
data logger. Data from the 1960s and early 1970s were recorded on tally sheets.
The original scale cards, acetates and data forms are archived at the ADF&G
office in Anchorage.
Age is determined from the annuli of scales taken from the
preferred area of the fish (INPFC 1963). The scales, which are mounted on gum
cards, are impressed in cellulose acetate using methods described by Clutter and
Whitesel (1956). The scale impressions are magnified with a microfiche reader
and age is determined through visual identification of annuli. Ages are directly
entered into the computer ASCII files using European notation.
The Catch per unit effort (CPUE) data type consists of catches of
salmon collected with standardized gear and fishing procedures by ADF&G
employees or other cooperating groups. Explicit location, time of day (if less
than continuous) and gear dimensions used to capture salmon are also collected.
CPUE are calculated from these data.
Test fisheries generally collect CPUE data
to monitor salmon migrations and relative abundance. CPUE data are also
collected as a secondary objective by other project types. For example CPUE data
are collected as the result of fishing to collect salmon to tag
(Capture/Recapture projects) or to estimate the species composition of sonar
counts. Fish wheels, set gillnets and drift gillnets have been used in AYK. CPUE
has been expressed for drift gillnets as number of salmon per 100 fathom hours
fished. CPUE for set gillnets has been expressed as catch per day.
Only CPUE data from Norton Sound and Kotzebue test fisheries currently reside in the AYKDBMS.
These data represent test fish projects operated in the mouth of
the Unalakleet River of Norton Sound since 1981 and the lower Kobuk River in the
Kotzebue area since 1993. Other AYK CPUE data will be included, as time allows.
Fishing location descriptions, methods, and estimation of daily CPUE have been
documented for the Unalakleet River by Kohler (2002) and for the Kobuk River by
Menard and Kent (2007).
The escapement count data type consists of daily counts or daily estimates of salmon in the AYK Region. Salmon
are counted by observers stationed along freshwater migration corridors. Salmon
were 1) counted as they were allowed to pass upriver through weirs, 2) counted
as they migrated upriver past observers in elevated locations (towers) and, 3)
counted by sonar equipment placed in river.
Tower and sonar counts generally
represent a sample and are expanded to represent a 24 h period. A number of
projects have collected counts since 1965 and represent total spawning
populations in major spawning rivers or their tributaries draining into Kotzebue
Sound, Norton Sound, Port Clarence, Bering Sea or the Yukon and Kuskokwim
Rivers. Location, daily count (or estimate), date collected, and count type
(observed or estimated) are included in a data record. Data are collected to
estimate or document total spawning abundance; and estimate and document daily
and seasonal timing of salmon migrating into the rivers of the AYK Region. We
have attempted to include all project data collected in AYK by federal agencies,
non-governmental organizations, and data sent to us by CDFO. New project data
will be added as we become aware of them.
Escapement count data collected by ADF&G are well documented in department publications. Counting location
descriptions, methods and estimation of daily totals have been documented for
each counting location and counting method (tower, weir, or sonar) following
routine procedures used by ADF&G. For examples in the Kotzebue area see
Dinnocenzo (1982) or LaFlamme (1995). Reports are published annually for
Kuskokwim area projects (Costello et al. 2006; Linderman 2005a, 2005b; Shelden
et al. (2006). Specific ADF&G reports can also be found at:
The harvest data type consists of catch and effort data collected
from commercial, subsistence, or personal use fisheries in AYK. Currently this
type of data is not in or can be viewed by the AYKDBMS.
Generally, a sales receipt (“fish ticket”) is issued each time salmon are sold by fishers
participating in Alaska’s commercial fisheries. Data recorded on the fish ticket
include fishers permit number, boat identifier if required, catch by species
recorded in numbers and pounds, area caught, date caught, etc. Electronic
records of these fish tickets from 1969 to the present are archived by the
Division of Commercial Fisheries, Computer Services Section, in the ADF&G office
in Juneau. Catch by individual fishers of catch purchased by individual
processors are confidential. Detailed information on subsistence harvests by
salmon species, number of households, dogs in each household, and other
information is collected and maintained by the Division of Subsistence of ADF&G
for the Kuskokwim, Norton Sound-Port Clarence, and Kotzebue areas; by ADF&G
Division of Commercial Fisheries for the Alaska portion of the Yukon drainage,
and by CDFO for the Canadian portion of the Yukon drainage. Annual harvests by
Alaskan community are included in a statewide database maintained by the
Division of Subsistence. Personal use fisheries only occur in the Yukon River
and are monitored by ADF&G. Personal use fishers must obtain and return permits
upon which they record harvest data. Commercial, subsistence, personal use, and
sport harvest data are well documented in department publications. The Divisions
of Commercial Fisheries and Sport Fish publish Annual Management Report by
fishery and area. Copies for AYK can be found at:
Survey counts The survey count data type consists of counts of migrating, pre-, or post- spawning
salmon in the AYK Region. Counts of salmon were made by observers conducting
surveys using aircraft, boats, or while walking in or along waterways. Surveys
were conducted by ADF&G, US federal agencies, non-governmental organizations,
and by CDFO in Canada.
The accuracy of survey count data can be highly variable
and is dependent upon a number of factors such as weather and water conditions,
timing of survey, altitude, experience of pilot and observer, streambed
coloration, and species of salmon enumerated. Surveyors evaluate and record
environmental conditions affecting survey quality, rate a survey as poor, fair,
or good, and include notes helpful in data interpretation. Counts, survey
location, date collected, observer, agency, environmental conditions, and
comments are included as fields in a database record of this data type.
Aerial or ground survey counts of salmon do not necessarily represent total abundance
at that location for at least two important reasons. First an observer is rarely
able to see all salmon present and the percent observed can vary by observer and
weather conditions. Secondly, not all salmon that will migrate into the survey
location are present on the day a survey is flown. Some may have arrived much
earlier, spawned and their carcasses washed out and some have yet to arrive.
Thus the counts are only an index of abundance.
Surveys are generally timed to coincide with peak salmon spawning activity but may be conducted earlier to
assess the build up of salmon in a river for fishery management purposes. You
should also note that all salmon may be counted but the timing of the survey was
chosen to coincide with peak spawning of only one species. Aerial survey methods
in AYK followed routine procedures outlined by ADF&G protocols (Barton 1984).
Barton (1987) details aerial survey methods and locations for the Yukon River
and documents the codes developed to describe survey conditions. Similar methods
and codes for the Kuskokwim Area were published by Burkey and Salomone (1999).
Methods and codes used by Burkey and Salomone (1999) and Barton (1987) are
applicable to the Kotzebue and Norton Sound – Port Clarence areas. Surveys flown
in Canada were conducted by ADF&G staff through 1987 and follow Barton (1987).
CDFO surveyors were asked to complete ADF&G data forms with the goal of
maintaining consistent data for the Yukon River. General references for aerial
salmon surveys include Cousins et al. (1982) and Bevan (1961).
The tag/mark data type consists of data relating to the release and recapture of
tagged or marked salmon. Data consists of tag number, location and date of
release, location and date of recovery, fish condition, and other project
specific datum. These data are not currently in the AYKDBMS. If
interested in these data contact project administrators. Tag/Mark data are well
documented in department publications. Copies for AYK can be found at:
The Mark, Tag, and Age Laboratory of the Division of Commercial Fisheries provides
detailed information about thermal marks induced in fish otoliths and maintains
a centralized State salmon DBMS for tracking salmon using microscopic tags
(coded wire tags among others). Coded wire tags have been placed in chum salmon
and Chinook salmon released into the Yukon River. The website for the tag/mark and age laboratory
Understanding our definition of a “project” and our attempt to assign each one to a Project Type is key to
navigating the AYKDBMS web site. Wiktionary defines “project” as a
planned endeavor, usually with a specific goal and accomplished in several steps
or stages. In AYK all salmon data were collected through “projects” following
planned data collection protocols to meet specific objectives for a defined
location or area. Furthermore projects can be categorized into types that share
common objectives and collect similar “data types”(Table 1). For example,
beginning in 1993 a project was operated on the Nome River which drains into
Norton Sound (Management Area). Its objective was to estimate the number of
salmon that enter the river to spawn and characterize their age, sex, and size
composition (project type: Escapement Monitoring). Salmon were counted as they
passed by a tower (data type: Escapement Counts and method type: Tower) from
1993 to 1995 and a weir thereafter (method type: Weir). Salmon were captured at
the site and biological measurements and scales were collected to estimate age,
sex, and size (data type: ASL). The objective to monitor escapement (total
abundance estimation or an index) is common to all projects of the type
“Escapement Monitoring”. A user could find this project by filtering on at least
one of its attributes: Norton Sound Management Area, Escapement Monitoring
project type, Tower or Weir method type and ASL or Escapement Count data types.
Once the project page is reached the user has the option of highlighting one or
more years of interest by data type collected at the project for viewing or
retrieval. They can also read background information prepared for the project
overall and year specific notes. We have developed descriptions for all
projects, which can be modified and maintained by project administrators.
Because of the large number of projects some generic descriptions were
developed. Escapement monitoring projects with data type of survey counts number
in the 100s and a generic description was developed. Similarly for ASL sampling
in general, we developed four generic descriptions one each for (1) escapement-
ancillary or spawning ground sampling projects (2) harvest-commercial, (3)
harvest-sport, and (4) harvest-subsistence. Project administrators have the
option of customizing project descriptions and year notes in the future.
Projects have been operated in AYK in which tags or marks are
placed on or in salmon to monitor migration pathways, spawning destinations,
travel time, or are used in mark–recapture experiments to estimate abundance
(Hamner et al. 2002). Project data either resides in spreadsheets or published
reports. Data from a radio telemetry project for Chinook salmon in the Yukon
River and spaghetti tagging projects for chum, sockeye, and coho salmon in the
Kuskokwim River and chum salmon on the Tanana River reside in project-specific
Access databases and Excel spreadsheets maintained by ADF&G CF staff. Brannian
et al. (2004) indicated that funds have not been secured to add tag and mark or
CPUE data from these projects to the AYKDBMS. They also recognized these
data as a future DBMS component. If ASL data were collected from these projects
it is in the DBMS. Metadata for tagging projects (spaghetti or radio telemetry)
conducted by ADF&G, federal agencies and NGOs are also included in the AYKDBMS.
The Mark, Tag, and Age Laboratory of the Division of Commercial
Fisheries provides detailed information about thermal marks induced in fish
otoliths and maintains a centralized State salmon DBMS for tracking salmon using
microscopic tags (coded wire tags, among others). Coded wire tags have been
placed in chum salmon and Chinook salmon released into the Yukon River. A web
site provides access to fisheries data in these databases through online
reports. The AYKDBMS direct users interested in these data to
http://mtalab.adfg.alaska.gov/. ADF&G oversees and regulates all salmon rehabilitation and enhancement projects conducted by the department or others. The permitting process for such projects requires the collection of data and approval by geneticists, pathologists, and biologists. Permit and production data are maintained by staff in the Division of Commercial Fisheries located at the headquarters office in Juneau . Few enhancement projects have occurred in AYK. Data from these projects are not stored in the AYKDBMS. Project description information such as name, location, years of operation, and other pertinent data can be viewed.
AYK projects which collect environmental data that supports our
understanding of salmon biology will be associated with this project type.
Examples would be projects with the sole objective of collecting climatological
or water chemistry data as it effects salmon production. Weather and water
condition data are collected at many of our escapement monitoring projects but
as a secondary objective. At this time environmental data (temperature, flow,
water chemistry, etc.) are not stored in the AYKDBMS.
ADF&G staff and others with collection
permits have routinely traveled to rivers throughout AYK with the sole objective
of collecting ASL data from spawning salmon. For other collectors ASL data may
have been a secondary objective. For many older datasets all we know now is that
these ASL data exist, collected from these locations, using these method types.
Samplers have captured salmon with beach seines, electrofishing gear, gillnets,
gigs, hook and line, or merely hand picked spawned salmon and carcasses from
sandbars and stream bottoms (all method types). For purposes of data storage and
retrieval each location sampled has become a project of type
“Escapement-Ancillary or spawning ground sampling”. These samples have been
collected in freshwater and are not clearly linked to another project for us to
associate these data with that project in the DBMS. For example; while Goodnews
River (Middle Fork) escapement monitoring project was operated as a tower
(1981-1990) it was difficult to capture Chinook salmon to sample for ASL at the
tower site. Instead staff would move upriver from the tower site to beach seine
or sometimes move high up in the headwaters to sample spawned salmon and
carcasses while floating downriver. As a result samplers coded these data to
different ASL project types (see labeled field in ASL data) which resulted in
different projects in the ASL salmon DBMS. It will be up to the project
administrator to associate these data in the future.
Escapement monitoring is a category of projects whose primary object is to
estimate or index salmon escapement. Furthermore, these escapement assessments
are often meant to represent the spawning population. Escapement monitoring
projects operate throughout AYK using a variety of method types and collecting a
variety of data types. Escapement monitoring projects either collect Escapement
Count data or Survey Count data. Escapement monitoring projects that collect
count data often also collect ASL data. Some escapement monitoring projects
really only monitor passage as fisheries are known to occur upriver. Examples of
these are main stem sonar projects on the Yukon River at Pilot Station and near
the Canadian border. Escapement monitoring projects that collect Survey Count
data represent surveys that are conducted of a river or lake to gather counts of
migrating, pre-, or post- spawning salmon. Generally a set of “index” streams
are surveyed each year, allowing for historic comparisons. Surveys are conducted
using aircraft, boats, or while walking in or along the waterways. Counts do not
necessarily represent total abundance but are only an index of abundance.
Surveys are generally timed to coincide with peak salmon spawning activity but
may be flown earlier to assess the build up of salmon in a river for fishery
management purposes. Surveys were conducted by ADF&G, US and Canada federal
agencies, and non-governmental organizations. Most surveys are aerial surveys
and are flown in either fixed wing aircraft or helicopters. A typical aircraft
is a two or four-place, single engine aircraft on wheels with a bubble window
(Super Cub). Generally an observer flies above the river of interest following
its course up or downstream counting salmon by species, live and dead. Counts of
salmon redds may also be included. Escapement monitoring projects that collect
escapement count data are stationary projects that count salmon as they migrate
upstream. Salmon are counted by observers stationed along freshwater migration
corridors (primary, secondary or higher order streams). Salmon are 1) counted as
they were allowed to pass upriver through weirs, 2) counted as they migrated
upriver past observers in elevated (towers) locations and, 3) counted by sonar
equipment placed in river. Tower and sonar counts generally represent a sample
and are expanded to represent a 24 h period. Data are collected to estimate or
document total spawning abundance; daily and seasonal timing of salmon migrating
into the rivers of the AYK Region. These data have been collected by ADF&G and
U.S., and Canada federal agencies and non-governmental organizations.
The Harvest – Commercial project type includes data collection
activities associated with monitoring commercial catch and effort levels and
describing the age, sex, and size composition of the salmon harvested. Harvest
monitoring activities include collecting sales receipts (“fish tickets”) issued
each time salmon are sold by fishers participating in Alaska’s commercial
fisheries. Fish ticket data have been entered inseason since 1981 in Emmonak and
1984 in Fairbanks, Nome, Bethel, and Kotzebue. Both hardcopy fish tickets and
electronic data are archived post season in Juneau. Commercial harvest data from
fish tickets is not currently accessible through the AYKDBMS. ASL data
have also been collected during harvest monitoring activities. Commercial
harvest monitoring projects have been defined by district for Kotzebue,
Kuskokwim, and Yukon Management Areas and by subdistrict for the Norton Sound
District of the Norton Sound-Port Clarence Management Area. Maps of AYK
Management areas and districts can be found at:
The Harvest – Sport project type includes data collection activities associated
with monitoring sport fish harvests. Currently the AYKDBMS has ASL data
from a few sport harvest monitoring projects generally of one year duration.
Other catch, harvest, and effort data collected from these fisheries are
archived and collected by ADF&G Division of Sport Fisheries. Users should
contact the Division of Sport Fisheries if interested in more complete ASL data
or other data collected with these projects. Again only a generic project
description (Table 2) was included for these projects. Project administrators
may prepare unique descriptions for their projects in the future.
ADF&G routinely monitors subsistence and personal use fisheries and
both activities are included under this project type (Harvest-Subsistence).
“Subsistence fishing” is defined in Alaska state law as the taking of fish,
shellfish, or other fisheries resources by Alaska residents for subsistence uses
(AS 16.05.940). “Subsistence uses” of wild resources are defined as
“noncommercial, customary and traditional uses” for a variety of purposes. These
include: direct personal or family consumption as food, shelter, fuel, clothing,
tools, or transportation, for the making and selling of handicraft articles out
of non-edible by-products of fish and wildlife resources taken for personal or
family consumption, and for the customary trade, barter, or sharing for personal
or family consumption (AS 16.05.940). Personal use fishing is defined as the
taking, fishing for, or possession of finfish, shellfish, or other fishery
resources, by Alaska residents for personal use and not for sale or barter (AS
16.05.940). Subsistence and personal use harvest monitoring projects have
been defined by district or area in AYK. Only ASL data collected through these
projects currently resides in the AYKDBMS.
For the purpose of categorizing all projects that have collected data on salmon in AYK,
projects which operated for a short duration and were generally not designed to
estimate abundance were considered research. Examples of research projects
involving adult salmon are those studying fecundity of AYK salmon or the
presence of disease (Ichthyophonus). Others have studied the freshwater
ecological or spawning behavior of adult salmon and these projects have also
been categorized as research.
For the purpose of categorizing all projects that have collected data on salmon in AYK, projects which operated
for a short duration with the emphasis on juvenile salmon were considered
research. Examples of research projects involving juvenile salmon are those
studying freshwater rearing habitat use, run timing and abundance at
outmigration, or juvenile energetics and biometrics.
Stock identification projects to identify and delineate stock structure have been conducted on salmon of the AYK Region. Various techniques used to differentiate stocks include scale pattern analysis and genetic techniques. A scale pattern analysis project for Yukon River Chinook salmon archives data in individual files and these data will not be included in the AYKDBMS. The Gene Conservation Laboratory of the Division of Commercial Fisheries has conducted studies on salmon in the AYK Region, using molecular techniques to detect genetic variants. These markers describe genetic relationships among populations and species and have been used to identify population units (discrete stocks) and individuals of particular stocks in mixed stock samples. The Gene Conservation Laboratory maintains a web site describing ongoing projects, publications, and staffing. Projects have also been conducted by the USFWS Conservation Genetics Laboratory.
Test fish projects employ standardized methods and fishing
procedures to provide an index of salmon abundance and run timing. Methods used
for test fish projects include set and drift gillnets as well as fish wheels.
Data are expressed as catch per unit of effort (CPUE) and commonly used for
inseason management of commercial and subsistence fisheries. Test fish projects
may also collect ASL data in an effort to characterize the age, sex and length
of the run going by. A test fishery may operate in conjunction with an
escapement project which utilizes sonar as a method type in an effort to
determine species apportionment and ASL composition. Whenever possible, salmon
caught in the test fishery are provided to the local population of subsistence
users to avoid waste.
The final filter developed for the AYKDBMS was “method type”. This
category represents the dominant gear, technology, or sampling method associated
with a data type, project, and year. Method types were defined as the vehicle
that carries observers making survey counts of escapement (aircraft, boat, foot)
or the type of gear used to capture salmon for ASL or CPUE data (fish wheel,
gill net, trap, etc.). Method can vary by year and by data type. For example at
an Escapement Monitoring project (project type); Escapement Count data (data
type) might be collected using method type “Tower” for the first few years and
method type “Weir” there after. Furthermore salmon might be captured for ASL
sampling using method type “Seine” for some years and captured in the weir trap
(method type “Weir”) in other years. When searching for data by project the
method type is listed by year for each data type collected. We have also
included method type for data not yet in the database. For examples for the
capture/recapture projects we have indicated whether the method type is
Tags/Marks External, Internal, or Radiotelemetry.
Salmon escapement is assessed from aircraft throughout the AYK region and for many streams form the
most extensive escapement time series available. Aerial surveys are intended to
index relative abundance of salmon escapement as opposed to providing an
estimate of total escapement. Generally an observer flies above the river of
interest following its course up or downstream counting salmon by species, live
and dead. Aerial surveys are restricted to clear water streams and lakes, which
exclude many salmon bearing waters in the AYK region where water clarity is
typically obscured by dissolved organics, glacier runoff, or sediment load.
Surveyors fill out a form indicating the standard latitude and longitude of the
water body surveyed, weather and water conditions at time of survey, and an
overall survey rating. For consistency, aerial survey counts are reported by
Salmon escapement is assessed from aircraft throughout the AYK region and for many streams form the
formally defined segments of the water body called index areas.
In the Yukon and Kuskokwim areas aerial surveys are conducted using fixed-wing
aircraft. Water bodies are typically surveyed one time each season during the
targeted species’ peak run timing. Chinook and sockeye salmon are the species
most often targeted in Kuskokwim area aerial surveys as these species are highly
visible to the surveyor and have a similar peak run timing, between late July
and early August. Chinook salmon are the species most commonly surveyed in the
Yukon area. Chum salmon have been surveyed in the past, but because they are
difficult to see from the air, survey counts are no longer used to index chum
salmon abundance in the Yukon and Kuskokwim areas. Coho are not often targeted
by aerial surveys because their late run timing often coincides with poor
weather conditions and limited aircraft availability during the fall hunting
season. Limited funding is also a factor in the decline of aerial surveys.
In the Norton Sound / Port Clarence
and Kotzebue areas aerial surveys are conducted to obtain abundance index
estimates for Chinook, chum, sockeye, and coho salmon. Fixed-wing aircraft are
generally used to monitor Chinook, chum and coho salmon; helicopters are used to
survey sockeye lake habitat. Escapement goals for sockeye salmon are based on
aerial survey counts.
This method refers to stream surveys of adult salmon
conducted from boats. Typically beginning at the upstream end of a surveyed
stretch, a crew including one boat operator and at least one fish counter drift
downstream to the designated survey termination point, usually the stream
outlet. The counter keeps track of the number of one or more targeted species
within each survey section. Similar to aerial and foot surveys, boat surveys use
counts as an index of salmon abundance and may be conducted once in a season
during peak abundance or at set intervals throughout the run. With a few
exceptions boat surveys have been conducted irregularly and have a historical
data series insufficient to gauge relative salmon abundance.
Electrofishing is a method type which uses electricity to capture fish.
Electrodes from a power source (battery or generator) are placed into the water
column and an electric current is passed into the water. The current shocks the
fish and stimulates them to swim into a net. Battery-powered backpack
electrofishers are typically used in wadable streams, and generator-powered
electrofishers are typically mounted on a boat or the shore in larger, unwadable
streams. Electrofishing has been found to be the most effective method to
capture the greatest variety of fish life stages and species, so electrofishing
is often used in stream fish community studies. Although a useful method type,
electrofishing is rarely used on adult salmon or trout because it is more likely
to injure larger fish. Small fish are less likely to be harmed by electrofishing
because they have less surface area exposed to the current. In addition to
stream fish community studies, electrofishing has also been used to capture
salmon for (1) tagging in capture and recapture projects and (2) sampling for
age-sex-length (ASL) data often associated with escapement monitoring projects.
Specific protocols vary by project and interested parties should refer to
published reports or contact project administrators for more information.
This method type utilizes a fish ladder or fishway to count migrating
salmon. Fish ladders are commonly used on dammed rivers to facilitate fish
passage upstream to spawning grounds and to collect stock abundance and run
timing data. Fish may be counted visually through a viewing window or by
electronic counters. Viewing windows also allow sex, general size and fish
origin (hatchery vs. wild) to be recorded. Fish ladders may be temporarily
closed off to allow scale, length, and genetic data collection from migrating
Fish wheels consist of trap-like baskets assembled to rotate
in a circle around a central pivot point or axle. The river current pushes the
fish wheel baskets around and as migrating salmon swim upstream, some are caught
in the fish wheel baskets and guided into a holding box. ADF&G uses fish wheels
as a method type in a wide variety of projects to monitor salmon abundance and
run-timing, collect age-sex-length data, collect genetic samples for baseline
data, and capture salmon for tagging.
This method refers to stream surveys of adult salmon
conducted on foot. Survey crew members walk along stream banks and visually
count salmon, keeping track of the number of one or more targeted species within
each survey section. Similar to aerial and boat surveys, foot surveys use counts
as an index of salmon abundance and may be conducted once in a season during
peak abundance or at set intervals throughout the run. With a few exceptions
foot surveys have been conducted irregularly and have a historical data series
insufficient to gauge relative salmon abundance.
Gillnet Gillnetting is a method
type used in many AYK projects to capture salmon during their spawning
migration. Gillnets are either drifted or set. Drift gillnets are deployed from
a boat with one end of the net attached to the boat and the other end attached
to a buoy. The boat drifts down current keeping the net perpendicular to and in
pace with the stream current. As fish swim into the nets, their heads pass
through the mesh of the net, catching their gills and trapping them in the net.
In contrast set gillnets are either deployed from shore and anchored offshore
perpendicular to the current or deployed from a boat and anchored at both ends.
The gear is stationary and salmon must swim into the net.
This method is used to gather spawned-out salmon near spawning
grounds. Carcasses or spawned-out live salmon are speared (gigged) or are
handpicked from stream banks and gravel bars. Intact fish are typically sampled
for age, sex and length following standard ASL protocols. Additional samples may
be taken for genetic analysis, otoliths for aging or microchemical analysis, or
tissue collections to test for parasites such as Ichthyophonus.
This method type utilizes a rod and reel to capture salmon for ASL data. In some
cases salmon caught by subsistence or sport fishers using a hook and line may be
sampled by ADF&G personnel and included under this method type.
Seining is a method type used to sample salmon populations with specific types of nets.
Seines trap fish by enclosing or encircling them or act as a barrier to keep
fish in a restricted area. Beach and purse seines are used in the AYK region. A
beach seine is typically deployed perpendicular to the stream current and
allowed to drift downstream close to the shoreline. For example, one person may
walk along the shore holding on to one end of the net while the other end of the
net is held out in the stream by a slowly drifting boat. A purse or bag seine
contains a centrally located bag or purse and as the seine is pulled through the
water, fish are herded towards the center and captured in the purse. Individual
methods of deployment vary by project and interested parties should refer to
published reports or contact project administrators for more detailed
Projects which employ sonar as a method type use
hydroacoustic technology to estimate salmon escapements. A transceiver projects
sound waves into the water, and when a sound wave encounters an object with a
different density than /-water, an echo is returned. The returned echo is
received by the transceiver, processed, and depending upon the technology used,
displayed on an oscilloscope, chart recorder, or computer screen. Sonar is an
effective method of enumerating salmon, and is often used when poor visibility
or river size limits the usefulness of towers or weirs. Echo-counters
manufactured by the Bendix Corporation* were the first sonar technology used in
the AYK region. Simply, echo-counters count all echoes above a threshold and
divide by the number of echoes per fish to generate estimates. Echo-counters are
effective at detecting fish close to shore and are easy to operate; however,
they are no longer manufactured and have been replaced with newer technologies.
Dual-beam and split-beam sonar typically operate at lower frequencies allowing
for detection of fish further offshore (roughly 250 m) and allow storage of the
data either electronically or as paper charts for post-season review. Counts
from dual or split-beam systems are obtained by counting fish traces on
electronic or paper echograms. In addition, split-beam sonar can measure the
target’s position in the beam, making it possible to determine direction of
travel (i.e. upstream or downstream). The latest technology, dual-frequency
identification sonar (DIDSONTM), produces video-like images of fish making it
possible to determine direction of travel; however, the high-frequency limits
the detection range making DIDSONTM suitable for short distances or use on small
rivers. DIDSONTM may also be used on large rivers such as the Yukon in
conjunction with split-beam to maximize detection throughout the desired
counting range. To maximize fish detection near shore where the beam is narrow,
a lead is often used to guide fish away from the bank and further out into the
river where the beam is wider. Although this lead is often called a weir, it
should not be confused with a weir method type as described elsewhere in the
glossary. A test gillnet fishery is sometimes coupled with a sonar project in
order to apportion sonar counts to species. In cases where a high percentage of
the salmon population is known to be a certain species, a test fishery may be
considered unnecessary. *Product names are included for completeness, but do not
represent endorsement by The Alaska Department of Fish & Game.
Tags or marks
are used to identify individual fish in studies involving capture/recapture,
movement, abundance, distribution, or stock identification. Data are collected
and later analyzed based on tagged/marked fish that are recaptured through a
variety of means. Tags may be external or internal. Commonly used external tags
include spaghetti and t-bar anchor tags which are inserted into flesh just under
the dorsal fin of the fish. Common internal tags include coded wire tags, and
radio tags. Coded wire tags are commonly used to mark fish from hatcheries.
Radio tags are small transmitters that may be surgically implanted into the
abdomen of fish or inserted into the stomach through the esophagus. Signals from
radio tags may be intercepted from radio towers placed along rivers or tracked
from aircraft or boats to identify the individual and to determine location. An
example of a mark is the banding of otoliths by artificially altering water
temperatures during incubation.
Tower Projects that use a tower as a method type monitor escapement by
visually counting migrating salmon. The tower provides a raised vantage point,
often employing a scaffold, and the crew keeps tally of how many of each
targeted species pass upstream for a portion of every hour. In order to improve
visibility, a flash panel is placed on the river bottom. A flash panel is a
sheet of heavy, light-colored material, often canvas, which allows a favorable
background for counting and identifying different fish species. An underwater
fence or weir is placed from the river’s edge to the flash panel in order to
restrict the number of fish swimming past at once and guide fish to the area of
improved visibility. The actual count is expanded to estimate passage for the
full hour. If, for example, the crew counts for 10 minutes (one-sixth) of every
hour the tally is multiplied by 6 to estimate hourly passage. At the end of
every 24-hour period the hourly counts are added to estimate daily passage. In
case of missed counts or days off, previous and subsequent totals are used to
obtain a passage estimate. Specific estimation methods vary by project and are
detailed in published reports. Tower projects often collect additional
information such as climatological, hydrological, and age-sex-length data, but
again these vary by project and can be found in published reports.
A variety of experimental traps have been used in the AYK region for sampling
purposes. If trap is noted as a method type used in conjunction with a weir,
this may refer to the fish chute or live trap where salmon are held briefly for
sampling before passing them upstream. For details on trap design and usage
please refer to published reports or contact the project administrator. Video
Video monitoring is a method type still in the early stages of development
within AYK. Feasibility studies have been conducted to assess the usefulness of
video technology used in conjunction with a fish wheel or weir to provide
abundance estimates or enumeration and run timing of salmon and identify tagged
fish for capture/recapture projects. Using video greatly reduces stress as it
allows salmon to migrate without impediment or delay and minimizes the need for
handling by humans. Video cameras have been deployed both underwater (i.e. to
record fish passage through an opening in a weir) or above water (i.e.
positioned to record fish as then pass from a fish wheel back into the water).
Weir Escapement monitoring projects that employ
an adult salmon weir as a method type generally collect a census of each
targeted species. These weirs span the entire channel width of a river and guide
targeted species towards a passage chute or gate for visual identification of
each fish. The weir is composed of a structure that supports pickets of metal or
plastic pipe. Pickets are spaced close enough together that targeted species
cannot swim between them, but water flows easily past. Live traps are generally
employed to collect fish for age-sex-length sampling and to recapture tagged
fish. Two styles of adult salmon weirs are used in the AYK region. Fixed-picket
or fixed-panel weirs are supported by a series of bipods or tripods across the
channel. These are said to be “fixed” because they are not designed to adjust to
changing water levels, and are vulnerable to serious damage during flood events.
Resistance board weirs are a flood resistant alternative to fixed-picket
construction. The pickets of a resistance board weir are positively buoyant and
are anchored to the riverbed at one end. The other end of each picket is
attached downstream to a resistance board that utilizes stream flow to suspend
it above the water’s surface. This portion of the weir is designed to float
during normal water conditions and sink during flood events, allowing debris to
pass freely over.