Glossary of Mark Terms

The following terms are used throughout the Mark Laboratory. Each term is followed by a definition and clicking on the term will produce a list of possible values and each value's corresponding code.

A-Stream

The Alaska Department of Fish and Game maintains a catalog of names identifying all bodies of freshwater where anadromous fish breed. As of this writing, it may be reviewed on the web at http://www.sf.adfg.state.ak.us/SARR/FishDistrib/FDD_intro.cfm . A-Stream numbers are based on a scheme which follows a particular body of freshwater from the statistical area of its marine estuary up through tributaries. A location that passes through many branches before reaching the ocean could have a very long A-Stream number.

Band

A distinct group of dark rings created by thermal marking procedures. Multiple bands are separated from each other by a space that is significantly greater those that occur between rings. Also see Thermal Mark.

Band-Width

The overall thickness of a group of dark rings created by thermal marking.

Broodyear

The year when adults return to spawn. If more than one brood present, the year reported is the dominant or first brood year.

Canada Watershed Codes

The province of British Columbia maintains the most popular stream catalog for identifying freshwater locations in both BC and Yukon Territory. Canada Watershed applies only to certain samples taken on trans-boundary river systems. For freshwater samples taken wholly within Alaska, the anadromous stream number ("A-Stream") is employed instead.

Circuli

Concentric, continuous lines representative of incremental growth patterns present on scales and otoliths.

Facility

The hatchery or facility where fish were reared.

Fishery Name

The name given to a commercial fishery that encompasses a given set of districts and/or subdistricts.

Gear

The method or means used to commercially catch fish.

Harvest

As used here, harvest is a code used to distinguish different types of commercial fisheries.

Hatch Code

An alpha-numeric code that represents a thermal mark pattern. It lists the number of rings within each band prior to and after the hatch mark on an otolith. For example: "8H3" represents a mark pattern that consists of an 8-ring band generated before hatching, and a 3-ring band that was created after hatch. The "H" symbol refers to the hatching event.

Hatch Mark

A circuli present on otoliths that is generated when fry emerge from their egg cases. The clarity of the mark varies within and among species.

Mark Summary Report

A web-based report that summarizes the absolute and relative number of thermal marked otoliths recovered from a fishery or escapement sample. Summary data are broken down by fishery, district, and sub-district.

Marked

The total number of otoliths in a given sample that had thermal marks (e.g. hatchery-raised fish).

%Marked

The proportion of thermally marked fish recovered in a given sample.

Not Marked

The total number of otoliths in a given sample that did not have a thermal mark (e.g. wild fish).

Otoliths

Otoliths are paired crystalline structures of the inner ear composed of calcium carbonate and protein that are located in the skull of teleost (bony) fishes that aid in balance, orientation, and sound detection. There are three pairs of otoliths that differ is size, shape, and function: the lapilli, asterisci, and sagittae. Because the crystalline matrix is laid down incrementally and deposition varies spatially and temporally, these structures provide a record of a fish's life history. The sagittae are the largest and are typically used for life history studies and thermal mark recovery.

#Preps

The total number of otoliths prepared and read for the presence of thermal marks for a given stat week and district. This number may not agree with the #Rcvd column if some of the otoliths in a sample were unreadable or lost.

Rbr

"Region - Band - rings." Rbr nomenclature identifies the location of the bands relative to the hatch mark. An RBr that begins with a "1:" indicates that all bands occur prior to the hatch mark; a "2:" specifies that all bands occur after the hatch mark. For example, an RBr of 1:1.5,2.2, signifying a first band of five rings and a second band of two rings both occur prior to the hatch mark. An RBr of 2:1.4 indicates a band of four rings is located after the hatch mark. For patterns that have bands in both the pre- and post-hatch regions, the post-hatch marks are preceded by a "+" sign. An Rbr of 1:1.3+2.5 indicates a 3-ring band occurs in the pre-hatch region, whereas a 5-ring band can be found in the post-hatch region.

#Rcvd

The total number of otolith samples received for a given stat week and district.

Ring

An individual dark circulus generated by thermal marking procedures.

Sample Date

The date on which the samples were collected from the fishery or spawning run. Often, samples are collected over a range of days within a stat week, in which case the sample date indicates the day on which sampling began.

Sample Location

The name of the district in which the fish were sampled from the fishery or spawning run.

Sex

The gender of a particular fish in a sample expressed as either male or female.

Source

Used to distinguish major types of fisheries, like sport, commercial (common property), cost recovery, escapement, hatchery racks, etc.

Species

The sub-genus classification of salmonids being sampled.

Stat Area

A numeric code assigned by the Alaska Department of Fish and Game indicating the district and subdistrict in which fish were sampled. The first three numbers indicate district, whereas the remaining two digits indicate subdistrict. If a sample was collected from multiple subdistricts, then the numeric codes for both are provided.

Stat Week Calendar

The ADF&G Statistical Week is 7 days long and runs from Sunday through Saturday. The first Statistical Week of the year may be less than 7 days and ends on the first Saturday. Subsequent weeks are numbered chronologically through the end of the year, thus there could be as many as 54 Stat Weeks in a year.

Strontium Mark

Exposing a fish to a solution of strontium chloride hexahydrate (SrCl - 6H20) at approximately 3,000 ppm for 24 hours creates a fluorescent band in the otolith that is visable when viewed with a scanning electron microscope equipped with a backscatter electron detector. By subjecting the fish to a series of exposures, unique patterns are created in the otolith that can be used to identify broodyear and hatchery of origin. This marking procedure is 100% effective, permanent, and has little or no impact on fish health. The fish, however, must be sacrificed in order to recover a strontium-marked otolith.

Survey Site

Identifies sampling places throughout the state. For commercial specimens, this is typically the location of the buying processor, NOT the place caught. Coded Wire Tag and Thermal Mark share a common set of Survey Sites, although a site used by CWT may not necessarily be used for thermal mark sampling and vice versa. Survey Site is local to Mark, Tag and Age Lab data and does not apply to other data such as fish tickets.

Thermal Mark

Exposing a fish to different temperature regimes causes distinct rings or "thermal marks" to appear in otoliths. By manipulating temperature profiles during early incubation, unique mark patterns can be created to identify the broodyear and hatchery of origin for hatchery-raised fish. This marking procedure is 100% effective, permanent, and has little or no impact on fish health. The fish, however, must be sacrificed in order to recover a thermal marked otolith. Thermal marks are varied by changing the number of rings and/or bands, as well as the spacing within and between them.

TMID

"Thermal Mark Identification." An alpha-numeric code that identifies the brood year and release site / hatchery of origin for each thermal mark pattern released into a fishery.