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Glossary of Terms
- Alizarin Complexone
- A red fluorescent dye used to stain tissues associated with calcification.
- Alizarin Mark
- A fluorescent mark visible under ultraviolet light that appears in the otolith matrix after the fish has been immersed in alizarin complexone.
- Anterior
- Situated before or at the front of; fore. In animals, pertaining to or toward the head or forward end of the body.
- Annulus
- A growth ring, or a series of rings, that can be used to estimate age.
- Band
- A band refers to a group of two or more dark circuli (i.e., rings) that are generated in an otolith during the thermal marking process. A thermal mark may consist of one or more bands. If a thermal mark is composed of multiple bands, then each band is separated by a space that is significantly greater than those that occur between each ring within a band. 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.
- Calcein
- A compound that can bind with the alkaline calcium of any calcified structure to produce a green fluorescent mark when viewed under ultraviolet light.
- Calcein Mark
- A fluorescent mark visible in calcified structures, such as otoliths, fin rays, and vertebrae, that is generated after a fish is exposed to calcein via immersion or ingestion.
- Cation
- Any positively charged atom or group of atoms.
- Circuli
- Concentric, continuous lines representative of incremental growth patterns present on scales and otoliths.
- Dry Mark
- A method of marking fish otoliths by altering water levels while the eggs are incubating. The resulting mark is visually identical to a thermal mark and can be observed directly with a light microscope.
- 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.
- 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.
- Oxytetracycline (OTC)
- A fluorescent antibacterial chemical that binds permanently to calcified structures and glows yellow when viewed under ultraviolet light.
- Oxytetracycline Mark
- A flourescent yellow ring that appears in an otolith after the fish has been immersed in oxytetracycline. The ring is only visible after exposure to ultraviolet light.
- Primordia
- The core of the otolith that provides a foundation for the precipitation of calcium carbonate and protein. Salmonid otoliths contain multiple primordia.
- 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.
- Ring
- An individual dark circulus generated by thermal marking procedures.
- Sagitta
- The largest "ear bone" of the inner ear of teleost fishes. Its primary function is associated with sound detection.
- Strontium Chloride
- (SrCl2): A water-soluble chemical used to mark calcified tissues.
- Strontium Mark
- A high concentration of strontium that appears as a bright fluorescent ring in an otolith, or any other calcified structure that grows incrementally, after exposure to strontium chloride hexahydrate (SrCl - 6H20). The ring can only be detected with an electron microscope.
- Sulcus
- A furrow or groove.
- 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.
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