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Glossary

Adaptive Management
A systematic process for continually improving management policies and practices by learning from the outcomes of operational programs.
Adult
Same as MATURE.
Age Composition
A group of individuals of a certain species that have the same age.
Anecdotal Evidence
Information passed along by word-of-mouth but not documented scientifically.
Avulsion
A change in the course of a river when the bank is breached or overtopped.
Base Flow
The typical flow rate for a given stream at a particular time of year.
Bed Load
Streambed materials that are washed downstream and redeposited in a new location.
Biological Productivity
A measure of growth in living systems.
Biological Trophic Level
Steps in the food chain from plants through plant-eaters to meat-eaters.
Biomass
The total weight of a living organism or a population of organisms.
Conservation
The management of human use of natural resources so that they may yield the greatest sustainable benefit to current generations while maintaining their potential to meet the needs and aspirations of future generations.
Conservation Aquaculture
A hatchery-based, captive culture program designed to preserve the gene pool (genetic variation) and natural age-class structure of wild fish through the release of hatchery-reared juveniles. The program is based on a breeding plan that includes protocols on adult broodstock collection, hatchery spawning and rearing, fish health, and genetics.
Discharge
Water flow volume, often used to describe a volume released from a dam.
Effective Population Size
An ideal population of a given size in which all parents have an equal expectation of being the parents of any progeny individual.
Electrophoretic Analysis
The process in which molecules (such as proteins, DNA, or RNA fragments) can be separated according to size and electrical charge by applying an electric current to them.
Empirical Data
Information derived from measurements made in "real life" situations (e.g., field data).
Endangered
Any species (or stock) that is likely to become extinct within the foreseeable future throughout all or a significant portion of its range.
Endogenous
Refers to feeding on internal food sources, e.g., egg yolk matter or energy reserves, as opposed to feeding externally.
Evolutionary Significant Unit
A distinctive group of animals that is uniquely adapted to a particular area or environment and cannot be replaced. Exogenous Refers to feeding on external food sources as opposed to the utilization of egg yolk matter or energy reserves within a fish.
Extinct Species
A species no longer present in its original range or as a distinct species elsewhere.
Extirpation
The elimination of a species or subspecies from a particular area, but not from its entire range.
Flow Regime
Same as HYDROLOGICAL REGIME.
Functional Extinction
Occurs when a population of a species declines to such a degree that it becomes virtually impossible for the population to survive, let alone recover. At such low numbers inbreeding starts to occur.
Genetic Diversity
A property of a community of organisms of a certain species, in which members of the community have variations in their chromosomes due to a large number of slightly dissimilar ancestors; this property makes the community in general more resistant to diseases or to changing ecological conditions.
Haplotypes
A way of denoting the collective genotype (the genetic constitution of an organism) of a number of closely linked loci (positions) on a chromosome.
Heterozygosity
Possessing two different forms of a particular gene, one inherited from each parent.
Hydrograph
The recorded variations in stream discharge over time. Useful when comparing effects and changes in stream flow and depth between average natural conditions and altered stream flows (i.e., from dams and diversions).
Hydrological
Regime The pattern and volume of river or stream flow throughout the course of a year.
Juvenile
A young fish or animal that has not reached sexual maturity.
Limnological
The science of the properties of fresh water including water chemistry, density, stratification and physical effects on living organisms.
Mature
A fish that is sexually mature and capable of producing eggs or sperm.
Microhabitat
Detailed description of where an animal lives.
mtDNA
Sequences The pattern or order of mtDNA which is the circular or linear DNA of the mitochondria. It codes for only a small but essential part of the mitochondrial proteins and for other specific genes.
Nucleotide
A subunit of DNA or RNA consisting of a nitrogenous base (adenine, guanine, thymine, or cytosine in DNA; adenine, guanine, uracil, or cytosine in RNA), a phosphate molecule, and a sugar molecule (deoxyribose in DNA and ribose in RNA). Thousands of nucleotides are linked to form a DNA or RNA molecule.
Nutrient Dynamics
The way nutrients are used and reused, over time and distance, in a biological system.
Population
Same as STOCK.
Population Dynamics Model
A mathematical description of a population that is designed to fully simulate the life cycle of animals in that population, and that has the ability to project relative effects of different environmental effects or biological characteristics of these animals.
Recovery
When the constituent populations of naturally produced fish belonging to an endangered population unit are sufficiently abundant, productive and diverse in terms of life histories and distribution that the listed unit as a whole will be "self-sustaining" into the future.
Recruitment Failure
A situation where a population is not able to naturally produce viable off-spring as a consequence of physical (e.g., blocked access to spawning areas, siltation of spawning areas, etc.) or biological (e.g., inadequate numbers of fish, reproductive senescence, etc.) factors.
Recruitment
Survival of juveniles until they become a member of the spawning population.
Relative Abundance
A comparison of the number in one category to another (e.g., number of one species to another, male to female, young to old, etc.). Typically expressed as a percentage or proportion.
Reservoir Drawdown
Removing water from a reservoir and lowering the surface water elevation.
Species
A group of individuals that have their major characteristics in common and (usually) can only breed with each other.
Stock
A grouping of fish usually based on genetic relationship, geographic distribution, and movement patterns. Also a managed unit of fish.
Stock Status
General health of a particular stock of fish in terms of numbers, age-class distribution, condition, distribution, and genetic diversity.
Total Population
Total number of individuals, of all age classes, in a population.
Tributary
A small stream or river, which enters and increases the volume of the receiving river, lake, or reservoir.
Vulnerable Population
Any species (or stock) whose numbers are not so low as to be considered endangered but whose status is such that further reductions in habitat quality, numbers or size distribution may make them endangered.
Year Class
All individuals of a fish population spawned and hatched in a given year.

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