<descriptor thcode="2"><thesaurus thcode="2" name="USGS Thesaurus" scope="Topics and methods of scientific study carried out by USGS, with product types, scientific disciplines, geologic time, and types of institutional structure and activities.  Broad and shallow, used to help people find scientific information." creator="U.S. Geological Survey" rights="Public domain" edition="2.0" date="2020-01-09" codetype="number" prefix="topic" uri="https://www2.usgs.gov/science/USGSThesaurus" tblname="term" nonpref="nonpref" relterm="relterm" root_code="1" contact="pschweitzer"><category><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/></category><altlabel><altlabel>USGSThesaurus</altlabel><altlabel>USGSThesaurus</altlabel></altlabel></thesaurus><term thcode="2" code="387" name="fish" parent="1269" scope="Cold-blooded aquatic vertebrates with fins for swimming, gills for breathing, and usually scales."/><uf><usefor name="anadromous fish"><usewith><term thcode="2" code="744" name="migratory species" parent="841" scope="Species that have a pattern of moving from one geographical area to another, primarily according to the seasons, and usually traveling long distances along established routes."/></usewith></usefor><usefor name="diadromous fish"><usewith><term thcode="2" code="744" name="migratory species" parent="841" scope="Species that have a pattern of moving from one geographical area to another, primarily according to the seasons, and usually traveling long distances along established routes."/></usewith></usefor><usefor name="fish inventories"><usewith><term thcode="2" code="379" name="field sampling" parent="376" scope="Collecting pieces or specimens or making measurements or observations at determined intervals or areas.  Results may be used as representative of the whole research area or population."/></usewith></usefor><usefor name="fishes"/></uf><bt><term thcode="2" code="1269" name="vertebrates" parent="45" scope="Animals possessing a vertebral column or backbone including birds, fishes, amphibians, reptiles, and mammals."/><term thcode="2" code="45" name="animals" parent="843" scope="Multi-celled organisms of the kingdom Animalia with eukaryotic cells (cells with distinct nuclei containing genetic material and bounded by thin membranes) that are heterotrophic (obtaining energy from organic substances produced by other organisms)."/><term thcode="2" code="843" name="organisms" parent="1174" scope="Living individuals that grow, reproduce, and die."/><term thcode="2" code="1174" name="topics" parent="1" scope="Themes, subjects, and concerns for which USGS information resources are relevant."/><term thcode="2" code="1" name="Categories" scope="Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."/></bt><rt><term thcode="2" code="570" name="ichthyology" parent="1268" scope="Branch of zoology concerned with the study of fish."/></rt></descriptor>