The National Environmental Policy Act (NEPA) requires the BOEM to prepare an Environmental Impact Statement (EIS) for each offshore oil and gas lease sale area offered through the DOI leasing program. The EISs provide an assessment of the potential environmental effects associated with major development proposals and communicate this information to decision-makers and the broader public (Wood, 2008). In complying with the NEPA, the BOEM relies on the best available science to evaluate potential effects on regional ecosystems and living resources. Our objectives were to review and synthesize current fish biology, ecology, and fisheries information to assist BOEM’s NEPA analysts in assessing environmental effects from planned future offshore oil and gas development on the Arctic OCS. BOEM’s NEPA analysts require detailed information about the biodiversity, life history, and population ecology of regional biota to assess adversity of impact in the EIS process. For Arctic marine fishes, impact is evaluated in terms of potential declines in abundance or changes in geographic distribution and recovery of populations to pre-impact status (thresholds of significance analysis; see Miner and Rivasplata, 1994, and Musick, 1999). To illustrate, adverse effects would require three of more generations for a population to recover (Bureau of Ocean Energy Management Regulation and Enforcement, 2011). The population understanding required for a robust EIS analysis is similar to what is required to assess Essential Fish Habitat under provisions of the Magnuson-Stevens Fishery Conservation and Management Act. The compilation of species information provides BOEM’s NEPA analysts and others with a single, authoritative scientific reference about the biology and ecology of marine fishes in the United States Chukchi and Beaufort Seas. Biodiversity is broadly assessed with respect to current understanding of (1) classification and taxonomy, (2) abundance and geographic distribution, and (3) life history and population ecology. A focus of this study has been on new information and discoveries about this fauna since the publication of Fishes of Alaska (Mecklenburg and others, 2002). As such, the species checklist, geographic distribution maps, and depth profiles represent new biodiversity products to science. This synthesis is unique because it is based on confirmed species occurrences in United States sectors of the Chukchi and Beaufort Seas. Confirmation is an important process because it assures the reliability of resource information in management areas of direct concern to decision makers. For most species, the link between occurrence and abundance remains tenuous given the nature of sampling conducted to date. As such, quantitative aspects of the dynamics of fish populations and their interactions with the Arctic marine environment are hindered by inadequacies of existing data and relative lack of Alaskan records. The emphasis on population dynamics and ecologic relationships in the species accounts provides an important basis for assessment of outstanding needs. Although knowledge about the marine fish fauna in the Alaska Arctic is among the poorest in the state, it has been slowly improving over time. However, much life history information presented in this report was acquired from scientific observations outside Alaska. As such, basic taxonomic science and population understanding is needed to support modern assessments and potential fisheries in the Arctic high seas. The goals of this report are to present the most current information about what is known about the marine fishes in the Arctic area of the United States with a special focus on geographic distributions, vertical structure, abundance, and life history parameters of key populations. The section, “Outline of Species Accounts” in chapter 3 serves as a users’ guide to information presented in the individual species descriptions. References Cited: Bureau of Ocean Energy Management Regulation and Enforcement, 2011, Proposed Final Outer Continental Shelf Oil and Gas Leasing Program 2012-2017, U.S. Department of the Interior, 211 p., website accessed November 13, 2013, at bttp://www.boem.gov/uploadedFiles/BOEM/Oil_and_Gas_Energy_Program/Leasing/Five_Year_Program/2012-2017/Program_Area_Maps/Alaska%20Program%20Areas.pdf. McDowall, R.M., 1987, The occurrence and distribution of diadromy among fishes: American Fisheries Society Symposium, no. 1, p. 1-13. Mecklenburg, C.W., Mecklenburg, T.A., and Thorsteinson, L.K., 2002, Fishes of Alaska: Bethesda, Maryland, American Fisheries Society, 1,116 p. Miner P., and Rivasplata, A., 1994, Thresholds of significance; criteria for defining significance: Sacramento, Calif., CEQA Technical Advice Series, Governor's Office of Planning and Research, 12 p. Wood, G., 2008, Thresholds and criteria for evaluating and communicating impact significance in environmental studies--'See no evil, hear no evil, speak no evil'?: Environmental Impact Assessment Review, v. 28, no. 1, p. 22-38.