Bottom Trawls

Demersal Fish and Epifaunal Abundance and Distribution

Bob Lauth, Bob Foy, and Brenda Norcross

Objectives – (1) Assess the current status of demersal fish and invertebrate communities and collect biological samples for further genetic, energetic, and trophic analyses, (2) compare results to earlier studies in the Chukchi Sea and to adjacent regions (Bering Sea and Beaufort Sea).

Bottom trawl surveys used for assessing demersal fish and shellfish stocks have been conducted sporadically in the Chukchi and Beaufort Seas over the past 45 years (Alverson and Wilmovsky 1966; Quast 1972; Wolotira et al. 1977; Frost and Lowry 1983; Barber et al. 1994; Feder et al. 2005; Bluhm et al. 2009; Rand and Logerwell 2010; Norcross et al. 2010); however, the sampling methodology has been inconsistent making the data of limited use for determining what marine community changes have occurred over time. A vessel was chartered to conduct a standardized bottom trawl survey of the Chukchi Sea during the late summer 2012 and a contractor to process, analyze, and summarize survey results. The proposed bottom trawl survey will use the same standardized gear and sampling methodology currently used by the RACE Division Groundfish Assessment Program in their bottom trawl surveys in the eastern and northern Bering Sea shelf and that was used for a BOEM-funded survey of the western Beaufort Sea in 2008 (Rand and Logerwell 2011) and a survey of the northeastern Chukchi Sea in 1990 and 1991 (Barber et al. 1994). In addition, a smaller beam trawl and finer mesh cod-end netting will be used by the UAF team to assess net selectivity of larger NOAA bottom trawl and will be used to take biological samples as well. See the “Biology Studies / Gear Comparison” page for a detailed comparison of the sampling equipment.

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