Fish Fauna In Nearshore Waters Of A Barrier Island In The Western Beaufort Sea Alaska

Abstract

Information on fish in coastal waters of the Alaskan Arctic is outdated or nonexistent, especially in areas targeted for oil exploration and increased transportation activities. To address this information gap, we sampled fish in nearshore waters of Cooper Island, a barrier island in the western Beaufort Sea, in August 2004, 2005, 2006, 2007, and 2009, and in September 2009. Fish were captured with a beach seine and bottom trawl (5 and 8 m depths) on the Beaufort Sea side of the island and with a beach seine on the Elson Lagoon side of the island to identify fish distribution, species composition, and habitat use. A total of 2,807 fish representing 16 species were captured in all sampling periods and with both gear types: 1,567 fish representing 14 species were captured in 24 seine hauls, and 1,240 fish representing 9 species were captured in 16 trawl tows. Of the total fish captured by seine from 2004 to 2006, 95% were from the Beaufort Sea (n = 9 hauls) and 4% were from Elson Lagoon (n = 9 hauls). The most abundant fish captured by seine were capelin (Mallotus villosus), Arctic cod (Boreogadus saida), juvenile prickleback (Stichaeidae), and juvenile sculpin (Cottidae) in the Beaufort Sea, and least cisco (Coregonus sardinella) and juvenile sculpin in Elson Lagoon. Trawl catch was similar by depth; the most abundant species were Arctic cod and slender eelblenny (Lumpenus fabricii). Of the total fish captured by trawl, 87% were caught in September 2009. Most fish captured were juveniles based on estimated size at first maturity and length frequency distributions. Total catch in the Beaufort Sea was lowest in August 2006; water temperatures were 4-8º C colder in 2006 than in any other year of the study. Species occupying coastal waters of the Beaufort Sea have remained relatively unchanged during the last 25 years; Arctic cod remain a dominant species, whereas capelin appear to be more widespread and abundant. Continued warming conditions in the Arctic Ocean will likely result in a reorganization of nearshore community structure–new fish species are expected to migrate to the Arctic with unknown consequences to existing stocks and food webs.

Introduction

The Arctic is one of the most rapidly changing ecosystems in the world, yet a large void exists in information on essential fish habitats and what species and life stages use these habitats. Rapid change in polar ecosystems is well documented: the Arctic Ocean Basin has experienced significant warming in recent decades with pronounced decreases in the extent and seasonal duration of sea ice (Moline et al. 2008). The minimum extent of Arctic sea ice in 2009 was the third lowest since the start of satellite measurements in 1979 (National Snow and Ice Data Center 2009). Loss of sea ice from global warming threatens marine life and habitat (e.g., increased coastal erosion) and has the potential to open up formerly inaccessible areas to oil and gas exploration, vessel traffic, mining, and commercial fishing. Increased human activity translates into increased risk to fish and habitat from development and oil spills. Given the new and increased risk to the Arctic, some researchers believe the United States is not prepared to prevent and recover from oil spills in this ecologically fragile area (Torrice 2009). Prior to major development or transportation activities in the Arctic, information is needed on fish distribution, species composition, habitat use, life history characteristics, food webs, and species at risk to make informed management decisions regarding potential effects from human disturbance.

Information on nearshore (shoreline to 8 m depth) [fish] in Arctic waters of Alaska is outdated or nonexistent. Information that is available is mostly from studies in the 1970s and 1980s in the eastern Beaufort Sea, prompted by the discovery of oil and gas in Prudhoe Bay in 1968-69 (Craig and Haldorson 1981, Craig et al. 1982, Haldorson and Craig 1984, Craig et al. 1985, Moulton and Tarbox 1987, Cannon et al. 1991). In the western Beaufort Sea near Barrow, Alaska, published information on nearshore fish fauna, distribution, and habitat use is scarce, especially for barrier islands with lagoons and adjacent coastal waters. Nearshore waters, particularly lagoons, are important feeding areas for anadromous and marine [fish] during the short Arctic summers (Craig 1984).  A species list of known [fish] occupying brackish nearshore and marine offshore coastal waters of the Beaufort Sea is provided in Craig (1984).