A nearsurface, daytime occurrence of two mesopelagic fish species (Stenobrachius leucopsarus and Leuroglossus schmidti) in a glacial fjord

Abookire, Alisa; Piatt, John; Speckman, Suzann

The northern lamp.sh (Stenobrachius leucopsarus, family Myctophidae) and northern smoothtongue (Leuroglossus schmidti, family Bathylagidae) are mesopelagic .shes, de.ned by their vertical distribution in the mesopelagic zone (200–1000 m) during daylight hours. Northern lamp.sh range from the Bering Sea to southern California (Shimada, 1948), where their abundance is highest along the continental slope and decreases over the continental shelf. They are the most abundant species in the mesopelagic zone of the Bering Sea (Pearcy et al., 1977; Sobolevsky et al., 1996), the Gulf of Alaska (Purcell, 1996), and the eastern North Paci.c Ocean off Oregon (Pearcy, 1964; Pearcy et al., 1977). Northern smoothtongue also concentrate in areas bordering the continental slope and are widely distributed from southern British Columbia to the Bering Sea (Peden, 1981) and are very abundant in the Okhotsk Sea (Sobolevsky et al., 1996). Although larval myctophids spend day and night in nearsurface waters (Frost and McCrone, 1979), juvenile and adult northern lamp.sh typically inhabit depths of 300–600 m during the day (Paxton, 1967; Pearcy et al., 1977; Frost and McCrone, 1979; Sobolevsky et al., 1996; Watanabe et al., 1999). Off the Oregon coast northern lamp.sh exhibit semimigrant behavior: a large portion of the population migrates from a daytime depth of 300–600 m to about 50 m at night, and a nonmigratory portion of the population has both a day- and night-time vertical distribution at about 500 m depth (Pearcy et al., 1977). This semimigrant behavior also occurs in the Gulf of Alaska (Frost and McCrone, 1979), in the western North Paci.c off Japan (Watanabe et al., 1999), and off California in both the San Pedro Basin (Paxton, 1967) and Santa Barbara Basin (Cailliet and Ebeling, 1990). After sunset, migratory northern lamp.sh have been collected at depths as shallow as 20 m in the Bering Sea (Nagasawa et al., 1997). We are unaware of any studies in which adult northern lamp.sh we

A nearsurface, daytime occurrence of two mesopelagic fish species (Stenobrachius leucopsarus and Leuroglossus schmidti) in a glacial fjord

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