Dissolved oxygen as a constraint on daytime deep scattering layer depth in the southern California current ecosystem

Netburn, Amanda N.; Koslow, J. Anthony

doi:10.1016/j.dsr.2015.06.006

Cited by 71 publications

(67 citation statements)

References 83 publications

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“…Despite regional differences, the collective range of depths reported for California swordfish are much shallower than those reported for other ocean basins (~ 400–1,000 m, Dewar et al., ; Abascal, Mejuto, Quintans, & Ramos‐Cartelle, ). The shallower daytime depths off California have been attributed to several factors, including high stratification and thermocline depth (~70 m Palacios et al., ), as well as the depth range of the oxygen minimum layer (~ 300–500 m; OML defined as <0.5 ml/L dissolved oxygen; Levin, ; Bograd et al., ; Netburn & Koslow, ). At depth, low dissolved oxygen levels have been shown to influence the lower boundaries of several pelagic species, as it can limit favorable habitat and also influence the distribution of mesopelagic prey (Bograd et al., ; Netburn & Koslow, ; Prince & Goodyear, ).…”

Section: Discussionmentioning

confidence: 99%

Movements and behaviors of swordfish Xiphias gladius in the United States Pacific Leatherback Conservation Area

Sepúlveda

Aalbers

Heberer

et al. 2018

Fisheries Oceanography

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This study reports on the movements of swordfish tagged within the Pacific Leatherback Conservation Area (PLCA), an expansive region (>500,000 km2) off the U.S. West Coast that has been seasonally restricted to drift‐gillnet fishing since 2001 to reduce leatherback sea turtle (Dermochelys coricea) interactions. Thirteen swordfish were outfitted with satellite‐linked archival tags scheduled for short (2–20 days, n = 11) and longer‐term (150 days, n = 2) data collection. All tags were deployed on basking swordfish using traditional harpoon‐based methods during the fall of 2012–2013, near offshore seamounts (35.6°N/122.9°W to 37.4°N/123.5°W). Depth and temperature data from 11 swordfish (~90 to 150 kg) resulted in <251 days of movement information from the PLCA region. All tagged individuals exhibited surface‐oriented nocturnal movements, spending >99% of the night above the average thermocline depth (37.5 m), with an average night depth of 8.3 ± 1.6 m. Daytime depth distribution was greater and more variable (mean 107.1 ± 21.2 m), with fish primarily displaying three behavioral patterns: (i) basking activity, 16.7% of the day, (ii) a mixed‐layer distribution between 3 m and the thermocline (26.8% of the day), and (iii) prolonged dives below the thermocline, 56.5% of the day. For seven of the tracks, daytime basking rates increased when thermocline depth was <37 m. As fish moved offshore, there was less variability in vertical movements with a reduction in both basking activity and mixed layer occupancy, as well as an increase in average daytime depth. These data are discussed with respect to the potential development of alternative fishery options for the PLCA.

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Section: Discussionmentioning

confidence: 99%

Movements and behaviors of swordfish Xiphias gladius in the United States Pacific Leatherback Conservation Area

Sepúlveda

Aalbers

Heberer

et al. 2018

Fisheries Oceanography

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“…Increased upwelling stimulates primary productivity, which affects the water transparency and dissolved oxygen concentrations. The extent and variation of vertical migration of DSLs varies with dis solved oxygen concentration (Netburn & Koslow 2015), as well as water transparency (Isaacs et al 1974), and has been shown to vary across seasons (Urmy et al 2012), latitude (Tont 1976, Hazen & Johnston 2010 and in regions of high productivity (Isaacs et al 1974, Kaartvedt et al 1996. In years of low oxygen, the decline of midwater fish abundance may be attributed to increased vulnerability to predation as DSLs move into more illuminated waters (Koslow et al 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Meso pelagic organisms often associate and migrate in distinct layers, called deep scattering layers (DSLs) due to their high acoustic reflectance, which produces layers of detections when observed with active sonar systems. It appears that mesopelagic fish seek refuge in dark waters and at the edges of deep oxygen minimum zones which are inaccessible or un suitable for their more aerobic and visually oriented predators (Seibel 2011, Netburn & Koslow 2015. Both absolute light levels, as well as the rate of change in light levels, have been proposed as triggers for changes in the behavior of vertical migrators, and there also seems to be an endogenous rhythm component to vertical migration (Benoit-Bird et al 2009a, Ochoa et al 2013.…”

Section: Introductionmentioning

confidence: 99%

Lunar cycles affect common dolphin Delphinus delphis foraging in the Southern California Bight

Simonis¹,

Roch²,

Bailey³

et al. 2017

Mar. Ecol. Prog. Ser.

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In the Southern California Bight, the common dolphin Delphinus delphis is the most abundant dolphin species and preys upon small pelagic fish, mesopelagic fish, and cephalopods. Mesopelagic fish and many cephalopods are available throughout the year, and they form deep scattering layers, some of which characteristically undergo strong diel vertical migrations. The extent of vertical migration depends on the degree of sea surface solar and lunar illumination. At their daytime depth, mesopelagic prey are beyond the range of shallow-diving dolphins. Autonomous acoustic recorders were used to monitor dolphin echolocation at 2 offshore recording locations from 2009 to 2014. Manual and automated classification techniques were used to identify periods of high echolocation activity, indicative of common dolphin foraging. Clear lunar patterns existed in cool months, when echolocation activity was highest during the darkest periods of the night and lunar month, indicating times when dolphins were foraging, possibly on mesopelagic prey. Echolocation was more abundant during warm months, but diel and lunar patterns in echolocation were weaker. Generalized additive mixed models show that the observed patterns in echolocation activity are correlated with lunar day and position of the moon in the night sky. Seasonal patterns may represent geographic shifts in common dolphin populations, shoaling scattering layers, or prey switching behavior during the warm months, whereby dolphins target small pelagic fish not associated with the deep scattering layers. Overall, dolphin foraging activity declined from 2009 to 2014 during warm months, which may be related to a declining abundance of small pelagic fish.

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“…Sars,' which took place from 1 May to 14 June 2013 (Melle 2013). The observations were made in the period 4 to 11 May during the first leg across the Norwegian Sea and into the Icelandic Sea (Fig.…”

Section: Methodsmentioning

confidence: 99%

Evidence for light-controlled migration amplitude of a sound scattering layer in the Norwegian Sea

Norheim¹,

Klevjer²,

Aksnes³

2016

Mar. Ecol. Prog. Ser.

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Dissolved oxygen as a constraint on daytime deep scattering layer depth in the southern California current ecosystem

Cited by 71 publications

References 83 publications

Movements and behaviors of swordfish Xiphias gladius in the United States Pacific Leatherback Conservation Area

Movements and behaviors of swordfish Xiphias gladius in the United States Pacific Leatherback Conservation Area

Lunar cycles affect common dolphin Delphinus delphis foraging in the Southern California Bight

Evidence for light-controlled migration amplitude of a sound scattering layer in the Norwegian Sea

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