Vertical distribution and migration of oceanic micronekton off Oregon

Pearcy, William G.; Krygier, Earl E.; Mesecar, R.; Ramsey, Fred L.

doi:10.1016/s0146-6291(77)80002-7

Cited by 122 publications

(49 citation statements)

References 11 publications

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“…Micronekton (animals between 2 and 20 cm) was sampled at night (19:OO to 04:OO h) with an IYGPT midwater trawl (mouth area l n12, mesh size 1000 pm) (see Young & Blaber 1986) fitted with an opening/closing codend (Pearcy et al 1977). The codend had an electronic timer to trip nets at set tlmes.…”

Section: Methodsmentioning

confidence: 99%

Biomass of zooplankton and micronekton in the southern bluefin tuna fishing grounds off eastern Tasmania, Australia

Young¹,

Rw²,

Lamb³

et al. 1996

Mar. Ecol. Prog. Ser.

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The southern bluefin tuna (SBT) supports a seasonal fishery off the east coast of Tasmania, Australia. The distribution of zooplankton biomass in this region was examined a s a means of finding out why the SBT are attracted to this area. We examined whether there was a particular area or depth stratum that supported significantly greater amounts of potential feed, directly or indirectly, for SBT Samples of zooplankton and micronekton were collected during the winter SBT fishery seasons in 1992-94. Five net types (mouth opening 0 25 to -80 m') w~t h codend mesh sizes ranging from 100 to 1000 pm were used. Samples were collected from 4 main hydrographic areas: warm East Australian Current water, cool subantarctic water, the front separating them (the subtrop~cal convergence), and the adjacent shelf. Four depth strata (50, 150, 250 and 350 m) were also sampled. In contrast to our expectations, the biomass in the subtropical convergence was no greater than that in the 3 other areas. Rather, it was the shelf, albeit with some inconsistencies, that generally had the greatest biomass of both zooplankton and micronekton. Offshore, there was no s~gnificant difference in the biomass of the depth strata sampled, although the biomass of gelatinous zooplankton in the surface waters increased during the study period. We suggest that the higher bionlass on the shelf is the result of increased nutrients derived from a mixture of subantarctic water and upwelling along the shelf break. This biomass is converted via krill and gelatinous zooplankton to small pelagics such as jack mackerel, and finally to top predators, amongst which is SBT The SBT, particularly sub-adults, may time their migration eastward to take advantage of the concentrations of prey present at this tune of year

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Section: Methodsmentioning

confidence: 99%

Biomass of zooplankton and micronekton in the southern bluefin tuna fishing grounds off eastern Tasmania, Australia

Young¹,

Rw²,

Lamb³

et al. 1996

Mar. Ecol. Prog. Ser.

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“…Diaphus theta and Tarletonbeania taylori begin diel vertical migration and actively feed in the epipelagic layer at night after transformation from larvae to juveniles (Pearcy et al 1977, Watanabe et al 1999, Moku et al 2000. In the highly productive subarctic and transition regions, adult D. theta feed actively, both during the daytime in the mesopelagic and at night in the epipelagic zones (Paxton 1967.…”

Section: Feeding Incidence and Diurnal Feedingmentioning

confidence: 99%

“…Thus, after transformation to juveniles, D. theta change their feeding periodicity from diurnal to all-day feeding, while T. taylori shift their feeding from diurnal to nocturnal after transformation to juveniles. Proto- myctophum thompsoni is a non-migrant species that begins to stay in the 200 to 400 m layer from the juvenile stage (Pearcy et al 1977, Watanabe et al 1999). Adult P. thompsoni feed both during the day and at night in the mesopelagic zone.…”

Section: Feeding Incidence and Diurnal Feedingmentioning

confidence: 99%

“…The larvae of these species are distributed in the productive upper 200 m layer of the transition region, both during the day and at night (Sassa 2001, Tsukamoto et al 2001. After transformation from larvae to juveniles, D. theta and T. taylori begin diel vertical migrations, while P. thompsoni shows no diel vertical migration and remains primarily in the upper mesopelagic layer at a depth of 200 to 400 m (Pearcy et al 1977, Watanabe et al 1999.…”

Section: Introductionmentioning

confidence: 99%

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Larval feeding habits of Diaphus theta, Protomyctophum thompsoni, and Tarletonbeania taylori (Pisces: Myctophidae) in the transition region of the western North Pacific

Sassa¹,

Kawaguchi²

2005

Mar. Ecol. Prog. Ser.

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We examined the larval feeding habits of the 3 dominant myctophids, Diaphus theta, Protomyctophum thompsoni, and Tarletonbeania taylori, in the transition region of the western North Pacific. Feeding incidence for D. theta and T. taylori larvae was higher during the day than at night (mean: 70.7 to 84.4% vs. 2.2 to 4.1%), indicating that they are daytime visual feeders. Larvae of P. thompsoni were also visual feeders, with a daytime feeding incidence of 83.0%. The proportion of nighttime feeding in P. thompsoni gradually increased with development, which suggests faster larval adaptation of this non-migrant species to the poor light conditions in the mesopelagic zone. D. theta larvae ≤7.9 mm in body length (BL) fed mainly on copepod nauplii, which were replaced by calanoid copepodites and Oithona spp. in larvae ≥8.0 mm BL. The most important prey for smaller P. thompsoni and T. taylori larvae ≤7.9 mm BL were nauplii and Oithona spp., which were replaced by calanoid copepodites and ostracods in P. thompsoni and copepod eggs in T. taylori with increased development. Competition for prey among the larvae of these 3 myctophids was mostly avoided because of diet and habitat-depth segregation. Interspecific comparisons of feeding habits among the 3 species, in addition to larvae of 3 other myctophids found in the study area, suggested that their feeding strategies were associated with mouth size, i.e. larvae with larger mouths tended to take larger prey rather than a large number of smaller prey. This interspecific difference in feeding strategy is reflected in the diverse morphological characters of myctophid fish larvae.

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“…The vertical distribution and migrations of adult T. crenularis differ geographically. In the center of the species distribution area, off Oregon, adults migrate between depths 0-850 m (peak 0-50 m) at night and 200-850 m (peak 350 m) during the day (Pearcy 1977;Pearcy et al 1977). In the southern part of their range, near the Baja California peninsula, they reside in slightly deeper depths whereas in the north off British Columbia, their vertical distributional range is narrower.…”

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confidence: 99%

Larval stage duration, age and growth of blue lanternfish Tarletonbeania crenularis (Jordan and Gilbert, 1880) derived from otolith microstructure

2010

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Tarletonbeania crenularis specimens were collected off Oregon in 2006 and 2009 and aged by enumeration of growth increments in otoliths (sagittae). Three microstructural zones were evident in the otoliths of juvenile and adult fish: central, middle, and external. The number of increments in the central zone are thought to be deposited during the larval phase which is restricted to the uppermost 350 m water layer. The middle zone constituted of barely visible increments, most likely represented a non-migratory behavior of transforming larvae and early juvenile stages. Well defined growth increments were found in the external zone which was presumably formed during extensive vertical migrations of juvenile and adult fish. If the enumerated increments were deposited daily, as previously validated for other myctophid species, the examined individuals indicated a shorter life span than has been formerly reported on the basis of length frequency analysis. The otolith microstructure interpretation was supported by otolith size to fish length proportions and somatic growth of larvae and postlarval fish. Otolith length to standard length relation was described by linear regression models for larvae and postlarval migratory stages with an abrupt disruption between these two groups. The number of growth increments in otoliths plotted against standard length showed a curvilinear growth for larvae and for the postlarval fish. The lack of information on the size at age of transforming larvae and non-migratory early juveniles did not allow us to estimate a complete growth model for T. crenularis. However, a pronounced decrease in growth between larval and postlarval migratory phases was distinguished. The uncoupling of otolith and somatic growth was interpreted as a merged effect of downward migration of larvae to the mesopelagic transformation depth, prolonged stay of transforming larvae and early juveniles at this depth without performing diel vertical migrations, and shrinkage during metamorphosis. Back-calculated hatch dates suggests a prolonged spawning season of this species without any distinct peak.

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Vertical distribution and migration of oceanic micronekton off Oregon

Cited by 122 publications

References 11 publications

Biomass of zooplankton and micronekton in the southern bluefin tuna fishing grounds off eastern Tasmania, Australia

Biomass of zooplankton and micronekton in the southern bluefin tuna fishing grounds off eastern Tasmania, Australia

Larval feeding habits of Diaphus theta, Protomyctophum thompsoni, and Tarletonbeania taylori (Pisces: Myctophidae) in the transition region of the western North Pacific

Larval stage duration, age and growth of blue lanternfish Tarletonbeania crenularis (Jordan and Gilbert, 1880) derived from otolith microstructure

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