Predicting the vertical distribution of the opossum shrimp, Mysis relicta, in Lake Ontario: a test of laboratory-based light preferences

Light and temperature strongly influence the vertical distribution of the mysid shrimp, Mysis relicta . We monitored the vertical movements and depth selection behavior of mysids exposed to different light intensities and light–temperature gradients in the laboratory and derived a mysid light preference function in units relevant to mysid vision: “mylux”. Mysids preferred light levels between 10−8 and 10−7 mylux (∼10−6 to 10−5 lux) and rarely moved into waters of 10−3 mylux (∼0.1 lux) and greater. A model that assumed equal weight and independence of mysid light and temperature preference functions successfully predicted the proportion of mysids found in two different temperature–light combinations in the laboratory. This model also predicted the depth of maximum mysid density to within 2 m on two spring nights and within 5 m on two summer nights of varying moon phase and thermal conditions in Lake Ontario. This study provides novel insights into how temperature and light interact to influence the vertical distribution of mysids. Our model may be used to predict mysid vertical distribution in any deepwater system inhabited by mysids in which the primary mysid predators are visual feeders.

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Vertical movements of “escaped” farmed Atlantic salmon (Salmo salar L.)—a simulation study in a western Norwegian fjord

ICES Journal of Marine Science ◽

10.1093/icesjms/fsn213 ◽

2009 ◽

Vol 66 (2) ◽

pp. 278-288 ◽

Cited By ~ 26

Author(s):

Ove T. Skilbrei ◽

Jens Christian Holst ◽

Lars Asplin ◽

Marianne Holm

Keyword(s):

Atlantic Salmon ◽

Vertical Distribution ◽

Salmo Salar ◽

Simulation Study ◽

Vertical Movements ◽

Atlantic Salmon Salmo Salar ◽

Wide Range ◽

Norwegian Fjord ◽

Farmed Atlantic Salmon ◽

The Vertical Distribution

Abstract Skilbrei, O. T., Holst, J. C., Asplin, L., and Holm, M. 2009. Vertical movements of “escaped” farmed Atlantic salmon (Salmo salar L.)—a simulation study in a western Norwegian fjord. – ICES Journal of Marine Science, 66: 278–288. To study the vertical distribution of fish that had been allowed to escape, farmed Atlantic salmon were tagged with acoustic tags equipped with depth sensors, and then released on five different dates in the course of a year from two fish farms in the Hardanger Fjord in western Norway. Release stimulated the fish to dive to deeper than 15 m during the first hours or days post-release, often down to 50–80 m. However, during the following 4 weeks, most of the escapees spent most of their time above the pycnocline at depths of 0–4 m. The fish were more widely distributed in the water column after release during winter, but still spent most of the time in the cold surface layers. There was a wide range in the vertical distribution of individual fish, and the proportion of detections below 14-m depth ranged from 0 to 90%. There was a significant diurnal cycle in all seasons except midsummer, when the fish were less abundant in the upper layer during daylight, especially on brighter days. The results suggest that salmon diving activity following escape may complicate the recapture of escaped fish at the farm site but that the subsequent tendency of most fish to stay near the surface, virtually irrespective of the time of year, may facilitate recapture.

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Travelling disturbances in the ionosphere

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1950.0095 ◽

1950 ◽

Vol 202 (1069) ◽

pp. 208-223 ◽

Cited By ~ 94

Keyword(s):

Seasonal Variation ◽

Vertical Distribution ◽

Sudden Change ◽

Frequent Occurrence ◽

Vertical Movements ◽

Short Period ◽

The Mean ◽

The Vertical Distribution

Methods have been developed for the examination of the horizontal and vertical movements of short-period disturbances in the ionosphere. It has been found that quasi-periodic travelling disturbances with periods of from 10 to 60 min. are of frequent occurrence in the F region by day. They appear as temporary variations in the vertical distribution of ionization which show a horizontal progression and a vertical progression downwards. The horizontal directions of travel have a well-defined mean direction on most days. The mean direction shows a marked seasonal variation with a sudden change at each equinox. The horizontal rate of travel is usually between 5 and 10 km./min., and the rate of vertical progression downwards is approximately half the horizontal rate. The disturbances are considered to be variations of a compressional type in the atmosphere resulting in changes in the distribution of ionization.

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Diel vertical distribution of fish larvae during the winter-mixing period in the Northwestern Mediterranean

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2004.07.022 ◽

2004 ◽

Vol 61 (8) ◽

pp. 1243-1252 ◽

Cited By ~ 42

Author(s):

A. Sabatés

Keyword(s):

Vertical Distribution ◽

Water Column ◽

Fish Species ◽

Fish Larvae ◽

Distribution Patterns ◽

Diel Variation ◽

Surface Layers ◽

Light Levels ◽

Vertical Distributions ◽

The Vertical Distribution

Abstract The vertical distributions of the larvae of shelf and oceanic fish species that spawn during the winter-mixing period in the Mediterranean are described from 22 vertically stratified plankton tows. Diel differences in the vertical distribution patterns in relation to physical data and potential prey abundance throughout the water column were examined. Even in absence of stratification, the larvae of the various fish species showed different patterns of vertical distribution and diel changes. The larvae of shelf-dwelling species were found in the surface layers, mainly above 50-m depth, and with some exceptions, with very little diel variation in depth distribution. Therefore, the vertical distribution of the larvae of these species coincided with the maximum concentrations of their potential food, nauplii and copepodite stages of copepods. The larvae of mesopelagic fishes showed deeper distributions in the water column and most of these species were located closer to the surface during the day than at night. Given the homogeneity of the physical characteristics throughout the water column, except for light, this behaviour may be determined not only by the higher concentration of prey in the surface layers but also by adequate light levels for feeding.

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Preliminary Observations on the Vertical Distribution of Pacific Salmon (Genus Oncorhynchus) in the Gulf of Alaska

Journal of the Fisheries Research Board of Canada ◽

10.1139/f64-086 ◽

1964 ◽

Vol 21 (5) ◽

pp. 891-903 ◽

Cited By ~ 12

Author(s):

J. I. Manzer

Keyword(s):

Vertical Distribution ◽

Sockeye Salmon ◽

Chum Salmon ◽

Coho Salmon ◽

Pacific Salmon ◽

Gulf Of Alaska ◽

Downward Movement ◽

Seasonal Differences ◽

Vertical Movements ◽

The Vertical Distribution

The vertical distribution of Pacific salmon in the high-seas areas of the Gulf of Alaska was investigated from mid May through July in 1959 and 1960 by fishing with gillnets (constructed from 41/2–inch nylon web and measuring 40 ft in depth and initially 400 fathoms in length) at five depth intervals from the surface with the deepest between 160 and 200 ft.Sockeye salmon exhibited diurnal and seasonal differences in their vertical distribution while chum salmon showed diurnal differences. The downward movement of sockeye salmon appeared limited by the thermocline, especially during late June and July. This relationship was observed for chum salmon during hours of darkness only in late June and July. Other factors must also influence seasonal and diurnal vertical movements of sockeye and chum salmon. Within the conditions of the experiment, no consistent differences in the vertical migrations between fish of different age were apparent. Catches showed pink and coho salmon were nearer the surface than either sockeye or chum salmon.

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