Pump controllers for radar and ultrasonic transmitters

Movements of six northern pike (Esox lucius) were monitored for 5 to 51 days by ultrasonic transmitters implanted surgically. The pike were inactive during 80% of the eight hundred and eighty-nine 5-min intervals monitored during summer and winter. No regular diel changes in activity were noted, except that pike were inactive at night. Swimming velocities calculated from gross displacements were maximum, 42 cm/s (0.91 body lengths (BL)/s); average, 23.1 cm/s (0.45 BL/s).Key words: movements, diel activity, seasonal activity, northern pike, Esox lucius; swimming speeds

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Reproductive interactions between fugitive farmed and wild Atlantic cod (Gadus morhua) in the field

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f10-066 ◽

2010 ◽

Vol 67 (8) ◽

pp. 1221-1231 ◽

Cited By ~ 22

Author(s):

Justin J. Meager ◽

Jon Egil Skjæraasen ◽

Anders Fernö ◽

Svein Løkkeborg

Keyword(s):

Mating System ◽

Gadus Morhua ◽

Atlantic Cod ◽

Spatial Dynamics ◽

Wild Fish ◽

Spawning Ground ◽

Males And Females ◽

Farmed Escapees ◽

Ultrasonic Transmitters

Atlantic cod ( Gadus morhua ) are being increasingly farmed in net pens adjacent to coastal populations that are currently at historic lows. One concern is that farmed escapees enter local spawning shoals and mate with wild cod. We tested for the potential of escaped farmed cod to interact and hybridize with wild fish by examining the spatial dynamics of, and associations between, fish tagged with ultrasonic transmitters. Based on these data, we also investigated the basic mating system of cod in the field. The spawning ground was best described as a lekking arena. Wild males aggregated near the seafloor and associations between individuals were frequent. Wild females had a pelagic and dispersed distribution and rarely associated with each other. Associations between individual wild males and females were also infrequent. Farmed males rarely associated with wild fish and had core usage areas above the wild males, suggesting that they were not admitted into the spawning arena. Farmed females were over the spawning arena more frequently than wild females and often associated with wild males at the depth of the spawning arena, indicating potential mating with wild males and the possibility of courtship interference. Hence, hybridization between escaped farmed and wild cod is likely.

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Simulation and experimental study of the influence of a front face layer on the response of ultrasonic transmitters

Ultrasonics ◽

10.1016/0041-624x(83)90074-4 ◽

1983 ◽

Vol 21 (4) ◽

pp. 177-183 ◽

Cited By ~ 5

Author(s):

Y. Jayet ◽

F. Lakestani ◽

M. Perdrix

Keyword(s):

Experimental Study ◽

Front Face ◽

Face Layer ◽

Ultrasonic Transmitters

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Diel Movement of Walleye, Stizostedion vitreum vitreum, in West Blue Lake, Manitoba, as Determined by Ultrasonic Tracking

Journal of the Fisheries Research Board of Canada ◽

10.1139/f76-255 ◽

1976 ◽

Vol 33 (9) ◽

pp. 2070-2072 ◽

Cited By ~ 10

Author(s):

J. R. M. Kelso

Keyword(s):

High Activity ◽

Body Length ◽

Stizostedion Vitreum ◽

Natural Activity ◽

Blue Lake ◽

Diel Movement ◽

Ultrasonic Tracking ◽

Sloping Bottom ◽

Ultrasonic Transmitters

Eight walleye (Stizostedion vitreum vitreum) between 2 and 5 yr of age were equipped with ultrasonic transmitters, released, and followed for periods up to 24 h. During the study period, September 24–October 2, 1975, West Blue Lake was thermally stratified. Movement was limited to the homothermous epilimnion, above 10 m, and to the region of steeply sloping bottom of about 5–10 m which was usually within 100 m of shore. Midbasin crossings of the lake were infrequent. Transmitter attachment caused temporary high activity after which a more normal rhythm was apparent with peaks of activity at dusk and dawn. The majority, 86%, of observed swimming speeds were under 1 body length s−1. Since much localized activity, too restricted to measure, was apparent, these observations must be regarded as only approximations of natural activity.

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