First feeding of Atlantic salmon, Salmo salar L., under different photoperiods and light intensities

Groups of pooled Atlantic salmon (Salmo salar) eggs were incubated in a "California" incubation system with and without astro-turf, an artificial substrate, and later transferred to separate feeding units. Alevins reared in astro-turf absorbed their yolk sac faster and more efficiently than alevins reared on a flat screen. Alevins reared on the flat screen developed yolk sac constrictions probably due to the backward and lateral force created by the high swimming activity. No such malformations were found on the yolk sacs of the astro-turf reared alevins. The fry hatched without astro-turf grew faster than the fry hatched with astro-turf during the initial feeding period, but later this was reversed. Mortality of alevins and fry hatched with astro-turf was lower during incubation and during first feeding.

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Photoperiod Control of Parr–Smolt Transformation in Atlantic Salmon (Salmo salar): Changes in Salinity Tolerance, Gill Na+,K+-ATPase Activity, and Plasma Thyroid Hormones

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f87-175 ◽

1987 ◽

Vol 44 (8) ◽

pp. 1462-1468 ◽

Cited By ~ 144

Author(s):

Stephen D. McCormick ◽

Richard L. Saunders ◽

Eugene B. Henderson ◽

Paul R. Harmon

Keyword(s):

Atlantic Salmon ◽

Thyroid Hormones ◽

Atpase Activity ◽

Salmo Salar ◽

Salinity Tolerance ◽

Continuous Light ◽

Day Length ◽

Atlantic Salmon Salmo Salar ◽

First Feeding ◽

Photoperiod Control

Atlantic salmon (Salmo salar) were subjected to artificial photoperiods to determine the manner and extent of photoperiod control of the parr–smolt transformation. Exposure to continuous light (L24) at first feeding and maintained throughout the rearing period inhibited increases in salinity tolerance and gill Na+,K+-ATPase activity that occurred in spring in fish raised under simulated natural photoperiod (SNP). Fish reared under continuous light and returned to SNP in October (L24OCT) underwent normal increases in salinity tolerance and gill Na+,K+-ATPase activity, whereas those returned in December (L24DEC) underwent delayed and intermediate increases. Plasma thyroxine peaks occurred simultaneously in all groups but were diminished in the L24 and L24DEC groups. Plasma 3,5,3′-triiodo-L-thyronine levels were not affected by any photoperiod treatment. Inhibition of the parr–smolt transformation decreased the potential for growth in seawater. In spite of changes in the timing of the transformation induced by photoperiod treatment, salinity tolerance and gill Na+,K+-ATPase activity were strongly correlated; correlation between changes in salinity tolerance and plasma thyroid hormones were, by comparison, weak. The results demonstrate that continuous light applied early in ontogeny and maintained throughout the rearing period inhibits osmoregulatory changes associated with parr–smolt transformation, whereas increasing day length during winter–spring stimulates transformation.

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Development of salinity tolerance in underyearling smolts of Atlantic salmon (Salmo salar) reared under different photoperiods

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f95-024 ◽

1995 ◽

Vol 52 (2) ◽

pp. 243-251 ◽

Cited By ~ 59

Author(s):

Åse I. Berge ◽

Arne Berg ◽

Trygg Barnung ◽

Tom Hansen ◽

Hans Jørgen Fyhn ◽

...

Keyword(s):

Atlantic Salmon ◽

Atpase Activity ◽

Salmo Salar ◽

Salinity Tolerance ◽

Continuous Light ◽

Short Photoperiod ◽

Subsequent Reduction ◽

Atlantic Salmon Salmo Salar ◽

First Feeding ◽

Natural Photoperiod

Groups of Atlantic salmon (Salmo salar), first fed in mid-February 1989, were reared under continuous light (LL) at 12–15 °C until late June. One group remained on LL, while the FEB, MAR, and MAY groups were subjected to segments of a simulated naturally increasing photoperiod (61°N), with initial daylength corresponding to February 1, March 15, and May 1, respectively. The MAR and FEB groups developed important smolt characters (increase in gill Na+,K+-ATPase activity, hypoosmoregulatory ability, and salinity tolerance) during the experiment whereas LL and MAY groups showed only incomplete changes in smolt status. The combination of continuous light during first feeding and early parr stages with a subsequent reduction to short daylength followed by a segment of simulated natural photoperiod allow important parts of the parr–smolt transformation to be completed. The period of exposure to short photoperiod is critical for the synchronization of smolt characters in underyearling Atlantic salmon.

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Ontogeny of Feeding Behavior of First-Feeding Atlantic Salmon (Salmo salar)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f91-225 ◽

1991 ◽

Vol 48 (10) ◽

pp. 1896-1904 ◽

Cited By ~ 35

Author(s):

David J. Coughlin

Keyword(s):

Atlantic Salmon ◽

Feeding Behavior ◽

Salmo Salar ◽

Exogenous Feeding ◽

Feeding Mode ◽

Atlantic Salmon Salmo Salar ◽

First Feeding ◽

Swimming Motion ◽

In The Wild ◽

Time To Learn

Feeding strikes of Atlantic salmon (Salmo salar) alevins preying upon Daphnia are described using videorecording of synchronous lateral and antero-ventral views. Based on examination of characteristics such as aiming inaccuracy and capture distance, it is demonstrated that feeding behavior significantly improves during the first 2 wk after initiation of exogenous feeding. With increasing experience, young salmon tend to capture prey more quickly and with greater accuracy. First-feeding alevins use a body-ram feeding mode, relying on their swimming motion to overtake and capture prey. After 7–10 d of feeding, the fish change to a suction feeding mode that effectively uses suction generated by expansion of the orobranchial chamber to pull in prey from a distance. Also, feeding behavior of alevins raised on a commercial salmon feed lags developmentally behind the behavior offish raised on live food. This lag time is short (2–3 d), indicating that despite reports to the contrary, hatchery-raised fish do not require a Song time to learn to capture prey effectively in the wild.

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