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Optimization of feed distribution to sea caged fish with an emphasis on Atlantic salmon (Salmo salar L.)


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Blyth, Peter John (2000) Optimization of feed distribution to sea caged fish with an emphasis on Atlantic salmon (Salmo salar L.). Unspecified thesis, University of Tasmania.

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The aquaculturist is faced with a number of difficulties when feeding fish. Apart from
the human time component involved in feeding a large number of fish to appetite, it is
important to feed an appropriate quantity at a suitable frequency to ensure that no
food is wasted and fish are satiated. Fish display preferential feeding patterns that
relate to endogenous rhythms and changing biological and environmental factors. This
study describes a new technology called the "Adaptive" Feeding System designed to
automatically feed fish by regulating feed input based on the levels of waste food
detected beneath a feeding zone. A series of trials with the system are also discussed.
The system consisted of a surface mounted microprocessor linked to an underwater
sensing device capable of resolving a single feed pellet. An internal algorithm
controlled the operation of the system. Feeding data was stored by the
microprocessor and down loaded via a data-logger to an IBM-compatible computer
for analysis with specific software.
Atlantic salmon, Salmo salar, in sea-cages exhibit feeding patterns which vary both
diurnally and seasonally. Hitherto, there are no data reporting feed rate and its
variation through a complete annual cycle. Here we present data from Scotland
showing diurnal and inter-seasonal variation in feeding patterns and feeding rates of
Atlantic salmon fed daily to satiation from shortly after transfer to seawater until
harvest about 11 months later. A major feeding peak regularly occurred soon after
dawn, and feeding rates remained high for approximately one hour. Over the
remainder of the day the fish fed at a lower, but steady rate. Relative feed intake
varied over the trial, being initially high in summer followed by a sharp decline in
autumn, and then further declining until fish reached harvest size at the beginning of
the following summer. Further investigations of the relationship between variation in
circannual feeding patterns and environmental parameters should now be carried out
to improve the understanding of the mechanism behind these patterns. Tasmanian Atlantic salmon (2-3kg) fed daily to satiation for four months over winter
displayed a diurnal pattern of feed intake. The first peak of intake commenced just
after dawn for 2-3 hours during which up to 60% of the total daily feed intake
occurred. Some feeding occurred during the middle of the day but this was eclipsed
by a significant feeding bout approximately 30 minutes before total darkness in the
evening. This typical diel pattern often disintegrated due to changes in environmental
factors but more significantly due to suspected disturbance by human activity or the
presence of predators. Surface activity of the salmon, in response to feed input, and to
a lesser extent swimming speed of the fish, were found to be reasonable indicators of
feed intake. A better indicator of feed intake was measured by monitoring small
quantities of waste feed sensed by the adaptive feeding systems' sensor.
A further study, investigating the effect of restricted feeding periods followed by refeeding
to satiation was carried out on Atlantic salmon (approx. 1.3kg) during
winter/spring on growth. Four treatments included those fed daily to satiation (A),
those fed for 5 days then starved for 2(B), those fed for 10 days then starved for 4(C)
and those fed for 7 days then starved for 7(D). Every 28 days growth was measured
by weight. Group A showed significantly higher growth (p<0.05) in weight than the
other treatments over 4 months. Groups B and C showed similar growth and Group D displayed the poorest growth. The ability of periodically starved salmon to catch up
in size to continually fed salmon was not apparent from this experiment. The results
differ from other studies that have shown finfish can compensate totally for lost
The application of the "Adaptive" feeding technology to other fish species, including
Atlantic salmon (Salmo salar) in Scotland, Chinook salmon (Oncorhynchus
tshawytscha) in New Zealand, barramundi (Lates calcarifer) in Northern Australia
and yellow-tail (Seriola quinqueradiata) in Japan, was undertaken. Improvements in
production performance due to satiation feeding and the use of the "feedback" system
were noted which included a reduction in FCR 5-20% and a 10-40% reduction in
production time for similar harvest weights.

Item Type: Thesis (Unspecified)
Keywords: Atlantic salmon, Fishes, Salmon
Copyright Holders: The Author
Additional Information:

Thesis (MAppSc (Aq))--University of Tasmania, 2001. Includes bibliographical references

Date Deposited: 25 Nov 2014 00:50
Last Modified: 11 Mar 2016 05:54
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