We take a look at technology in the aquaculture industry

1. FISH FARMING
TECHNOLOGY
SUPPLEMENT
SUPPLEMENT
The MAG seal
deterrent system
The MAG seal deterrent is the most effective
and cetacean-friendly device on the market
Temperature stress
Water temperature and stress control

2. FISH FARMING TECHNOLOGY
Sound technology The MAG seal deterrent is the most effective
and cetacean-friendly device on the market
For the last 20 or so years the
Airmar DBII+ has been considered
the best Seal Deterrent on the
market. And whilst this system is
as good as ever, Mohn Aqua felt that as the
Control System uses 1980s technology, it
could do with modernising.
So, with the help, advice and blessing of
Airmar, Mohn Aqua developed a new, state-of-
the-art Control Box – the MAG Seal
Deterrent – which, amongst other things,
increased the system from a four projector
system to one that offered the choice of two,
four or six projectors. As such, it can be set
up as a standard four-Projector System and, if
a site is experiencing problems, another two
Projectors can be added.
'Another important advantage of the new
system', says Mal Scott, General Manager of
Mohn Aqua, 'is that the Pulses can be varied, in
power, duration and firing pattern. Plus, it is 50
per cent more efficient than the DBII+, which
means half the batteries need to be used, or
existing batteries last twice as long during
power outages.'
The MAG Seal deterrent was also devel-oped
after discussions with both the Seal
Mammal Research Unit and the Salmon
Aquaculture and Seals Working Group, where
two concerns with current ADDs were iden-tified.
The first was that operators could not
immediately tell that a system had a fault until,
for example, there was a sudden increase in
morts. Secondly, there is a growing feeling
that systems need to become more Cetacean
Friendly.
As such, the MAG Seal Deterrent has
Fault Indicators for each Projector. After a
'soft start' Switch – designed to not instantly
frighten Cetacean, the super bright LEDs turn
from Amber to Green, with the Projector that
is firing at the time flashing Green. This lets the
operators know from a huge distance away
that all is good.
Any faults on a Projector or Cable are
instantly recognised by an internal Processor,
and the channel is automatically shut down,
preventing damage to the Control Circuits.
The LED for that Channel instantly turns red
and the operators know which channel and
which projector has a problem. This is par-ticularly
useful for audits, which are now are
carried out in monitoring Seal problems. The
next Generation of projectors, which will be
available as soon as Airmar have finished trials
and start manufacture, have an inbuilt Sensor
that will give even more fault information to
the new control box.
Cetacean-friendly
Mohn Aqua also believe that the MAG
Seal Deterrent is the most Cetacean-friendly
system available. It can be put into
a 'Standby' mode, where the output can be
toned down to very low levels when there
is not a current threat to the site. This way,
Cetacean, always know the system is there,
keep a distance away, but are not frightened
by it. When a threat does occur, the system
can be switched back to normal operation
through the 'soft start' sequence. This is far
better than a 'detection' system that will lay
dormant, almost asking Cetacean to come
close, then fire unexpectedly, causing fear and
panic.
This system is also fully compatible with cus-tomers'
existing DBII+ Projectors, meaning
that to upgrade sites only have to replace the
Control Box and not the full installation.
The MAG Seal Deterrent system has been
installed at a number of Scottish Seafarms
002 | INTERNATIONAL AQUAFEED | Fish farming Technology

3. (SSF), Marine Harvest and Scottish
Salmon Company sites, as well as
three large Salmones Magallanes
sites in Chile, where they have
proved to be extremely effective. For
example, as Ewan Gibb, site manager
at SSF Summer Isles, explains: 'Early
on in the year we had a severe seal
issue at one cage in particular. Once
the new system was installed, over-night
the seal problem stopped at
that cage; and progressed to another
cage.
'What I like about them is that they
can be programmed on site, they
don't need to be taken away, and
you can also vary frequencies, pulse
rates, the gaps between the pulses
– everything is adjustable on it. It's
really doing the job well.'
This is echoed by Colin MacDonald,
site manager at SSF Scallastle: 'It's a
very good system and the display
panel is very clear and easy to read',
he explains. 'Since we've had it
installed we've had no problems with
seals; we have no complaints with it
at all.'
Mohn Aqua is also beginning an
agreement with Scottish Seafarms
in Shetland, which will see the
company carrying out an audit of all
SSF Shetland’s existing Airmar/Mohn
Aqua Seal Deterrent equipment. This
will lead to SSF Shetland receiving the
optimum efficiency from its existing
equipment and recommendations for
modification and upgrades to ensure
that they continue to have the very
best possible protection in the future.
FISH FARMING TECHNOLOGY
We think this is the
best Seal Deterrent
on the market
(so does Airmar, which is why they tested and approved it)
• 50% more efficient than the Airmar DB11
• Varies pattern, length and breaks of pulses preventing seal attacks
• Works perfectly with existing projectors, just upgrade the control box
• Fault protection, upgraded cover, cetacean friendly
Replace your Metal halide lights with our
Revolutionary LED light system
• Reduces 75% of electricity use
• Weighs only one kilo, can be installed by one person
Scotland: +44 (0) 1309 678270
Norway: +47 53 500 740
info@mohnaqua.com
www.mohnaqua.com
Fish farming Technology | INTERNATIONAL AQUAFEED | 003

4. FISH FARMING TECHNOLOGY
Temperature stress
Planning water temperature and stress control through aquatic feeds
by Ruijian Sun, Haifeng Mi, Lu Zhang, Wugang Wang,Yuanhong,wen, Chuny Xue（Technology center of
tongwei Co., LTD Chengdu, 610041
Most aquatic animals are
poikilothermic whose
metabolism and growth
are closely related to the
environmental temperature. All farmed fish
and shrimps have their optimum range of
temperatures for growth. At temperatures
outside this range, metabolism and growth
are severely affected and may eventually
cause death if the water temperature drifted
too far away from the optimum range. This
article provides a review on the nutritional
physiology of aquatic animals affected by
temperature fluctuations with some recently
published data.
In recent years, the erratic changes in
global temperatures have caused huge losses
to aquaculture in China and elsewhere.
Guangxi Aquatic animal husbandry and vet-erinary
Association reported that in 2011
alone, fishery economic loss affected by tem-perature
was more than 100 million Yuan.
China-Fishery net reported that in 2013
Jiangxi aquaculture economic loss affected by
low temperature was more than 80 million
yuan; Anhui fishery economic loss affected
by high temperature was as high as 100
million yuan.
The influence of water
temperature on fish
behavior and physiology
Water temperature and fish feeding
The change of environmental tempera-ture
directly affects the fish feeding and
growth. When temperature increases within
the range of optimum temperatures, cor-responding
metabolism, food intake, growth
also increases. Both feed intake and feed effi-ciency
will decrease at temperatures higher
or lower than the optimum temperature.
It is important for aquaculture industry to
understand the growing temperature to
optimize feeding management and minimise
the feed cost.
The influence of water
temperature on fish immunity
The change in environmental temperature
also affects fish immune and metabolism. Qin
Chuanjie reported that water temperature
mainly affects the antibody secretion and the
activity of immune active cells and quantity,
lysozyme activity and complement activation
pathways and activity. When the environmen-tal
temperature is higher than physiological
adaptation range, specific and nonspecific
immune activity of fish are subdued. However,
within the optimum temperature range, if one
of the immune system (one of the specific or
non-specific immunity) is weakened by a small
temperature change, some other immune
systems are usually improved.
Water temperature and
energy metabolism
Study on fish energy metabolism analyses
the quantitative relationship between energy
balance components and the effect of various
ecological factors. Cui and Wootton first put
forward the idea of restricted feeding during
abnormal temperature to keep the balance
of each energy component in sunfish. Then
Xie & Sun and Cui et al. reached a similar
conclusion in a study with southern catfish
and grass carp. But Sun Yao found that the
temperature significantly affects energy bal-ance
model in black bream, red porgy and
black Jun. Within the appropriate temperature
range, feed intake, growth, metabolism and
excretion rate showed a trend of slow growth
with increasing temperature. That is to say,
under the condition of ad libitum feeding,
fish energy distribution pattern is still affected
by temperature. Because of differences in
adaptive mechanisms among various groups
of fish species it is important to establish the
energy budget for individual species to be able
to determine the energy required for basal
metabolism and for other metabolic activities
at various temperatures.
Temperature is an important factor of
affecting basal or resting metabolism, which
is mainly the amount of energy required to
maintain homeostasis when inactive. Within
the appropriate temperature range, respi-ration
and oxygen consumption increases
with the increase of environmental tempera-ture
[12].In this case, with the temperature
increasing, metabolism, enzyme activity, basic
metabolism of fish will increase causing higher
energy requirement for basal metabolism. On
the other hand, as the water temperature
exceeds the optimum range, oxygen con-sumption
rate will drop down decreases with
the rise of temperature. It happens because
of decreasing metabolic requirement because
of reduced enzyme activity, degeneration or
004 | INTERNATIONAL AQUAFEED | Fish farming Technology

5. inactivation of various enzymes and may be
because of altered physiological state.
The influence of water temperature
on fish digestive enzyme activity
Growth rate of fish is closely related
to the environmental temperature, which is
again, closely related to all digestive enzymatic
activities. Chen found that activity of protease,
amylase and lipase in juvenile red sea bream
increases with the increase of temperature
within limits, and then decreases when the
temperature exceeds the optimum level. A
similar result was reported in grass carp, com-mon
carp, silver carp and bighead carp, all
showing significant effects of water tempera-ture
on digestive enzyme activities.
However, the effects of a specific water
temperature on digestive enzymes activities
vary from species to species and affected by
their diets, feed composition and quality and
habitat quality. For example, Hong et al., in a
study with juvenile amur sturgeon, reported
much higher temperature (between 28oC
and 21oC) for optimum protease activities
compare to those for optimum lipase activity
(14oC).
Water temperature on
gene expression
In modern ichthyology research, a grow-ing
phenomenon is to study the effects
of temperature
on various gene
expressions. The
recent studies
mostly focused
on genes
affected by tem-perature,
such
as heat-stress
or heat-shock
proteins (HSP),
warm tempera-ture
adapta-tion
proteins,
cytochrome oxi-dases,
and antifreeze proteins. Heat stress
proteins such as HSP70 could improve
the stress resistance ability to temperature.
Warm temperature acclimation protein,
affected by temperature, is a serum gly-coprotein
produced by fish in warm tem-perature,
and affects physiological functions
of fish. Cytochrome oxidase is a electron
chain transport enzyme, gene expression
of which is usually significantly affected by
temperature. Antifreeze proteins area class
proteins enabling fish to withstand freezing
temperature were originally found in the
serum of marine fish in Antarctic and Arctic
regions. Understanding the effects of tem-perature
on these sensitive proteins would
help to explain the effect of temperature
FISH FARMING TECHNOLOGY
on metabolism of cold-water fish and their
ability to withstand temperature stress on
molecular level.
Effect of fish nutrition on
temperature stress
Temperature stress is a major cause of
productivity loss in aquaculture. It not only
affects fish metabolism and growth perfor-mance
by damaging the enzymes, but also
causes self-protection to withstand the stress
of temperature variation. Spending too much
energy for self-protection during high-temper-ature
periods affects growth and immunity,
and the animals become more susceptible
to secondary infections. Therefore, decreas-ing
the effect of heat-stress using nutritional
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www.oj-hojtryk.dk
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CVR.: 73 66 86 11
Fish farming Technology | INTERNATIONAL AQUAFEED | 005
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Fax: +45 82 28 91 41
mail: info@oj-hojtryk.dk

6. FISH FARMING TECHNOLOGY
means would be highly beneficial to the farm-ing
industry. Hence, nutritional regulations
with appropriate dietary supplements such as
energy-yielding or anti-stress substances can
improve fish immunity and anti-stress activity,
and may well result in reduction of the loss of
productivity due to heat stress.
Nutrition regulation under high
water temperature condition
Many published studies have discussed fish
physiological responses under high tempera-ture
but few researches elucidated nutritional
regulation to reduce the effect. Fish shows
lower growth and higher protein turnover rate
during heat stress. An increase in dietary pro-tein
to energy ratio might meet the increased
need of proteins. Glencross et al. (2010)
reported that increased dietary protein to
energy ratio of barramundi (Lates calcarifer)
provided significant benefits in terms of reduc-ing
the impact of growth retardation under
heat stress. However, it was not observed
in Atlantic salmon that can be related to the
narrow range of dietary protein to energy
ratio. In Nile tilapia (Oreochromis niloticus),
Caroline et al. (2012) reported decreased
synthetic rate and concentration of blood
cell, reduced the activity to transport oxygen,
under heat stress affecting fish health. The
authors showed that dietary supplementation
of vitamin B6 could enhance blood cell syn-thesis
resulting in better growth performance.
Nutritional regulation at
low temperature stress
The membrane fluidity is decided by the
fatty acid composition in membrane lipid and
usually decreased during low temperature.
Earlier studies showed that the unsaturated
fatty acid concentration in cell membrane
is positively correlated to the cold stress
resistance capacity in fish-
-. Thus, increasing the
dietary poly-unsaturated
fatty acids, especially the
n-3 unsaturated fatty
acids, can improve the
cold stress resistance
capacity in fish.
An increase in dietary
tryptophan, methio-nine
and tyrosine can
also improve cold-stress
resistance during winter.
Tyrosine is the precursor
of catecholamine, which
is the precursor of nor-epinephrine
(NA) and
adrenaline (Adr). Both NA
and Adr can regulate the
metabolic balance helping
fish to adapt to the stress.
The supplementation of
tyrosine increases the cold
resistance capacity of fish by improving the
biosynthesis of catecholamine.
On the other hand, tryptophan, a pre-cursor
of 5-hydroxytryptamine (5-HT) that
regulates secretion of some hormones, can
improve fish’s cold stress resistance capacity
by regulating feed intake. Methionine, as the
methyl donor, is involved in the methylation
process of hormones, nucleic acids and neu-rotransmitters.
Cheng et al. [32] showed that
the lack of methionine may lower fish’s cold
resistance capacity.
The supplementation of dietary vitamin
E and vitamin C under cold stress has also
shown to eradicate the peroxide and the over
all concentration of free radicals, which can
improve immunity and maintain physiological
homeostasis. Pitaksong et al. reported that the
supplementation of vitamin E and vitamin C in
diet improves growth performance of catfish
under cold stress and enhance its physiological
and immunity conditions.
The supplementation of dietary minerals
is also good for fish to resist the cold stress.
Minerals such as Zn and Fe in combination
with the antioxidants, can erase the peroxide
in fish. The supplementation of dietary Zn
can increase cold resistance by keeping the
mitochondrial membrane balance in fish under
cold-stress [34]. Where as, supplementation
of Fe may improve respiratory enzyme activity
and prevent anemia. However, higher supple-mentation
of minerals in fish feed than the safe
amount may become toxic and do more harm
than good.
Recently, researches indicated the capacity
of some Chinese herbs to improve immune
response in fish. The natural components
of Chinese herbs, such as flavonoids and
curcumin, can serve as antioxidants enhanc-ing
the antioxidative activities in fish. Thus,
the supplementation of Chinese herbal can
increase the immune function and cold resist-ance
capacity of fish.
Moreover, high dietary protein or energy
may help fish to resist the cold stress. Kevin
reported showed higher growth performance
and feed efficiency under cold stress in Asian
sea bass (Lates calcarifer) fed high energy
diets compared to those fed the low energy
diets. On the other hand, Qiang et al found
that tilapia fed with high protein feed showed
high glucose, cholesterol, total protein and
triglyceride levels in their serum, which can
supply energy during cold stress.
Commercial Tilapia feed adjustment
program in Guangdong
Tilapia is a popular food fish cultured
mainly in Guangdong, Guangxi and Hainan.
They are omnivores and well adapted to
hypoxia, while they are intolerant to low or
high temperature. The optimal temperature
for tilapia growth varied between 22 and 32
℃. Their feed intake halts at temperature
below 15 ℃, and usually dies at temperature
below 10℃. Based on the research findings,
we made a feed adjustment program for
tilapia according to annual water tempera-ture
profile in Guangdong. The performance
of tilapia fed following the program seems
encouraging (Table 1).
Conclusion
Climatic condition is complex and tem-perature
change is acute in china, inducing
huge losses to the aquaculture industry.
In order to get better value for money in
aquaculture, enhanced resistance to the
stress from temperature fluctuation beyond
the optimum range becomes very impor-tant.
Therefore, in addition to improving
the quality of fish fry, the strengthen-ing
of research to enhance the resistance
to temperature stress
regulated by nutritional
means is necessary.
We reviewed the
effects of temperature on
fish, nutritional regulation
of temperature stress and
developed a successful
feed-management solu-tion
for tilapia under such
stresses. We hope the
study can provide refer-ence
for improving the
accuracy of dietary nutri-ents,
developing cost-effective
functional feed,
thereby reducing damage
to the farming industry
caused by temperature
stress.
References
Available on request
Table 1: Tilapia feed adjustment program in Guangdong
Months Temperature
conditions Affects Feed adjustment plans
Dec - Feb
Low
temperature,
some days
below 15℃
Feed intake is
low and growth
is slow
Increase the proportion of protein to
maintain the growth and health; keep
the lipid level to prevent shedding
weight and resistant to low temperature
stress; energy feed was not effective
in this period, phosphorus can be set
lower.
Mar - May
Water
temperature
increased and
can reach 25℃
Increased feed
intake &fish
recovered
Keep the protein stable, increase
lipid level and add vitamin and
immunopotentiator
Jun - Sep
Water
temperature
reached 30℃
Much high feed
intake, active
metabolism and
rapid growth
Increase the proportion of protein
and lipid, supply enough vitamin and
mineral and ensure the health of liver
and intestine
Oct - Nov
Water
temperature
decreased to
25℃
Feed intake
was large
Increase the proportion of protein
and lipid, reduce additives for health,
add additives for lipid absorption like
choline.
006 | INTERNATIONAL AQUAFEED | Fish farming Technology

7. FISH FARMING TECHNOLOGY
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