Southeast Asian Fisheries Development Center Aquaculture Department
SEAFDEC/AQD Institutional Repository http://repository.seafdec.org.ph
Journals/Magazines Aqua Farm News
1992
Science and future of aquaculture
Aquaculture Department, Southeast Asian Fisheries Development Center
Southeast Asian Fisheries Development Center, Aquaculture Department (1992). Science and future of aquaculture. Aqua Farm News, 10(6), 12-16.
http://hdl.handle.net/10862/2613
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Special Feature
SCIENCE and the future of AQUACULTURE
T he year's end alw ays m akes people aw are that the next ye a r is som ething yet to behold. The astute a q u a cu ltu rist w ill have to be m ore attentive to the application of existing technolo gies in order to achieve new bre a kth ro u g h s in production and profits. This issue's special feature focuses on te ch n o lo g ie s -- biologica l and physical -- that w ill m ake an im pact in and eventua lly d irect future a q u a cu ltu re system s. Lest te ch n o lo g y's ultim ate aim -- b e tte r quality of life -- be forgotten, the view s of fo rm e r S E A F D E C /A Q D C hief Dr. Flor Lacanilao are also presented.
Biological technology
The biological sciences in general and biotechnology in particular will play an increasing role in aquaculture. The trend will be driven by international competition and consumer preferences. The R and D that will be conducted will vary according to the stage of development of the particular aquaculture species in relation to the mar
ket. With new species, the emphasis is often on basic culture through the life cycle.
Species that have entered the market un
dergo a rapid research with emphasis on solving production problems and increas
ing survival and growth. In species whose production in some areas of the world has leveled off, the emphasis is on increasing production efficiency.
New species.
Given that there are over 20 000 spe
cies of fish on earth and over 15 000 species of mollusc many of which are sought as food items, it is ex
pected that aquaculture researchers constantly test new species for culture. The selection of a new species is usually associated with strong market demand linked with high value and a
limitation of natural stocks. Consumer demand for high quality aquaculture products in Japan, Western Europe, and North America based on perceived health benefits and lifestyle factors is expected to continue. This demand will lead to the economic feasibility of culturing additional species. In the culture of tropical freshwater fish, certain carps, tilapias, and catfish pre
dominate. But recent years have seen the emergence of aquaculture of other indigenous species. Examples are the culture of the pacu
Colossoma sp. and other indigenous fishes inBrazil, and the culture of the indigenous carp
Puntius gonionotus in Thailand.Nutrition. Future research on nutrition is expected to focus on (1) the search for alterna
tive protein and lipid sources for making cost- effective feeds for high production; (2) nutri
tional requirements of cultured species and in
gredient digestibility of feeds, and (3) the opti
mization of quality and nutritional value at har
vest. The latter topic has become very important in light of the benefits of omega 3 poly
unsaturated fatty acids (PUFA) in hu
man health. These
health b en e fits
have led to increased fish consum ption. Thus, it m ust be ensured that fish products from aq uaculture contain sa tisfactory levels of PUFA.
A recent com parison has show n that the lipids of wild catfish co n ta in 27.6% om ega 3 PUFA com pared to 10.2% in fa rm e d catfish. W hen expressed as the om ega 3 to om ega 6 ratio, the ratio in w ild catfish is 2.5 versus 0.6 in cultured catfish. T here is a cle a r need to d e velop fin is h ing diets that w ill optim ize nutritional value as well as physical q u a lity at harvest.
G ro w th . In anim al husbandry, re d u c tio n o f th e p ro d u c tio n c y c le through increased g row th rates has, fo r econom ic rea
sons, alw ays been a key area fo r g e netic and endocrine research. T he relatively long production cycles of cultured anim als currently range up to sev
eral years. G enetic selection has resulted in s ig n ific a n t im p ro v e m e n ts in g ro w th rates.
E ndocrine te ch n iq u e s th a t could va stly im prove grow th rates are also currently under developm ent. R esults to date indicate that the horm one som atotropin (from the pituitary gland) is the m ost prom ising fa c to r fo r grow th accel
eration. M am m alian and bird som atotropins produced fro m b iotechn ology can accelerate grow th of Pacific salm on, both the freshw ater juveniles and the se a w a te r grow -out stage.
Initial success has also been achieved in the catfish. In the future, research w ill fo cus on fo u r areas: (1) efficient m ethods of adm inistration of som atotropin by im plant, the oral route, o r by im m ersion; (2) d e ve lop m e nt of som atotropin analogs having a higher potency; (3) d e velop
ment of fish som atotropin s by biotechnology;
and (4) fu rth e r investigation o f o th e r grow th fa c tors.
G en e banks.
W hile the technology now exists to c ry opreserve fish sp e r
m a to zo a , th e c o n cept of gene banks has, to date, been little utilized in aquac
ulture. In the future, gene banks can be used for: (1) indefinite storage of g enetic inform ation fro m w ild strains of a va rie ty of species for incorporation in breeding p rogram s and d e v e l
opm ent of g e n o m ic libraries; (2) storage of sperm atozoa from selectively bred fish fo r use in fu tu re crosses; (3) storage o f g a m e te s for the production of m onosex stocks; (4) the storage of sperm fro m one breeding season to the next to increase the effective size of th e breeding population and thus reduce inbreedin g; (5) the m aintenance of co ntrol lines in selective b re e d ing program s; (6) the d e ve lo p m e n t of in te r
specific crosses.
T ran sg en ic fish . T ra n sg e n ic fish are produced by the introduction of fo re ig n DNA into the egg o r em bryo in such a m a n n e r th a t it is incorporated into the genom e. M ice d e v e lo p ing from eggs m icroinjected w ith th e grow th horm one gene g re w fa s te r and la rg e r th a n n o r
mal mice. There has fo llo w e d a surge of re
search to develop tra n s g e n ic fis h w ith en hanced production ch a ra cteristics. In research conducted to date, a D N A sequen ce has been m icroinjected into goldfish, and fu sio n and g ro w th h o rm o n e
genes into rainbow trout. The presence o f s o m a to tr o p in a n d a c c e le r a te d grow th in individual second generatio n transgenic carp has b e e n d e m o n strated.
W hile th e em phasis to date has b e e n on the de ve lo p m e n t of fa s t-g ro w in g stra in s of transgenic fish, research is also un d e rw a y on freezing resistance in A tla n tic salm on. Future research w ill fo cus on th e im p rovem ent of such factors as flesh color, e xternal appea ra nce, disease resistance, fatty acid content, and ability to utilize low -cost d ietary ingredients. It m ay also be possible to produce sterile fis h by e x pressing in the g o nad a gene th a t prevents gonad developm ent.
Production ch a ra cte ristics influenced by single genes are the m ost likely to be im proved by the develop m e nt of tra n s g e n ic fish, w h e re a s characteristics regulated by m ultiple gen e s are m ore am enable to selective breeding.
Aqua Farm News X (6) November - December 1992 13
Integration of biological technologies.
There is a need for integration in aquaculture R & D, either of research from separate disci
plines to solve major problems, or of several technologies into production systems. An example of the former is the investigation of the role of genetics, nutrition, and stress in the disease susceptibility of cultured organisms.
An example of the latter is the integration of endocrine and genetic technologies to pro
duce monosex populations.
In the case of production systems for coho salmon, studies on the production of age 0 smolts, and of sterile age 1+ smolts were con
ducted separately.
Androgen treatment in te rfe re s w ith smoltification. Thus, when the two proce
d ures w ere in te grated at the pilot production level it was necessary to time the androgen
treatment, temperature, and photoperiod ma
nipulation to avoid negative interaction.
Physical technologies
Oxygen and aeration. The aeration of ponds has increased yields as much as 30-fold.
The application of oxygen in raceway or tank culture has increased production easily by a factor of 7 to 10 and almost all conventional fish farms could double production through the proper application of the newer types of oxygen injection systems.
Oxygen is now readily available e ith e r as liquid o xyg e n as supplied by the m ajor pro d u c
ers o r it can be g enerate d on location by new m odern and e fficient o xygen generating e quip
m ent. T he key requirem ent fo r oxygen g e n e ra tio n is a depe n d a b le supply of electricity.
N ew m ethods of oxygen injection in
clude pressure system s w hich produce super s a tu ra te d w a te r a n d /o r tin y m icrobubbles. C o n ta in e rize d m ixing devices know n as packed co lu m n s o p e ra te very efficiently w ith little o r no en e rg y required. T hese new devices transfer oxyg e n into w a te r at efficiencies ranging from
80 to 95% . Past te chnolo gy on ly pro
vided tra n s fe r e ffi
ciency of 30 to 60% , s u b s ta n tia lly in creasing cost of o x y g e n s u p p le m e n ta tion.
B enefits from
oxygen supplem entation include nitrogen strip
ping, substantially increased stocking densi
ties hence yields, im proved fish health, less m edication, and im proved feed conversions.
S u p ero xid es of o xyg en . By treating w ith e ith e r e lectrical o r photoch em ical energy, oxygen m olecules are tra n sfo rm e d into super
oxides of oxyg e n w h ich have very pow erful oxidizing properties. T hese superoxides, prop
erly introduced into aquacu lture system s, can act as sterilant and oxidant. B enefits include significant reduction in bacterial num bers in w a te r su p p lie s; th e o x id a tio n o f unionize d am m onia to less toxic nitrates; the oxidation of o rg a n ic s in c lu d in g h a rm fu l c h e m ic a ls and agents w hich induce off flavors; and a reduction in surface tension. S uccessful applications of superoxides include oyste r depuration, efflu
ent tre a tm e n t in recycling system s, and reduc
tion of virus and im proved survival of shrim p larvae in hatcheries.
T em p eratu re m an ag em en t. Since the m etabolic rate and g row th of cold-blood ed ani
m als is d e term ined by te m p e ra tu re and each species has its ow n preferred tem perature at w hich it perform s the best, tem perature m an
agem ent in aquatic system s w ill receive m ore attention. O xygen supplem en tation allow s the anim al to grow fa ste r at h igher tem peratures w hich w ere p reviously though t to be harm ful.
T he principles of therm al engineering are w ell established. H eat p um ps and heat ex
change rs are readily available. T he challenge will be to use the best
available te ch n o lo gies in a co s t-e ffe c tive m anner to take a d v a n ta g e o f th e econom ic potentials derived fro m proper tem perature control.
E ffluent m an ag em en t. The single m ost im portant resource fo r aquaculture d e v e lo p m ent is w ater. This resource, if properly m an
aged, is renew able. B ecause it is in the best interests of the aquacu lture industry to protect this resource, w e anticipate that the industry w ill respond positively and co n structively to m anage effluent w ater. T he only option to voluntary action w ill be regulated com pliance.
The single most im portant source of w ater pollution is feed, e ith e r as w a ste d uneaten feed o r as m etabolites produced by fish from c o n sum ed feeds.
E m phasis in feed fo rm u la tio n w ill shift from cost optim ization to “pre cisio n fo rm u la t
ing” such that fe e d conversion efficiency is high. Less nitrogen, phosphorus, and organic substance s w ill go into pond w ater. H igh d i
gestibilities result in less w a ste s and low er o x y gen dem and. T hese new feeds w ill cost m ore, but w ill be cost-effective com pared to other m ethods of effluent m anagem ent.
N ew and im pro ve d d e vice s and te ch n iq u e s to settle, suck, spin, filte r, a n d /o r flo a t o u t s e ttla b le a nd s u s p e n d e d so lids are co nstantly ap pearing in the m ar
ket. R em oval e ffi
ciencies are being im proved. A new filtration device reports th e rem oval of a b o u t9 0 % o f sus
pended solids, 80 % of th e phosphorus, and 40% of the nitrogen.
D issolved solids can be rem oved b io lo g i
cally using b io filtration tech n o lo g y o r through the addition of w aste converting bacteria, a new tool that has tre m e n d o u s potential. T he ch e m i
cal o xidation of o rg a n ics using superoxide s is also a viable alternative. Im agine potable w ater from fish farm s.
T hrough the application of these new technolo gies, m ore fa rm s w ill use recycle sys
tem s. A lthough the tech n o lo g ie s fo r effective effluent m anagem ent exist, w hat is lacking is the econom ic analysis and d e m onstratio n of the proper linkage of these tech n o lo g ie s in typical farm ing operations.
H andling, grading, and co u n tin g . In
ventory m anagem ent m ust be done properly
fo r any business to succeed. It is now p o s s ib le to m o ve , g r a d e , s o r t, a n d c o u n t a q u a tic a n i
m als accurately and safely. The need to count is of prim ary im portance and new
products and tech n o lo g ie s are a p pea rin g each year to perform this process fa s te r and m ore ef
ficiently.
T he ultim ate o b je ctive is to count anim als in th e ir natural e n viro n m e n t w ith o u t handling them W e are not quite th e re yet, but th e re is no
reason w hy this problem c a n ’t be solved.
Feeding system s . T here are fe eders and feeding system s available fo r a lm ost e very application and the ch alleng e be co m e s fin d in g the best suited fo r cu rre n t and future needs.
S tand alone type fe e d e rs such as d e m and fe e d e rs o r those po w e re d by m e chanical springs, rechargeable b atteries, o r so la r po w e r w ill be very p o pula r b ecause th e y are highly dependable, very flexible, and m ore affordable .
In those farm ing o p eration s w h e re h ighly controlled and m anaged p roduction is an o p e r
ating standard, m echanical typ e fe e d e rs linked to control system s w ill be preferred. A n o th e r advantage of program controlled fe e d in g is that w a te r quality p a ram eters are m a intained w ithin m ore narrow ranges. This in turn ca n a ffe ct the design and cost of effluent m a n a g e m e n t sy s tem s.
An electronic dem and fe e d e r w ill soon be available.
R e g u la tin g fe e d s u p p ly b a s e d on anim al behavior is a very sound p rin
ciple. Electronics allow s fo r precision a d justm ent, m o n i
toring, and feed de live ry control. This device w ill be invaluable in research.
C o m p u terizatio n . T he deg re e of c o m puterization w ill depend on w h e th e r th e b u s i
ness is a fish fa rm o r a fish factory, th e fo rm e r being influenced by m ore natural environm en tal factors w hereas the la tte r w o u ld be co m p le te ly Aqua Farm News X (6) November - December 1992 15
and e n viro n m e n ta lly m anaged and controlled.
C ertainly, the c o m p u te r w ill play an e x
p a n d e d role in th e area of research and d e ve l
o p m e n t as it has a tre m e n d o u s capacity to c o lle ct and a ssim ilate data.
B io electro n ics. In the future, it is p o s sible to m o n ito r fish physiolog y and fish health th ro u g h sensing d e vice s attached to a sam ple o f th e popula tion. T he electronic transm issions
allow p rediction of a n im a l c o n d itio n s and responses be
fo re visual and d i
a g n o s tic o b s e rv a tio n s c o u ld be m ade. R obotics, la
s e rs , fib e r o p tic s , s u p e r conducto rs, and h igh-tech c e ram ics have not been included althoug h m ost assuredly, th e y w ill be part of th e te chnolo gy of the future.
C on clu sio n s. Environm ental constraints plu s th e m ore effective a pplicatio ns of new te c h n o lo g ie s w ill m ove aquacu lture d e ve lo p m ent to w a rd s land-based system s. These s yste m s p erm it m ore control and predictability and allow m ore intensive cu lture o peration s to succeed. T hese system s w ill not be highly so p h is tic a te d o r co m p lic a te d but instead w ill c o n ce n tra te on g o o d design, sim plicity of o p eration, an d e ffective m anagem ent. R egard
less of w h a t system is used, th e y all m ust focus on p ro d u c in g h ig h -q u a lity , v e ry d e s ira b le pro d u cts fo r the co n s u m e r m arket.
W a te r reuse and recycling system s w ill d e v e lo p m ore rapidly due to increased interest and p rom otion. T he agricultural com m unity is lo oking fo r and ce rta in ly needs com plim entary e n te rp ris e s to s u p p o rt s tru g g lin g a g rib u s i
nesses. A g ricu ltu re fa rm e rs understand anim al husban dry, th e y are creative and they are w illin g to te s t these
new system s. W a te r re cyclin g s y s te m s w ill be used near fish m arkets to a llo w p ro m p t d e livery of live o r fresh p ro d u c ts to c o n sum ers.
A n other o p p ortun ity fo r aquaculture is to link the aquatic anim al system s w ith plant cul
ture. T his provides the benefit of g reater nutri
ent utilization w ith p ra ctically no effluent prob
lems.
It w ould be w ell fo r all of us to heed the advice of a w o rld fam ous scientist w ho com m ented “ Im agination is m ore im portant than know ledg e.” His nam e? A lbert Einstein.
Sources: (1) E.M. Donaldson. 1988. Science and the future of aquaculture. p. 299-309; (2) T.R.
Zeigler. 1988. Aquaculture technology in the future.
p. 311-315. In: Aquaculture International Con
gress Proceedings; British Columbia, Canada; 6-9 Sept. 1988.
Technology and the environment
T here is no q u e stio n th a t research plays a role in develop ing the aquacu lture industry in the region. This w a s seen in th e utilization of re
search by the shrim p industry. T he fast d e vel
opm ent o f a quaculture in S outhea st A sia is ex
e m p lifie d by shrim p cu ltu re , p a rtic u la rly in T h a ila n d , In d o n e s ia , a nd th e P h ilip p in e s . T h a ila n d ’s shrim p aquacu lture production, for exam ple, has grow n fro m 12,000 tons in 1986 to o ve r 110,000 tons in 1991.
H ow ever, th e u n c o n tro lle d spread of shrim p fa rm in g has resulted in m assive envi
ronm ental deterioratio n. In th e Philippines, the negative co n sequ ences are that: (1) the bene
fits of shrim p aquacu lture do not trickle dow n to the po o r people in the area, (2) intensive shrim p farm ing m arginalizes sm all-scale fisherm en, (3) the culture system does not generate desir
able alternative em ploym ent fo r displaced fish
erm en, and (4) large-scale shrim p culture com prom ises the local environm ent, resulting in salinization of arable land, low ering of ground- w a te r level, pollution of co astal areas, and health hazards. In effect, th e coastal folk bear the social co sts of large-scale aquaculture develop m e nt, including loss o f traditional liveli
hood fo r the fishing com m unity, ejection from th e ir residence site, and degrada tion of natural coastal resources. A dd to this the social co n flict resulting from resource use, that is, the fish culturists as against the fisherm en.
