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Farming the Green Mussel_86 |
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FARMING TH! GREEN MUSSEL_
by
Tanielu S. Su'a.
With A..�istance Prom PAO Project TCP / Sam t 6652.
1986.
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INTRODUCTION
Investigation of the possibility to cultivate the PHILIPPINE
GREEN MUSSEL in Western Samoa was started by the Fisheries
Division 0£ the Department 0£ Agriculture in 1981. Green mussel
was considered a possible "cash-crop", rich in protein and sui
table £or cultivation at the village level. In 1982 a pilot
culture project was started close to Apia and closely supervised
by the Fisheries Sta££. In 1983 new pilot projects were started
at remote areas bn Savai'i lind Upolu islands, as shown in thf
figure below, to see how mussel cultivation would develop under
village conditions. Now the Fisheries Division 0£ the Department
of Agriculture is ready to assist the villages to expand mussel
cultivation. Initially for the local ma�ket, later maybe for
export.
Site 3:Asau J3oy
SAVAI 'I
IO km {.ap_prox)
0
0
Site I :Mulinu'u Boy
2:FishC!ries
llarbour
Up OL U
PILOT MUSSEL CULTURE SITES IN WESTERN SAMOA
In this paper we will now set out some basic guidelines and inV�.:-;�•··
formation regarding the "£arming" of green mussel. However this
paper is only to help you remember some of these £acts. The best
way to learn about mussel £arming is to go out with the staff of
the Fisheries Division and see things with your own eyes. Even
better would be to work for a sher� period with fisheries staff
on mussel farming.
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SOME NOTES ON THE BIOLOGY OF THE MUSSEL
The green musael farmed now in Samoa is also farmed in the
Philippines, Thailand and Tahiti. The mussel produces threads, by
which they can attach themselves to rocks, ropes, etc. and
because of this ability they are easy to £arm, as they can easily
be collected, transplanted and attached to bamboo or rope.
The (sexually> mature mussels release eggs and sperm freely into
the sea where fertilization takes place. The fertilized eggs
develop into larvae within 24 hours and remain £ree swimming £or
15 to 10 days in the sea, after which they attach themselves to
rocks or ropes, etc. These young mussels we call SPATS.
Mussels usually grow in coastal areas in clusters (groups) to
getn-er. They- -can grov- as------big as--15 -em. -The._average g.r_cwtb__rate_of
the green mussel is about 1 cm. per month, allowing them to be
ready for selling (when they are 4 to 6 cm.> in 4 to 6 months.
That also depends in the availability of food in the sea water.
BASIC PRINCIPLES OF MUSSEL FARMING
Spat availability
With SPAT we mean the juvenile mussel as has been explained
before. Mussel farming depends entirely on an easy and ready
availability of spats. At present W. Samoa is completely
dependent on spats from the hatchery <sort of nursery> in Tahiti.
Sofar little spat is produced locally.
Very important is the choice of the right site �or succesful
mussel farming. For selection of the right place, the following
points must be considered:
t� Qj t.hw .. i
• The site should be pr6tected' £ram strong winds and
waves.
• The tidal range (that means the dif£erence in water
level between high and low tide) in the area should be
enough £or water exchange. The greater the water
exchange the better, as more food is broughta,. t� tpe
mussels and waste is more easily removed.
The water should contain enough £cod for the mussels.
Generally, "clean" or "clear" water do not contain enough
food to make the mussel grow well. A greenish colour in the
water is an indication of food availability for the mussel.
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�It... ·;2allll, ·tidal currents should be strong so that new water
brings new food to the mussel. Strong currents also
uaR�:prevent settlement of silt in the water.
, ..� ...
Ill) th,The site should be relatively deep, at least 5 meters
during low tide.
•
It should not be close to an area where rainwater
during the rainy season enters the sea. Rainwater makes
the sea less salty, which is .bad for the. mussel.
L-:ai3't._ C..r L·- • 1• •
.- 1.
•
The site should be free from pollution and sewage,
because these may make the mussel. unfit for
consumption.
Ji- - .. .. JC-, C),
.) I
_• 1:
...... :-.1 \\..: -
; -::;. 1- •.t.')cj.·
The site should be su£ficiently enclosed to retain the
larvae for spats.
1t
Preferably the site should be close to a road for easy
transportation of th� mussel.
CONSTRUCTION AND CULTURAL OPERATIONS
Basic considerations'1'
*
Cultures are always under water, even at low tide. This
is because green mussels have a natural preference for
living below the lowest tidal level.
•
Cultures should always be off the bottom of the sea.
This prevents predators (the enemies of the mussel>,
such as starfish, crabs and others from crawling up the
culture ropes.
*
Materials to be used should be durable to last at least
until the harvest of the mussel crop. These materials
will be more expensive to begin with, but, they will
P · , , . · rpay o:ff in terms o:f the number o:f crops they can be
B1, ·. ,;used 'for.
J"( .:)'"' c.'\\ ,,,, i, :' ' • . �
tf't � ..• '· !
•
The area for mussel 'farming should be two or three
times larger than the actual culture site. This will
allow the farm to be moved from one section to another
one to avoid degradation of the area.
•
Di course structures should not be in the way to
-. Dbstruct navigation.
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Re£t Culture: materials and design
Mussels are cultivated with the help a£ ra£ts. This way the
mussels are growing on the ropes, which hang £ram the ra£t down
. in the water (see drawing). The ra£t consists a£:
•
A £irm £ramework £ram which the ropes are hung. This
£ramework is kept above water and the materials used
£or its construction should be strong enough to support
the weight 0£ the mussels, but not so heavy as to need
�-r- a lot 0£ £lotation. Bamboo or light lumber are ideal.
Common sizes 0£ ra£ts are 5 by 4m, 6 by Bm, etc.
•
Floats or buoys to keep the £irm £ramework £lasting on
the water. Used metal or plastic drums, styrofoam block
or ferro-concrete buoys are some 0£ the materials that
can be used to £lost the raft. The choice of the kind
of £lasts to be used should be based on local
f availability, durability and cost.
•
Production or growing ropes. These ropes, onto which
the mussels will be attached, are hung 1 meter apart
from each other. Thus a ra£t from 5 by 4 meter hes 30
such ropes. The ropes should not touch the bottom 0£
the sea at low tide, ea has been explained before.
Normally the growing ropes ere not more than 5 meters
long, as mussels do not grow well below that depth.
Each rope has to have an object tied to the end to keep
it weighted down. Polypropylene and polyethylene ropes
with 12-20 cm. diameter may be used as growing ropes.
An important £eature ox·growing ropes are the PEGS -
thin bamboo or any wooden pieces about 25cm long and
1.5 cm. wide inserted into the lay 0£ the rope at 30
cm. intervals. These pegs prevent the heavy load 0£
rapidly growing mussels·from slipping down and o£f the
Placement of rafts for culture should take place two weeks before
spat attachment. This makes it possible £or algae to grow on the
ropes which would give the spats £irm attachment to the ropes.
Two anchors are needed for each ra£t, one on each side and their
total combined weight should be twice that of the total weight oi
the raft with its mussels. The length of the anchor rope should
be £our to six times that 0£ the water depth at low tide
To attach spats, the growing rope is hoisted up and spats are
bound onto it by wrapping the length 0£ the rope, spirally, with
strips 0£ cotton or gauze or old small mesh netting.
recommended.
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o/ u
ii
\\i
:z:
Q
H
uE
:::i
Q
Q
aQ.!
ii
-a -ra- ft -fo� r m:�u�s �se II farm In 9
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General farm management
A raft farm is easy to maintain due to its independence from the
tide. Maintenance consists of the following activities, after the
spat has been attached.
•
Net slitting - if an old net is used to bind the spats
onto the growing ropes, this should be split after 10-
14 days to allow the spats to grow out.
By this time, the spats should have attached to the
ropes. Cotton gauze, if used, would fall apart (rot)
after a few days and would therefore not need slitting.
•
Adding additional buoys whenever necessary. As the
mussels grow, the ropes become heavier so that additio
nal buoys must be provided to keep the framework above
the water and prevent the ropes from sinking to the
bottom.·
• Protecting the mussels from predators, getting rid of
parasites, pests and silt.
Growing ropes should be inspected regularly for crabs,
sea urchins and other sea animals which can damage the
mussels. These can be removed by hand. Organisms that
grow on the mussel shells or on the ropes (such as
barnacles) can be removed by scraping them off with a
knife or by exposing the ropes for a short period in
the sun. Ropes may have to be "shaken" periodically to
dislodge silt settled on the shells of the mussels.
The farm must also be guarded, especially when the
mussels have reached the right size for harvesting.
This is to discourage po�ching.
*
Peg and bamboo replacement. Decayed (rotten) pegs and
bamboo should be replaced. If necesarry, additional
pegs may be useful to support large mussel clusters.
Harvesting
The mussel should be harvested when they reach a size of about
40-60 mm Cis 4 - 6 cm). The mussel grow at about one cm. per
month, Therefore, mussels can be harvested about 4 to 6 months
a£ter spat attachment.
Also the mussels should be harvested when their meat is fat. A
•tat• mussel is full-bodied and attractive in appearance. Males
have a rich, creamy appearance, while the females are filled with
bright-orange eggs in almost every part of their body.
In contrast, the flesh of thin mussels is "watery" and transpa
rent.
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Detach mussels from the growing ropes by scraping with a sharp
knife or by grasping their threads. This avoids damaging the
mussels, which helps keeping them alive longer. If necessary,
wash them before transporting to the market, or whatever place
you are going to sell them. During transporting the mussels
should be kept in moistened sacks protected from the heat of the
sun.
Freshly harvested musseLs generally retain their freshness about
one to two days if they are kept in moist s�ck� at nQrm�l room
conditions.
��YIELDS, PRODUCTION COSTS AND INCOME
... ' ! l: ...-
Mussel farming has not been-done yet in W. Samoa in a commercial
way in the villages. But the results of the initial growth trials
done in Asau, can be used to give us an idea about possible
yields, production costs and income.
COST ESTIMATE TO INSTALL ONE MUSSEL RAFT OF 6 by 5 meter
Quanty
Material
Price/unit
Total
13 pieces
bamboo
4 buoys
styrofoam buoys
$40 each
160
2 coils
polypropylene
$120/coil
240
rope, 12mm, 200m
per roll
2 rolls
cotton gauze
S30/roll
60
38,000
spats
$6/1000 spats
228
transportation to site
50
----------------v-a-r-io-u--s--s-ma-l-l---co-s-t-s------------------------62---
TOTAL INVESTMENT S 800.-
The returns over a period 0£ 3 years £or the above raft, with
production ropes oz 3 meters, is as £ollowa:
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Year 1
Year 2 Year 3
-----------------------------------------1----------1----------
Initial investment
800
I
I
I
I
•Maintenance
380 I 380 380 I 380 380
I
I
Gross earnings (2 yields
1134 1134 11134 1134 11134 1134
per y&ar>
I
I
I
I
N-e--t--e-ar-n--i-ng-s---pe-r---ye-a-r------------$--10--8-8-----I ---$--15-0-8----I ---$--15-0--8--
• coat of spats, gauze and transportation plus some various cost
The total net income over a period of 3 years, for the work done,
i� $ ioea � e 1soa � e 1508 = s 4101.-
These cost end benefit analysis is made taking into the account
the following:
•
the person already hes a boat
•
the yield per meter of growing rope is 9 kg 0£ mussel
•
the mussels will be sold at a price of Sl.- per kilo
•
their will be two harvests £ram the ra£t per year
IF YOU HAVE ANY MORE QUESTIONS ABOUT
MUSSEL FARMING
CONTACT THE FISHERIES OFFICE
THEY WILL BE GLAD TO ASSIST YOU
The present revised edition 0£ this paper was prepared by Mr.
Tamielu Sue, £ram the Fisheries Division, with assistance from
FAO Project TCP/SAM/6652
Apia, October 1986
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SEAFARMING DEVELOPMENT PROJECJ
INS/81/008
?a�:�on� :en�cr�r-smee Scm�arc: =cr::c=ra�1ro
Munamm�d �ur=;an1
arc
Ca-vc �1�ant�
Direktorat Jeoderal Perikanan
BALAI BU Of D AYA LAUT
PO. Box 74/TK. Telnk Benmg
Tdex: 45260 FAOR£P IA
United Nations Development Programme
ExecutingAgency
Food andAgriculture Organiz.arion
of theUnited Nations
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10
The inclcence ot oarasites in mussels is also low. rn
January 1 19B6. c□oeocd Ostrinicola so. anc Bomolucu� sp. were �ounc
in the mantle ct samp�es from Kuala Penet 1 Mar,ngga:. The former 1s
believed to �e tne main cause contributlng co tne under-weight of
mussels and abnormal growth of gonad� while the later may cause h1�h
mortality of the mussel our!ng the period. To date� known mussel
diseases or parasites 1 aoparently are not harmiul to man.
6.6 Poacner-s
Perhaps the greatest danger to a mussel farm 1s causea oy
human pcacners. To discourage tn1s. the farm mus� oe guarded at all
times 1 especially when the mussels have grown to marketaole size
6,7 Reolacement of pegs
The gro'Wi ng ropes snould be i nspec�ed --egul arl y to see 1 -f the
pegs are stlil pro�erly supoorting the mussel clumps. Decayeo pegs
should be reolaced. If necessary, aadit1onal pegs may be providea to
supoort exceptionally large mussel clusters.
7 • HARVEST! NG
Factors to be considered in harvesting mussels are s1:e ano
quality and market demand.
7.1 Size of mussels
Althougn it is premature to 1aent1fy a consumer preference
for the size of mussels markets in Indones:!.a, it is lif::eiy tnat the
IHl"ket prefers medium or "b1 te-size" (6-8crr. to�al length)
7.2 Qualitv of the oraduct
The mussels should not be harves�ea when they are too tnin.
Thinness or fatness is indicated by the degree to which the meat
shrinks after cooking. A fat mussel is fuil-bodieo anc attractive in
appearance. Males have a rich creamy appearance while females are
filled with brignt-orange eggs in almost every part of the body. The
flesh of fat mussels shrinks only slightly after cooking while that
cf thin mussels is watery transparent. This conditions is relatad to
seasonal changes. The grower needs to know the state of his crop and
what month it should be harvestec. At Kuala Penet� Maringgai,. Lampung
the period is between October and December. To take aovantage of this
seasonal phenomenon 1 mussels should be harvested when they are �n the
resting stage ct their reproductive cycle when large amounts of
glycogen are stor�o in mesosoma and mantle lobe. When they are in
prime condition� raw flesn contributes about 55 oer cent of the total
$hell-on weight while ,ookeo flesh constitutes from 23-35 oer cent at
the totai shell-on weight, deoending on the canc�t:�n of the mussels.
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l1
Pdralv�:c s�e:!f1sn 001son1n9 -r=� 2a�:nc sne1:fisn con-
tam1n.;rced oy tc:::: :::�2.n;:• -:on. usual:.y of :ne �enus Gonvau:ax. :s 6
orco1em 1� some carts o� c�e worla (Fig 8). .�h::.e tne 02,ralyc:c
shellfisn 001scn1n� nas net oeen reoor-:20 :n incones1a, researc� :s
neeaed to verify cnls, esce�:ally 1n areas wnere rec c:c� has be��
frequent!y ooservea.
7.3 Mar�et cemand
Market demanc 1s an imoortant fac:or afiectin� :he marxet
price. !f cne demana is low, the narvesc snoula oe posc:::oneo anc tne
mussels allows to grow to a larger s1:e. A maJor oeterrent := :ie
demana for mussels 1s coss1ble concam1nac1on of tne water wnere tney
are grown aue to f2rc:lity. This form of poilu::on ooes nae ki:l :�e
mussels. ano 1n fac: prc�1ce nutrients whic� oromo:e g�owth of the
phytoplanKton with util�zea by the muss2!s. Cansum□t:cn of !nace
auately cc□� mussels csn cause serious 1:iness to numans.
Harvesting r?qu1res scec:ai care. Aiter t�e �amoca sca�e ar
rape is brought to the coat, tne musse!s are scracec aif ov means of
iron bar witn a snare end. The use of cul� s�raooers. or remova: af
t�e mussels by au1ling cn2m from the sta�es w1!l �9sr cne byssal
threads from the bocy resu:ting in loss of mc1s�ure after narvesc:nq
or physical damage to the animal. The mussels w11l c1e w1tn1n a few
hours if tne threacs are oulled out to 1nciuce tne muscular s�:::
ports.
8. POST-HARVEST
Mussels reau1re littl� o� no proc?ss:ng. After muc an□ sana
are remove□. They are sole rresn 1�ith the shell, and t�ansoorted to
marKet in basKecs, gunny sac�s or Jute sac�s. lt ooss1oie. cne
mussels effectively conserve moisture ano thereoy live longer. During
transoor: t� markec 1 the mussels snou!c be kept in moisceneo sac�s
procected from the heac of t�e sun. The musse� cluster snould be
broken up just before being displayed for sa1e 1 again with a shar�
kn1ie or a pair of scissors. In Incones1a. as well as in other
countries in Southeasc Asia. poor sales of irssh mussels are mainly
due to their unrel1ao1e auality. Development of quality control
measures snould ev?n�ually improve consumer acceptance. The 1n
creas2a sales deiin1cely woulo offse� cne case !ncurred in taking
such control measured.
8.1 Sanitation
Mussels 1 being filter feeaers. tenc �c acc�muia:2 f:l�erea
matter 1n tne1r guts. In tne �recess: �ac:er1a and o:ner micro
organisms presenc :n tne surrouna!ng waters mav accumuiate an□ reac�
levels wn1cn pose a �EdlC� Mazar□ to tne consumers.
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12
Dur:ng ::s:-�arves: ,anal:��- mu5sel mea: can �E c::i:am1naced
if unclean wa.:.ar 2n::srs :n2 s:-ie_i. ca0.v::·, :;L..-:n::; s�::::"aC: c:-- ;n:�meni:.
since cne mussels cannoc c!cs2 ::ieir s�e::s as ::q:i:!v as a�s:ers a�c
begin cc gape after s2veral �our; cu� �i wa:er. C�nta�lnac:a� can
also oe oue :a ;:awcn of s�o1ia�e �ac:erta :::a::i□�ens aur1nq :ransoort
or storage. The oac:2r:a: �at:io�2ns cr:::�a::�g irom ::ie �a::sr :�
wn1cn the mussels are gr�wcn mav grew anc :�crease gr�ac!v tn numoer
when the environment in c:ie C�:i:3::ier :s ravcrso:e.
Ac:ectao1e leveis of �ac:er:a for raw snel_f:s0 meac tn
Singapore are :
11
Aer□:nc o:. ace c: □un: eoue.l s co ar less t:ian 51)!) 1)1)(1 MPN/q. Es-
cner: :::ilc, ca!: coun-: ei::.uals to or iess cnar. 20 MF'i'l/q. Vi:::iro oara-
naemc.!.v-ci-::us CO!..lfl': e~uais
less than !00 MPN/�. Salmcnel!a,
Sh1ceila ana Vior10 choiera :s n1i in :5 g
The FAO/UNDP Seafarm1ng }ave1□cment Frc;ec: ( L iS /E l/ 1)08 1
monitored the neavy metal ana =ac:er:a leveli :- ��e water mua ana
musse! meat From t�e iarm area 1n Mar1nq;ai. Lam=�ng. �esui:s ;no�ec
tnat cne leveis ara. en tne avera�e, �i1:�1n acce�ta�:e 11m1�s (Table
16 1 and Taole 17).
8 ":· Deouration
To mar1<et fresn. sne1: on mussels. thesa snculo ce :ur�ec of
collui:::ants and toxins. A s1moie metnoc is to rel�y �:ie animals to
unpollutec wacer sites or place t�em in clean water uncer ccncrc::ec
:cnditicns.
8.2.1 Relav1nc methoa
Areas used for rElav1ng musi2ls snoula ce cai:::noqen free.
After the mussels are held 1n t�e pacnogen free water, oacter1a ana
pathogens will oe removec from tne shell cav1ty, t�e surfacs c� the
oooy ano from the d1gest1ve tract througn -:�e :::irccess oi feeding.
Time reouires 1s from 24 nours to several aavs.
8.:.: Pur1ficat1on in chlor1nat20 wat2r
Oeourat1on can oe acne cy hc!cing mussels :n s2awacer treatea
with chlorine. Seawat=r is cre3t?a for a� lease 8 nrs av c□ntac: �1:�
chlorine at the rate of 3 porn, ana oecnlor1nacea by sO01um cn1osul
phat2. After 24 hrs immersion. cne water is ora1nec oif i tne musse1s
nosec to remove aohering mussel fdecas� and a second 24-hrs bath
given. Aftar nosing ana fiusning again, cne mussels are finai:y
c1eaned bv immersion in wacer canca1n1ng ac�1ve cnlorine for one
hour. The pur1f1eG muss2ls are then oacxec 1n c!2an olascic oaqs anc
seaiea beiore dispatch.
!/ MPN = Most Prooaoie Numoer
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13
· :'. tra·1~ oiec. r.:!c 1 at.: ::in (�V) anc c7 r-c alsc =an �e useo as
ster1lizl nQ ~cErts. The former mav oe mcst su::1o!e 1 cr :ncc�es1an
s1tua�1□n because:: ,as no res1cua. e��ec:. :: :s sasv ==rr�aracive
ly in exOGns1ve ?nc :2;ves no oif-T1avors :� :�e ��:er. �c�evar :�:s
recuires sKii:, or l� usec in :onc�ncrs:i=ns ac�ve tne m1n1mum. it
=an weaken er even �::! musse!s.
V
=� recirc ulating cne stsr :l !zen water w1 :~ 1n - ne oe~ uratio n s vstem. it
is poss1cle rEcuc� caL:er:al :oa�1ng :n che mussels from >2460 E.
c::il i MPN/g meat to an acce□ca□ie level of <�O �P�/g w1th1n 24 hrs
(Cheong anc Bene:; 1 L 984) .
8.3 Handlin□
Hanoling for large quant:t1es cf fres� mussais af:er narvest
at a time is one of the main constraints 1n mussel farming. For
small-scale o□erac:on, :n1s 1s acne manually �e fam1iy mem□ers o� c�e
farmer. For :ar�e-scale o□erac1ons� mec�an:za::on cf .:.he �est-harvest
handling oaera:�on sucn as cec�uscerec. cEcear:�r ano Jesneller las
:llust,-a.:.ea in cneonc; and Senc; .• 984i mav □e reou1rea.
8.4 Produc� forms
Normally for ccmesc1c marKe:s. :n2 muss21s ar: s□cc at reta1i
as snell stocK ano reacn tne consumers a11ve 1n s�211. Mussels can
be also processec in otner forms sue� as smoKe□ ! Jr1nec. anc p:�K:ec.
The prooucts canoe pac�e� in Jar�, cans or vacuum cacks whicn
Jocular in American 3nc Euro�ean mar�e:s. W1tn refr:gera.:.!on fac:!1t�
1es, cco�ea mussel meat can be frozen 1n �locK or g!azed in in
div1aual oort1ons. Musse1s can a�so on mar�2: :n cr:e� musse_ mea�
wh1cn are aapuiar among Chinese �or sou□ or s�ew. Th1s form at
proauc� 1s 1n nign demano in oo�� ccmest:c anc �nt2rnat:cna: mar�ets.
Recipes for preparing mussels are given in A□pendix 1.
8. 5 She!f-li fe
Handling ot mussels during harvesting nas a s1gn1�1cant
Effect on their keeo1ng quality. Freshly harvescea mussels generally
retain their freshness aoout one to two davs if they ar2 Keot :n
moist gunny sacks under normal room conoit1cns. Stuo1es snow that
shelf-life can oe extencec to as muc� as four aays if cne mussels are
placed in clusters 1n shallow trav rece1v1ng a steady flow of
sterilizec water (Cheong anc Beng 1 !984).
Boyd and Wilson (1978) use□ score sneei: as outl:ne□ i� Table
18 to assess the freshness of green mussels on a scale of� for very
fresn mussels to O wnen i�eaiole. During s.:.craqe. :nera is also a
loss of fresn mussel odor, ceve!oomen� ot off-f:avors. anc a cnange
in t2H�ure of mussel meat. Ali t�ese cnanges cc=urs wn1le c�e mussel
is still alive. The rat2 of loss �n cua!1ty cf ::ve mussels csoenas
on cne i:emoeracure at whicn the mussels are s:orec (Ta□le 19). The
loss o·f flavour o·f i1ve green mussel. F·er�a c?.na:1c!.t�us a�i:er :-;1movec
from the water :s snown in Fig. 9. �usse:s t�a: nave �een �eo: :n 1c2
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14
wn1c� oe+i�1:e �f�-+lavc�r �ec:n
have a sne!f-::fe at only :�□ c�\\�.
If the
:c1 :-.:: .3.::
:□ s□cear. cne� :�e :cec mussels
Boye anc w1!s�n !97E sno�ec :nae :ne f:rs: mcr:ality cf the
New Zealana �reen muss2!, [. cana!:culus, occ�r-2c af�sr four =avs
when keot ac 15-!8 ae�ree C=ls:us.
= , ·0:.1 C'::5D l
occurrec •fter oniv twa cays ana tne m:n1mum c�a:::v grace of 3 was
reacnec after three aavs. CM1ll1n; tne musseis �etween �-7 ce�ree
Celsius extsnaea t�e time aefare fldv□ur losses were ae�eccable to
three-ano-a-�alf days. They �ecame unac=ec:a□le af:er 5 cays. A� 0
aegree Ce!s1us messeis 012 anc :ne sne!f-1:fe is rec�cec co one day.
When cnill1ng was o�!aveo for 24 hrs af�er narves:. cna cua�::y
rem,unea
f�r el�n:-anc-�-:;a!f days and che iirst
mortality was coserveG af:er nine aavs. �nen cn1l!2c four nrs after
harves;:. the musse:s remaln a�!VE anG acove gr3�a 3 for 14 days
<Warw1c:<, 1985).
Boyd ana �1lscn's �ac�:ng :2c:1nlcue 1Ao;:ienc1:{ :::> lS a
successful cne ana now oe1ng useo co exoor� tne i1ve green mussel
from New Zealand to restaurants cnroug:-i out cne Un1cea Scates.
Hong�ong and French Polynesia.
Shell on mussels can also oe scored 1n c:;e freez�r ac -30
aegree c�ls1us far as icng as s1x rnontns ca a year. They can suose
quencly be ccoKec, w1ch no ce�er1orat1cn 1n meac quaiicy, oy olung1ng
cnem c1rect�y 1nco �01l1ng wa�er. Th1s orevencs cear1ns of tne meat
quality, wn!c� wo�lc o��erwise �c=ur lf t�? frc=en �LI55els �ere '-�3�
allowed to thaw.
Processea mussels :-iave aiong ::nelf-11 fe. C:::c;: :r.ea:, fc.r
examole, can remain fresn in c:-ie refr:g2racor for one to two weeks
and in tne freezer for as iong as two tnree montns. If □lasc-�r:n:en.
the meat can be storeo for as long as one to two years with no
deteriorat!□n 1n quality. Glaz:ng of lno1v:�ually cu1cx fro:en (IO?)
mussels he�ps to re:aln the snaoe of cne mussels and enable easy
hanoling aur:ng def�osc1ng.
The snelf-l1fe of ar:ed mussel meat 1s ae□encenc on ��e
moisture content cf �ne meat. Far a oro�ucc with a moisture content
of about 10 per cent of dr1eo mea� we1gnc� �ne mea� can oe s;:oreq fer
aoout four months, □rov1aea that lt is keoc 1n a1r-t1gnt containers.
9. ECONOMIC CONSIDERATIONS
The cos,: of aroauc�:on of mussels 1s a□ouc 104 �□/kg for �ne
�aft mechoo� and costs aoout Ro113 ana Rp.16 and Ro121 for stake,
suspenoec lines from +1xet scruc:ure. anc long-1:nes metnoa r2s�2c
t1vely. �asec on the financial ana!ys:s. on:y raft ano stake method
are econom:ca1ly v1aole for :he sm2.i:-scale ooerat!on.