.
.. '
This paper not to be cited \\1thout reference to the authors
International Council for
the E~llloitation of the Sea
Shellfish committee
C.M. 1995/K:·H Ref. F
The Azorean squid Loligo jorbesi (Cephalopoda: Loliginidae) in
captivity: feeding and growth
.
Filipe M. Porteiro, Joao M. Gomralves, Frederico Cardigos, Paulo Martins
& He1en R. Martins
Oepartamento de Oceanografia e Pescas, Universidade dos Aerores. PT - 9900 Horb, Aerores
Abstract
Two sets of feeding gro\\th experiments w~re carried out (EXP94 and EXP95). Squid were fed
mainly "1th Trachurus picluratus. Scomber japonicus and Pagellus bogaraveo. Ouring the
first trial feeding and grO\\th was assessed for a11 the squid as a group. Oaily feeding rate
(OFR) \\as low (0.39%) and almost a11 the squid showed negative daily gro\\th rates (average
DGR = -0.5%). Squid maintained during E.XP95 were significantly sma11er than those kept in
EXP94. The majority of them fed on a regular basis. The average DFR was 4.09% and the
average DGR was 0.06%. However, when considering only squid that showed a considerable
gro".th (DGR>0.5%) the average DGR increase to 0.99%. Maximum DGR (1.42) \vas
achieved by a squid with initial body weight of 270.5g. Daily feeding rate for maintenance was
very high (3.78% DFRM), when compared with other cephalopods in captivity. The average
food conversion rate (FCR) was 10.6% and the conversion ofefficiency (CE) was 32.7%.
Feeding bchaviour is described. High percentage of fish heads rejection was observed. ll1e
number of the ingestcd otoliths, eye rens and fins \\ere recorded. Concerning head rejection a
re1ationship betwcen fish (prey) and squid (predator) size seems to exist.
•
Introduction
i.
Tne Azorean population of Loligo forbesi contain the larger loliginid squid knO\\n even "hen
compared "1th the conspecific pcpulations of the European shelf (see Boyle & Pierce, 1994).
Male squid can reach a dorsal mantle length (D~IL) elose to one metre and more than S kg of
body weight (!\Imins. 19~2; Martins & Porteiro, 1988; Porteiro & Martins. 1994). A
preliminary study of ageing has bt;~n done by Martins (1982) "ho found and a ma'Ümum of
450 statolith rings for a male "ith 75 cm DML. This value roughly fits an average gro\\th rate
of 5 g1day. Recent work using statoliths showed to similar results (Esracio, et. al., 1995).
Culture cxperim~nts havc bcen us.:d for gro\\th cstimation of some squids. both ommastrephids
(O'Dor et ai., 1980; Sakurai er ai., 1993) and loliginids (Hurie)' et ai., 1976: Hanlon et al..
19S3; Turk et al.. 1986; Yang er ai. 1986). Some ofthese authors contemplated the entire life
cycle of the target spccies \\ hile others aimed at a partic:.l1ar phase cf dcve1opment. Based cn
culture of dle ycungcr stages. it is accepted that ~xponential ,growth is a characteristic cf the
first stages of cephalopcd's life cycle followed by apower or logarithmic growth (Fors~the &
Van H.:ukc!cm. 19R7). Prcvious studics on gro\\th of captive L. forbesi were carricd I)ut by
Fors~thc et ai., 19S9 (see also Hanlon er al.• 1989 and Fors:1he, 1993). Ho\\ever, squid size
attained during that experiment was very smalI, comp:lred with the \\ ild population.
Cephalopods are active opportumstlc camivorous. Their diet change during ontogeny
(Boucher-Rodoni et al., 1987) and adult loliginids prefer fish as food. Several studies on the
diet of L. forbesi have been published (Martins, 1982; Ngoile, 1987; Collins et al., 1994;
Pierce et al., 1994; Rocha et al., 1994) and all of them were based on stomach contents
analysis. Feeding beha\iour of adult L. forbesi was reported by Porteiro et al. (1990).
A high food conversion rate and efficiency is a characteristic of cephalopods. Their energetic
demands are analyscd comprehensively by O'Dor & WeHs (1987). Recently, laboratory
calibration ofthe energetic expenses (metabolic rates) ofadult L.forbesi has been done aiming
at the in~erpretation of the squid eco-behaviour in the field (O'Dor et al. 1994). A tracking
research programme was performed using acoustic telemetry techniques. Life style and
energetic expenses for such activity were described.
Presently, a c10sed sea-water system for squid culture was buHt up at the University of the
Azores (see Gon~alves et al., 1995). It gave the opportunity to carry out this study on feeding
and gro\\th of captive squid.
Material and Methods
Two sets of experiments were performed. Experiment I (E..XP94) 5tarted on 23.10.94 and
finished on 27.12.94 and the second trial (EXP95) was executed between 09.02.95 and
18.04.95. All the squid were caught by jigging and transported ashore into black plastic bags
with a flO\v-through water. Squid were numbered, weighed (nearest O.lg upto 1500g and to Ig
for he:nier squid), measured (nearest I mm) and sexed. The elose sea water system used for
the experiments is composed by 3 circular tanks (TI, T2 an T3) each 3.6 m diameter and 0.90
m high (see Gon~alves et al., 1995 for details oftransport, handling and design ofthe elose sea
water system).
Thirty-three adult squid were submitted to observation during EXP94 and 23 during EXP95.
Howe\'er, accurate data of squid weight on EXP94 were obtained only after 21.11.94 where 19
squid were studied. Therefore, gro\\th was estimated only after that day (EXP94a). The squid.
of EXP94a had an average initial body wcight of 1489.7g (587.4 g- 3880g BW) which was
about three times more than squid maintained during EXP95 (529.0g, ranging from 95.0 to
2854g). During EXP95 squid were marked \\ith a heated rod for indi\idual identification. The
number ofanimals inside each tank was variable (I to 7) and different combinations of sexes
were maintained. In EXP94a an average of 5.7 squid was maintained simultaneously in
captivity (2 to 13 squid) and the average survival was 9.6 days (4 to 26 days). During EXP95
we kept an average of 6.7 squid (I to 10) squid and the average survh'al was 21.4 days (3 to
47).
Feeding data were recorded differently during the two assays.
EXP94 - grollp squid stlldy. Fish were prO\ided every day. Freshly dead Trachunls picturatlls
wcre the main food item used. However, few juveniles of Page/llls bogaraveo. Trachynotlls
O\'atllS, Scomber japonicus and slices of LepidopllS caudatlls and T. pictllratus wcre also
pro\ided. The amount of fish fumished to each tank were weighed (nearest to O.lg) and the
food not eaten by the squid removed, weighed and deep-frozen. In general, feeding took place at
1800 hr.
EXP95 - Individual squid Stlu(v. Predominantly frozen fish were used. Squid were fed 2 times
a day, at 0900H and 1800H, \\ith Trachunls pictllratlls. PagelIlls bogaraveo cr Scomber
japonicus. Fish wcrc weighcd and mcasured indh,;dually bcforc being introduced into the
tanks. They were supplied one by one to allow the identification of the squid !hat ate them.
Afterwards, the pans of fish rejected by each squid were removed from the tank, weighed,
labelIed anddcep frozen.
2
•
•
-
--
In both experiments the rejected portions were recorded as number of entire fish, heads and
fms (pcctoral, pelvic and caudal). A sub-sample of the rejections was analysed. Heads were
dissected and the number of otoliths and eyes recorded.
After death squid were measured. weighed and deep frozen for posterior biological sampling.
Daily gro\\th rate (DGR), daily feeding rate (DFR), daily feeding rate for maintenance
(DFR.\I), food conversion rate (FCR) and conversion efficiency (CE) were calculated
according to O'Dor et al., 1980.
Temperature was recorded daily and several water nutrients (N-NH4, N-N02, N-N03, % DO)
were perfonned on a regular basis. Average temperature during EXP94, EXP94a and E."'(P95
was 15.2 ± 1.7 (sd) °C, 13.2 ± 0.8 (sd) oe and 18.3 ± 0.8 (sd) oe, respectively (see Gonerah'es
et al.,1995 for more infonnation).
Results
•
Squid ate all the fish species fumished. even when supplied in slices. The average weight of the
fish ";.as 33.3g (7.7 - 69.0g) during EXP94 and 52.8g (18.6 - 275.0g) in EXP95.
Data conceming the features ofthe food supplied during both experiments is presented in Fig1.
3
-
---- - - - -
Tabk I. R sults of [he ft:eding grO\vlh experiment EX P95 für captive squid L. jorbesi. Squid A was kept in tank A (TA), squid B in TB and squid C in TC.
Shaded olumns illdicate squid \vilh pOSiliv!:: growlh. * refcr tü squid with a daily groWlh rate higher than 0.5% (DGR>0.5%).
(Iuid .'cf.
Survival
A2
A~
A3
7
13
A5'"
6
39
A6'"
9
A7'"
9
A8": BI
9,
82
21
83
20
B4"
8
28
B5"
28
B6": Cl
28;
22
C2
C4
8
luilial hod)' wcight
95.0 135.0
F'inal hody ",cighl
86.6 140.7
Incrcmcnl
-8A
5.7
-15.8
42.3
34.1
4(i.6
naily illl:l'cmcnt (g/dllY)
-\.2
0.4
-2.6
1,1
3.8
5.Z
Hail) gl'lll\'th I'ale wcight
-1.3
0.3
Tllial .-ation (g)
7.1
75.2
-1.0 -1.2
1.3 ,·0.61
0.0
I
I
12.1 507.4 223.1 270.8 197.0 1 540.2 504.5213.3849.8838.4676.5 1486.9135.2
Mean daily ralion (g)
1.0
5.8
2.0
13.0
24.8
30.1
Mcall daily fecding rale
1.1
4.2
1.7
7.1
6.7
7.5
8.3
15.3
17.2
17.8
35.3
34.5
Foot! cOllversioll rate
17
C7
7
28
129.4 162.1 354.4 385.2 354.811582.6 885.0 607.9 393.0 381.2 270.51853.5 810.6 555.2 932.5 805.4
I
I
113.6 204.4 388.5 431.8 374.0 11593.2 729.2 551.5 473.5 558.9 405,0 1 874.3 728.4 505.8 858.8 820.4
-2.2
7.6
COJn'ersion efficicncy (nct)
0.6
1.0
I
19.21 10.6 -155.8 -56.4
I
-7.8 -7.1
2.1 1 0.5
I
I
21.91 25.7
I
6.0 1 1.6
I
9.71
I
26.3 1
No. of IUcals
1
6
1
32
7
9
Nu. of starving days
6
7
5
8
3
3
No. 01" tlllYS wilh two meals
o
o
o
JO
1
3
16.4
31.9
30.1
61
I
51
I
21
I
32.8 i
1
I
80,5 177.7 134.51 20,8 -82.2 -49.4 -73.7
I
2.9
6.3
4,8
0.9 -10.3 -2.9 -10.5
'I
0.7
J.4
1.41 0.1 -1.3 -0.5 -1.2
25.2
26.7
30.4
29.9
3.1
4.6
7.0
6.4
9.5
21.2
20.6
52.2
33
35
~.O
1
---------------- -----------------------,---:
Mean I'lltioll
C5
I
24.21 22.1
I
7.2 1 2.6
I
92.5
15.0
0.5
0.1
0.0854.3
16.9
5.4
0.0
30.5
2.2
1.0
0.0
3.8
1.8
19.91
I
42.2 1
4..3
281
J0
4
4
0
29
14
4
13
7
4
61
o o
2
I
24.2 48.7 33.8 23.1
'
1
o
5
0.0
29.5
1
---------------.---------------
6
10
9
]5
12
2
5
3
o
2
2
]0
10
90.0
50.5
23.7
I
25.8 24.0
61
I
4
----------
~~~~~~~~~-~--
.
Feeding behcnliollr
In this study squid ate the majority of the guts of the fish even from those where only a small
fuction of the emire fish Was consumed (e.g. P. bogaraveo from EXP95). Squid refused the
majority ofthc heads ofthc fish (Table 2).
Table 1. Percentage of the bod)' structures rejected by captive L. forbesi for the species eaten during
EXP9~ and EXP95 (sub-sample). n - number offish sampled; fw - average fish weight in grams;
EXP94
n
Species
%*
%
%*
%
head caudal pectoral pehic
fw
(g)
•
EXP95
n
fw
38A
%
%
%
%
head caudal pectoral pehic
T. picturatus
295 35A
79
37
16
12
26
96
96
93
96
P. bogar~'eo
53
17.2
7.5
2
0
0
21 151.0 100
73
81
77
S. scombrus
4· 35A
75
50
75
75
8
69.5
100
75
44
33
S. pilchardus
0
5
78.1
100
100
0
100
,.. - based on a sub-sample of 168 T. picturatus
This behaviour was quite consistent except when small P. bogaraveo were furnished during
EXP94 (see Fig 1). The average weight ofthe heads collected was around 20% ofthe average
fish weight. Larger squid rejceted fewer heads than smaller squid.The position of the "neck
bitc" is always thc same. Howevcr, the squid Can eat almost thc whole head (rcjeeting only thc
jawsl showing a gradual behaviour to throwing away the head intact with the jugular area and
paircd fins. Some of the complete heads had several clean vertebrae attached. Thc heads in this
condition were nonnally from large 5sh. Also. often. the squid ate excIusively the viscera and
the muscIe ofthe dorsal area ofa large fish (e.g. P. bogarm'eo during EXP95).
Tablc 3. Percentage of eye lens and utoliths (sagittae) in the heads rejected by L. forbesi, during
EXP94 and EXP95 (Species "ith less than 5 heads rejccted are not incIuded).
•
.
. -
.
EXP9'
.
T. pictllratlls P.bogaraveo S. scombrns T. picturatus P.bogarm·eo S. scombrns S. pilchardus
otoliths
kns
01
,0
01
10
lens otol.
%
0/
,0
0/
,0
0/
10
01
,0
0/
,0
%
%
%
lens
otol.
lens
otol.
Icn:>
otol.
lens
orol.
lens
%
otol.
-
-
-
0
0
9.5
0
0
14
-
-
-
11.5
4
9.5
0
0
-
-
-
88.5
96
SI
100
100
0
28
39
1
19
19
-
2
53
42
-
0'
,0
lens
%
otol.
0
-
-
86
-
-
-
The majoriry of th~ paircd tins wcre consumed. These fins when rcjccted wcrc normally
attachd to the head. Howevcr. same lsoJatcd pectoral fins were refused. \\11en squid from thc
EXP95 werc fed wirh P. bogarm'eo they often rejccted the spiny part of the dorsal fin. The
5
•
caudal fin rejections were most commonly observed. Normally, only the caudal fin was refused
but 30 variable part of flesh associated \\ith that fin mayaiso be discarded. Few of these parts
had clean vertebrae.Tbe percentage of the heads that contains 0, 1 or 2 otoliths and eyes was
calculated (Table 3).
Discussion
Squid maintained during the first experiment EXP94 fed proportionally less (small DFR) than
squid kept during EXP95. Also, the frequency of meals was smaller for EXP94 squid. Tbat
behaviour probably is related mainly to squid size since squid of EXP94 was roughly 3 times
heavier than those of EXP95. Differences of squid feeding rates (and consequently metabolie
rates) during their ontogeny are referred by O'Dor & WeHs (1987) as a natural feature ofthe
majority of cephalopods; that is, ''No ecosystem could susciin large squid that fed at the rates
of small ones". Moreover, male-male agonistic interactions were most common during EXP94
duc to squid size and courtship (see Porteiro et al. 1995) and the stress produced by such
behaviour affect greatly feeding (Hanlon, 1990). However the temperature during EXP94 was
remarkably lower that in EXP95, which can influenced the feeding activity. Temperature
seemed to affect the feeding in EXP94 but no correlation between them could be detected in
EXP95 (probably due to small temperature variation. 3°C). Other factors such as intraspecific
interactions, prey size, stress caused by transport and handling, lesion provoked by collision on
the tank wall, are also important in regard to feeding, gro\\th and survival.
Tbe average daily feeding rate (4.09%) obtained during E.'XP95 is probably lower than of\\ild
squid, \\ith the same size. Trus value at a mcan temperature of 18.3°C correspond to a daily
gro\\th rate (DGR) of 0.1 %. However, if we only considering squid that showed positive
gro\\th (see Table 1) the DFR increase to 5.8% and the DGR to 0.7%. For squid \\ith an
average body weight of 438.3 g the latter rate allow an increment of 3.07g a day. Squid in such
conditions, would attained lkg (average body weight of mature female squid, Porteiro &
~fartins, 1994) in 183 days (note that the majority of squid were female). FoHowing the same
thinking, squid that showed the maximum DGR would achieve the same weight onlY in 91
days. Tbis rough approach seems to be quite reasonable since squid were caught at February~tarch and by luly the fishery decrease as a consequence of low abundance of mature squid
(Porteiro, 1994).
Tbe results obtained put in evidence some differences between L. Jorbesi and the
ommastrephids Tadarodes pacifiC'.ls and lllex illecebrosus. whithin similar range of weight
(Sakurai er al., 1993; O'Dor et a1., 1980, respectively). Lower values of DFR and DGR were
achieved by thc specimens of T. pacificus (2.60% to 3.72% and 0.42% to 0.81 %, respectively)
when compared \\ith the values attained by some individuals of L. Jorbesi. However, the food
conversion rate (FCR) achieved by squid ofboth species is similar (14.53% to 24.2% for T.
pacificus). Despite thc fact that indi\iduals of L. Jorbesi showed a DFR as high as lllex
illecebrosus. the DGR (as the FCR) of that ommastrephid was significantly higher. Tbe
conversition efficiency of L. forbesi (\\ith a positive DGR and a DFR >DFRM) was smaller
than those calculated for the two ommatrephids (39% for T. pacificus and 40% for I.
i/lecebrosus), but it also shO\\TI a high variation. Tbe daily feeding rate for mamtanence
(DFR..\I) calculated for L. forbesi (3.78%, see Fig. 2) is very high when compared \\ith the
DFR..\t of T. pactficus (1.67%) and that of I. illecebrosus (1.1%). However. the experiments
donc by Sakurai er al. (1993) ~d O'Dor er aI., (1980) \\'crc carricd out at 15.6°C which c~
compromise these comparisons. However, these results should be regarded \\ith some reserve
since some squid starvcd (and conscquently lost wcight) during few days prior to dying (e,g.
squid..\8 in Fig. 3)
6
•
•
•
...
•
•
The speed-respiration of L. forbesi has been assessed in laboratory using a eombination of
video records, telemetcred mantle pressure and repirometer by O'Dor et al. (1994). This
information was used for inferences about the eosts of different behaviours telemetered in the
field as well as to suggcst a life style for this squid iri nature. In this study an average feod
equivalcnt of 1.9% BW d-I of metabolie rate maintenanee (DFR.\l) ,....as ealculated from 4
squid. Also a food equivalent of0.21%, 1.45% arid 0.47% was eomputed for resting, climbing
and ho....ering, respectively. Unfortunately, the costs of fin swimming was not assessed. All the
previous estimations presented low values eompared ,..ith the results obtained in eaptivity.
S\'~immiI1g is required to a\'oid sinking (squid have negative bouyanee) and although jetting
was observed, fin propulsion aecounted for more ca. 99% of the squid motion in the tanks. Tbe
high DFRM ealculated is related \\ith highmetabolic rate. Tbe energetic demands ofthe squid
should be associated \\ith high stress levels or "ith the costs of permanent use of fins. Tbe
latter explanation seems unlikely since low costs of fin swimming should be expeeted. Tbe first
assumption is sustained by a weak squid survival (average survival ,vas 21.4 days duririg
EXP95).
Several times fatty faeces were observed floating on the surface reflecting the high lipid
contents of the food fumished and the inability of those animals of lipid absorption and
metabolization (see O'Dor & Wells, 1987).
T. pictllratlls, wcre chosen for diet beeause that species are important items of L. forbesi in the
Azores waters as recorded by Martins, (1982) and Pieree et al., (1994). Also, ,..ild squid can
eat S. japonicus and P. bogaraveo. When fishing for demcrsal fish "ith a bottom long-line, in
eoastal water. those species carne to the surface bitten arid eaten by squid (observation by
Fl\IP).
Some aspects of feeding beha,iour of captive adult L forbesi has been previously deseribed by
Porteiro et al: (1990). The rejection of hald structures such as head. vertebrae and caudal fin,
has b~en observed in several species (e.g., Hanlon et al.. 1983, for loliginids; by O'Dor et al.,
1980: for IIIcx ilIecebrosus). Howevcr the bulk of the studies of fceding eeology of squid are
based on the analyses of hard structures found in stomaeh eontcnts as otoliths, eye lenses,
bones. and mrcly teeth (see for exarnple Martins, 1982, Collins et al., 1994, Pierce et a1.,
1994, and Rocha er al., 1994 for L. forbesi).
I\lartins (1982) conc1udcd that Loligo forbesi do not rcjeet the head smee otoliths and eyc
lenses of fish were found frequently in the stornach eontcnts. Although. the ingestion of an
emire fish oecur, it depends of the re!ationship between squid size and prey size. Also, the
variation ofthe feeding behaviour probably depends on the prey spccies and the squid appetite.
Subevaluation of some food itcms at the eost of others can oeeur if no intormation of fccding
bcha\lour cxists. It is not yct knO\\n if prefercnces of prey size exist in L. forbesi. but. :lS other
Ioiiginids. they probably fced on a \\ide sizc range of tish. Squid in the "ild might havc a
similar beha\iour, smee feeding behaviour is stereotyped. If thcy seize the same sort of prey.
thc probability of finding statoliths of T. pictllratus would be 61 % and 2%, respectively. fcr
squid ,..ithin the same range size ofthose maintained in EXP94 and EXP95. TIIe use of otoliths
and other hard structurcs used to stud~10 infcr about the feeding ecology of aquatie animals has
been critically reviwcd by Jobling & Breiby (1986).
The ideal methodology when feeding ecology is concemed \\ill be the combination of
scrological methods. stomach contents analysis (as done by Kear, 1992) and studics
feeding
behaviour.
on
AcknowJedgments
111ankS are due to ~orberto S.:rpa and Lesl.:y Gallaghcr • our best squid fishennen.
l1lis work was funded by the European Commission \\ithin the fuur.e of EC research
progratr.me in the Agriculture and Fishcries sector (AIR, Contrnct ~o. AIR l-CTn-573).
7
•
Thanks are due to the Regional Secretariat of Agriculture and Fisheries of the Azores
Goverrunent who gave us perrnission to use their installations at the Whale Station, Porto Pirn
Beach (Horta) and supported its running costs.
References
Boucher-Rodoni, R. E. Boucaud-Camou &. K. Mangold. Feeding and digestion. pp. 85-108, in:
Cephalopod Life Cyc/es. Cvmparative Reviews. P.R. Boyle (Ed.). London, Academic Press.
Vol. H. 441 p.
Boyle P. R. & G. J. Pierce (Eds.), 1994. Fishery biology of northeast Atlantic squid. Fisheries
research, 21 (1-2): 314 p.
Collins M. A., S. De Grave, C. Lordan, G. M. Burnell & P. G. Rodhouse, 1994. Diet of the squid
Loligo forbesi Steenstrup (Cephalopoda: Loliginidae) in lrish \Vaters. ICES Journal of
Marine Science. 51 (3): 337-344.
Esticio, S., J. M. Gonl;:l1ves & H. R. Martins, 1995. Reading and staining of L forbesi statoliths.
International Counci/for Exploration ofthe Sea, (abstract), Ip.
FOfS)the, 1. W., 1993. A working hypothesis on how seasonal temperature change may impact the
field grO\\th of young ceph:l1opods. pp. 133- 143, in: Recent Ach'ances in Cephalopod
. Fisheries Biology. T. Okutani, R.K. O'Oor & T. Kubodera, (Eds.). Tokai University Press,
Japan. 752 pp.
ForS)the, J. W. &. R. T. Hanlon, 1989. Gro\\th of the Eastem Atlantic squid. Lo/igo forbesi
Steenstrup (Mollusca: Ceph:l1opoda). Aquacu/ture and Fisheries Jlanagement, 20: 1-14.
ForS)the. 1. W. &. W. F. Heukelem. 1987. Gro\\th. Pp. 135-156, in: Cephalopod Life Cyc/es.
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•
9
B
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Fig,l - Hclalil'c cOlllposilion of Ihe food ilellls furnishcd during lhe Iwo sels of experimenlS: A in nllmbers for EXP94: 8 in 1I1111lbers for EXP95; C in Weighl for EXP); D in
IVcighl fOI EXPl.J5, Pb· f'ageill/~' bogorcIVeo; Tp - li'(.u:hun/:i' picluralus; 5s - Scolllberjaponicus; Sp - Sordino pilchordus
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Fig. 2 - Daily feeding rate (DFR) for some squid that gre'.v with:m average daily ~ro\Vth
rate !Iigh:::r th:lIl 0.5% (DGR > 05%), S.::e text ,md Tablc Ifor more :nfomlation.
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.
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DFR(%)
Fig. 3 - Linear regression between daily feeding rate (DFR) and daily growth rate (DGR) of squid
group EXP94a and individual squid from EXP95.
•