First record of an egg mass of Loligo forbesi (Cephalopoda: Loliginidae) in the Ligurian Sea, with notes about egg laying patterns in southern populations

2009·5 MB·English

by  Lidia Orsi Relini

Boll. Malacol., 45 27-33 (suppl. 2009)
First record of an egg mass of Loligo forbesi (Cephalopoda:
Loliginidae) in the Ligurian Sea, with notes about egg laying
patterns in southern populations
Lidia Orsi Relini (EH), Alessandro Mannini, Luca Lanteri
& Eugenio Beccornia
Dip.Te.Ris, Laboratori Abstract
di Biologia Marina During the trawl survey MEDITS 2005, an egg mass of Loligo forbesi was collected in the western Ligurian
ed EcologiaAnimale, Sea, on a muddybottom atabout600 m ofdepth. Thisrecord, thefirstin thestudyarea, isdiscussedtaking
Universitàdi Genova into account general information about spawning in L. forbesi Mediterranean and Macaronesian popula-
Corso Europa 26, 16132
Genova, Italy, tions. Theoccurrenceofdifferent reproductive patterns in Loligospeciesare underlined and in L. forbesithe
[email protected] existence ofegg strands heavierand lighterthan the sea water isconsidered indicative ofa spawning strat-
egyevolving with time and age ofthefemale.
Riassunto
Si riporta il primo ritrovamento di uova di L. forbesi su fondi fangosi batiali del Mar Ligure occidentale, a
circa 600 m di profondità. Percommentare questo repertoed inquadrarlo nella biologia della specie, si rias-
sumono le informazioni sulla riproduzione reperibili nella letteratura relativa al Mediterraneo e all'Atlantico
adiacente. Queste riguardano: 1) la presenza di zone di deposizione in prossimità del limite piattaforma/
scarpata, chefu accertatacirca un secolofa dai ricercatori della StazioneZoologica di Napoli; 2) l'associazio-
nedellecapsuleovigerea celenterati colonialiche risulta dallestesse ricerche; 3) losviluppoembrionale, con
simili dimensioni alla schiusa in materiale del Mediterraneo e delle Azzorre; 4) osservazioni sul comporta-
mento condotte alle Azzorre sia su individui marcati, sia su individui in cattività: di questi ultimi è stato os-
servatol'accoppiamentoe ladeposizionedelleuova; 5) un recenteritrovamentodi uovadepostea circa 730
m di profondità nell'Egeo. Questa rassegna degli aspetti riproduttivi è suggerita dal fatto che L. forbesidel
Mediterraneo e del nord Europa sarebbero distinti a livello di sottospecie e che nelle due sottospecie della
congenere L. vulgaris(L. v. vulgaris, L. v. reynaudii)vengono descritti comportamenti riproduttivi sostanzial-
mente differenti. Si conclude che nelle popolazioni meridionali di Loligo forbesi, le capsule ovigere possono
essere deposte in un intervallo di profondità di oltre 500 m; le capsule ovigere possono presentare diverse
tipologie, cioè essere piu dense o meno dense del mezzo ambiente, verosimilmente in funzione dell'età
dellefemmine. Capsuleovigere erettesul fondo, rispondenti ad esigenze di visibilità, suggerisconocompor-
tamenti riproduttivi complessi come quelli descritti in specie o sottospecie di Loliginidae non presenti nel
Mediterraneo (Loligopealei, L. opalescens, L. vulgaris reynaudiiecc.).
Key words
Loligo forbesi, Mediterranean, egg capsules, spawning strategies, Cephalopoda.
Introduction The aim of this note is to describe a recent record of L.
forbesieggs in the Ligurian Sea and to report old and re-
The veined squid Loligoforbesi Steenstrup, 1856 (Cepha- centdata,from MediterraneanandadjacentAtlanticwa-
lopoda: Loliginidae), isdistributed throughouttheMed- ters. Available literature about reproductive patterns,
iterranean and adjacent Eastern Atlantic, in the latitudi- which are supposed tobe conservative, are re-examined
nal range 20°-60° N, with theAzores Islands as its west- in detail to clarify similarities and/or differences with
ern boundary (Roper et al., 1984). This species, which is respect to northern populations. The description of the
often confused and/or dealt with together L. vulgaris, "state of the art" about reproduction in the southern
represents a valuable fishery resource in the Atlantic, populationsofL.forbesialsoshowsuncertaintiesorgaps
while in the Mediterranean it is an irregular by-catch of ofknowledgeaswell asprovidingindicationsforfuture
trawl fisheries. research.
Clearly, the knowledge about the populations living in During several Mediterranean trawl surveys, both na-
this large range of latitude and longitude (Fig. 1) is un- tional and European, L. forbesi has been caught from 50
m
balanced, with a pole of intensive research in Scotland to 600 at the Balearic islands (Quetglas et al., 2000),
and scarce data in the South: such a polarity reflects the from 84 to 115 m off the French coast (Boletzky & Man-
economic importance of the species in the NE Atlantic, gold, 1985);fromtherange50-100mtotherange500-650
with the largest landings in the UK. On the other hand, mintheLigurianSea (Relinietal.,2002);from 100to400
both morphometric and genetic studies, have indicated m in the North Tyrrhenian sea (Mannini & Volpi, 1989;
relevant differences in northern and southern popula- Beicari & Sartor, 1993); from 40 to 620 m in Sardinia
m
tions (Guerra, 1992; Pierce et al., 1994; Brierley et al., (Cuccùetal.,2003);from 70to560 intheSicilianChan-
m
1995). nel (Ragonese & Jereb, 1986); from 75 to 425 in the 27
al., 2002), by a haul located off the Gallinara Island (Fig.
2). Itlasted onehour,thestartingpositionswas43°57'91"
N-08°18'19"E,theendingposition43°56'00"N-08°17'68"
E, the average depth 614 m; the seabottom temperature
13.6°C.
TheMEDITSproject(MediterraneanInternationalTrawl
Surveys) (Bertrand et al., 2002), which presently con-
cerns 10 European countries, is based on a spring-sum-
mer survey which is primarily aimed at obtaining esti-
matesofabundanceindexesforaseriesoftargetspecies.
Theselectedstationsarebasedonadepthstratifiedsam-
pling scheme that includes five depth strata: 10-50, 50-
Lidia
100, 100-200,200-500and500-800m.Thetrawlnethas20
mm
Orsi stretched mesh size in the codend. During the haul
Relini, Fig. 1.DistributionareaofLoligoforbesi. Southernpopulationslivealong continuous measures of temperature and depth are re-
an axisabout6,000 Km long. corded. The GRUND project (ItalianTrawl Surveys) has
Fig. 1.ArealediLoligoforbesi. Lepopolazionimeridionalisonodistribuite similar aims and a similar depth stratified sampling
Alessandro lungo unasseestesopercirca6.000km. scheme, with more numerous hauls which are carried
outinautumn. InthepresentstudyareatheGRUNDnet
North Ionian sea (D'Onghia etal., 1995); from 276 to 715 meshhas thesame size than the MEDITSnet.
m
Mannini, in the North Eastern Ionian sea (Lefkatidou et al., Theeggmasswasfrozenonboardand, oncetransferred
2003). In the southern Ligurian Sea, a recent mappingof to the laboratory, itwasthawed and fixed in 10% forma-
Luca the distributions of L. vulgaris and L. forbesi shows the lin. Eggswereobservedwith avideocameraattached to
m
latter squid located from 80 to 600 (Ria et al., 2005). a stereo microscope. Counts and measurements were
Lanieri
Loligoforbesi therefore appears to be a circalittoral and taken from the images by means ofthe LeicaQWin soft-
&
bathyal species, which is mostly separated from the ware.
strictlycoastal L. vulgaris.
Eugenio
In the Atlantic, such a separation disappears progres-
sivelytothenorthand L.forbesiextendsitsrangetoshal- Results
Beccornia low coastal waters: thus, near Plymouth, where it coex-
istswithL vulgaris,ithasbeentrawledupfrom 13to 104 Theeggmasscomprised 13capsules,8-8.5cmlong,each
m
of depth (Holme, 1974) and in Scotland, where the containing 36-40 eggs. The egg capsules merged at the
presence of L. vulgaris is scarce, from 18 to 371 m (Lum- base in a common pointwhich retained a small quantity
Kong et al., 1992). In the Moray Firth (Scotland) a spe- of mud, thus suggesting that the group was attached to
cific trawling for juveniles is carried out in autumn at some hard object laying on thebottom; however nopart
m
only 10 (Pierceetal., 2006). ofanyobjectwasfound.
Six eggs were randomly extracted from the jelly mass
and measured; the largest diameter was ca. 3 mm. The
Material and methods developmental stages of embryos appeared to be very
similar in all the eggs and corresponded to stage 16 of
The egg mass described herein was collected on the 12 Segawa etal. (1988).
July 2005 during the trawl survey MEDITS (Bertrand et We assigned theegg mass to L.forbesion thebasis ofthe
following combination of characteristics: 1) egg size; 2)
8°00' 8°30’
Albenga • number of eggs per capsule; 3) general aspects of the
capsule, such as transparency of the jelly and irregular
Gallmara Island surface (seefurtherbelow);4) depth ofthe record.
44°
.start
Discussion
• end
First observations on Lforbesi egg masses were carried
Imperia 100
200/ out at the Zoological Station of Naples. Jatta (1896), de-
500 scribing the species, stated that eggs were unknown;
howeverhe figured, in plate3 fig. 1 ofhismonograph, a
1000 group of five capsules laid on a thin branch of thebam-
boo coral Isidella elongata (Fig. 3 A) and wrote: "these
eggs must be assigned to a Myopsid squid; they are
m
found at 150-200 depth and are collected in the vicin-
Fig.2. LocationwheretheeggsofLoligo forbesiwerecaughtbytrawl. ityofCapri island. Such massesareverysimilarto those
28 Fig.2. Luogodi raccoltaastrascicodelle uova diLoligoforbesi. of L. vulgaris and I think they belong to L.forbesi”. Later
onboth Lo Bianco (1909) and Issel (1932) confirmed Jat-
ta's identification.
Lo Bianco (1909) noted that egg masses were found on
branches of Isidella and other gorgonians and also on
Corallium rubrum in theperiod fromApril toJune: "they
are opalescent, rather trasparent, cylindrical with an ir-
regularsurfaceand two taperingends. Thelengthofthe
capsulerangesfrom8to 11 cm,witha diameterofabout
15 mm; itisverysimilar to thecapsuleofL. vulgaris, but
it is more transparent and larger. Capsules are laid on
muddybottomsand oncoralligenousreefs,at150-200m
depths".
First
The notes of Lo Bianco (1909) placed the spawning area
of L.forbesi approximately at the shelf break, while the record
indicated spawning season is spring, so that the pres- of
ence of recruits should occur in the following summer. an
However Lo Bianco (1909) noted also that L.forbesi was egg
nota species continually present in the Gulfof Neaples.
mass
It could appear in September, sometimes in large num- of
bers,butnotinalltheyears.Theassociationofeggswith
gorgonians is not mentioned in any further paperand is Loligo
intriguing. In particular I. elongata, standing on compact
muddybottomsinalargedepthrangeoftheslope(Pérès forbesi
& Picard, 1964), in the past should have offered to the
squid large quantities of living hard substratum, but at
presentit almost disappeared from trawledbottoms, in- (Cephalopoda:
cludingtheirdeepestrangeatabout700m depth,where
the trawlers target thered shrimpsAristeusantennatus.
Other basic studies carried out in Naples regarded the
Loliginidae)
comparative anatomy of the Loliginidae. Naef (1923),
describing the general morphology of L. forbesi, men- in
tioned the occurrence in males ofaccessory glands with the
a possible content of luminescent bacteria, a feature Fig. 3. Loliginid egg capsules lighterand heavierthan seawater. A. Egg
which, in modern taxonomical approaches, might re- capsulesofLoligoforbesiInthefigurefromJatta(1896);thecapsulesare Ligurian
movethisspeciesfromthegenusLoligo(Alexeyev, 1992). attachedtoaverythinbranchofthebamboocoralIsidellaelongata,sug-
gesting that they are lighter than sea water B. Egg capsules of Loligo
Naef noted that juveniles of this species have a thicker vulgaris-clearlyheavierthanseawater-Inasheltered locationon rocky Sea,
head than L. vulgaris of the same size. He could not ob- bottom. with
servefullymatureanimals,butwrote: "Thematuremale Fig. 3. Capsule ovariche di loliginidi meno e più dense dell'acqua del
is much slenderer, the length of the mantle is at least 6 mare. A. CapsuleovarichediLoligoforbesiin unafiguradaJatta(1896); notes
times its width". Naef's observations were confirmed le capsule aderiscono ad un sottilissimo ramo del corallo-bambù Isidella
elongata, mostrando una minore densità rispetto all'acqua del mare. B. about
whenMartins (1982) described forthefirsttimethe fish- CapsuleovarichediLoligovulgaris-chiaramentepiùdensedell'acquadel egg
ery and the biological characteristics of L.forbesi at the mare-in un posto protettosufondoroccioso.
Azores Islands, where very large specimens were laying
found.
Martins (1982) examined 1/3ofthe totalannual catchof evant, a smallersize ofhatchlings in respect ofsouthern
anartisanal fisheryusinghand linesinHorta,Faial,fora populations (see later), i.e. 3.26 and 3.13 mm at the tem- patterns
total of 622 specimens. The jigging had taken place at peratures of8 and 12°C (Gowland etal., 2002). in
m
215-270 ofdepth. The catch consisted of a majority of In Naples fishermen never confused the two species of
mature individuals (80.2%) whose length range was 31- Loligo L. forbesi was called "occhione" (= big eye) be- southern
:
90cmDMLinmalesand25-41 cm infemales. Duringthe cause of its large eyes (Naef, 1923). The distinction was
yearofthestudy thehighestdegree ofmaturity was ob- probably related to the respective commercial value: in
served in springand the lowest in autumn. factbecause of their large size and tough flesh, L.forbesi populations
From the notes of Martins (1982), several affinities with arecheaperthanL. vulgaris (Nesis, 1971).Atpresent(end
the Mediterraneanpopulationareevidentaswellasdif- of 2005) in the Ligurian landings of cephalopods, the
ferencesfrompopulationsofNorthernEurope. Asto the small catch ofL.forbesi (Fig. 4) is divided into two com-
latter, beside having a different depth distribution, as mercial categories, the large and the small specimens,
previouslynoted,theyarecharacterizedbysmallersizes thelatterbeing also the mostexpensive.
(Holme, 1974), by a different reproductive season (i.e. After these first studies, apparently the reproductivebi-
from December toJune in coastal water of Scotland, ac- ologyofMediterranean L.forbesiwasneglectedformany
cording to Lum-Kong etal., 1992) and, what is more rel- years. Mangold-Wirz (1963) observed very rare speci- 29
(Porteiro et al., 1990). Mating occurred in captive speci-
mens - male 46 cm DML, female 35 cm DML - which
m
werekept in a tank of3 in diameter. After 13 days the
female laid 50 strands of eggs (80-100 eggs per strand),
mostofwhichwherefixedtosmallstonesonthebottom.
The female died two days after spawning. In the same
locality, eggs were found also on a artificial substratum
(Porteiro & Martins, 1992), anoctopus trap, formed by a
segmentoftubularPVC, witha diameterof 13.5 cmand
oneend sealed withconcrete. The trap wasplaced at25-
m
30 depth and, at recovering, it contained 20 capsules,
eachwith39to50eggs.Thisrecordseemed surprisingto
Lidia
the authors: in fact, in theAzores, squidsbearing acous-
Orsi tic transmitters, tracked both day and night, had been
Relini, tFriga.wl4.suCravtecyheMsEDofITLSoli(geondfoorfbesspiroinbgs)eravnedd GinRtUhNeDLig(uaruitaunmnS)e,adduurriinngg tthhee observed to movebetween20 and 550 m, so the authors
period 1994-2005. considered surprising that and adultsquid would come
Fig. 4. Catturedi Loligoforbesieffettuate nel MarLigure nell'ambitodel up to lay eggs in shallow waters. However this record
Alessandro trawl survey MEDITS (tarda primavera) e GRUND (autunno), nel periodo and others to be mentioned later on, suggest that egg
1994-2005. laying can occur at any level oftheir depth distribution.
The two clearly different egg masses of L. forbesi ob-
Mannini, served in Horta (L vulgaris isnotpresentin theAzores),
mens of Lforbesi in the Catalan Sea fisheries, but about deserve some further comments. Spawnings of about
Luca
twenty years later, the squid appeared with interesting 4,500 and 900 eggs respectively, could be due to spawn-
numbers on the Provencal coast (Boletzky & Mangold, ers of different size, a large and a small female respec-
Lanieri
1985); in trawls carried out between 85 and 115 m, both tively (defacto the former was due to a large female, 35
&
adults and juveniles were observed. Similar events oc- cm ML). Howeveralso themodesofegglayingchanged
Eugenio curred in the Ligurian Sea. In theperiod 1977-81 during completely: inside a hollow object and on stones on the
a study of bathyal fishing grounds no L. forbesi was bottom, respectively.
found. During the '80s some specimensbeganto appear In the literature, such different modalities of egg laying
Beccornia in the trawl catches and at present with the trawl sur- are generally ascribed to different species or subspecies
veysoftheItalianprojectGRUNDandthoseoftheinter- ofLoliginid squids: the two subspecies ofL. vulgaris can
nationalprojectMEDITS, startedin 1994,catchesremain serveasexamples.
veryvariable (Fig. 4). In L. vulgaris vulgaris of the Mediterranean the eggs are
In the '80s substantial information oneggs and embryos commonly observed on rocky areas at about 20-30 m
of L. forbesi were achieved both on Mediterranean and depth (Fig. 3B): they are heavier than the sea water and
Azorean material. In both cases, females captured alive their placement apparently scarcely fulfils the need of
laid egg capsules which were raised in the laboratory to visibility. Social interaction during spawning are appar-
hatching; although egg laying may have been triggered ently limited to the fact that females, in presence oflaid
by stress, the development was apparently normal. Bo- eggs strings, add their own to those previously fixed on
letzky (1987) observed that a female caught by trawl at the substratum (Mangold, 1963, 1989).
95-105 m in November and maintained in a tank on- On the contrary, in the other subspecies, namely L. vul-
board, deposited two capsules before dying. The cap- garis reynaudii, the mating process is very complex and
suleswerebroughttothelaboratoryofBanyuls-sur-Mer thereare threedifferentwaysofsperm transmission. Fe-
and raised together with freshly laid capsules of L. vul- males, already mated and bearing sperm in a buccal re-
garis. Eggs of L.forbesi hatched 60 days after the deposi- ceptacle, reach mating arenas, i.e. areas covered by sev-
tion, at a temperature varying from 12 to 15°C; hatch- eral egg mops (1-3 m diameter). Around each mop ago-
lings measured 4.5 mm ML and thus corresponded to nistic behavior of large males and intrusion of sneaker
juvenile L. vulgaris one to several weeks old (Boletzky, males are observed (Sauer et al., 1997; Hanlon et al.,
1987). Egg strands were obtained also from mature fe- 2002). Winner males transfer their spermatophores in-
males in captivity in a wooden cage maintained for this side the mantle of the female; sneaker males to the egg
purposein theHortaharbour(Porteiro& Martins, 1992). masswhichisformingin thearmsoffemales. Theresult
Live eggs, after 11 days at about 15°C in the harbour, is that multiple paternity is assured to eggs of a single
were transported to Texas and raised there at 12.5°C. capsule (Shaw and Sauer, 2004). The egg masses erected
Segawa et al. (1988) illustrated 30 embryonic stages and on the bottom, are very visible and they represent im-
observed a range of DML of hatchling (4.3-4.9 mm) in portant visual signals for the spawners. In fact, large
the same size range as indicated by Boletzky (1987). The maleswait forthe arrival offemales remainingnearegg
sizeofembryos ofL.forbesimirrors the fact thatthis spe- masses and after mating they escort the female to the
cies is considered the largest Loliginid squid (Nesis, mops (Hanlon et al., 2002). Touchingegg strands, males
1971). also take specific reproductive pheromones (Buresh et
30 Other aspects of egg laying where observed in Horta al., 2003).
1
In southern populations of L.forbesi two modes of egg ment occurs in 60 days (Boletzky, 1987) and produces
mm
layinghavebeenobserved: a)eggcapsulesheavierthan hatchlings measuring4.5 ML.
sea waterwhich hang from thesubstratum like tiróseof Recruitmentprocesses arenotwell known, however the
L. vulgaris: examples can be found in the egg capsule distribution of young individuals is connected with the
figured by Boletzky (1987) and those found in the octo- shallower levels at about 60-80 m. Sporadical observa-
pus trapofHorta (Porteiro &Martins, 1992);b) eggcap- tions on the behaviour of captive specimens suggest
sules lighter than sea water which are standing on the complex social interactions regarding mating and egg
substratum: examplesareegg massesadheringtosmall laying,inparticularcompetitionamonglargemales,and
stones of the bottom (Porteiro et al., 1990), as well as the production of buoyant egg strings, suitable to as-
those laid on Isidella elongata (Fig. 3A). The latter cap- sume maximum visibility on their substratum.
sules had to be light, otherwise a more robust part of Are the above-mentioned features present also in the
the colony should have been used. This kind of egg latitudinalaxisofdistributionofL.forbesi, fromMorocco
First
strands suggest their collocation in mating fields. May to Norway, and how far can they be tracked to the
these differentmodalitiesofegg layingbe related to the North? record
ageoffemales? Taking intoaccountthatan intermittent Genetic studies have separated L. forbesi of the Azores of
terminal spawning occurs in Loliginidae (Rocha & from North European populations, from North Spain to an
Guerra, 1996) and that the firmness of body tissues of the BritishIsles, at thelevelofsubspecies (Brierleyetal., egg
the spawnersdeclineswith time (Macewicz etal., 2004) 1995): have the two subspecies, which remain unnamed
mass
this supposition seems reasonable. Older females, i.e. probably because of unresolved affinities of the genus
of
those engaged in the last steps ofspawning, mightpro- (Vecchioneetal., 1998), identical reproductive features?
duce a lighter jelly and buoyant egg strands, which Spawning areas similar, depth-wise, to the Mediterra- Loligo
could be more suitable for mating arenas. Loliginid nean ones were reported by Lordan & Casey (1999) off-
squids show themostcomplex socialbehavior, particu- shore the coast of Brittany. At the end of March 1995 a forbesi
larlyinthegenusSepioteuthis (Moyniham & Rodaniche, largeamountofegg masseswerefound ina haulcarried
1982);inthegenusLoligotopperformancesareassigned out at 135 m; the bottom temperature was about 11°C.
to older and larger individuals, in particular to large This record maybe very important to explain the repro- (Cephalopoda:
males which are the leaders of nuptial choreographies ductivebiologyofL.forbesi. Infactitrepresentsthemost
(Sauer et al., 1997) but could also be assigned to large recentdocumentationoftheexistenceofspawningfields
females. If it is so, it is not surprising to find such strat- on muddy bottom, after those indicated by the use of
Loliginidae)
egyinL.forbesi, thespecies that reachesthe largestsizes Isidella elongata in the Mediterranean.
and the most important sexual dimorphism. However, In the followingyears, twootherrecords, lessimportant in
many questions remain to be answered: why sometime asquantities,occurredwestofIreland,at300and 500m, the
egg laying seems occasional and sometime so "organ- with bottom temperatures of 10.7°C and 10.8°C respec-
ized"? Are the latter phenomena related to population tively (Lordan & Casey, 1999). These, in the opinion of Ligurian
densities? the authors, could have been detached eggs that were
The mostrecentrecord ofan eggmassofL.forbesi in the not laid in the area where they were caught. All other Sea,
Mediterranean was reported in the Aegean Sea (Salman eggmassesmentioned in theliteratureoftheBritishIsles with
& Laptikhovsky, 2002). On March 1996, two egg masses (e.g. Lum-Kong et al., 1992; 1993; Collins et al., 1995;
m
were recovered from a depth of 720-740 attached to Gowland etal., 2003) were found in coastal shallow wa- notes
smallrubble;embryoswereinanadvanced phaseofde- ters and frequently on artificial substrata, such as creels
about
velopment. This record isverysimilar to thepresentone for lobsters. The possibility oftwo kinds ofegg laying is
and for both the transport of detached materials cannot thus confirmed also in NE Atlantic populations albeit at egg
be excluded. However every new find of bathyal loca- different latitudinal levels (North France and Ireland- laying
tion of eggs reinforce the possibility of real very deep Scotland respectively).
egglaying. Moreover,thedetail ofthesmall stonesrecall TheChannel couldbeasignificantboundaryforL. forbe-
theexistenceoflighteggstrands,erectonthebottom,i.e. si, separating boreal neritic and deeper southern forms patterns
probably laid by old and/or large females which could (Tait, 1968). However, as already noted, genetic studies in
live deeper than young females. contrast such hypothesis indicating a homogeneous
populationstretchingfromNPortugaltoScotland(Shaw southern
etal., 1999). Unfortunately,southerncontinentalpopula-
Conclusions tions, including all the Mediterranean ones, remain un-
explored froma genetical point ofview. populations
In conclusion, along the major axis of its distribution, These brief notes on spawning characteristics of Loligi-
fromtheAegeanSea to theAzores, Loligoforbesiappears nidae, indicatethatmanyaspects,rangingfromgenetics
to be a deep water species - circalittoral and bathyal - to social behaviour, remain tobestudied in the Mediter-
which lives in a vertical space of about 500 meters and ranean.
hasspawninggroundsaroundtheshelfbreakandonthe Reproductive strategies are certainly one ofthe most in-
muddy bottoms of the slope. In the Mediterranean this terestingaspects,because theycanbe related to the fish-
habitat is homogeneous in terms of temperature (13- ery management (Pierce et al., 2006) as well as to cepha-
14°C); in fact, in this optimal temperature the develop- lopod general biologyand evolution. 3
Acknowledgements Issel R., 1931. Cefalopodi. Enciclopedia Italiana Treccani. Voi. 9:
638-647.
We wish to thank prof. Roberto Pranzato for the kind JattaG.I., 1896. CefalopodiviventinelGolfodiNapoli. Fauna
permission to rise his underwater photograph of Loligo undFlorades Golfesvon Neapel,23: 1-268 +30pits.
egg masses in thispaper. Lefkaditou E., Mytilineou Ch., Maiorano P. & D'Onghia
G., 2003. Cephalopod species captured by deep-water ex-
ploratorytrawlingin the NortheasternIonianSea.Journalof
NorthwestAtlanticFisheryScience,31 431-440.
:
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