opment of hake Merluccius merluccius (L. 1758)
)uincoces & Marina Santurtim
eM 1998/0PEN:19
,di Irla sIn 48395, Sukarrieta, Bizkaia, Basque Country, Spain.
INTRODUCTION
Hake (McrlUf.xius 1t/('/"hn:ciIL~ L I i58) is agadifonn fish \\;de!y distributed finm Iceland to Mauritanian
walers. in the Mediterranean and Black Sea. It is touj1d between 70-370 m depLh, hUI also occur from
inshore (30 m) to 1000 m. In the \ortheast Atlantic multispecific European fisheries calch 01is species
from· ICES Sub-area IV 10 IX. Spain and France fish about 80% of total catches; other countries
involved in the fishery are United Kingdom, Ireland and Portugal. For Spain and France Hake is the
basis ofa very economically important fishery .
Two stocks have been recognised for assessment and managemem purposes: the nortl'tem stock (Div.
IVa, VIa, Sub-area VlI and Vlllab) and lhe southern one (Div. VIlle and IXa). The catches (landings
and discards)oflhe two stocks amounted in 1996 for41,754tandca 8,900 lrespectivel)' (ICES eM,.
1998).Inthe BayofB~(Di\·. VJfia,b,d) 17,800 lofHake were caught in 1996mainlybyl~
''bakaR_, "bem"- and VHVO (\'ery high vertical opening) pair-tra\\ters.
I:lIJ: 10 the economical importance of this species !here are abundant studies about: !he biology, ecology,
and puwth. This information is referred mainly to its morphology, taxonomy and geographical
distnbution (Whitehead el aI .• 1986; Smith et .01., 1986; Agnew, 1989; S8nchez et aI., 1991). There
are also some studies abotn reproductive and other biological aspects in the Bay of Biscay and in
adjacenl waters (perez & Pereiro. 1981; Martin, 1991):
In this work lhe resullS or a histological study on reproduction ofHaJre. M. merluccius. <:aJTied out
on a monthly basis sampling in 1996-1997 in the Bay of Biscay (Div. VIlla,b,d) are presented.
MATERIALS AND METHODS
During 1996-1997, an intensive sampling program was carried out on a monthly basis 10 obtain
representative nwnber of M.merluccius in orderto advance in the reproduction biology knowledge
of the species. Biological samples were collected III sea and at the main fishing ports of the
Basque Country from vessels that operate in Div. Vllla,b,d.
ned "ith hacmatoxilyn-eosin. To do the identificalion ofEhe structures easier, lhev. have
The ~nads (ovaries and testes) were collected after fish were caught For histological studies,
fue ann oflhe sampling was to obtain the gonads of a maximwn of 10 females and 6 males by
1 em length range and by month. along a "biological year" in lhe [1996-1997] period. Gonads
were fixed in a 4% formaldebyde buffered solution. Later, in the labomtory, the gonad samples
were embedded in glycol methacrylate resin (Technovitt 7100), sectioned at 2-3 p.m, stained
with Harris haematoxylin and 1% aquose yellowish eosin and mounted with Eukitt on slices
with a coverslip on surface. At the end of the study. a total of 163 histological samples of male
and 266 samples offemale Hake were prepared, examined and described. The reading of the
histological samples were made by means a binocular microscope under transmitted light at
different magnifications. Some of the more representative samples of the different maturation
stages were photogmphed.
RESULTS
gration); L: Lumen.
A total of:; gonad development ~es for both females and males were considered I Immature
or Virgin. II In Maturation or Restmg, III Maturing, IVSpawning, and V Post.spawning. The
different development stages of the oocytes (Oogooia, Chromatin nucleolus stage, Perinucleolus
stage. Vitellogenesis. Nuclearrnigration and Hydratation), and ofthespennatozoa(Spemlatocytes.
Spennatids and Spermatozoa) have been also described. Post-ovUlatory follicles and atretic
oocytes are also described in spent ferrulles (see Table I).
The structures identified for each maturity stage assigned to females and males are shown in
Column "FEMALEsn [(I)-(8)] and Column ''MALES'' [(1)-(6)] respectively. Structures have
been marked with different labels (numbers, leuers, bla.ck or white points, etc.)
DI~CUSSION
The process of oocyte maturalion in Mel'luccius mel'luccius is similar to other demcISal fish
described in previous works .
Oogonias were observed in all maturity stages. Chromatin nuclear and perinucleolar stage were
described in inmature and maturing females. Vitellogenic oocytes appeared in pre- and spawning
females while hrydaled oOC}1eS were observed in spawning fenia"Jes. Necrotic oocytes were
observed in post.spawner females. Posl-spawning follicles were also observed although there
are not shown.
The results of the histological analysis showned a very e:tpanded spawning period for Hake in
Div. VlUa,h,d that extends from January to May with a peak in January-february-March. The
long duration of this period musl be caused by the addinon of several factors: different period
of the year ani! different sea areas of the Bay of Biscay in which adult (large and mediwn-sized)
Hake ~ The idemification of!he different structures observed coincided with me maaosoopical
analysIs deployed 10 establish the spawning period. Thus. histology appears as the validation
method for the maturit~· stages assigned de l'isu 10 Hake in this sea area
ACKNOWLEDGMENTS
This work was founded by the European Union DO X1V, the Basque Government and by the
Spanish Ministry of Education and Culture through a fellowship 10 I. Quincoces.
Hlstologlal Maturity
Stages
I
Immalun: or \~~In
"
'"
~"'llIrin\l
Females
Onl~-
o.,gonia. Chromalin nudrolus sIBg~.
(),-'~,'nla. Cbr<'ll1!ftlin nuclo:olus S(~<".
l'c"nI..:kolu. SUlj;<:. ~a,ly "ildl"~..:!w~i.
,I'",I"I''''''';''!!
Males
Spcnnalob'OOia Hnd S~alOC:yfC present,
Sr<:rrnall,:zmds "bsen!.
Sl"'nIlH(<>p'olli~
ami Spcnua!ocylc
pn.~I,
few
Spcn,,"(ol-"id~.
~ Sp<-nnah ....nids P'c\l,lIuinalll Sl"'o'"IIOSonia
• amI Spcon.hlCylt Iflewnl (lilly i" .be lesli~
:ltt..I .. "" .. '
I·...... p... o;ol:
<V
SII .... ni"l:
I
~'II1<'X.
: Mi~"'h'" m''''''''l~'''~''aIKlO''(,')1 ... bidr.IIaI;''1I I
i ()'>j! .. ".1 ,,,,,I d"·"tI .....-immllll'... 'Ull""'''' ... al,tI •
P'''-'''''1..
rnm ... <.", lilli\'"IHr al"";,IS ",><I
'~""'''IA "",II·I".~""" ... ""d,·,,I'" ""1'"
"""'''''''''''-'1)
all~lj~,,,,,·)·tc,
l'm!1i\' "·millil'·,,,1 ,11..-1,. 1,"'I<1i...1
SI"·..".I1;"..,,b ;",,1 "'". SI"'nlH",~.",i;1
Histological studies of the gonadal development (
I
AZT' ,,\
Paulino Lucio, lfiaki Quincoces (.
AZTI. Dept. of Fishel·ies Resources. Txatxarramendi Irla sIn 483
FEMALE
Light microscopy photomicrographs of hislOlogical strucrures of M. merlucclus ovaries in din~r<:ni stages of maturation. The histological preparations are stain~ with haematoxilyn-wsm
been marked with different labels (numbelS, letters. black or white points, etc.) and at different magnifications.
I)
2)
3)
4)
5)
6)
7)
8)
Ovary in stage I (Immature-or Virging). Thin black arrow: Oogonia; I: chromatin nucleolus siage; L: lumen.
Ovary in stage It (Resting). Thin black arrow: Oogonia; I: chromatin nucleolus stage; 2: perinudeolar stage OOC}te; L: lwnen.
Ovary in stage ill (Maturing), Thin black arrow: Oogonja~ 2: perinucieolar stage oocyte; 3: early \'itellogenic oocyte; L: Iwnen.
OvaI).' in stage IV (Spawning). Thin black arrow: Gogonia; 3: early vilel10genic ooC)tc; 4: hydrated oocyte; L lumen.
Detat! of a Ovary in stage II (Resting). Thin black arrow: Oogonia; 1: chromatin nucleolus stage; 2: perinucleolar stage oocyte; L: lumen.
Detail of a Ovary in advanced stage m (Maturing). Thin black arrow: Oogonia; I: chromatin nucleolus slage; 3: advanced viteUogenic oocyte (nucleus migration); L Lumen.
Ovary in slage V (pQst-spav,'ning). Thin black arrow: Oogonia; 1: chromatin nucleolus stag.e: ~: atretic oocyte; L: Lumen.
Ovary in stage V (PoSl-spa\\.T1ing) .. Thin black arrow: Oogania; I: chromalin nucleolus siage; 3: Vilellogenic oocyte; S: atretic oocyte; L: Lumen.
MALE
l.il!-ht UlicnlSC\'p~ phmllllli..:wrrapils "I" hi,I"I<'l'I(;l1 slructures of .It. 1II("I·fmdll.~ ,<,sIcs ill JI i"kl~'1 : "l<1~"" ,'f malliratinn. 'l1,e hist(ll(Jgi~'al prcpm :Iti<ms all.' ~Iaincd Wilh ha<,malllXilyn-cosl'
llcen ll1:1rh'd Ililh dln~r<'1l11i1bd" IlHlllllwl'. kt1~·h. h];Id,: \If while pClillh. ,'lei :1I1<I:tt ,1I11.-r,·11I ill. ,'11 Ir!o.::11 hlll."i
I) ·!"c.'s\id.. ill sla~l' 1 (11I1I1I<1l1lh'l \\ hilt· 111\11 :"1<''''' '11CnmJIOJ!<l1lia: hl:lt"k lhm ;ur"I~: ~I'CII1I;II", .
21 "1"...·'11rk ill sl:IJ"'IIII~"",IIII;'1 \'.1111<" Ihl1l.I'I"I' '1','rtll<llllgnnia: Mad lhin ;111<111 "1','1111.110,,'. '"
11 ·),·... lid,· ill ,I ai'" 111.1 \1:11111 III!' 1 \\"1 III,' 111111 ,111"" 'p.... llIl<lhlgnllia: l'lad-. 111I1l :11" '\1 ,\,,'11'
41 1i:~IIt"k ill ... 1"i'" 1\' ! I'h"'hIP" lilT'!' '" 'jl:'" 11I11!' I \\"hil~' '(ilL Sp,'Ullal"h 11.1,
51 1).-1:111 ,,]":1 h··.II,l<" III '.Ia;',· III ,\1.01'11 "'" I \\ luil' 111111 ;lrT.I\\": S!ll·llll:Il"!""II:l. 111.1.-1. :llIn ..
to) Ikl;lil "j",II,-ql,k III q.I",·\\· ,1',,· ;""'1111". ,II "I'OI'llltll)" ,rlnl,'·.I.1I "'1'1"1'":011\/",<1'
illl>' ,Iar
Sl'l'l"mal(l)'~lids:
\ I"l-" ... 1:11
whil(' .:ih·k
'l'lTIIl:lIIl)'nius
"·!lHllili.·I"II~
1\Ihuk