Gilis, Ch.

Open Marine Archive

N. North Sea
71
Lemon Sole, Herring
1947 and 951 fiih in 1948. This represents a de- Monthly Landings of Herring.
ciease of 35-6 % and is borne out by trawl skippers Number ^eight landed Averagecatch
who, throughout'1948 have found the species scarcer of Total for one for one fishinglanding dayperjldeye-than at any time since the end of the war. landings (tons) (tons)" lop'ed H.P.(kg)
B. B. Rae.
July 22 403 18 5
August 79 2,259 33 9
September 101 6,074 60 17
15Herring. October 52 3,040 58
Total 254 12,104 48 13Continued Observations on the Herring
Concentration on the Fladen Ground, the
Gut, and Environment, 194-8. <z' 0 ;. <. 6' 8»
r-sfs? "fi"/»I^a ct1. Fishing Grounds and Landings. d a-.*.;^«1 ^*t I yf..^I d-<J^1 <
As in the preceding years the herring concentra. A
ft
SCM^Z.
^
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t »
tions in the northern area of the North Sea were &y 5S'.n"
n*f
^
.
58 ^
again actively trawled by Belgian fishermen. T »;r
uTf --
The ssss\ Iff^w t /'T^ Ir-^
I ^^f\
grounds worked by them during _the period July to ; :'i:s & ^ Suhr^M */ » n^*" u » IOctober are situated between 55° to 58°30' N.Lat. a St. i f ^finiA FlSriE^f SK.y\ .US ...
and between 0°30'W.and 2°E. Long. (see _the / s ^
I Sn^t ^ BWI^-Af f /-,j)*/rtaf/ Jutlfvl ^^" \
^
I
T
TSJi
accompanying chart). 62 trawlers were attached to s fu^lll-k
tui. ^
« t'AAk &II
I t ». .L 66this fishery. The average duration of a voyage is ^1 <% s?r-^56 / ^ tu.U /r**;' /
calculated to 11-5 days, or 8 days effective fishing. & i&^ te.rfI tI I ~r - *»1 * <0'"A I/ ;»* /I * jy I^ hf- 'ffitn tA.-tI t> w<fr fl:* a JA~TiS^10 p*v< <*; 0^fr] WCfttk f t*f CLAY ;.&n,'ff DEEPl
2. Biological Statistics. <1 f^Wtllf^l t <^Ih
The material has been collected during the w 5<
"^ ta>|
Aarf 0ff ff0 *< m.,.As.,54 64n »-*<.^. a
period August to October. _It includes 18_series_pf z 0 2' «. 6' n". .
50 herrings each, i.e^ a total of 1,000 .herrings, 400 Fishing grounds exploited by Belgian herring trawlers
for August, 400 for September and 200 for October. during July-October 1948.
As in 1946 and 1947, the results have been
divided in monthly periods, so as to observe the
variations which might occur in the composition of
the herring concentrations defined groups: one group including herring in
The various biological characters of each stage maturity stage I to IV, the spawning of which will
of maturity have again been examined, _i.e., the total probably not take place before the beginning of
number of vertebrae, the number of prehaemal1949, and a second group_ including the herring of
vertebrae, and the number of keeled scales. Thematurity stages V to VIII-II, i.e., herrings in full
results confirm once more the presence of two well- reproduction or'very near maturity.
Size Distribution (Measurement to the millimeter). Weight.
Period cm. 22 23 24 25 26 27 28 29 30 31 Mean g. Mean
27-5 165August 0-5 0-5 6-2 16.8 40-8 28-2 6-8 0-2
159September 0-2 0-2 4-0 18-2 37-5 30-5 8-8 0-5 27-6
October 3-0 8-5 7-0 19-0 25-0 28-5 7-5 1-5 26-2 134
Total 0-9 1-7 1-7 7-9 19-0 37-0 25-0 6-5 0-1 0-2 27-3 157
Sex Maturity Stages (Percentage Distribution).
MalePeriod 11 in IV v VI VII vin-n
0/0
5-0 3-0 3-2August 53-7 0-5 4.8 10-8 23-5 49.2
3-5 8-7September 51-5 1-2 2-5 14-0 12-2 24-5 33-2
October 52-0 1-5 1-0 2-0 28-0 39-5 5-5 22-5
Total 52-5 0-7 3-2 10-1 14-7 35-1 23-2 3-7 9-3
fij'
72
Mesentertc Fat. (Percentage distribution according to periods and according to groups).
Period 0 + M Group 0 + M
August 23-5 35-5 23-0 18-0 1st (maturity
September 31-2 34-0 15-0 19-8 stage I.IV) 1-4 10-1 39-4 49-1
October 32-5 57-5 7-0 3-0 2nd (maturity
Total 28-4 39-3 16-6 15-7 st.V.VIII-II) 39-3 57-3 7-4 2-0
Age (Percentage distribution).
Age (^ears) 3 4 5 6 8 9 10 11 Number of7
Year-Classes in before fish with1945 1944 1943 1942 1941 1940 1939 19381948 1938 readable scales
August 0-6 12-7 9-1 21-2 14-5 20-6 11-5 2-4 7-3 165
September 20-5 12-3 17-8 13-7 9-6 9-6 5.5 11-0 73
October 6-0 24-0 6-0 6-0 20-0 14-0 4-0 10-0 10-0 50
Total
1948 1-4 16-7 9-4 77-7 15-3 16-7 9-7 4-5 8-7 288
1947 5-3 8-7 17-2 13-7 18-7 11-9 10.9 4-4 9-1
1946 4-4 9-5 11-5 23-9 14-3 10-7 11-3 7-4 4-8
Vertebrae.
a) Total number of vertebrae. b) Prehaema vertebrae.
Percentage distribution according to periods.
Period 54 55 56 57 58 59 Mean 21 22 23 24 25 26 27 Mean
Aug. 0-5 2-0 45-5 42-2 9-5 0-2 56-590 0-2 4-0 28-5 42-8 19-8 4-2 0-5 23-92
Sept. 0-5 4-2 37-0 5.2-0 6-0 0-2 56-595 2-8 24-8 51-5 16-0 4-2 0-8 23-97
Oct. 7-0 35-0 53-0 4-5 0-5 56-565 2-5 26-0 48-5 20-5 2-0 0-5 23-95
Total 0-4 3-9 40-0 48-3 7-1 0-3 56-587 0.1 3-2 26-5 47-4 18-4 3-8 0-6 23-95
Percentage distribution according to groups.
Groups 54 55 56 57 58 59 Mean 21 22 23 24 25 26 27 Mean
1st 3-1 27-5 54-4 15-0 56-812 1-7 18-5 48-4 25.1 5-6 0-7 24-16
2.-.J 0-6 4-2 45-2 45-9 3-9 0-4 56-496 0-1 3-8 29-7 47-0 15-7 3-1 0-6 23-86
*/.0
Keeled Scales (K2). 59A A DPercentage distribution according to_periods. ///Periods 12 13~ 14 15 16 17* 18 Mean / 0t a
/
^- 1
Aug. 0-5 11-0 42-5 38-0 7-0 0-8 0-2 14-43 I
Sep. 0-8 17-0 40-5 31-5 9-0 1-0 0-2 14-35
Oct. 7-0 38-5 38-0 14-0 2-0 0-5 14-67 t
t
t
Total 0-5 12-6 40-9 35-4 9-2 1-1 0-3 14-45 It
\9 //
Group 12 13 14 15 16 17 18 Mean / \^ \/
,'^ \K \-r/ ^
1st 1-0 23-0 44-3 27-9 3-8 14-104 0 + H It 11IS IS It <1 '1
2nd 0-3 8-4 39-6 38-4 11.4 1-5 0-4 14-585 r<B c
.
i» »
t
\ tl 1
I
I I
I I
Fig. 14. * I; 41? / t/ I
I
A. Quantity of fat content. <1
Vf \IB. Number of vertebrae. 1I I
\I
C. Number of prehaemal vertebrae. \\I \
\. \D. Number of keeled scales. / \^ ^^ ^e
sn !S se n sa ^9 ai as sa a» n K '7
1st group (Mat. stage I to IV).
2nd group (Mat. stage V to VIII-II). Fig. 14.
\
N. North Sea
73
Herring
3. Some Considerations. Stomach Contents.
Percentaee distribution.If we judge from the biological characters _ of haleach maturity stage we find again that the herring Period full fuii emPtyconcentrations, fished by the Belgian trawlers on the
Fladen and the Gut, consist of_populations_of differ. Aug. 1-0 9-5 89-0
ent origin at least during the period July to Sep- Sep. 10-5 89-5
. .
Oct. 23-0 39-5 37-5tember one in some way or other related to
spring spawners, the other resembling the autumn Total 5-0 15-9 79-1
spawners of the North Sea type. Nature of contents
The subdivision of our observations into monthly
periods gave also good results. The biolosical com- Aug. schizopods, copepods
position of the concentrations proved to remain Sep. schizopods, copepods, herring eggs
practically uniform, during the months July to Sep Oct. copepods.
tember, while from October it was subiected to
heavy changes, i.e., an appreciable decrease in the
ymx.: 191Smean size and weight, an increase in the well y t9»*
^ *. *10advanced maturity stages and the appearance of the 1139++. far 1"713W '"' <»!.spent stage, a decrease in the mesenteric fat, in the .... . .10 »»*.> + * ++ «
I/ 1 * + . .vertebral mean, and in the mean of the prehaemal 0
vertebrae, and an increase in the number of keeled >.». W.: 1919o »M
hi£scales. Fig. 15. + t * "" ISIInmy 4- 410All these changes indicate clearly a sudden de- Biological scale of ym^c. . .+ + 42 + +a
ficiency of spring spawners, beginning with the herring concentra- ysaix. i lavations on Fladen,month of October, in other words they sugsest that Sa isw18W »»>»I f It fGut and environ-
the southerly limits of this population should be m
t9^S <.<.*! <»i»
ment, 1946, 1947 191S10 4 *mi <*.*situated between 55° and 56° N. Lat. and 1948. . . .440
«»« 1, « 7 e » la*nA
Monthly Distribution of the two Herring Populations.
Percentage distribution The frequency of the year-classes proves the pre.
Months Latitudes North Spring- Autumn- sence of 5 good recruiting classes, i.e., 1944, 1942,
apawners spawners 1941, 1940: and 1939. The 1945 class, 3-year.olci
August 58°30' 56° 39-5 60-5 herring, which appears for the first time in the
September 58° 56° 30-0 70-0 concentration, is very poorly represented and con»
October 57° 55°15' 4-5 95-5 stitutes thus a very bad recruiting class.
Total 58°30' 55°15' 28-7 71-3 Ch. Cilis.
The Dutch Herring Fisheries in 194-8.
Drift.Net Fisheries. The distribution of the fleet in 1948 shows a
As a continuation of the paper on this subject difference from 1947, especially in the month of
in the Vol. IV of this series we are presenting here August. As the market preferred small herrings,
the charts of the Dutch herring season 1948 (charts and at that time the catches in the more northern
1 16). part of the North Sea consisted of larger herrings,
The charts are composed in the same way as in the fleet was fishing more to the south.
the previous paper. We got data of about 110 As the charts show, the mean catch per shot on
vessels, covering about 50 o/g of the fishing activity the different grounds differs largely in some months
of the whole lugger fleet. Most of the vessels were when compared with the same grounds in the same
fishing with 60 nets in May, with 80 in June, and months of 1947. Especially in the first months of
with 100 or 110 nets in the other months, the nets the 1948 season, the catches were poor; in some
being set either for surface or for deeper water other months the catches were better than in the
fishing. previous year
.
.
This year we got some information about the Table 9 gives the total quantity of drift-net her-
quality of the herring caught on the different ring landed. The total amount landed, calculated
ounds (matj'es, full, spawning, spent) . The charts in kg., is 97,681,500 kg.j^»U^I 24 refer to this specification. /. de Veen,


Continued observations on the herring concentration on the Fladen Ground, the Gut, and environment, 1948

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