Greinar (Vísindafélag Íslendinga) - 01.01.1943, Page 177

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W. Long.) July 17th, 1936. The total length of this speci-
men was only 41 cm and the length of the mantle 17.5
cm. It was immature as all the individuals in the samples
nieasured. The other specimen was found washed up on
the coast near Grindavík (S.-Iceland) ab. January lst
1940. This was an adult male with a well developed milt,
and the mantle measured 64 cm.
If we now summarize what has been said above on
the size of the spuid in Icelandic waters we come to the
following results:
Date July 17th Mean-length (Mantle) 17.5 cm Time- difference Growth- increase Growth- increase per 30 days
Aug. 3rd 21.8 — 17 days 4.3 cm 7.6 cm
Sept. 8th 28.0 — 36 — 6.2 — 5.2 —
Oct. 14th 31.3 — 36 — 3.3 — 2.8 —
If we assume, as stated previously, that all the squids,
found in Icelandic waters in the same season, belong to
a single yeaí’-group, we must come to the conclusion
When length and growth are taken into consideration, that
the whole stock must be the O-group. All the stock must
then originate from the previous spring, March—April,
as shown in the figure. This corresponds also very well
with the very fast but rapidly decreasing growth during
the season, for it is 7.6 cm per 30 days in the period July
17th—August 3rd, but only 2.8 cm in the same unit of
time, Sept. 8th—October 14th.
A few words should be said on the age of the specimen
found in Grindavík. It was, as already stated, an adult
raale. It exceeded the average length from October 14th
by 64.0-^31.3=32.7 cm, which corresponds to an increase
°f 12.7 cm per 30 days, or much more than the average-
growth in the height of the growth-season (7.6 cm p. 30
d-). This specimen can not therefore possibly belong to
the O-Group, i. e. the squid Ommatostrephes todarus does
not reach maturity at the end of its first year. When ma-