Náttúrufræðingurinn - 1951, Síða 23

ÁTAN OG SÍLDIN
165
Niðurstöður þær, seni gerðar liafa verið að umtalsefni í þessari
grein, benda eindregið í þá átt, að síidveiðiflotanum yrði að því mik-
ill stuðningur, að skipulagðar átumælingar yrðu tengdar síldarleit-
inni. Gæti slíkt skip ekki annazt aðrar athuganir en síldarleit, átu-
mælingar og hitamælingar. Engar horfur eru á, að rannsóknarskip
okkar geti annazt þetta starf, nema önnur aðkallandi verkefni væru
lögð á hilluna, en við það myndu atliuganaraðir undanfarinna ára
rofna, og er ekki liægt að rnæla með, að það verði gert. Það verður
því að vísa því til úrskurðar forráðamanna útgerðarinnar, hvort
reynt skuli að hagnýta þennan árangur rannsóknanna og hvernig það
skuli gert.
ABSTRACT
The present essay tleals with preliminary investigations on plankton qiumtities in
Icelandic waters, during tlic years 1948—1951, made in collahoration with Mr. I’ór Guð-
. jónsson, M. Sc.
In tlie beginning of the work, in 1947, it was noticed that samples from the surface
layers, taken with Hardy's l’lankton lndicator and l’lanklon l’umps, did not give
satisfactory values, when taken during daytime. Therefore the present investigation was
based on vertical hauls with the Hensen net.
The plankton volume was measured by water displacement on board the research
ship. ön thc charts, fig. 2—10, double shading means plankton contcnl > 20 ml;
oblique shading 10—20 ml; white areas between the dots (denoting the stations) 1 — 10
ml; and open circles < 1 ml.
Localities where catches of herring werc made are representcd by dots on inserted
charts, or the fishing grounds arc divided into 13 areas, shown in fig. 4, and tlie vield
of each area is diagrammatically shown in thousands of ,.mál“.
Vcry good agreement was generally found between abundance of herring and abun-
dance of plankton, as shown in figs. 2—10. Tt is concluded that il would be possible to
trace the areas of abundant plankton by thc above mentioned method, and that this
would eventually be of considerable importance to thc fishermen in locating tlic main
concentrations of the lierring.
A characteristic feature of the plankton distribution during 1951 was, that ihe
Calanus plankton (fig. II. black columns) occurred exclusively at the outer edge of the
shelf.