70 
the consumers of the plankton rely essentially upon the producers of the plankton; 
in the neighbourhood of the coasts the detritus of the benthos also contributes 
to increase the mass of the plankton animals, which here like that of the benthos 
fauna is large; in the open seas where the quantity of the benthos detritus is 
small, the plankton has only its own producers to rely upon; its mass is therefore 
smaller and there is only a very sparse benthos fauna here; »the region of the 
very deep sea far from land may be called deserts when compared with the 
teeming life of the surface and shore waters«, writes John Murray in 1910 after 
his last expedition in the Atlantic with Johan Hjort onboard the »Michael Sars«. 
Whatever the conditions may be, I am of the opinion there can be no doubt, that 
in the Limfjord the food of the fishes (eel, cod and plaice) is obtained in greatly 
preponderating degree from the benthos fauna; this is represented in Table V. 
The food of this benthos fauna is the dust-fine detritus which again arises in 
the main from the benthos flora, namely Zostera and marine algae large and 
small. It is thus this flora which is the basis of the fish-life in the Lim- 
fjord and certainly in many other coastal waters. In the specially plant- 
rich and enclosed parts of the Limfjord this flora is probably. too abundant to 
offer suitable conditions of nourishment for the small animals of the benthos 
fauna; at other places in more open parts it is perhaps too scarce to produce 
the maximum animal dry matter per m.? This leads naturally to the suggestion, 
that in future the vegetation might also come under suitable treatment, 
such as removal from some places, transference to others, for example by cutting 
down, just as is done in the case of other plants in freshwater cultures, dredging, 
collection of seaweed or perhaps by intensive eel-spearing in the plant belt; a 
large production of the food-animals of the bottom-fauna (worms, Molluses 
etc.) is obviously the first condition for a rich production of eel and 
plaice. Of these we can get a sufficient quantity of the young; the limit of 
production of eels and plaice is clearly set by the available amount of fish-food. 
As is known, the Limfjord was the first expanse of salt water, where the 
endeavour was made to eke out the stock of plaice by transplanting fish from 
overcrowded places to places with greater possibilities of growth; a method which 
had long been known in the case of the freshwater fisheries. The possibility of 
combating the harmful animals has for long claimed attention in the Limfjord; 
artificial hatching of these fishes is superfluous, though perhaps the rearing of 
lobsters and prawns is a different matter; legislation has been in force in 
the Limfjord for hundreds of years; the only thing remaining therefore is treat- 
ment of the bottom, so that its economical management may on the main prin- 
ciples be raised to the level of that of.the freshwaters, and the present investi- 
gations seem to offer many possibilities for such treatment. In the case of the 
freshwaters, as is known, bottom-treatment of various kinds plays a very great role. 
It is our hope that these investigations of ours will lead to a series of 
similar investigations in other lands; we believe that our methods and apparatus, 
at least in a form suited to the various conditions, will fill a more or less consciously 
felt want with many who are engaged in the study of the metabolism of the sea. 
We have not yet made investigations in the dense part of the plant belts, 
it is true, but with'a change in the 0.1 m.? bottom-sampler it is certain that such 
