86 DI{. PEIEUSEN's KEPOllt OF THE DANISH BIOLOGICAL STATION, 



since oxygen may be presumed to be in ample abundance, I do not 

 see that mere crowding need unfavourably react on the growth of 

 the fish. In any case, one may venture to suggest that an attempt 

 to tabulate the stomach contents of fish, and the proportionate quantity 

 of food organisms per acre, would greatly enhance the interest of 

 the statistics given. 



Granted that overcrowding means in great part underfeeding, theie 

 seems no reason to quarrel with the conclusions which Petersen bases 

 on his statistics ; and if I am constrained to criticise the figures 

 themselves, it is chiefly in regard to the manner in which they are 

 set forth. 



The statistical work was undertaken, as we have seen, with a view 

 to ascertaining the local population in the different broads, and the 

 fishing was done entirely with seines. 



Tlie word seine is capable of rather a wide interpretation in this 

 country, and probably in Denmark also ; but as no details are given, 

 one must assume that the nets used, if not of uniform pattern, were 

 at least of approximate efficiency in proportion to their sizes. It 

 appears that the plaice-seines are hauled into boats in about three 

 fathoms of water, and may be supposed to be similar in general make 

 to the " tuck-net " of the Plymouth district, since an ordinary bottom- 

 seine without a central bunt could not easily be raised in so much 

 water without risk of losing the fish. In calculating the results, 

 Petersen shows that a seine shot from a boat covers, theoretically, a 

 triangular area of ground, marked out by the net as base and the 

 two lines as sides. Thus, if twenty fathoms of line are used, and 

 the net is twenty fathoms long, it covers, theoretically, an equilateral 

 triangle, the sides of which are each twenty fathoms. On this basis 

 the area covered by a number of hauls is computed in Danish " Tender 

 Laud," and the population per " T. L." ascertained by proportional assign- 

 ment of the total catch of fish. 



While my own experience leads me to the belief that the seine is 

 the most efficient engine that could be used for the statistical enumer- 

 ation of bottom fish in shallow waters, it is perliaps my ignorance of 

 the local conditions which leads me to suspect that Petersen, although 

 he acknowledges that his figures are only approximate, hardly lays 

 sufficient stress on the possibilities of error. 



In this country the state of the tide has the greatest possible effect 

 on the efficacy of a seine, not only in determining, by its rise and fall, 

 (1) the amount of ground that can be covered, and (2) the movements 

 of the fish, but also in influencing the action of the net. So far as 

 the first question is concerned, we learn that the rise and fall in the 

 fjord is only about a foot in extent, so that it need not be considered ; 



