506 AN EXrERIMENT IN THE TRANSPLANTATION OF PLAICE FROM 



All the males, on the other hand, were above the average size at 

 which this sex is found mature in the Barents Sea ; two were actually- 

 found to be spent on being returned to the Laboratory after a few 

 days of liberty. This fact makes the growth observed all the more 

 a matter of surprise, as we usually find large male plaice grow very 

 slowly. * 



E 3884, caught in February, was observed to be recently spent, and 

 had thus taken part in one reproductive period in the North Sea. 

 The ovaries of E 3875 were such as one observes in female plaice 

 which are apparently maturing for the first time. 



On the basis of these last five fish, as discussed below, it would be 

 absurd to attempt to base any definite conclusions. In discussing 

 them, the main desire is to bring to notice the suggestive results that 

 this small experiment has attained, so that when the opportunity 

 again arises similar experiments may be attempted on a larger scale, 

 since it can no longer be doubted that a rational development of the 

 plaice fishery of the North Sea would be possible under a carefully 

 planned scheme of transplantations. 



Below have been drawn up a few notes on the changes of which 

 the last five fish returned have given evidence, regarded from the 

 following points of view : — 



1. Increase in size. 



2. Increase in weight. 



3. Increase in value. 



1. Increase in Size. — The eight fish caught in July all show a 

 slight shrinkage, as is usual in marked fishes retaken shortly after 

 liberation. It is usual with some investigators to estimate shrinkage 

 between death and remeasurement at 0'5 cm., but in order to depress 

 the observed growths rather than to exaggerate them this convention 

 has been disregarded throughout. 



The two specimens reported in November had increased in length 

 from (male) 34-4 to 38'1 cm., and (female) 35'8 to 39-6, or 3"7 and 3'8 

 cm. respectively. The next fish was retaken in February, and the 

 growth from 43'5 to47"3, or 3*8 cm., is a very rapid growth for such a 

 large male. Another male fish came back in May, and had increased 

 6 cm., from 33'9 to 39-9 cm. The last fish returned gives an astonish- 

 ing increase for so large a fish, having grown from 42^5 to 50"3, or 

 7"8 cm. (female). 



* It is interesting to note in comparison with this experiment, that Strodtmann trans- 

 planted plaice from the Baltic to the Elbe L.V., making the passage to tlie North Sea 

 through the Kiel Canal. These were chiefly mature fish, and though many were retaken 

 very few had grown at all after several months in tlieir new surroundings. Cf. Reichard, 

 Die deiUschcn Versuchc mit gezeichncten Schol/cn II, p. 34. 



