19 



concentrated upon the perfecting of mechanical means for 

 the capture and safe keeping of fry hatched in the open 

 sea ; their system is perfect in respect of these opera- 

 tions but it fails to rear a sufficient weight of fish per 

 acre as it makes no provision to supplement the 

 limited food supply produced naturally within the ponds. 

 As a consequence of this limited food supply cannibalism 

 is prevalent and but a comparatively small number of fish 

 survive. No intensive culture is attempted and until it 

 is, Arcachon fish farming will remain an industry only 

 partially developed and will be unable to yield the further 

 profits which a vigorous policy of development on scienti- 

 fic principles would certainly yield. 



At the same time it will be noted with satisfaction by 

 French culturists that the produce per hectare compares 

 favourably with the much vaunted results of German 

 carp culture, an industry now highly organized and 

 widely spread throughout that empire. Estimates of the 

 annual produce of carp reared in ponds as given by 

 German scientists, range from 65^ to 164 kilos per 

 hectare *, and it seems certain that the average cannot 

 be placed at more than 1 10 kilos, whereas at Arcachon 

 we have seen that the ascertained yield per hectare for 

 one year was 2 2 6 - 8 kilos and for the succeeding year 

 325*5 kilos, per hectare, or 276 kilos average for the 

 two seasons. The superior results given by the empirical 

 French methods over those directed by German science 

 show how responsive fish-culture is to the crudest of 

 treatment in the presence of favourable natural condi- 

 tions, temperature being one of the principal. In 

 Germany the rigors of winter are so severe that for 

 months the growth of fish suffers arrestment, whereas at 

 Arcachon the winters are notably mild and inclement 

 weather is of short duration. 



The illustrations on plates II to IV represent graphi- 

 cally the construction and method of operating the sluices 

 of Arcachon fish ponds. Figs. 1 to 4 show sluices 

 constructed of wood p'anking, while those on plate IV 

 are two examples of more modern forms where concrete 

 is the material employed for the walls and floor. The 

 sluice depicted in fig. 6 is of the most modern type 



* Brandt, Ueber d. Stettiner Haff, Wiss. Meeresunt. Kiel Kovim,, 1S96. 



