160 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



different boats, and so affect the result. At the best, it 

 can only be an approximation that will be obtained; but, 

 still, it can scarcely be doubted that the annual destruc- 

 tion is enormous, and that the young flat-fish so lost are 

 potentially very valuable. It seems probable that the 

 total annual destruction of young fish by shrimping in 

 our district is to be measured by the hundred million. 

 "We know, moreover, that the Lancashire shrimping 

 grounds constitute our most valuable fish nurseries, which 

 bear a definite and important relation to the fishing 

 ground off-shore, and we may assume that if young fishes 

 are allowed to grow undisturbed on the in-shore nurseries, 

 they will later on become marketable fishes on the off- 

 shore fishing grounds. We may state also that as all the 

 common flat-fish pass through a stage in which they 

 inhabit a shallow-water area, the number of marketable 

 fishes on the off-shore grounds will vary as does that of 

 the small fishes in the nurseries. If, then, we are able to 

 protect our young fishes in the coastal waters, under 

 ordinary circumstances they should turn up a year or two 

 later on the grounds outside. The preservation of 

 immature fishes ought to be very beneficial to the off- 

 shore fisheries — more beneficial even than the preserva- 

 tion of spawn, because the mortality during the period 

 between hatching and the stage when the young fishes 

 make their appearance in the nursery is so very great that 

 a given number of young fishes represents many hundred 

 or thousand times that number of eggs or embryos. 



TvTow, this a 'priori argument is probably quite a 

 good one, and if we had no other means of investigating 

 the matter, we should probably be justified in relying upon 

 it. But the points enumerated in the last paragraph in 

 relation to the life-history of the fish, are eminently suit- 

 able for biological and statistical investigation. And it 



