ISO TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



might have enabled us, from a consideration of the 

 relative increments in the catches from year to year, to 

 have connected the increase on the Blackpool ground with 

 its closure against the destruction of immature soles by 

 shrimp trawling. But comparatively few hauls have been 

 made on the Blackpool ground, and the opportunity has 

 been lost. 



~No regular observations regarding the distribution of 

 the plankton or of the bottom invertebrate fauna of the 

 Mersey ground have been made, and we have therefore no 

 material for a possible explanation of the fluctuation in 

 the fish fauna outlined above. It is particularly un- 

 fortunate that regular and exact physical determinations 

 of temperature, specific gravity, salinity, &c, were not 

 made during the last eight years. These must be 

 essential portions of any future investigation of this area.* 

 The nature of the sea bottom is very peculiar, and a com- 

 plete investigation of this is to be desired. 



We believe that observations on this ground, with a 

 view to the regulation of the fishing, will be unsatis- 

 factory unless accompanied by enquiries into the relations 

 of its fish population with the spawning fish on the off- 

 shore grounds on the one hand, and with the larger 

 immature fish population of the offshore grounds on the 

 other. Such investigation and enquiries into the stability 

 of the immature fish population of the shrimping ground 

 are very relevant. 



See scheme given in this Report, p. 149. 



