SEA-FISHERIES LABORATORY. 359 



tKing with much older Plaice), or they migrate to the 

 deeper portions of the nursery ground such as the 

 channels. The latter seems to be the case with the Mersey 

 nursery. Great quantities of young Plaice are to be found 

 there on the sandbanks, where the water is shallowest, 

 during July, August and September, maximum quantities 

 being taken in the latter month. During the winter 

 months, however, comparatively few are found there, but 

 they are abundant in the channels where the water is 

 deeper. This local migration then goes on independently 

 of the larger movement. The Plaice move from the 

 shallow water to the deeper as the colder months approach 

 and from the deeper water in the channels to the shallow 

 banks as the temperature rises. 



The young Plaice on these nursery grounds form part 

 of an exceedingly abundant vertebrate and invertebrate 

 fauna. They are associated with other Pleuronectid and 

 Gradoid fishes — the dab, flounder, sole and solenette (Solea 

 luted), with occasionally young brill and turbot and the 

 whiting, haddock and cod. Young sprats (Clu/jea 

 sprattus), sand-eels (Ammodytes), Cottus, sting-fish 

 (Trachinus) and Centronotus are also found; all these with 

 the exceptions of the sting-fish, sprat and solenette are 

 young and immature fish. Of the Gradoid fish the whiting 

 are very abundant. These are young fish, in their first 

 year probably, and generally not exceeding live inches in 

 length. The invertebrates are usually crabs (Portunus) 

 and star-fish (Asterias), and great numbers of shrimps 

 (C rang on). The crabs alone often form nearly half the 

 total bulk of the catch. 



These young fish are continually being captured in 

 the shrimp trawl, which having a square mesh of \ inch 

 side, retains them. We may quote one single catch to 

 give an idea of the bottom fauna of the Mersey nursery 



