126 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
to determine practically whether the young fish brought 
up in the trawl-net are worth returning to the sea, and I 
hope that similar “‘ vitality investigations’’ will be carried 
on on board the fishery steamer here. A large tub or wooden 
tank should be fixed on deck through which by means 
of the hose and a waste pipe a circulation of sea water 
can be kept up. Then after each haul of the trawl-net a 
few fish should be picked out and put in the tub, their 
species, size, and condition (e.g., ‘lively,’ “exhausted,” 
&c.,) being noted on a form, along with a statement as to 
the time trawl was down and kind ofnet used. The fish 
should be allowed to remain a definite time, say 30 or 40 
minutes, in the tub and then the result (e. g., ‘‘recovered,”’ 
‘dead,’ &c.) would be added to the form. Such statistics 
would give a definite idea of the proportion of fish caught 
under certain conditions which might be reasonably ex- 
pected to recover if returned promptly to the sea. 
In making any regulations in regard to immature fish 
the aim should be to allow as many fish as possible to 
spawn once at least before being caught. Hence it becomes 
of importance to know for our district the size at which 
the various species become sexually mature. During this 
coming breeding season we shall record the size, and the 
condition as regards maturity, of all fish examined, with 
the view of arriving at the minimum measurement at 
maturity, and also the maximum of immaturity so as to 
fix upon a fair average size below which no fish should be 
taken. We want also to know for our own district (some 
of these things cannot be taken from elsewhere, such as 
the east or south coasts) exactly when (at what age) each 
species spawns, and what the rates of growth are,* and 
the average sizes in successive years, exceedingly difficult 
matters to determine, as artificially reared fish may be 
* See also Cunningham, British Association Report for 1891, p. 658. 
