99 



presumed analogy, it may be taken as probable that the virtual 

 disappearance of sardine shoals during one or several consecutive 

 years is due to a certain periodic combination of unfavourable 

 conditions in inshore waters entailing the non-production in 

 sufficient profusion of the diatomaceous growth which constitutes 

 the inshore attraction to these fishes. Possibly these adverse 

 conditions will be found to begin in or be largely influenced by 

 exceptional disturbances of the sea at critical junctures, by 

 exceptional long-shore currents abnormal in power or in direction, 

 or by changes produced in the density of the inshore water 

 either by lack or by superabundance of monsoon floods, more 

 especially at the end of the south-west monsoon when the inner 

 coastal zone ceases to be current-swept and settles into a stillness 

 lasting for several mouths. It is my strong personal opinion 

 that this last factor will be found to be of supreme importance ; 

 even now fishermen hold the belief that there exists a connection 

 between rainfall and the abundance or otherwise of fishes. 

 They express this conviction clearly in their saying " Poor 

 crops ashore, a big harvest at sea." Now on the Malabar 

 Coast an unfavourable season for the agriculturist comes, not 

 from a scarcity of rain but from a superabundance or from an 

 abnormal distribution, the former principally. Poor crops in 

 this district may generally be correlated with excessive rainfall 

 and this, in turn, by lowering the density of inshore water is 

 likely to stimulate diatom growth to increased activity so 

 producing greater food supplies both for the adult sardines 

 and for their fry, thus increasing greatly the attraction which 

 inshore waters have for sardines at certain seasons. It is a 

 natural ground-baiting of the shallows on an immense scale. 

 As a working hypothesis in the investigation of this sardine 

 problem this possibility will be useful ; a study of the density 

 of sea- water at different distances from shore at different 

 depths at selected points' on the sardine coast, should form an 

 integral section of the work to be undertaken, together with a 

 comparative study of the local rainfall to ascertain if there be 

 any correlation to be established. It will not be possible to 

 carry this on along the whole coast or even at several stations * 

 we shall probably have to be content with observations made at 

 one centrally situated station during the critical time from the 

 middle of August to the beginning of October, a period which 

 includes both that immediately preceding and that coincident 

 with, the advent of the shoals in shallow water. During this 

 period an intensive study of the environment and habits of 

 the sardine should be carried on, and of all the biological 

 and physical conditions in any way likely to influence its 

 movements. 



