OYSTER PROPAGATION IN P.E.I. 57 
SESSIONAL PAPER No. 38a 
THE QUEST FOR CULTCH. 
Unless man has placed clean cultch in the water, nature provides only the old 
shells of dead oysters, mostly buried in mud, or the outsides of the living oysters. 
These and other exposed shells are more or less covered with slime, silt, and mossy 
growths of both animal and vegetable nature. Millions of other larve also needing 
cultch, such as “ deckers,” “ jingles,’ “barnacles,” etc., have pre-empted the best 
places and are busy feeding on every living thing they can swallow. Worst of all, 
through the open valves of the older oysters and of mussels, clams, etc., currents of 
water flow, bearing all sorts of plankton, presumably also oyster fry, to be used as 
food. How small a chance these fry have of escaping and finding a foothold! If 
they cannot fixate they are doomed to destruction. But vast numbers do find a 
foothold and do succeed in growing, and crowding each other, and competing with 
all the other oysters for food. In this struggle the survivors ultimately overgrow 
and smother the previous generations. Great as is the loss through crowding, it is 
exceeded by or anticipated by an earlier destruction, sometimes including all the spat 
on most of the shells. 
THE ENEMIES OF GROWING OYSTERS. 
The numerous little Nassa snails are constantly exploring the surfaces of shells 
and scraping off all the newly set spat. Those that escape may reach the size of a 
fingernail, and then, along comes a boring snail] and drills a hole through them, or a 
erab nips them off, or mud stirred up by storm smothers billions in a day, or the frosts 
of winter kill them. Later come the starfishes opening the oysters by their patient 
rrall, or bottom fishes may crush them in their paved jaws and throats. Last of all, 
man comes with tongs, and rakes, and dredges, and takes the few survivors. Thus 
ends this eventful history. The fisherman then wonders why the Creator doesn’t 
supply new oysters the next season to replace those taken: usually the best answer 
given to this question is to bow in meek submission to Providence. 
CONDITIONS FOR PROPAGATION. 
A little insight into oyster biology should enable any one to see that the production 
of oysters depends on the co-operation of four conditions, viz: (1) suitable cultch, 
(2) in waters stocked with a sufficient number of spawning oysters, (3) lying close 
enough to ensure fertilization of the eggs, (4) on a bed sufficiently extensive to fill 
the water, over a considerable area, with oyster plankton to such a degree as to over- 
balance the larval mortality. 
When the large oysters, which furnish the bulk of the spawn, are yearly removed, 
as well as the cultch to which they are attached (including the young oysters attached 
either to them or to the cultch), then the bed is robbed in three-fold degree, viz., the 
cultch is decreased, the large spawners become fewer, and the “rising generations ” 
are many times decimated. If the production of spawn is reduced to half, and the 
available cultch to half, then the production is reduced to a quarter. 
When shells, hitherto buried, are uncovered by working on a bed, they become 
available as cultch, but this advantage is greatly reduced through the fact that much 
silt is scattered upon the shells by the very operation which exposed them. In oyster 
fishing, ultimately all the cultch utilized by spat will have been removed, and then we 
have remaining simply an oyster reef covered by a layer of mud, upon which not an 
oyster can be produced. even though a current rich in oyster plankton, derived else- 
where, should flow over it at a time when the fry are matured to the sessile stage. Clam 
production is much simpler, for no cultch is needed. 
