OYSTER-BEDS, DETERIORATION OF. 



713 



1,000 marketable one's that is, out of every 

 1,421 oysters, 1,000 were full-grown. And he 

 gives it as his decision that about 1,000,000 

 eggs are spawned by each oyster, and that 

 about 44 per cent of the oysters on a bed 

 spawn each season. From the above it is evi- 

 dent that 1,000 oysters would void every sea- 

 son 440,000, 000 eggs, and that only 421 of the 

 resulting embryo would survive, or 1,045,000 

 eggs would perish whare one survived. Hut 

 the medium oysters also spawn, though send- 

 ing forth a less number of eggs, and Mobius 

 estimates that 421 in the community would 

 produce about 60,000,000, or the 1,421 would 

 spawn together about 500,000,000 eggs, and 

 from these 500,000,000 only 421 oysters would 

 be produced, or, where one oyster arrived at 

 maturity nearly 2,000,000 eggs or oysters per- 

 ished ! 



Some efforts have b3en made to obtain data 

 in regard to decrease in number and increase 

 in size of American embryo oysters. These 

 efforts were put forth in Tangier and Poco- 

 moke Sounds in the summer of 1879, when a 

 number of earthenware tiles were deposited as 

 " spat "-collectors. On inspection it was found 

 that the oysters continued attaching until about 

 the 20th of August, and that the largest num- 

 ber attached about the first of the month ; be- 

 tween August 23d and October 10th the mor- 

 tality was shown to be fully 50 per cent; fut- 

 ure examinations of the " spat "-collectors will 

 probably show a diminished mortality, as the 

 animal will be better able to protect itself as it 

 increases in size, but the destruction among 

 the unprotected, delicate embryos must be im- 

 mense, and (as it is as great as 50 per cent 

 after attachment) it must be much more serious 

 prior to that event. 



Lieutenant Winslow gives, as the result of 

 his observations in 1879, that on a natural 

 unworked bed the ratio of young oysters to 

 those of mature age is as one to two, or where 

 there are 1,500 oysters 1,000 would be matured 

 and 500 young. Professor Brooks estimates 

 the number of eggs voided by the American 

 oyster at from 9,000,000 to 60,090,000 ; 10,000,- 

 000 may be taken as an average. The 1,000 

 mature oysters in the community would then 

 spawn 10,000,000,000 eg^s, and as the young 

 European oyster lias been found to spawn about 

 one third as many as the mature animal, wo 

 may consider the same to be true for the Ameri- 

 can variety. The 500 young would then spawn 

 1,600,000,000 eggs, or the total number in the 

 community would spawn 11,600,000,000 eggs, 

 from which would result 500 oysters, or about 

 20,000,000 eggs or oysters would perish where 

 one was preserved. Lieutenant Winslow's ob- 

 servations convince him that the beds of Po- 

 comoke Sound at least are in a condition very 

 similar to the French beds before they were 

 subjected to the action of protective laws. As 

 these have been made to yield again a profita- 

 ble return, it may be well here to take note 

 how protection is rendered effectual. 



The French Government assumes control of 

 all oyster-beds and fore-shores. Dredging is 

 fixed tor a certain time, which is determined by 

 the local commission. A third or a fourth of 

 a bed is buoyed off each year, and dredge<i 

 only for removing weeds, mud, vermin, etc. 

 The remainder of the bed is open to all licensed 

 persons for a specified time. The following 

 year another part is reserved, and occasional! v 

 portions are reserved for longer periods. In 

 accordance with government regulations the 

 beds are not to be opened for fishing until the 

 " spat " has acquired strength to resist the ac- 

 tion of the dredge, say until the end of Janu- 

 ary. A bed with well-established breeding 

 qualities has a fourth or fifth part of its area 

 set apart as a reserve, and dredging over such 

 part is prohibited. A fishery guard-boat is ex- 

 pected to take part in the working of each 

 bed. A bed encumbered with weeds or other 

 noxious matter is opened for dredging until 

 cleansed. Beds on which there is never any 

 production of "spat" are to be kept open 

 through the season, and after working any 

 bed it is required to be examined, and, if nec- 

 essary, the " cultch " replenished. The close- 

 time is between May 1st and August 1st, and 

 is strictly observed. 



By these means the beds on the French coast 

 have been much improved. It may be well to 

 see how foreign experience can be utilized for 

 our good in this matter. 



The deterioration of an oyster-bed and its 

 impaired fecundity will be shown in five sev- 

 eral ways: 1. By the general appearance and 

 condition of the beds and animals, the preva- 

 lence of mud and sand, the oysters being large 

 and single, and the shells covered with worms, 

 etc. 2. The ratio of young to mature oysters 

 will be abnormally large or small. 3. The 

 amount of debrix in the bed will be very largo 

 (say as much as 50 per cent of the contents of 

 the dredges). 4. The number of oysters on 

 the bods will be found to decrease each year. 

 5. The discovery of unusual inhabitants of the 

 beds other than oysters, or, in general term*, 

 marked changes in the fauna of the beds, indi- 

 cate deteriorations. In cases like these protec- 

 tion must be assured in order to prevent entire 

 destruction. If deterioration is due to exces- 

 sive fishery, that must bo prohibited ; but, as 

 many of our poorer fellow-citizens find sup- 

 port in this industry, restriction manifest ly 

 must be used, not entire prohibition. The 

 larger the area, of course the K-" exhaustive 

 will be the fishery in any particular locality, 

 for the fishermen will naturally leave old and 

 worn-out beds .-ml seek for those newly dis- 

 covered and well stocked. Fortunately for us. 

 the nrea covered by oysters along the coast of 

 the United States is so groat that at pre-ent 

 when any bed or locality begins to fail the 

 fishery is transferred to other points. This is 

 shown by the fact that vessels have left the 

 sounds and work now in the beds in Chesa- 

 peake Bay. 



