NATIONAL FISHERY CONGRESS. 329 



complete. Of these, 26 state the cause as pearl-hunting, mainly or wholly, and 10 refer 

 to other agencies, one or two each to high or low water, deposits of sand or mud, ice, 

 boats, hogs, and rats. Of 7 answers from Wisconsin, where so many pearls of remark- 

 able beauty were found in the early " nineties," 5 report the shells as nearly or entirely 

 exhausted, and 2 refer to rapid reduction, due to ignorant and careless persons taking 

 the small and young shells as well as those more likely to contain pearls. 



A Tennessee paper alludes to the same reckless habit, and estimates the shells 

 remaining as about 5 per cent only of the number in former years. The destruction 

 of young shells is also mentioned in Indiana. In New York it is stated that a good 

 pearl-fisher can "clean out" a bed of 500 shells in a day. The Ohio paper speaks of 

 hundreds being opened daily. In Iowa one states that the river will be exhausted in 

 two years. Of those that speak of little change, several remark that not much is 

 known or done in regard to pearls at their localities. Of the probability of recovery, 

 one, Tennessee, says that the beds are cleared out about every two years and renewed 

 in four; one that they exhaust yearly and bed again in one or two years; another that 

 the shells return every year, but in less numbers, and a Texas paper reports that 

 many beds that had been worked out are recovering, through the growth of the young 

 shells that were left unmolested. 



NATURAL AND ARTIFICIAL REPLENISHMENT OF FRESH-WATER MUSSELS. 



The inquiry as to whether exhausted beds recover, and in what time, is closely 

 connected with the preceding one. It is unanswered in 22 of the papers, and 7 others 

 report no knowledge or opinion on the subject; 64 replies are given, of which several 

 are indefinite or conjectural. Out of about 60 papers, therefore, or two-thirds of the 

 whole, the following data are taken : 16 report the belief that the beds are replenished 

 from year to year; 4, in one or two years; 3, in two or three years, and 4, in four 

 years; 4 name periods between four and eight years, and 6 between eight and twelve 

 years; 1 gives twenty years, 1 gives twenty-five, and 2 estimate the recovery as 

 requiring a century or more; 3 papers say that many years are necessary; 5 say "a 

 few," or "soon"; 2 report no exhaustion as noticed, and 6 report no recovery; 4 papers 

 are indefinite or uncertain. Two of the papers that give estimated dates for recoveiy 

 do so with an expression of doubt (" if at all," "if evef ") as to whether it really occars. 



The Tennessee paper before referred to says that the shells return each year, but 

 in less numbers. As it is customary, more or less, to leave the young and small shells, 

 the questions are resolved largely into two, viz, how far they have been carefully 

 spared, and how long it takes them to attain their growth. This probably differs in 

 different species, as is intimated in some of the answers, and it may also be influenced 

 by various external conditions. The Tennessee paper estimates the recovery as slow, 

 from the fact previously brought out very markedly that the young shells are those 

 that are most exposed to all natural enemies and accidents. The New York paper, 

 which thinks that there is no recovery, states that few young shells are found. 

 A Texas pearler says that young shells are found in two years, but contain no pearls. 

 One (mentioned under the last head) says that many beds are recovering by the growth 

 of the young that were left before. On the other hand, in Indiana, one states that 

 when a bed has been worked out, plenty are found the next season, and an Iowa 

 pearler reports young shells abundant everywhere. One Tennessee answer probably 

 gives a very fair average statement, to the effect that the beds recover somewhat every 

 season, and would perhaps recover entirely in a few years if not molested. 



