WHEN THE FATHER OF WATERS GOES ON A RAMPAGE 



383 



myriads, need to pass the first few weeks 

 of their independent existence on the 

 gills of fishes. If the fishes are not pres- 

 ent at the proper time, the mussels can- 

 not survive. Furthermore — and this is 

 a most interesting feature of the co-rela- 

 tion of fishes and mussels — the young of 

 particular kinds of mussels require the 

 gills of particular kinds of fishes as 

 nurseries. 



The black bass is host for several sorts 

 of mussels, the crappies for several 

 others, the catfishes for others. The 

 skip-jack, a kind of herring, is the only 

 known host for the best of all mussels ; 

 and as this fish is not by any means abun- 

 dant, its maintenance is of prime impor- 

 tance to the welfare of the button indus- 

 try In 1 9 19 more than one and a half 

 million skip- jacks were rescued. 



AN IMPROVEMENT ON NATURE 



The peculiar requirements of the 

 young mussels having been carefully de- 

 termined, the Bureau of Fisheries has 

 gone extensively into the business of arti- 

 ficial propagation of pearly mussels by a 

 method which is a vast improvement on 

 nature. The spawning mussels, held in 

 ponds, are at the critical period provided 

 with the special fishes needed for the at- 

 tachment of the young. The fishes ob- 

 tained in the rescue operations are turned 

 into the ponds at the time the mussels 

 are spawning and become thickly inocu- 

 lated. They are then liberated in the 

 open water and distribute themselves and 

 the mussels throughout a wide stretch 

 of river. Thus two important branches 

 of the Bureau's work go hand in hand. 



The artificial propagation of fresh- 

 water mussels is one of the functions of 

 the United States Fisheries Biological 

 Laboratory located on the Mississippi 

 River near Fairport, Iowa. Each year 

 from 200,000,000 to 300,000,000 young 

 mussels are thus brought in contact with 

 the gills of rescued fishes and given a 

 proper start in life. The maintenance 

 of the mussel supply is thus being greatly 

 aided. 



That this work is not a mere experi- 

 ment, but is yielding practical results, is 

 shown by various pieces of evidence. For 

 instance, pearl buttons have been made 

 from Mississippi River mussels grown 



from larvae that had been artificially im- 

 planted on the gills of a black bass less 

 than two years before and had been 

 under constant observation. These mus- 

 sels would have attained full commercial 

 size at the age of four and a half years. 



DISTRIBUTION OE FISHES TO OUTSIDE 

 WATERS 



This account of the rescue work would 

 be incomplete if no reference were made 

 to the sending of small numbers of 

 salvaged fishes to waters more or less re- 

 mote from the Mississippi. These fishes 

 serve the same purpose as do the product 

 of the hatcheries. They are intended for 

 replenishing depleted waters or for stock- 

 ing newly formed lakes and ponds that 

 may have no fish life or no suitable sup- 

 ply of food or game fishes. 



Fishes as taken from the landlocked 

 waters of the Mississippi Valley are not 

 in a condition to stand distant shipment. 

 It is therefore necessary to subject them 

 to a hardening process before it is safe 

 or wise to send them on a long railway 

 journey. The hardening is done at sev- 

 eral depots along the river, notably at 

 La Crosse, Wis., and Bellevue, Iowa. 

 At these and several other points are 

 small buildings containing tanks in which 

 the fish are kept, without food, in cool, 

 clear, running water for several days. 



The fish, then ready for shipment, are 

 placed in large cans and loaded into 

 railway cars, in which they make their 

 journey in safety and comfort. Minor 

 shipments for short distances may be 

 made in baggage cars, with an attendant. 



The new all-steel distributing cars of 

 the Bureau of Fisheries embody the very 

 latest ideas in fish transportation. These 

 cars, with their permanent crews and 

 with all modern improvements for keep- 

 ing fish supplied with water and air, are 

 hauled on fast passenger trains and have 

 been used for forwarding from the Mis- 

 sissippi the special lots of rescued fishes 

 designed for planting in adjoining States. 



Sometimes a car-load of fish may be 

 taken in its entirety to a single point of 

 deposit, but more frequently detachments 

 are delivered en route to applicants who 

 have been notified in advance, by mail 

 or telegraph, to meet a given train with 

 receptacles for taking their fish away. 



