The Sharks-Part Tivo 341 



volcanic ash 150 miles out to sea. In 1931, a massive earthquake leveled 

 Managua, the capital of Nicaragua. And 2,000 to 5,000 years ago, near 

 Managua, a volcanic eruption left a memorial to its victims. Cast for- 

 ever in hardened mud are the footprints of humans, a deer, a cat, and 

 other animals that fled the eruption. The mud changed into stone, leaving 

 the prints as stark as they were on the dav they were made. 



From evidence such as this, geologists have spun the theory that 

 Lakes Nicaragua and A4anagua were once part of a huge bay of the 

 Pacific, which was sealed off when the earth erupted long in the past. 

 When the cataclysmic writhing of the earth ceased, the bay had van- 

 ished. In its place was a thick arm of earth with the Pacific on one side 

 of it and two lakes on the other. Trapped within the lakes, according to 

 this theory, were numerous sea fishes. As rivers flowing into the newly 

 formed lakes gradually freshened them, some of the marine fish— the 

 sharks, sawfish, and tarpon, at least— adapted themselves to fresh water 

 and survived. 



But why have sharks appeared only in Lake Nicaragua? The geo- 

 logic theory does not answer this. Nor does it answer the claims of 

 natives (never adequately investigated by ichthyologists) that tivo 

 kinds of sharks live in Lake Nicaragua— reddish-bellied tintoreros and 

 white-bellied visitante or immigrante. The natives around the lake insist 

 that the visitante are smaller and livelier than the tintoreros because 

 the visitante have had to enter the lake by making their way up the 

 rapids of the San Juan River, the lake's link to the sea. 



Despite the sandbars and the rapids that make the San Juan a difficult 

 river to navigate, a shark could struggle up the river and into the lake. 

 In fact, even today natives fear the shark of the river as much as they 

 fear the shark of the lake. And the San Juan was long navigable, even 

 to ships. Though virtually impassable to ships today, the San Juan in the 

 nineteenth century formed part of a circuitous route, little known to 

 readers today, to the gold fields of California. Gold-hunters from the 

 East Coast of the United States, rushing to join the forty-niners, took 

 ships in the States that deposited them at the mouth of the San Juan on 

 the Caribbean coast. There they boarded riverboats operated by Com- 

 modore Cornelius Vanderbilt, journeyed up the San Juan to Lake Nica- 

 ragua, and crossed the lake. At the western side of the lake, they boarded 

 stage coaches that carried them to the Pacific coast of Nicaragua, where 

 they embarked for California. As recently as 1882, at least, a good-sized 

 ship was able to navigate the San Juan. In that year, the steamer Victoria 

 was built in Wilmington, Delaware, sailed down to the mouth of the 

 San Juan, made its way up the river, and entered the lake. 



If ships could do it, why not sharks? 



But if the existence of sharks in Lake Nicaragua is explained by 



