330 NATURAL HISTORY OF AQUATIC ANIMALS. 



105. THE PILOT-FISH NAUCRATES DUCTOE. 



The Pilot-fish, though of little or no economic importance, deserves passing mention, since it is 

 so frequently referred to in literature. It is occasionally taken on our coast. Captain Atwood 

 mentions a specimen which was taken in a mackerel net in Proviucetown Harbor, in October, 

 1858. A whale-ship had come in a few days before, and he supposes that the Pilot-fish had fol- 

 lowed it into the harbor. 



"The Pilot-fish (N. ductor) is a truly pelagic fish, known in all tropical and temperate seas. 

 Its name is derived from its habit of keeping company with ships and large fish, especially sharks. 

 It is the Poinpilus of the ancients, who describe it as pointing out the way to dubious or embar- 

 rassed sailors, and as announcing the vicinity of land by its sudden disappearance. It was there- 

 fore regarded as a sacred fish. The connection between the shark and the Pilot-fish has received 

 various interpretations, some observers having, perhaps, added more sentiment than is warranted 

 by the actual facts. It was stated that the shark never seized the Pilot-fish; that the latter was 

 of great use to its big companion in conducting it and showing it the way to its food. Dr. Meyer, 

 in his 'Reise um die Erde,' states: 'The Pilot swims constantly in front of the shark; we ourselves 

 have seen three instances in which the shark was led by the Pilot. When the shark neared the 

 ship the Pilot swam close to the snout, or near one of the pectoral fins of the animal. Sometimes 

 he darted rapidly forwards or sidewards, as if looking for something, and constantly went back 

 again to the shark. When we threw overboard a piece of bacon fastened on a great hook, the 

 shark was about twenty paces from the ship. With the quickness of lightning the Pilot came up, 

 smelt at the dainty, and instantly swam back again to the shark, swimming many times round his 

 snout and spl.ishing as if to give him exact information as to the bacon. The shark now began to 

 put himself in motion, the Pilot showing him the way, and in a moment he was fast upon the 

 hook. 1 Upon a later occasion we observed two Pilots in sedulous attendance on a blue shark 

 which we caught in the Chinese Sea. It seems probable that the Pilot feeds on the shark's excre- 

 ments, keeps his company for that purpose, and directs his operations solely from this selfish 

 view.' We believe that Dr. Meyer's opinion, as expressed in his last words, is perfectly correct. 

 The Pilot obtains a great part of his food directly from the shark, in feeding on the parasitic crus- 

 taceans with which sharks and other large fish are infested, and on the smaller pieces of flesh 

 which are left unnoticed by the shark when it tears its prey. The Pilot, also, being a small fish, 

 obtains greater security when in company of a shark, which would keep at a distance all other 

 fishes of prey that would be likely to prove dangerous to the Pilot. Therefore, in accompanying 

 the shark, the Pilot is led by the same instinct which makes it follow a ship. 



" With regard to the statement that the Pilot itself is never attacked by the shark, all observ- 

 ers agree as to its truth ; but this may be accounted for in the same way as the impunity of the 

 swallow from the hawk, the Pilot-fish being too nimble for the unwieldy shark. 



"The Pilot-fish does not always leave the vessels on their approach to land. In summer, 

 when the temperature of the sea-water is several degrees above the average, Pilots will follow 

 ships to the south coast of England into the harbor, where they are generally speedily caught. 

 Pilot-fish attain a length of twelve inches only. When very young their appearance differs so 

 nmch from the mature fish that they have been described as a distinct genus, Naitclerus. This fry 

 is exceedingly common in the open ocean, and constantly obtained in the tow-net; therefore the 

 Pilot-fish retains its pelagic habits also during the spawning season, and some of the spawn found 

 by voyagers floating on the surface is, without doubt, derived from this species." 2 



'In this instance one may entertain reasonable doubts as to the usefulness of the Pilot to the shark. 

 'GOUTHER: Study of Fishes, p. 414. 



