SPINOUS FISH. 



309 



iter is immediate destruction : on the other 

 land, some fishes, that live in our lakes and 

 ponds, cannot bear the salt water. Whence 

 this difference can arise, is not easily to be 

 accounted for. The saline quality of the 

 water cannot properly be given as the cause; 

 since no fishes imbibe any of the sea's saltness 

 with their food, or in respiration. The flesh 

 of all fishes is equally fresh, both in the river, 

 and in the saltest depths of the ocean; the 

 salt of the element in which they live no way 

 mixing with their constitution. Whence 

 then is it that animals will live only there, 

 and will quickly expire when carried into fresh 

 water? It may probably arise from the supe- 

 rior weight of the sea-water ; as from the great 

 quantity of salt dissolved in its composition, it 

 is much heavier than fresh water, so it is pro- 

 bable it lies with greater force upon the 

 organs of respiration, and gives them their 

 proper and necessary play ; on the other hand, 

 those fish which are used only to fresh water, 

 cannot bear the weight of the saline fluid, and 

 expire, in a manner suffocated in the gross- 

 ness of the strange element. 



But though there are some tribes that live 

 only in the sea, and others only in fresh water, 

 yet there are some whose organs are equally 

 adapted to either element ; and that spend a 

 part of their season in one, and a part in the 

 other. Thus the salmon, the shad, the smelt, 

 and the flounder, annually quit their native 

 ocean, and come up our rivers to deposit their 

 spawn. This seems the most important busi- 

 ness of their lives ; and there is no danger 

 which they will not encounter, even to the 

 surmounting precipices, to find a proper place 

 for the deposition of their future offspring. 

 The salmon, upon these occasions, is seen to 

 ascend rivers five hundred miles from the sea; 

 and to brave not only the danger of various 

 enemies, but also to spring up cataracts as high 

 as a house. As soon as they come to the bot- 

 tom of the torrent, they seem disappointed to 

 meet the obstruction, and swim some paces 

 back: they then take a view of the danger that 

 lies before them, survey it motionless for some 

 minutes, advance, and again retreat; till at 

 last summoning up all their force, they take 

 a leap from the bottom, their body straight, 

 and strongly in motion ; and thus most fre- 

 quently clear every obstruction. It sometimes 

 happens, however, that they want strength to 

 make the leap ; and then, in our fisheries, they 

 are taken in their descent. But this is one 

 of the smallest dangers that attend these ad- 

 venturing animals in their progress : number- 

 less are the methods of taking them ; as well 

 by the hook, as by nets, baskets, and other 

 inventions, which it is not our business here 

 to describe. Their capture makes, in several 

 countries, a great article of commerce; and 



being cured in several different manners, either 

 by salting, pickling, or drying, they are sent 

 to all the markets of Europe. 



As these mount up the rivers to deposit 

 their spawn, others, particularly the eel, de- 

 scend the fresh water stream, as Redi assures 

 us, to bring forth their young in the sea. 

 About the month of August, annually, these 

 animals take the opportunity of the most ob- 

 scure nights, and when the rivers are flooded 

 by accidental rains seek the ocean. When 

 they have reached the sea, and produced their 

 young, for they are viviparous, they again 

 ascend the stream, at different times, as op- 

 portunity offers, or as the season is favourable 

 or tempestuous. Their passage begins usually 

 about the end of January, and continues till 

 towards the end of May, when they are taken 

 in the river Arno by millions, and so small 

 that a thousand of them goes to a pound. 

 There is nothing more certain than that they 

 descend our own rivers after floods in great 

 abundance, and are thus caught in nets to 

 very great advantage. They are possessed 

 also of a power of climbing over any obstacle ; 

 for, by applying their glutinous and slimy 

 bodies to the surface of the object they 

 desire to surmount, they can thus creep up 

 locks, weirs, and every thing that would 

 prevent their ascending the current of the 

 stream. 



But the length of the voyage performed by 

 these fishes, is short, if compared to what is 

 annually undertaken by some tribes, that con- 

 stantly reside in the ocean. These are known 

 to take a course of three or four thousand miles 

 in a season, serving for prey to whales, sharks, 

 and the numerous flocks of water-fowl, that 

 regularly wait to intercept their progress. 

 These may be called fish of passage, and bear 

 a strong analogy to birds of passage, both from 

 their social disposition, and the immensity of 

 their numbers. Of this kind are the cod, the 

 haddock, the whiting, the mackarel, the tunny, 

 the herring, arid the pilchard. Other fish live 

 in our vicinity, and reside on our coasts all the 

 year round ; or keep in the depths of the ocean, 

 and are but seldom seen : but these, at stated 

 seasons, visit their accustomed haunts with 

 regular certainty, generally returning tho 

 same week in the succeeding year, and oftei* 

 the same day. 



The stated returns, and the regular progress 

 of these fish of passage, is one of the most ex- 

 traordinary circumstances in all the history of 

 nature. What it is that impels them to such 

 distant voyages ; what directs their passage ; 

 and what supports them by the way ; and what 

 sometimes prompts them to quit, for several 

 seasons, one shore lor another, and then return 

 to their accustomed harbour ; are questions that 

 curiosity may ask, but philosophy can hardly 



