Illustration by Neil Caudle 



Scoping the catch as it swims 



With the flip of a switch, one piece 

 of electronic wizardry — a depth 

 recorder — listens to the sea beneath a 

 fishing boat and shows the captain 

 graphically what it hears: fish. He sees 

 his catch before he ever lowers a net. 



The depth recorder works like this: a 

 transducer, mounted on the boat's 

 hull, transfers electrical impulses into 

 mechanical sound vibrations that are 

 broadcast at millisecond intervals 

 down into the water in a conical beam. 

 When the vibrations strike objects in 

 the water, such as fish, the pulses are 

 reflected back toward the surface. The 

 transducer receives the pulses and con- 

 verts them back into electrical signals 

 which are fed into the depth recorder. 



By calculating the time it takes for 

 sound pulses to reflect back from ob- 

 jects or the ocean floor, the recorder 

 can produce a display on paper or on a 

 color video screen that shows the 

 fisherman a sketchy image of what is 

 beneath him. 



Depth recorders can determine 

 water depths, record a graphic profile 

 of the ocean floor, indicate the com- 

 position of the bottom and locate fish 

 beneath the boat. Today's commercial 

 and recreational fishermen consider 

 this piece of electronics almost as 

 valuable as their first mate. 



"You're wasting your time if you 

 fish without a depth recorder," says 

 Ken Kramer, a Morehead City com- 

 mercial fisherman. "If you don't have 

 one, you're putting yourself at a disad- 

 vantage by not being competitive." 

 Kramer has had his boat equipped 

 with a recorder for ten years. Kramer 

 bottom fishes. He uses his recorder to 

 locate schools of fish and determine the 

 composition of the ocean floor. He 

 looks for areas with a hard bottom 

 made of shell, rock or coral — one that 

 attracts the baitfish on which larger, 



more valuable fishes feed. 



Depth recorders are also called 

 echosounders or fish finders. But 

 Kramer says the term "fish finder" is 

 an advertising term. "A depth re- 

 corder, or fish finder if you want to call 

 it that, doesn't find anything you 

 don't run the boat over," he says. 



To use a depth recorder fishermen 

 have to do a little detective work to 

 determine what kind of fish are being 

 displayed. Recorders only provide 

 clues fishermen can use along with 

 their own knowledge of fish charac- 

 teristics to make an accurate "guess" 

 about the fish's identity. For example, 

 fish with a swim bladder or air sac 

 return stronger soundings than fish 

 without the sacs. 



Three types of depth machines are 

 on the market — flashers, paper re- 

 corders and color scopes or 

 "chromascopes." The flasher, the least 

 sophisticated and least expensive, 

 flashes the water depth on a digital 

 readout as the boat moves along. 

 There is no recorder, other than the 

 fisherman's own memory. But the 

 fisherman can tell if he is over a wreck, 

 trough or reef, areas where fish might 

 congregate. Duncan Amos, a gear and 

 electronics expert with the Rhode 

 Island Sea Grant Marine Advisory 



Services and a columnist for National 

 Fisherman, says fishermen have to 

 watch the flasher very closely if 

 they're going to be useful. A good 

 flasher will cost about $500, Amos 

 says. 



The paper recorder, the middle- 

 range in expense and sophistication, 

 graphically records a continuous 

 profile of the area between the boat's 

 hull and the sea floor on a strip of 

 paper. Jim Bahen, Sea Grant's marine 

 advisory services agent for the 

 Wilmington area, recommends the 



Transducers on boat's hull pulse 

 sonic waves, recording the 

 "echoes" of fish 



paper recorder over the flasher if the 

 fishermen can afford it. Bahen says the 

 paper recorder offers the advantage of 

 having a record of the area covered. 

 "The fisherman can take the paper out 

 of the machine, write the loran coor- 

 dinates for that area and return there 

 if the fishing is good," Bahen says. 

 Paper recorders range from $300 to 

 $16,000. 



The state-of-the-art in fish finders is 

 the color scope. On a small, computer- 

 like video screen the fisherman can tell 

 what is between his boat and the bot- 

 tom by differentiating between colors. 

 Denser objects are displayed in bright 

 red; less dense objects are shown in 

 yellow, green, purple and blue. Blue is 

 the background color that represents 

 water. 



A color scope will cost fishermen be- 

 tween $2,000 and $18,000. But like 

 other expensive electronics, as more 

 manufacturers produce color scopes, 

 prices will begin to fall, Bahen says. 

 Color scopes are luxury items that only 

 a few North Carolina fishermen can af- 

 ford now. 



Continued on next page 



"You're wasting your time if you fish without a depth 

 recorder. " 



— Ken Kramer 



