SCIENCE AND THE SEA 



SHRIMP FISHERIES 

 Coastal regions along the South Atlantic and Gulf coasts of the 

 United States are richly endowed with excellent shrimp resources. 

 This fishery furnishes more food, employs more people and supports 

 a larger packing industry than any other in this geographical area. 

 American shrimp fleets also travel far afield, with vessels working off 

 Mexico, Honduras, Nicaragua, and Panama. Recently, vast new 

 shrimping grounds were discovered off French Guiana. Some author- 

 ities believe the area contains the largest unexploited grounds in the 

 Western Hemisphere. Estimates of the potential production capability 

 have been set at 100,000,000 pounds annually. A new processing plant 

 with dockside facilities has been erected at Cayenne, French Guiana, 

 to handle the harvest. This plant will process 40,000 pounds of 

 shrimp tails daily, and ship them in frozen form to the United States. 

 Mexico has a highly-developed shrimp fishery on both her Pacific 

 and Gulf coasts. Over 1,000 vessels participate in harvesting the 

 Pacific crop, with 300 craft working from Mazaltan, Mexico, alone. 

 The east coast fishery is concentrated in the Gulf of Campeche. A 

 substantial percentage of Mexico's rich harvest is imported by the 

 United States. 



Australia, Pakistan, Kuwait, and Nigeria are but a few of the 

 many nations displaying considerable interest in developing commer- 

 cially profitable shrimp fisheries. Any successful fishery must enjoy 

 an abundant supply of raw material, adequate processing and storage 

 facilities, good transportation connections, and the all important 

 markets, domestic or foreign. Pakistan, for example, has a fairly 

 abundant supply of shrimp but lacks sufficient local markets and 

 distribution facilities. With the aid of modern freezing plants, 

 however, Pakistan has been able to develop a good export trade. 

 Australia has a young and very promising shrimp fishery under 

 development. Authorities, anxious to both expand and conserve the 

 fishery, have embarked on a detailed research program to learn more 

 about the migration, mating, and feeding habits of shrimp. Through 

 such research and close cooperation with the industry, they hope to 

 achieve maximum production potential without exploiting the crop 

 beyond safe levels. 



Shrimp live on the sea floor and are limited in their distribution 

 to areas having muddy or sandy bottoms. With the exception of the 

 Royal Red shrimp, which occur in depths between 175 to 300 fathoms, 

 they are normally harvested in depths under 50 fathoms. Most shrimp 

 caught are in their first year of life. Relatively few ever reach a fuir 

 two year class. This indicates that a severe natural mortality rate 

 sets in after the yearlings spawn. It soon becomes evident that a 

 highly developed fishery cannot be siistained by a single year class 

 without proper crop management. 



Figure U Shrimp trawler 



American shrimp fishermen harvest three major species in the 

 southern fishery, which also embraces the Campeche grounds, white 

 shrimp, pink shrimp, and brown shrimp. White shrimp are normally 

 found in bays and inshore waters under 15 fathoms in depth. Fishing 



for this species is conducted during the day using conventional otter 

 trawls having an average mouth opening of 80 to 100 feet. Pink and 

 brown shrimp are usually taken in depths of 25 fathoms or more. 

 Fishing for these two types is better at night. Vessels engaged in pink 

 and brown shrimp fishing use double-rig trawls. Each trawl is 40 to 

 45 feet across the mouth, and is towed from an outrigger boom, one on 

 each side of the vessel. To- avoid fouling rigs, one trawl trails 150 feet 

 behind the other. Double- rig trawls provide better catches, are 

 easier to handle, are safer, and suffer less damage than the large, 

 single type. 



Before either trawl is streamed a small try-net, with a 10-foot 

 mouth, is put over to determine if sufficient shrimp are present to 

 make a drag worthwhile. Trawling limes vary, but average between 

 2 and 3 hours. In addition to the shrimp that are harvested, consid- 

 erable trash is picked up. This trash consists of fish, crab, shells, 

 sponges, and other unwanted material. After the trawl is dumped on 

 deck, the shrimp are removed from the trash, beheaded, and packed 

 in crushed ice. The trash is thrown overboard again as no profitable 

 means of processing it at sea has yet been found. 



TUNAS 



Tuna fish, or tunny as they are called in many fisheries, are truly 

 an international resource, migrating over vast expanses of the tropical 

 and subtropical seas. Although tuna fishing is pursued by most 

 maritime nations bordering these waters, Japan and the United States 

 harvest 90 percent of the world crop. France, Spain, and Peru also 

 have very active tuna fisheries. While Japan's fleets range worldwide, 

 the United States effort is concentrated in the eastern Pacific region, 

 and around Hawaii. American tuna clippers from west coast ports 

 fish from Canada to Peru, occasionally over 500 miles offshore. 



Over a dozen species of tunas are taken by the various world 

 fisheries, the five most important being: albacore, yellowfin, bluefin, 

 bigeye, and skipjack. Albacore possess the whitest meat hence are the 

 most valuable of all catches. 



Harvesting techniques and paraphernalia vary widely. Around 

 the Japanese archipelago, live-bait fishing is used for albacore and 

 skipjack. Japan's offshore fleets employ long-line methods. American 

 landings are almost entirely by purse seines. In the Bay of Biscay, 

 French and Spanish vessels traditionally troll for tuna. Mediterranean 

 fishermen still rely heavily on weirs and pound nets for their share 

 of the harvest. 



Since both long-line and purse seine fishing have alreadly been 

 covered, no additional discussion of those techniques, with regards 

 to tuna, will be made. 



Vessels engaging in live-bait tuna fishing must stop after leaving 

 port and fish for small sardines, anchovies or smelts. This bait is kept 

 alive in large deck tanks by circulating sea water until needed. Large 

 clippers carry up to 15 tons of bait per voyage. 



Schools are generally sighted by an experienced lookout stationed 

 aloft. Some vessels have expanded their spotting capability by carrying 

 a small seaplane, or by hiring free lance pilots working from coastal 

 airfields for this chore. Once a school has been intercepted, the 

 clipper is positioned and live-bait is thrown overboard to keep the 

 school around. All available hands turn to during the ensuing period 

 of intense fishing activity to fully exploit the school. 



The crew fish from low-railed platforms secured to hull outside 

 the gunwales. Fishing rigs consist of a barbless hook covered with 

 feathers called a striker or jig connected by a short stout line to a 

 bamboo pole. Excited by the live-bait, the tunas become so voracious 

 they seize anything in sight. Upon striking the jig, the tuna is quickly 

 pulled from the water and swung over the fisherman's shoulder, and 

 deposited on deck. When fish run large, two, three or even four men 

 will work together, each with a separate rod connected by means of a 

 swivel to a single hook line. 



TUNNYMEN 



Tunnymen and tuna fishers in European waters bear no resem- 

 blance to the more spacious, elaborately equipped. Pacific tuna clippers. 

 Vessels engaged in this important fishery off the French and Spanish 

 Biscay coast are in the main, either powered craft called pinnaces, 

 or large sailing and auxiliary powered yawls and ketches The latter 

 are usually under full sail presenting a picturesque sight with their 

 brightly colored sails and hull. The number of these vessels still 

 working, however, is small. 



Sailing tunnymen range from 65 to 85 feet in length, carry a 

 crew of eight and fish up to 500 miles from their home ports. The 



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