FISHERIES 



VESSELS 



AND GEAR 



By J. N. Spinning 



Maritime Sfifety Division, 



U. S. Naval Oceanogrnphic Office 



The unprecedented expansion of fishing fleets throughout the 

 world and the development of new fisheries and harvesting lechni(|ue> 

 are matters of ever-increasing importance to every watch officer. A> 

 encounters with the vessels, men, and gear competing lor this rich 

 protein supply become more frequent, the need for mutual safety will 

 become more demanding. To adequately meet this demand watch 

 officers need more than a seamanlike curiosity of those with whom tho\ 

 share the sea. This article explores the dominating factors which 

 create, develop, and sustain a fishery, and fashion its tools of harvest. 



Today, there are well over one million vessels actively engaged 

 in the time-honored fishing profession. Vessels range in size from the 

 large factory mother ship down to the most primitive native canoe. 

 Each vessel, however, regardless of size, shape or means of propulsion, 

 shares one common goal: to catch fish as efficiently as the circum- 

 stances permit. 



The type of fishery and means of harvest play a significant role 

 in the design and equipment of every fishing vessel. Although only a 

 few ve.ssels are so specialized that they can engage in just one fishery, 

 most ve.ssels are limited to one harvesting technique, or perhaps two 

 for different seasons. 



For generations prior to the Second World War, fishermen 

 working from small vessels were content to fish the waters contiguous 

 to their home ports. Relatively few ventured far from their native 

 shores. World War II saw large numbers of fishing craft lost, 

 destroyed, or rendered unseaworthy due to deterioration and neglect. 

 Faced with a hungry post-war population and a meager fleet, the 

 fishing industry embarked on an urgent program of rehabilitation 

 and expansion. 



Stimulated by government, and aided by far-reaching technolog- 

 ical advances in science, food processing, and harvesting techniques, 

 the industry has made tremendous strides toward meeting the world's 

 need for fish. This fact can readily be appreciated when we note that 

 the total world catch has more than doubled during the past 15 years. 

 Figures from the Yearbook of Fi^kerij ^lalislics, now considered the 

 most reliable .source of what, where, and how much is caught, reveal 

 that 217 countries, territories and island groups caught a total of 

 51.6 million metric tons of fish and other marine animals during 1064. 

 The Yearbook also shows that of these 217, only 42 had catches over 

 100,000 tons and that they accounted for 95 percent of the catch. 

 Only 12 countries had catches in excess of one million tons. 



The following table shows the relative standings of the 12 major 

 fishing nations based on the metric tons landed during 1964. 



CLASSES AND METHODS 



Fish are classified as either pelagic or demersal. Pelagic fish are 

 those species that live at or near the surface; included in this group 

 are salmon, tuna, menhaden, mackerel, and herring. Demersal fish 

 are those varieties that live at or near the bottom; included in this 

 group are haddock, cod, rosefish, pollock, flounder, and all types of 

 shellfish. 



While there are virtually endless variations in the methods of 

 harvesting fish, they can all be listed under one of three major groups: 

 direct attack, snaring or luring. Direct attack embraces all techniques 

 using such gear as harpoons, spears, dredges, rakes or tongs. Snaring 

 covers all methods of making the catch by nets such as trawl nets, gill 

 nets, purse seines, ring nets, or pound nets. Luring includes all forms 

 of bait fishing where the fish or crustacean is enticed to bite a hook 

 or crawl into a trap. 



One fishing community may prefer one particular technique for 

 harvesting the crop while a different method is favored elsewhere. 

 The vital factors of capital to finance the operation, local market 

 conditions, abundance of fish, and type of grounds all play key roles 

 in the ultimate choice. 



FOOD CYCLE 



Relatively few of the more than 40,000 species of fish exist in 

 sufficient concentrations to make commerical harvesting economically 

 feasible. A large concentration of fish requires a proportionately large 

 food reservoir. It follows, therefore, that commercial fisheries can 

 develop only in those areas where the physical properties of the sea can 

 support ample organic growth. 



The food cycle is predatory in nature. It begins with tiny surface 

 plants called phytoplankton using the sun's energy, through photosyn- 

 thesis, to build organic tissue from dissolved inorganic materials in the 

 sea. This involved process can only take place in the light-penetrated 

 surface layers called the eiiphotic zone. These tiny phytoplankton 

 serve to feed a multitude of small animals called zooplankton. Zoo- 

 plankton provide the main source of nourishment for small pelagic fish 

 which in turn fall prey to larger species of pelagic and demersal fish. 



This food cycle tends to be long and inefficient when there is little 

 change in the water layers within the euphotic zone. As the rate of 

 surface water replenishment increases, due to upwelling and mixing of 

 moving water masses, the abundance of marine life increases. Up- 

 welling is caused primarily by water from the lower depths rising to 

 replace the surface water which has moved away from the shore. This 

 surface movement is due to the action of the prevailing alongshore and 

 offshore winds coupled with the normal deflection caused by the 

 earth's rotation. The resultant exchange of nutrients stimulates 

 vigorous organic activity. It is in the areas of greatest upwelling and 

 mixing that most of the commercial crop is harvested. 



TRAWLERS 



.\ frequent error made by watch officers, and lookouts alike, is 

 the assumption that every fishing vessel sighted is a trawler. The basis 

 for this assumption undoubtedly stems from the large number of 

 actual encounters and the fact that they appear in all sizes and 

 shapes. Trawlers may be broadly classed as either side or stern trawl- 



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