BIOLOGICAL OCEANOGRAPHY 



Although the sea harbors at least 40,000 species of fish and an 

 even greater number of other aquatic organisms, only about 300 kinds 

 of fish and shellfish are utilized for food in the United States. Further- 

 more, of the nation's total annual catch, 60% is composed of only 

 9 species. This overspecialization in only a few of the species available 

 places a severe limitation on the expandability of the source. It 

 appears evident that future demand will gradually necessitate a wider 

 usage of the many edible species now classified as commercially un- 

 important. Oceanography will play an important role in determining 

 the exploitability of new stocks. 



Biological research has provided several methods of augmenting 

 existing stocks of commercial fishes. By artificially rearing fish in 

 controlled hatcheries and on fish farms, eggs and larvae can be pro- 

 tected from a number of adverse conditions, thus assuring a higher 

 rate of maturation. The productivity of a water-mass can also be 

 enhanced by artificially raising its food content, either by fertilization 

 to encourage the growth of organisms upon which the larvae feed, or 

 by introducing cultured fishfood into the area. Transplantation of 

 desirable species from one environment to another has, in many cases, 

 been successful. 



To realize the full potential of harvest from our oceans, 

 however, effective methods of utilizing the many species inhabiting 

 the extensive geographic regions of our open oceans must be devised. 

 Many of these resources, like those of the tuna family, may form 

 natural aggregations only periodically, may make themselves avail- 

 able only seasonally to existing fishing systems, or may be widely 

 dispersed thoughout the sea. Exploratory expeditions conducted by 

 various nations have resulted in the discovery of several new offshore 

 fisheries of commercially valuable fish. It seems reasonable to assume 

 that many more await discovery in the vast reaches of our oceans. 

 However, economical exploitation of any new oceanic species must 

 be preceded by a careful appraisal of the creature's shoaling, feeding, 

 spawning, and migratory habits so as to forecast and chart the areas 

 of highest concentration. 



Equal in importance to the discovery and forecasting of their 

 aggregative traits, increased harvests of offshore species will require 

 vast improvements in capturing gear and techniques. Most methods 

 in use today evolve from systems designed to capture fish within 

 close proximity to land, relying on environmental features and bio- 

 logical characteristics of fish to form required concentrations. The 

 perfection and effective application of fishing gear is impossible 

 without a sound knowledge of the reactive processes of fishes, partic- 

 ularly their shoaling behavior and the characteristics of their sense 

 organs by which they orient themselves to fishing gear. The form, 

 size, color, and other properties of capturing gear, and the region in 

 which it is applied, have a definite bearing upon its effectiveness. 



Refinements in fishing techniques may require the use of more 

 sophisticated capturing methods, to facilitate economical harvesting. 

 The attractive influence of strong artificial light upon fish is well 

 known, and fishermen the world over have exploited its use. Recent 

 experiments have further revealed that fish behavior is affected to 

 some extent by the color, as well as intensity, of artificial light. 

 Biologists have recently confirmed the fact that fish respond to an 

 electromagnetic field, first, by orienting themselves to the lines of 

 flux, then by swimming toward the anode. By placing an electrode 

 in front of a trawl, shoal fish can be attracted and guided into the 

 catching area. Furthermore, experiments show that by the use of 

 direct, alternating, or pulsating current, electrical fishing gear can be 

 made to frighten, block, or "fence" fish, or to narcotize or kill them. 

 Guiding herring into nets or traps by use of a wall or stream of air 

 bubbles has been experimented with and employed with some success. 

 Perfection of such techniques, however, will require a better under- 

 standing of the behavioral reactions of fishes to artificial stimuli. 



FOULING AND DETERIORATION 



Among the many important problems associated with marine 

 biology, none has greater economic significance than the control of 

 marine fouling and deterioration. Anyone familiar with the sea and 

 ships is well acquainted with the costly effects of marine growth on 

 ships' hulls and salt water intakes. Equally important is the damage 

 of shore installations resulting from the penetration of wood, plastics, 

 concrete, and other structurally important materials by several 

 marine organisms. It has been conservatively estimated that the 

 annual cost to the Navy alone for the protection and maintenance of 

 ships, waterfront structures, and offshore equipment against biological 



deterioration and fouling is approximately $100,000,000. Far more 

 importantly, however, uncontrolled fouling and deterioration by 

 marine organisms can effectively reduce the combat readiness of 

 naval ships and shore facilities. 



Sections of 6-inch pipe taken from over boiler on Natnf ship. 

 The pipe is almost closed by marine-fouling growth. 



The fouling of ship's hulls is, of course, an age-old problem. 

 Man's historic efforts to discourage marine growth has resulted in the 

 development of chemical agents which today, can protect hull surfaces 

 for as long as 24 months. The problem is far from solved, however, 

 for the development and use of submerged equipments vital to naval 

 operations and technological progress constantly introduce new 

 requirements for enduring antifouling agents. 



The biological fouling of a sonar transducer can seriously impair 

 its effectiveness by attenuating sound transmission. In certain areas 

 of the world, critical fouling of unprotected surfaces can occur within 

 a few months, rendering sonars unfit for ASW operations. Some 

 success in developing reliable protective coatings for sonar domes has 

 been realized, but the problem is complicated by the requirement 

 that the agent used must not alter the equipment's acoustic properties. 



The growing use of underwater optical instruments presents 

 further complications. Complete fouling of an underwater television 

 lens can be accomplished in an incredibly short period of time. 

 Obviously, the lens cannot be painted with antifouling paint as in the 

 case of a ship's hull. The development of durable but transparent 

 protective coatings is a necessary preliminary to the planned instal- 

 lation of submerged optical equipment such as television monitoring 

 stations. 



Moreover, the proposed construction of large, stationary struc- 

 tures in relatively deep ocean waters for various military and commer- 

 cial projects creates additional fouling problems. Already, the 

 underwater structures used in the recovery of offshore petroleum 

 are approaching deeper waters. Because of the size and permanency of 

 proposed structures frequent maintenance will be impractical, if not 

 impossible. Therefore, anti-fouling agents of enduring effectiveness 

 must be developed. But little field data is available at the present 

 time to warrant the assumption that deep-ocean fouling will not 

 differ from that occurring in shallow coastal waters. For this reason, 

 far more data must be obtained about the ecology of fouling organ- 

 isms in the deep sea before reliable fouling deterrents can be developed. 



Wood gribbles bore into a piling. 



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