BIOLOGICAL OCEANOGRAPHY 



F. W. Fricker 



Maritime Safety Division 



U. S. Naval Oceanographic Office 



Oceanography, a relatively new word in our vocabulary, has 

 been generally defined as the "application of the sciences to the 

 phenomena of the oceans". Broadly speaking, oceanographic research 

 can be said to embrace four major scientific disciplines: biology, 

 chemistry, geology, and physics. Oceanography can, therefore, be 

 further defined as the corporate study of the biological, chemical, 

 geological, and physical components of the world's oceans and 

 adjacent waters. 



Biological oceanography specializes in the study of the living, 

 or organic, content of the sea, its myriad plants and animals. It is, 

 in its own right, a broad field of scientific effort embracing separate 

 disciplines of which morphology concerns the form and structure of 

 organisms, taxonomy their classification, physiology their functions, 

 and ecology their environmental relationships. Of these, ecology is 

 the dominant field in modern marine biology as biologists strive to 

 understand the complex interrelationships that exist between marine 

 organisms and their environment and between the organisms them- 

 selves. The importance of understanding these relationships is tied 

 to a number of existing and anticipated problems. 



From an economic and social standpoint, the sea contains vast 

 quantities of foodstuff upon which much of the present world popula- 

 tion looks for sustenance. As the burgeoning population of the future 

 will place fantastic demands upon this source, scientists, industrialists, 

 and statesmen the world over have begun to focus their attention 

 upon the seas as a vast latent source of nutrients. To cultivate, foster, 

 reap, and conserve this fabulous natural resource is an important part 

 of biological research. 



From the purely military aspect, the sea, as a three-dimensional 

 medium for naval operations, has assumed new significance. 

 Extensive efforts are being expended to find possible means of combat- 

 ing the limiting and damaging effects of marine organisms upon ships, 

 installations, and equipment; to investigate the source of the 

 scattering effect upon sonic impulses; to catalog the sounds created by 

 marine animals; to determine the predictability of bioluminescence; 

 and to explain numerous other phenomena which affect naval 

 operations. 



In brief, biological oceanography is cast in an important- role in 

 the conquest of earth's last remaining frontier, inner space. To 

 highlight this role is the purpose of the following article. As a complete 

 monograph of the science is quite beyond the scope of a single article, 

 it has been limited to those facets of apparent interest to mariners. 



BIOLOGICAL ASPECTS OF FISHING 



It has been generally estimated that 10% of the world's present 

 protein supply is comprised of aquatic organisms. Disregarding 

 possible inaccuracies in this rate, sufficient evidence now exists to 

 predict a much greater usage of seafood in the not-too-distant futiu-e. 

 Theoretically, the presumption that the sea can provide incieasing 

 amounts of food is well founded. Scientists realize, however, that 

 fulfillment of this promise can only be achieved through progressive 

 advancements in fishery technology. Better conservation measures 

 must be instituted, new fisheries discovered, capturing techniques 

 improved, and the range of useful products widened to ensure that 

 the world's fisheries keep pace with expected population demands. 

 The issues involved are essentially biological in nature and, certainly, 

 oceanographic in scope, for the development of rational theories 

 concerning present and future exploitation of oceanic resources must 

 be based on a more complete knowledge of the various organisms and 

 their interrelationships with environment. 



Fish are very similar to land animals in that each kind has its 

 own preference of food and environment. Because of this, they tend 

 to congregate in regions where their particular food is most plentiful 

 and water temperature is agreeable. Most fish migrate during certain 

 seasons of the year along comparatively well defined routes, stimu- 

 lated by an unconscious urge to spawn, feed, or winter in a different 

 location. Many species tend to feed and migrate as a group, or shoal. 

 Obviously, a sound knowledge of the migratory cycles, routes, and 

 shoaling behavior of desired fishes is necessary in forecasting the most 

 favorable catch areas. Fishery charts, currently being developed on 



a worldwide scale, are largely based on this knowledge. As the many 

 species have varying habits, the task of collecting, collating, and 

 cataloging the required data is enormous. An example of the details 

 investigated as a result of research in this field is the recently de- 

 veloped theory that salmon migrations are initiated by the organism's 

 preference for water of varying salinity, due to a change in the rate 

 of its thyroid activity. 



Food is undoubtedly the most dominant influence in the lives of 

 fishes; and consequently, their behavioral patterns, as well as their 

 growth, are largely affected by the type, location, and abundance of 

 their food supplies. The fact that the world's great fisheries coincide 

 with the areas of bountiful plankton growth is no mere accident. The 

 first link in the sea's food chain is its drifting algae, or phytoplankton. 

 Feeding upon these vast quantities of microscopic plants are the 

 myriad zooplankton, tiny shrimplike creatures barely visible to the 

 naked eye. These creatures form the staple diet of most commercially 

 important fishes at some stage of their development. The fishes, in 

 turn, are preyed upon by larger predators, mammals, and birds, thus 

 completing the chain. As productive imbalances at any level of this 

 progression may adversely affect commercial production, intensive 

 studies of feeding relationships is an important part of fishery re- 

 search. The construction of rational methods of exploiting our 

 fisheries would be impossible without an understanding of the manner 

 in which a particular fish exploits its food resources and the nature 

 of the relationships between the fish and others which consume the 

 same food. 



At the present time, the greatest danger resulting from a con- 

 stant expansion of our marine fisheries is that of overfishing. Biologi- 

 cally, overfishing is that condition created by excessive catches in 

 which the reproductive capacity of a remaining population of fish is 

 unable to compensate for the losses sustained. Economically, the 

 practice eventually results in a proportionate decline in catch per 

 effort expended, making further production of a fishery unprofitable. 

 While the latter condition probably prevents fishing of a species to 

 the point of extinction, it is of little consolation to the fisherman and 

 the conservationist. Although the imposition of conservation 

 measures rests with legislative bodies, the problems involved are 

 basically biological. 



Ocean perch infested by parasitic copepods. 



In addition to the adverse effects of overexploitation, there are 

 many natural conditions which affect reproduction and maturation 

 of marine organisms. Several bacterial and virus diseases attack 

 fish, and some fungi can kill them. Parasites do enormous harm, and 

 predators take a huge toll of commercial fishes. The amount of fish 

 consumed by piscivorous birds is very large, so that in areas where 

 they abound birds can cause serious losses to fisheries. Mussel 

 poisoning on our west coast results from periodic blooms of the plant 

 Gonyaulax, and a similar one-celled organism, Gymnodynium brevis, 

 has been associated with the fish killing "Red Tide" along Florida's 

 west coast. In the interest of enhancing our fisheries, biologists must 

 develop methods of reducing or eliminating these harmful elements. 



Researchers are also combating relatively new threats to fish 

 survival. Pollution of the seas by oil and other substances has a serious 

 adverse effect on fish by upsetting their metabolisms, contaminating 

 their food supplies, and destroying the reproductive qualities of spawn- 

 ing areas. The blocking of spawning grounds by dams, log rafts, and 

 debris has grave effects upon reproduction. 



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