PART VIII — AQUATIC ECOSYSTEMS 



Figure VIII— 5 — SOME ZOOPLANKTON 



(Copyright 1965. Houghton Miftlin Company, Boston. Mass! 



The illustration shows drawings of some zooplankton, enlarged about five times. 

 Ostracods: 



1. Gigantocypris mulleri: (a) adult with eggs, (b) and (c) two views of young 

 and more transparent specimen 



2. Conchoecia ametra 



3. Cypridina (Macrocypridina) castanea 

 Copepods: 



4. Arietellus insignis, female 



5. Gaetanus pileatus, female 



6. Euchirella maxima, female 



one trophic level to the next higher 

 level might be considered to be on 

 the order of 10 percent, the loss 

 being 90 percent. This means that 

 the total production (hence potential 

 yield) of zooplankton is much greater 

 than that of small fishes feeding on 

 zooplankton, and the latter in turn 

 far exceeds that of larger fishes prey- 

 ing on small fishes. Such small fishes 

 as anchovies, sardines, and herring 

 actually make up the bulk of the 

 world's total catch of fish. As the 

 exploitation of living ocean resources 

 becomes more and more intensive, 

 man will sooner or later look into 

 the possibility of utilizing small 

 planktonic animals, the abundance 

 of which is enormous. 



On a very limited scale, zooplank- 

 ton has been used for many years 

 in some countries of Asia. In Japan, 

 for example, brackish or inshore 

 species of mysids (Anisomysis, Acan- 

 thomysis, and N eomysis) have been 

 used as materials for a traditional 

 food called "tsukudani" and also as 

 feeds for aquaculture. A deep-sea 

 pelagic species of sergestid shrimp 

 (Sergestes lucens), which grows to 

 40-50 millimeters, has long been 

 processed into dried shrimp. In 

 Southeast Asia (Malaysia, Thailand, 

 Indonesia, and Singapore), shrimp 

 paste manufactured from inshore 

 species of sergestid shrimps, mysids, 

 and other small crustaceans has been 

 a popular food consumed in substan- 

 tial quantities. The total amount of 

 zooplankton now utilized, however, 

 is negligible compared with the 

 amount available in any part of the 

 ocean. 



For large-scale harvesting of zoo- 

 plankton, certain conditions would 

 have to be met. It would not be 

 economically feasible to harvest zoo- 

 plankton indiscriminately. Harvest- 

 ing must be done in areas where 

 dense concentrations of larger forms 

 of zooplankton occur, and special 

 plankton fisheries must be developed 

 for this purpose. Such concentrations 

 of larger forms are found in many 

 areas at certain times. 



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