Natural life history studies are needed and human impacts on abundance should 

 be explored. These include the effects of commercial removal and the 

 potential effects of various perturbations such as dredging, spoil disposal, 

 oil spills, and discharge of contaminants, on each species at various life 

 stages . 



When all factors, both natural and artificial, are known, questions such as 

 the following may be answered: 



1. Why have shrimp landings decreased so sharply? 



2. How are scallop beds formed and why are catches so erratic? 



3. Do worms prefer particular sediment types and/or detrital amounts in 

 the substrate? 



4. Which cyclic events in life histories of populations relate to 

 harvest levels? 



Many theories attempt to answer the above questions. In the past, correlation 

 of a single abiotic or biotic factor with harvest has been attempted. It may 

 be more valuable to correlate a variety of variables with species abundance 

 and distribution. The ecosystem approach rather than the single species- 

 single factor approach is necessary. 



12-33 



10-80 



