APPENDIX Tit APPENDIX III 
quantities are available for major commercial development. 
A Texas study concluded that rock shrimp probably cannot 
support a fishery alone, but may supplement the brown 
shrimp fishery if stable markets are created. NMFS explora- 
tory fishing for the deepwater crustaceans located some 
resources, but not in sufficient quantities to encourage 
commercial development. 
Environmental considerations 
A potential problem, which could affect available 
resources, involves sustaining environmental conditions to 
assure that the general level of shrimp stock will continue 
to be available in the future. The success of recruitment 
and survival depends heavily on environmental conditions 
in the nursery areas, which are subject to pollution from 
various sources including dredging and urban and industrial 
construction and growth. 
Environmental deterioration of the Mississippi Delta 
System is a major concern. The Delta estuaries and wet- 
lands form a resource that, in view of biological produc- 
tivity, must be considered one of national importance. 
The delta estuaries of Louisiana's coast account for about 
25 percent of the total fish harvest of the conterminous 
United States. 
For the most part, Gulf shrimp resources are annually 
renewable and consist of short-lived animals with a life 
cycle of oceanic and estuary phases. Marked fluctuations 
in the size of shrimp populations can probably be induced 
by yearly differences in spawning success and survival of 
young which depend to a large extent on biological and 
physical environmental conditions. 
During the past 30 years about 500 square miles of 
delta land mass has been lost. Some environmentalists 
interpret the decline in catch per unit of effort as indi- 
cative of estuary deterioration. By 1973 the amount of 
shrimp landed for each unit of effort declined to less than 
half the 1967 level. 
Harvesting capability 
Capability to harvest the available resource may exceed 
that necessary for an optimal harvest and is subject to 
increasing operating costs. 
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