means, and the most efficient means of harvesting shrimp is with a trap on the areas' outlet (just 

 as we have done in our studies). Moreover, we know from our own experience that the even more 

 fragile organisms that will be attempting to leave at the same time, such as menhaden and 

 anchovies, will nearly all die in the traps before they can be released. 



From the preceding paragraphs, it can be seen that wild species will be inhibited or prevented 

 from entering any area of extensive mariculture; those that do get in will have to compete with, 

 and will be preyed upon by, the cultured species; and most of the surviving wild individuals will 

 probably be killed as they attempt to leave the area. For all practical purposes, any area used for 

 mariculture will be lost to the natural fishery. Mariculture proponents may say this will not affect 

 the catch of wild species, but this is incorrect at least for shrimp, Louisiana's monetarily most 

 important fishery. Turner (1977) found a statistically significant positive correlation between 

 commercial yields of penaeid shrimp and area of intertidal vegetation, both in Louisiana and in 27 

 locations throughout the world. Also, according to Turner and Boesch (1987), similar findings were 

 reported by Jothy (1984) for Malaysia, by Pauly and Ingles (in press) for the Philippines, and by 

 Staples et al. (1985) for Australia. Although not as well documented, there is good reason to 

 believe the same correlation holds for many species of sport and commercial finfish. 



Table 3 (derived from our quantitative 2-year study funded by the U.S. Soil Conservation Service; 

 see "Fisheries Studies" section) shows the average annual export of fisheries organisms per hectare 

 from our unweired pond. From trawl samples taken concurrently in that pond and an adjacent 

 totally natural pond, it appears that even the presence of our trap system reduced production in 

 the unweired pond. Thus the values in the table are probably underestimates of natural 

 productivity for this region of the marsh. Also, natural productivity and species composition vary 

 somewhat from region to region. Nevertheless, the table does give an indication of the amount 

 of loss to natural production that will occur for each hectare of marsh used for mariculture. We 

 fee such losses to mariculture represent losses of a public resource for the purpose of private gain. 



Note that the "all other species" category in Table 3 represents over 90 additional species. Most 

 of these have no present direct economic value, sport or commercial, but their loss will have 

 considerable indirect economic effect because many are important in the food web of species of 

 direct economic value. Moreover, loss of production in the marsh will adversely affect production 

 even of many offshore species that never enter the marsh. There is much in the scientific 



Table 3. Average annual number and weight per hectare of some economically 

 important organisms exported from the unweired pond, February 1983 through 

 February 1985. 



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