zone varies from $1.36 to $1.38 with the 26-30 fathom grouping being the highest with $1.46. These data correspond to the generalized shrimp portrayal in Fig. 34, Vol. 1. 1/ Pipeline corridors will be established, wherever possible, in the area of this sale. (See Vol. 2, Sec. V. C.). Pipelines within the corridors will be buried to a depth of 3 feet out to the 200 foot contour. Less than two percent of the total shrimp catch in the western Gulf is seaward of the 200 foot contour. Additional measures to require burial of pipelines seaward of the 200 foot contour for protection of the small shrimp catch taken in that area in light of its value could be considered if information is provided concerning the frequency, location, or severity of incidents involving trawling operations and unburied pipelines. 3. Contamination of Fish by Spilled Oil Fish which are either externally coated or internally contaminated with oil are unmarketable. It has been shown that fish that live in the vicinity of chronic spillage are likely to be internally contaminated. Ehrhardt (1972) has found that oysters taken near the entrance of the Houston Ship Channel in Galveston Bay, Texas are contaminated with a high content of petroleum-derived aromatic hydrocarbons. Because aromatic hydrocarbons are much more soluble in water than paraffinic and naphthenic hydrocarbons, the oysters most likely take up 1/ Fig. 38 is a composite portrayal of the shrimp fishery depicted in Bureau of Commercial Fisheries' Gulf of Mexico Shrimp Atlas, Circular 312, U.S. Dept. Interior, 1969. the aromatic fraction as a watery solution through their gills and, being filter-feeders, as particulate matter. The author found the composition of the oyster contaminant to be similar to many Texas crude oils, among them Conroe, Beaver Lodge, and Lee Harrison. Connell (1971) has shown that a kerosene-like tainting in Australian mullet is due to the presence of kerosene-like hydrocarbons in the flesh. He found the contaminating compounds to be similar to substance isolated from river sediments, and that government Fish Board condemnation records show that periods of condemnation coincide with periods during which mullet have just left the estuaries and large catches are made. The river used by the mullet flows alongside oil refineries and associated storage and wharf facilities. Volatile hydrocarbons were found in the water adjacent to petroleum storage facilities and also in the river's estuary near a sewage outfall. Scarratt (1971) has found that commercial species of scallops ingested spilled Bunker C oil. Subsequent chemical analysis revealed the presence of Bunker C in the mantle, digestive gland, adductor muscle, and gonad, leading to the conclusion that the scallops have assimilated the ingested Bunker C oil. Oyster beds have been contaminated in the past from oil spilled in the marshes, bayous, and bays in the delta region of Louisiana. We are unaware that contaminated catches have ever been taken in the open waters of the Gulf, but note that this may be due to fishermen avoiding oily areas. We believe there is a distinct possibility that contaminated fish could be found in the norhtwestern Gulf if appropriate analyses were made. In summary, the general consensus of Gulf fishermen is that underwater stubs present the greatest problem; the presence of offshore structures are a moderate inconvenience; and, the debris problem is minimal. Based on past OCS experience, we anticipate no impact to result from contamination of catches. F. Conflict with Ship Traffic and Navigation In seas adjacent to the United States, including the Gulf of Mexico, safety fairways have been established for the safe passage of vessels enroute to, or from, U.S. ports. However, an unknown number of ships do not use these fairways, greatly increasing the possibility for a collision with drilling rigs, permanent platforms, and their attendant vessels. Impacts which could result include loss of human life, spill of oil, release of debris including part of, or the entire drilling rigs, and the ship, if it sinks. The contents of the ship's cargo could pose a serious threat to the environment if it includes toxic materials such as chemicals, crude oil, or Statistics on ship-platform collisions were given refinery products. in section III. B. Floating trash accidentally lost off platforms also constitutes a hazard to boats. Damaging collisions can result between small fast boats and floating drums, cans, and wood. The screws of all sizes of motor boats and vessels can be fouled on floating plastic sheeting and plastic or nylon ropes. The extent of this problem is unknown. |