Almost all tho bottom insido lli fathoms is cloai' and suitable for trawl- 

 ing excopt foi' Sabino and Heald Bank and the vicinity' of t'n:*ecks and 

 snapper banks. There are also ref^ions of soft mud, such as off Timbaliar 

 Pass and tho Atchafalaya Rivor, and extensive amounts of shell in 8 to 

 iJi fathoms off Sabine, but either these hasixrds are not extensive, or they 

 do not hinder fishing \d.th nodorn gear. Between nine fathoms and tho 

 shoro there are numerous obstacles to trawling in the region from Freoport 

 to tha Colorado River. Numerous snags and largo amounts of soft mud ("suck 

 sand") iiialce fishing virtually impossible except in small prescribed areas. 

 These small pockets are very productive at times, but even the most ex- 

 perienced local fishermen sometimes lose gear. Presumably the Colorado 

 and the Brasos Rivers deposit logs and mud isjhich roake this locality un- 

 suitable for travdingt, 



Paralleling the coast from the Colorado River to about 27°N. is 

 a belt of bottom inside Ik fathoms that is suitable for trawling. There 

 are very few hazards to tra\ding in this region. 



From about 27°M. to ten miles south of the Rio Grande there is 

 an area that is vuisuitable fox* trawling because of soft inud, coral, shell 

 and topogi^aphic ii'rogularities » At 26° {48' N, ai'e found the small finger- 

 like ridges ajid valleys discussod by Mattison (I9ii8), Some of these ridges 

 are reputedly topped by dead coral. Much of the ground off Port Isabel, 

 according to the fishormon, is covered with prickly conch, Murex fulvescens, 

 and other shell. Shell bottom can be tra^/led, but net damage is much 

 greater than on mud or sand bottoriis. A few patches of clear bottom are 

 present, such as around the whistling buoy and a small ti-act along the 

 beach about l5 miles north of Port Isabel. Fishermen with small boats aid 

 small nets fi;;hed much more of the inshore area in former years than is 

 now fished by the large trawlers. 



The grounds along the oast coast of Mexico suitable for white 

 shrimp trawling are equcil to about one-tenth of tho white shrimp grounds 

 in the Louisiana-Texas area. In part this is due to the much narrower 

 continental shelf, but there are also large areas of coral, volcanic 

 rocks and soft mud. 



Generally the production of white shrimp along the northern 

 coast of Taraaulipas is very small, although fishermen in the Port Isabel 

 area report that a run of white slirhnp occurs about once every ten years. 

 Presujiably these fluctuations are caused by changes in the hydrographic 

 condition of Laguna Madro del San Antonio, the only extensive nux'sery 

 ground along the coast. There is a small stretch of trawlable bottom 

 that begins about ton miles south of the Rio Grande and extends about 

 70 miles down tha coast. From this ground to Tampico tha bottom is 

 mai'ked as hard on the tiydrographic charts. According to Texas fisher- 

 men it is rough and covered vdth prickly conclis. Presumably "pockets" 

 could be traxjled, and iiideed an extensive area near the Tairipico Light 

 produces shrimp. From Taiapico to Tuxpan there is very little trawling 

 groimd. Near Cabo Rojo a few white shrimp are caught» 



23 



