THE AMERICAN SHRIMP INDUSTRY 591 



shrimp (P. aztecus) , {P. duoarum), and (P. hrasiliensis) ; and the "sea-bob" or 

 "seven beards" (Xiphopenaeus) . The three species of hrasiliensis were formerly 

 included in one species of grooved shrimp. However, it was proven by Burken- 

 road (1939) that these constituted three distinct species. 



According to the estimates of the above investigators the common shrimp 

 (P. setiferus) is by far the most numerous of these five species. Although the 

 percentage composition of the catch varies to some extent from year to year, this 

 species composes approximately 95 per cent. The fishermen do not ordinarily 

 distinguish between the various species. Occasionally when the catch contains a 

 larger proportion of the hrasiliensis group, sales resistance is encountered because 

 of the slight difference in color. This group is commonly called "brasiHan" shrimp 

 or "brownies." 



The most abundant of the grooved shrimp is P. aztecus, with P. duoarum second 

 and P. hrasiliensis last. The largest production of this group of shrimp is during 

 the late spring and early summer. Several other species are taken by the trawlers, 

 but the quantity is quite small and in some cases the identity is not entirely clear. 



Handling Shrimp on the Vessels 



Shrimp are one of the most popular of all sea food products available to the 

 consuming pubHc; consequently, there is an almost universal demand for it 

 throughout the year. The requirements for supplying the market are satisfied 

 by the wide distribution of the fishing grounds and the success with which a good 

 quality product can be preserved by freezing and canning. Some states have 

 closed seasons on shrimp fishing. They do not run concurrently, however, so 

 shrimp are caught somewhere in the area throughout the year. 



Practically all shrimp are captured by means of a trawl which is towed slowly 

 along the ocean floor. This trawl is a large funnel-shaped bag flattened at the top; 

 otter boards on the right and left sides hold it open so that the shrimp can be 

 entrapped. At intervals, depending upon the volume of shrimp in the bag, it is 

 hoisted aboard the vessel and emptied on the deck. The net is again thrown over- 

 board for another drag while the crew of the vessel separate the shrimp from the 

 various other species which may also have been caught in the trawl. As the shrimp 

 are sorted, they are stored with alternating layers of ice in bins in the hold of the 

 vessel until the bins are full. Some crews, while at sea, remove the heads. This 

 saves considerable space in the storage bins since the tails of the shrimp are the 

 only edible portion and, therefore, are the most valuable. When the shrimp are 

 landed whole, the head portion is sent to a meal plant and manufactured into 

 shrimp meal, which is valuable as a poultry feed. 



This first handling operation aboard the vessel has a particular bearing on the 

 market value of the shrimp. If permitted to lie on the deck of the vessel in the 

 hot sun for several hours shrimp deteriorate rapidly, and, as a result, the quahty 

 is reduced. No matter whether the shrimp are to be sold fresh, cooked, canned, 

 or frozen, they must be packed in adequate ice at the earliest possible time. Care 

 should be exercised in handling to be sure that the shrimp are not injured since 

 a bruise causes more rapid deterioration by reason of enzymatic and bacterial 

 action. 



The vessels journey for 10 to 50 miles to obtain their catch. They fish in waters 



