are abandoned when fish are scarce. Each 

 resident trawler averaged 3-1/2 trips a month 

 during the study period. 



Most vessels fishing for industrial bottom- 

 fishes pull a single otter trawl from a boom 

 located amidship and projecting aft. A few 

 trawlers tow two trawls, or a "double-rig," 

 from the port and starboard booms which 

 project laterally. Gulf of Mexico bottomfish 

 trawls, commonly of the "balloon" type (in 

 contrast to the "flat" design that is widely 

 used for catching shrimp), are uniform in 

 configuration but vary considerably in dimen- 

 sion. Net width along the lead line of trawls 

 used by "single-rig" vessels varies from 60 

 to 110 feet, whereas "double-rig" vessels 

 fish smaller nets ranging in width from 50 to 

 80 feet. The net is held open by two otter 

 boards, or trawl doors, to each of which a net 

 wing is directly attached. The doors are hung 

 on a bridle that joins the vessel's towing 

 warp. Mesh size varies from 1-1/4 to 2-1/8 

 inches, stretch measure. A detailed descrip- 

 tion of trawling gear designed especially for 

 the industrial bottomfish fishery is given by 

 Bullis, Captiva, and Knake (1960). 



Before the first drag or tow with the main 

 gear begins, a small 10-foot- wide trawl called 

 the "try" net is towed from a stern davit to 

 locate profitable concentrations of fish, pref- 

 erably Atlantic croaker. During actual fishing 

 operations, the "try" net is fished with the 

 larger trawl to determine periodically the 

 species composition and to estimate the quan- 

 tity of fish being caught by the main gear. 

 Generally, the main trawl is towed at a speed 

 of 2 to 4 knots for 1 to 3 hours. The fleet fishes 

 both day and night, with the largest catches re- 

 portedly being made during darkness. 



To fulfill the needs of petfood and fish meal 

 processors, some shrimp fishermen retain the 

 industrial bottomfish they catch and, especially 

 in periods of lowbrown shrimp abundance, seek 

 fish during the day and shrimp at night. 



CATCH-PROCESSING METHODS 



soybean meal, and vitamin supplements. The 

 fish are then precooked, or preheatedby steam 

 before being packed into cans. The cans are 

 filled with petfood, sealed, and deposited in 

 metal baskets which are placed in large 

 retorts. The cans are cooked according to 

 predetermined temperatures and lengths of 

 time, both of which depend on the net weight 

 and initial temperature of the canned product. 

 Pressure is applied to ensure adequate steri- 

 lization within a reasonable length of time. 

 The cans are removed and cooled with water 

 before labeling, and are subsequently packed 

 in cases for shipment to national wholesale 

 and retail outlets. During 1959-63, the ex- 

 vessel price varied little from $35 a ton. 



In 1962 Mississippi led all states in the 

 processing of bottomfish for canned petfood, 

 accounting for 40 percent of the total U.S. 

 pack of such products. This production was 

 worth $14.9 million to Mississippi petfood 

 processors (U.S. Fish and Wildlife Service, 

 1963). In the same year the total U.S. pack 

 of pet food from fishery resources was more 

 than twice the salmon packs, and approximately 

 one-half the total pack of tuna for human 

 consumption. 



Reduction to Fish Meal 



Fish and shellfish are unloaded as described 

 for canning and conveyed immediately without 

 culling to a pressurized steam cooker equipped 

 with feed screw. After cooking, the material is 

 passed through a rotary dryer, and then ground 

 by a hammer mill. No oil or solubles are 

 extracted in the process. Some petfood proc- 

 essors supply fish meal producers with the 

 culled material resulting from their opera- 

 tions. Reduction plants pay $20 a ton for fish 

 reduced into meal. 



Fish meal, a valuable source of protein, is 

 used by the poultry industry as a supplement 

 in feed rations. It is usually mixed with dried 

 materials such as alfalfa meal, bran, or other 

 vegetables. Meal produced from Gulf bottom- 

 fish is now marketed in the Midwest. 



General 



Unloading the vessel is accomplished by 

 flooding the hold and pumping out the water 

 and the fish. The fish are delivered to a 

 conveyor belt where undesirable species and 

 debris, such as catfish, skates, crabs, shells, 

 etc., are removed together with fish and shell- 

 fish of edible size which are sold separately. 



Canning 



Whole fish are automatically weighed as 

 they move to the holding tanks filled with 

 brine. Next they are conveyed to the extruder 

 where a cutting worm minces the fish, after 

 which it is blended with assorted grain cereals, 



Freezing 



Preferred species for mink food include 

 members of the Sciaenidae, or drum family, 

 particularly the croaker, spot, sand seatrout, 

 silver seatrout, and southern kingfish. After 

 being washed and inspected, the fish are 

 quick-frozen in 50-pound, open-top, tray-type 

 fish boxes. Smaller sized boxes are frozenfor 

 use as crab bait. After freezing, the fish are 

 held in cold storage and then shipped to mink 

 ranches in the Midwest. Edible fish, crabs, and 

 shrimp are marketed separately. Petfood 

 processors can most of the culled fish. The 

 price to the fisherman for fish destined for 

 mink food and crab bait varies from $25 to 

 $30 a ton. 



