CONVERSION OF "WHOLE " AND "HEADLESS" WEIGHTS 

 IN COMMERCIAL GULF OF MEXICO SHRIMPS 



by 



Joseph H. Kutkuhn* 



Fishery Research Biologist 



Bureau of Commercial Fisheries 



U. S. Fish and Wildlife Service 



Galveston, Texas 



ABSTRACT 



Shrimp landing statistics provided by the Gulf coast fishing industry are now 

 published by the Bureau of Commercial Fisheries in terms of "headless" (or 

 "heads-off") weight units. Reliable factors are needed by statistical agents to con- 

 vert landings of "whole" (or "heads-on") shrimp to headless units, and by biologists 

 and others to reconvert the published statistics to whole-shrimp units. 



Measurements of whole and corresponding headless weights permitted estimation 

 of weight conversionfactorsfor five of the most common Gulf of Mexico Penaeidae. 

 Factor variation due to area, season, and sex proved negligible from a practical 

 standpoint. Differences between species were generally significant while all factors 

 departed significantly from the single factor heretofore employed for converting 

 weights in all species. Equations and factors for predicting whole or headless 

 weights are given for the brown, white, pink, and rock shrimps, and the seabob. 

 Weight conversion nomographs foi the brown, pink, and white shrimps are also 

 provided. 



Statistics describing the extensive com- shrimp stocks and the economic condition of 



mercial fisheries for Gulf of Mexico shrimps fisheries they support. 

 (Penaeidae) are routinely collected by the 



Branch of Statistics, Bureau of Commercial As a convenience to the fishing industry. 

 Fisheries. These are published monthly in commercial catch statistics are tabulated 

 tables entitled Gulf Coast Shrimp Catch by Area, according to weight in terms of "headless" 

 Depth, Variety, ami Size. They include corre- (or "heads-off") shrimp. Biologists, however, 

 spending information onnumber of fishing trips find such notation somewhat unwieldy. Think- 

 by commercial trawlers, the total amount of ing of what shrimp harvests represent in 

 time spent fishing, and the dockside value of terms of the proportion of the total shrimp 

 total landings. Such data have wide application biomass removed, they must, therefore, re- 

 in studies dealing with the conservation of sort to devices which enable them to convert 

 headless back to "whole" (or "heads-on") 



iThe author wishes to acknowledge the assistance of units. A single conversion factor which has 



K. N. Baxter who painstakingly made most of the pre- served this function for many years within 



liminary computations. the shrimp industry itself, was incorporated 



