237 



Abstract. -This paper tested the 

 null hypothesis that the statistical re- 

 lationship between monthly sea turtle 

 (species combined I stranding rates 

 (strandings per 100 km of accessible 

 shoreline) and monthly shrimp fishing 

 intensities (days fished per 100 km 2 ) in 

 the northwestern Gulf of Mexico was 

 the same in 1990-93 as in 1986-89. The 

 expectation was that regulations re- 

 quiring use of turtle excluder devices 

 (TED's) in shrimp trawls during 1990- 

 93 would reduce the incidental catch of 

 sea turtles and thereby diminish or 

 eliminate the statistical relationship 

 between stranding rates and fishing 

 intensities. Significant positive corre- 

 lations were detected between the log- 

 transformed stranding rates and fish- 

 ing intensities for shrimping landward 

 of the 20-fathom (36.6-ml contour in 

 1990-93. The null hypothesis was not 

 rejected; therefore TED regulations did 

 not result in diminishing or eliminat- 

 ing the statistical relationship between 

 sea turtle stranding rates and shrimp 

 fishing intensities in the northwestern 

 Gulf. Various hypotheses were sug- 

 gested as possible explanations. 



Relationship between sea turtle 

 stranding rates and shrimp fishing 

 intensities in the northwestern 

 Gulf of Mexico: 1986-1989 versus 

 1990-1993 



Charles W. Caillouet Jr. 



Galveston Laboratory. Southeast Fisheries Science Center 

 National Marine Fisheries Service, NOAA 

 4700 Ave U, Galveston. Texas 77551-5997 



Donna J. Shaver 



Padre Island National Seashore, National Biological Service 



United States Department of the Interior 



9405 South Padre Island Drive. Corpus Christi, Texas 78418 



Wendy G. Teas 



Miami Laboratory, Southeast Fisheries Science Center 



National Marine Fisheries Service, NOAA 



75 Virginia Beach Drive, Miami, Florida 33149 



James M. Nance 

 Dickie B. Revera 

 Andrea C. Cannon 



Galveston Laboratory, Southeast Fisheries Science Center 



National Marine Fisheries Service, NOAA 



4700 Avenue U, Galveston, Texas 77551-5997 



Manuscript accepted 4 October 1995. 

 Fishery Bulletin 94(21:237-249 (1996). 



Endangered Species Act amend- 

 ments of 1988 mandated an inde- 

 pendent review of scientific and 

 technical information pertaining to 

 conservation of sea turtles and the 

 causes and significance of turtle 

 mortality, including that caused by 

 commercial trawling (National Re- 

 search Council, 1990). Incidental 

 capture of sea turtles in shrimp 

 trawls was identified as the most 

 important human-associated source 

 of mortality in juvenile, subadult, 

 and breeding sea turtles in coastal 

 waters. It was concluded that 

 shrimping could be compatible with 

 sea turtle conservation if adequately 

 controlled, especially through man- 



datory use of turtle excluder devices 

 (TED's) at most places and times of 

 year. Federal regulations requiring 

 use of TED's by offshore (seaward 

 of the COLREG's demarcation line 

 [the boundary used by the U.S. 

 Coast Guard to distinguish inshore 

 from offshore waters]) shrimp 

 trawlers longer than 25 ft were pub- 

 lished in 1987 (Federal Register, 

 vol. 52, no. 124, p. 24247-24262, 28 

 June 1987). These regulations did 

 not require TED's in "try nets" 

 (small trawls towed and retrieved 

 intermittently during shrimping op- 

 erations to sample abundance of 

 shrimp), and TED's were used only 

 sporadically in the northwestern 



