Abstract.- A logbook program 

 was initiated to determine the rela- 

 tive abundance of selected fish spe- 

 cies around oil and gas platforms off 

 the Louisiana coast. Logbooks were 

 maintained by 55 anglers and 10 

 charterboat operators from March 

 1987 to March 1988. A total of 36,839 

 fish were caught representing over 

 46 different species. 



Principal component analysis (PCA) 

 grouped the seventeen most abun- 

 dant species into reef fish, pelagic fish, 

 bluefish-red drum, Atlantic croaker- 

 silver/sand seatrout, and cobia-shark- 

 blue runner associations. Multiple 

 regression analyses were used to 

 compare PCA groupings to physical 

 platform, temporal, geological, and 

 angler characteristic variables and 

 their interactions. Reef fish, Atlan- 

 tic croaker, and silver/sand seatrout 

 abundances were highest near large, 

 structurally complex platforms in 

 relatively deep water. High spotted 

 seatrout abundances were correlated 

 with small, unmanned oil and gas 

 platforms in shallow water. Pelagic 

 fish, bluefish, red drum, cobia, and 

 shark abundances were not related 

 to the physical parameters of the 

 platforms. 



Factors Affecting the Abundance 

 of Selected Fishes near Oil and Gas 

 Platforms in the Northern 

 Gulf of Mexico* 



David R. Stanley 

 Charles A. Wilson 



Coastal Fisheries Institute. Center for Wetland Resources 

 Louisiana State University, Baton Rouge, Louisiana 70803 



Louisiana has long been recognized as 

 having abundant fisheries resources 

 as evidenced by the large number of 

 recreational and commercial fishing 

 opportunities. This is particularly 

 true of its offshore waters which 

 Moore et al. (1970) characterized as 

 having high densities of demersal 

 fishes and Gunter (1963) postulated 

 were the most productive waters on 

 earth based on fishery harvests. 



Saltwater sportfishing off Loui- 

 siana is concentrated around oil and 

 gas platforms with an estimated 37% 

 of all saltwater angling trips (Witzig 

 1986) and over 70% of all recrea- 

 tional angling trips in the Exclusive 

 Economic Zone (more than 3 miles 

 from shore) occurring around plat- 

 forms (Reggio 1987). All of the 3700 

 oil and gas platforms off the coast of 

 Louisiana are thought to act as ar- 

 tificial reefs and have contributed to 

 Louisiana's designation as a fishing 

 "paradise." 



Gallaway (1984) estimated that oil 

 and gas platforms constitute 28% of 

 the known hard substrate off Loui- 

 siana and Texas. This is of particular 

 importance off the Louisiana coast 

 since the nearest natural hard bottom 

 habitat is approximately 92 km from 

 shore (Sonnier et al. 1976); therefore, 

 oil and gas platforms provide the only 

 source of hard-bottom habitat close 

 to shore. The continued growth of the 



Manuscript accepted 28 September 1990. 

 Fishery Bulletin, U.S. 89:149-159 (1991). 



* Contribution No. LSU-CFI-89-04, Louisiana 

 State University, Coastal Fisheries Institute. 



offshore oil and gas industry in Loui- 

 siana has provided habitat expansion 

 for organisms dependent on hard 

 substrate (Sonnier et al. 1976, Galla- 

 way et al. 1981a, Continental Shelf 

 Associates 1982). 



Oil and gas platforms are unique as 

 artificial reefs because they extend 

 throughout the entire water column. 

 Their effects are not confined to ben- 

 thic and demersal fishes; pelagic 

 fishes also benefit (Gallaway et al. 

 1981a, Continental Shelf Associates 

 1982). For example, pelagic baitfish 

 (i.e., round scad Decaptarus puncta- 

 tus, Spanish sardine Sardinella an- 

 chovia, and scaled sardine Harengula 

 pensacolae) often maintain a position 

 from nearsurface to mid-depth with- 

 in or upcurrent from oil and gas 

 structures feeding on plankton and 

 zooplankton, while large predatory 

 pelagic fishes (i.e., king mackerel and 

 blue runner) are reported to swim 

 from the surface to mid-depth around 

 structures, rarely venturing within 

 the structure (Hastings et al. 1976, 

 Gallaway et al. 1981a). 



Although oil and gas structures, 

 like most artificial reefs, are con- 

 sidered to increase production and 

 attract fish, there are few accepted 

 techniques to assess their effective- 

 ness. A method of testing the success 

 or importance of an artificial reef is 

 to track the number of fish caught 

 over time. Due to the complex con- 

 struction of oil and gas platforms, 

 sampling with traditional fisheries 



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