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Fishery Bulletin 88(4), 1990 



merged surface area 8000-14000 m^) in 70-100 m of 

 water. 



Charterboat operators had larger vessels than pri- 

 vate vessel anglers due to the business nature of their 

 fishing and larger party size. Using larger vessels, they 

 were able to fish in deeper waters farther offshore than 

 private vessel anglers for both offshore bottom fishing 

 and trolling. Charterboat operators also fished in 

 deeper water while fishing nearshore; however, this is 

 probably not a direct function of boat size, but of past 

 success and preference. 



A high diversity of fish exist around the oil and gas 

 platforms as evidenced by the reported catch of over 

 46 different species. The types of fish caught ranged 

 from relatively common and highly desirable species 

 such as spotted seatrout, red snapper, tarpon, blue 

 marlin, king mackerel, and yellowfin tuna to rather 

 rare fishes such as hake, bearded brotula, and squirrel 

 fish. However, catches by angling are selective and 

 biased towards larger, carnivorous individuals due to 

 the gear utilized (Grimes et al. 1982). Therefore, species 

 not susceptible to angling were not represented. 



Comparison of CPUE estimates between this study 

 and logbook programs from other parts of North 

 America revealed CPUE estimates were generally 

 much higher off the Louisiana coast than from other 

 studies. CPUE estimates from Sztramko (1986) for 

 Lake Erie, Ontario, private vessel anglers and charter- 

 boat operators were approximately 0.15 for the target 

 species of smallmouth bass Micropterus dolomieui and 

 coho salmon Oncorhynchus kisufch. while Casselman 

 et al. (1985) reported CPUE estimates of 0.30 for 

 northern pike Esox lucitis by sportfishing guides on the 

 St. Lawrence River, Ontario. Only CPUE estimates 

 from logbooks maintained by commercial fishermen 

 trolling for Pacific salmon (Jordan and Carter 1987) 

 were as high as CPUE estimates from this study. 



Catch rates in this study, presented as number offish 

 per angler per hour, are not directly or statistically 

 comparable with those reported by Brusher et al. 

 (1984), Brusher and Palko (1985, 1987), and other 

 earlier studies from the Gulf of Mexico because they 

 used number of fish caught per boat per hour (CPH) 

 as a unit of relative abundance. Since the number of 

 anglers on a sportfishing vessel can be highly variable, 

 catch per vessel hour may also be highly variable. By 

 calculating the number of fish caught per angler hour, 

 catch is broken down to its most standard unit, assum- 

 ing the skill level of anglers is equal, thus eliminating 

 this source of variance. 



CPH rates by bottom fishing and trolling from this 

 and other studies off the Louisiana coast were much 

 higher than in other regions of the Gulf of Mexico and 

 the southeast Atlantic. However, when mean number 

 of anglers was multiplied by CPUE for charterboat 



operators from this study and compared with Brusher 

 et al. (1984) and Brusher and Palko (1985, 1987), 

 similar catch rates were noted for the Louisiana 

 coast. 



Comparison of the catch rates and composition of 

 trolling from this study and others revealed few dif- 

 ferences. Brusher et al. (1984) and Brusher and Palko 

 (1987) found trolling catches of charterboat operators 

 off Louisiana were primarily comprised of dolphin, 

 Spanish mackerel, red drum, little tunny, king mack- 

 erel, and blue runner. We found little change in this 

 trend with the exception of red drum. Based on our 

 results, red drum do not appear to be associated with 

 oil and gas structures. Other logbook programs off the 

 Louisiana coast did not distinguish between areas 

 fished (near oil and gas platforms or otherwise) (Dugas 

 et al. 1979), and consequently red drum catches may 

 have been high in areas not covered by our logbook 

 program, which may explain their absence from our 

 results. 



When catch rates and composition of our study were 

 compared with those of other logbook programs and 

 a creel census for offshore bottom fishing, major dif- 

 ferences in catch composition were noted. Past studies 

 conducted during 1978 by Dugas et al. (1979), in 1982 

 by Brusher et al. (1984), and during 1984-85 by 

 Brusher and Palko (1987), found that Atlantic croaker 

 and silver/sand seatrout dominated catches of charter- 

 boat operators while we found that red snapper catch 

 rates were often an order of magnitude greater than 

 for all other species caught. Since many of the same 

 charterboat operators were utilized by both ours and 

 earlier studies, these differences may provide evidence 

 that there has been a shift in the species abundance 

 near oil and gas platforms in offshore waters with little 

 or no change in the composition of the structure (i.e., 

 the number of oil and gas platforms) off the Louisiana 

 coast. Comparison of our nearshore catches around oil 

 and gas platforms with those of creel surveys of Texas 

 bay charterboat operators from 1978 to 1979 (McEach- 

 ron and Matlock 1983) showed that spotted seatrout 

 dominated the catch rate and composition of nearshore 

 Texas fishermen as they did in Louisiana, although 

 spotted seatrout catches off Louisiana were much 

 higher than for Texas sport fishermen. 



Overall CPUE's of all species between private vessel 

 anglers and charterboat operators were very similar; 

 however, charterboat operator CPUE was generally 

 less variable. Few trends were identified from com- 

 parisons between years or user groups. Only for 

 spotted seatrout was charterboat operator CPUE con- 

 sistently higher than private vessel angler CPUE; 

 otherwise few differences were noted between the two 

 groups. The similarity of the CPUE's indicated that the 

 anglers participating in the logbook program were avid. 



