Comparison of Fishes Tai<en By 

 a Sportfishing Party Vessei Around 

 Oii Piatforms and Adjacent iNJatural 

 Reefs l\iear Santa Barbara, California 



Milton S. Love 



Marine Science Institute, University of California 

 Santa Barbara, California 93106 



William Westphal 



VANTUNA Research Group, Occidental College 

 1600 Campus Road, Los Angeles, California 90041 



Since 1958, 29 oil platforms have 

 been sited in the southern Califor- 

 nia Bight of which 28 still remain in 

 place. However, with the exception 

 of a few papers (Carlisle et al. 1964, 

 Bascom et al. 1976, Allen and Moore 

 1976), little is known of the fish pop- 

 ulations surrounding these struc- 

 tures, particularly those sited in 

 water deeper than 30 m. Moreover, 

 except for a brief reference in Car- 

 lisle et al., no scientific papers have 

 been published on the use of south- 

 ern California platforms by sport 

 fishermen. 



In the course of research on the 

 Santa Barbara, California, party 

 vessel sport fishery, it was noted 

 that the platforms off Santa Bar- 

 bara supported considerable sport- 

 fishing activity. Those platforms, 

 located to the southeast of Santa 

 Barbara in depths of 48-62 m (Fig. 

 1), were particularly important and 

 were fished intensively for various 

 rockfishes (genus Sebastes). When 

 fishing a platform, the vessel pulled 

 up to within 5-10 m of a platform 

 and drifts along one side, with the 

 vessel operator using intermittent 

 power to keep it near the structure. 

 Most of the desirable species, par- 

 ticularly rockfishes, remained close 

 to the platforms, rarely venturing 

 more than perhaps 20 m from the 

 structure. The party vessels also 

 spent considerable time fishing over 



nearby natural reefs. In this survey, 

 it was noted that there appeared to 

 be differences in species catch com- 

 position and fish size between oil 

 platforms and these natural reefs. 

 Increased offshore oil drilling off 

 California has raised interest in the 

 role platforms play in marine sys- 

 tems. Questions have been raised 

 regarding what fish live around 

 platforms, how these structures in- 

 fluence populations over surround- 

 ing reefs, and whether the platforms 

 act as fish enhancers (promoting re- 

 cruitment) or only as aggregators. 

 These questions are particularly 

 relevant when the platforms are to 

 be decommissioned and the possibil- 

 ity of allowing them to remain as ar- 

 tificial reefs is raised. This paper 

 describes the results of our study on 

 the fish populations around oil plat- 

 forms and nearby natural reefs off 

 Santa Barbara. 



Methods 



The study was conducted aboard 

 the 16-m sportfishing vessel Hornet, 

 berthed in Santa Barbara. During 

 the course of this study the Hornet 

 operated 6 days per week; 3 three- 

 quarter day trips (7 am-3 pm) and 

 3 half-day trips (7 am-noon, 12:30 

 pm-5:30 pm). The Hornet carried a 

 maximum of 40 passengers. Fish 

 taken aboard the Hornet were sam- 



pled weekly from April 1975 to April 

 1978. All fish landed were mea- 

 sured, even those returned alive to 

 the water as undesirable or in com- 

 pliance with bag or size-limit regu- 

 lations. Each was placed on a plastic 

 measuring sheet and the length 

 marked. Total length was recorded 

 to the nearest mm for all fish except 

 members of the jack (Carangidae) 

 and mackerel (Scombridae) families, 

 for which fork length was taken to 

 the nearest mm. Also recorded 

 were the number of anglers aboard 

 the vessel, hours fished, and the 

 location and depth of fishing effort. 

 Of particular importance was the 

 total time the Hornet fished around 

 or over all the fishing sites. This 

 information was obtained through 

 biweekly interviews with Hornet 

 operators throughout the 3-year 

 survey. 



Data from this study could not 

 give an unbiased estimate of species 

 composition. Most angling involved 

 fishing with live bait (primarily north- 

 ern anchovies Engraulis niordaj') or 

 with lures simulating fishes or small 

 crustaceans at the three sites used 

 in this study. Thus, because the 

 sample was biased toward relative- 

 ly large-mouthed, piscivorous spe- 

 cies, we determined distributional 

 patterns of whatever species were 

 taken by these methods, rather than 

 describing entire fish communities. 



For this report we have divided 

 the study sites into three locations 

 (Fig. 1): 4 Mile Reef, 6 Mile Reef, 

 and five platforms. Twenty-one 

 other reefs and kelp beds located 

 well away from this area are not in- 

 cluded. The 4 Mile Reef is an aggre- 

 gation of 1-7 m high pinnacles in 

 40-50 m of water. The oil platforms 

 fished included Platforms A, B, Hill- 

 house, Houchin, and Hogan. These 

 are steel structures 25-45 m on the 

 side, situated in water depths be- 

 tween 54 and 62 m. The 6 Mile Reef 



Manuscript accepted 22 March 1990. 

 Fishery Bulletin. U.S. 88:.599-605. 



599 



