Love and York Relationships between fish assemblages and bottom horizontal beams of oil platforms 



547 



T 1 r 



1W6 1948 20(11) 21)02 



Hidalgo 



(I 1 



" 1 o 



Harvest 



1996 1998 2000 2002 

 Year 



1996 1998 2000 

 Year 



Grace 



2002 



1996 1998 2000 2002 

 Year 



1996 1998 2000 2002 



1996 1998 2000 2002 

 Year 



Figure 3 



Mean size of gap between beam and sea floor on a scale of 0-4 at each platform, by year. Platforms 

 are ordered from northernmost to southernmost. = beam was completely covered and not visible; 

 l = only the top of the beam was visible; 2=the beam was partially exposed — the bottom of the 

 beam remaining in contact with the sea floor; 3 = the beam was completely exposed and formed an 

 open crevice less than 0.5 m high; 4 = the beam was completely exposed and formed an open crevice 

 more than 0.5 m high. 



Many species appeared to avoid certain beam con- 

 figurations; that is, they were found in numbers far 

 less than expected by chance. For instance, blue, flag, 

 greenblotched, halfbanded, pinkrose, squarespot, and 

 vermilion rockfishes, and bocaccio were all significantly 

 less abundant in areas with either no horizontal beam 

 or where that structure was not well exposed (exposures 

 and 1). On the other hand, a variety of taxa, such as 

 greenspotted rockfish, YOY lingcod, painted greenling, 

 and sanddabs were relatively uncommon where there 

 was a large gap between the bottom of the beam and 

 the sea floor (exposure 4). Widow rockfish (S. entome- 

 las), in our study comprising almost entirely YOY indi- 

 viduals, tended to avoid areas where the beam was ex- 



posed. Calico and copper rockfish, along with sharpnose 

 seaperch, tended to avoid both sea floors with no beam 

 present and sea floors where the beam structure was 

 completely exposed (and the gap was significant). 



Discussion 



Species generally occupied those parts of the beams 

 that appear to be most similar to their natural habitats 

 (Feder et al., 1974; Yoklavich et al., 2000, 2002; Love 

 et al., 2002). In our system, there was a suite of spe- 

 cies that were less abundant or nearly absent when the 

 beam was exposed. These species included blackeye goby 



