174 



Fishery Bulletin 105(2) 



Patch use 

 A S. hopkinsi 



Patch selectivity Microhabitat 



use 



100% 



50% 



B S. flavidus 



Cs 



pauaspinis 



1° Substratum 



Rock 

 y/.^ Boulders 

 r~1 Cobbles 



Sand 



Mud 



«3 



100% 



50% 



— I r— 



R B C S M -60-40-20 20 40 



Patch type Selectivity index 



Figure 5 



Intermediate and fine-scale habitat use by rock and boulder associates: 

 (A) squarespot rockfish (Sesbastes hopkinsi) (B) yellowtail rockfish (S. flavi- 

 dus), and (C) bocaccio (S. paucispinis). At the intermediate-scale, patch types 

 (i.e.. R=rock, B = boulders, C = cobbles, S = sand, and M = mud) are represented by 

 primary (tick labels and shading) and secondary (sequence of ticks within each 

 primary category R, B, C, S, and M) substratum categories and are ordered 

 from hard ( left = rock-rock [RR], rock-boulder [RE], rock-cobble [RC]...) to soft 

 (right = ... mud-cobble [MC], mud-sand [MS], mud-mud [MM]) substratum 

 types. "Patch use" depicts the mean number offish plus standard errors (SE) 

 found in each patch type. "Patch selectivity" depicts the relative patch use 

 by fish, standardized by patch availability: graphs indicate positive (right- 

 hand side of the plot) or negative (left-hand side of the plot) associations with 

 patch types (ordered from hard (top = RR, KB, RC.) to soft (bottom= ... MC, 

 MS, MM) substratum types) and the relative strengths of these associations. 

 Fine-scale microhabitat use is represented by the proportion of fish found on 

 or above a particular substratum type. 



sal fish species dominated by small rockfish species. 

 Although hard stratum was the least common of the 

 three strata (Anderson et al., 2005), it supported the 

 highest overall densities of fish, including more com- 

 mercial species, than either mixed or soft strata. High 

 fish densities, a dominance of small rockfish species, 

 and the presence of large commercial species over high- 

 relief outcrops have been recorded in other submersible 



surveys in California (Yoklavich et al., 2000, 2002), 

 Oregon (Stein et al., 1992), Washington (Jagielo et al., 

 2003), British Columbia (e.g., Murie et al., 1994), and 

 Alaska (O'Connell and Carlile, 1993). For example, 

 Yoklavich et al. (2000) found high numbers of large 

 commercially important rockfish species (e.g., S. pau- 

 cispinis, S. ruberrimus, S. levis [cowcod]) associated 

 with discrete rocky outcrops in a submarine canyon 



