224 



Fishery Bulletin 88(2), 1990 



SE 1 • vRedondo 



Figure I 



Map of study sites within central Puget Sound. HRl Orchard Rocl<s. 

 HR2 Blal<ely Point, LRl Bainbridge Island, LR2 Blake Island, ARl 

 Blake Island, AR2 Boeing Creek, SEl Redondo, SE2 Port Madison. 



features required by recruits and different habitats 

 utilized has been only qualitatively described. It is likely 

 that habitat requirements of juveniles and adults differ, 

 as juveniles may require shelter from predation and 

 associate more closely with structural algal cover (Hob- 

 son 1972, Carr 1989). Ebelingand Laur (1985) experi- 

 mentally demonstrated that young surfperches sought 

 and were restricted to microhabitats that offered pro- 

 tection from predation. Carr (1983) suggested that kelp 

 may provide a refuge from predation for YOY rock- 

 fishes including three species found offshore as adults 

 {Sebn>;tes pnucispinus, S. pinniger, and S. minlatns), 

 that recruit to kelp beds in central California. Because 

 rockfish produce pelagically dispersed larvae and juve- 

 niles, local adult density is probably a poor predictor of 

 local recruitment and future adult density. Rather, the 

 limited availability of habitat with which young-of-the- 

 year and juvenile associate may be the critical determi- 

 nant of local recruitment. Determining the habitat re- 

 quirements of young rockfishes can be crucial to our 

 understanding of local rockfish dynamics. If algae, sea- 

 grasses, or other habitats provide YOY rockfishes 

 essential shelter from predation and increased access 

 to food, then recruitment could be suppressed by elimi- 

 nating such shelter or enlianced by adding more shelter. 

 Habitat affinities and requirements are an unknown 

 for YOY and juvenile rockfishes in Puget Sound. 



Copper, quillback, and brown rockfishes inhabit a 

 variety of habitats, yet the relative importance of each 

 habitat and seasonal uses are unknown. Additionally, 

 differences in habitat use by different life-history 

 stages are poorly understood. For example, do young 

 rockfishes settle on reefs and remain there for life, or 

 do the different age groups (young-of-the-year, sub- 

 adult, and adult) later move to separate or different 

 habitats? Understanding how and when the different 

 habitats are exploited provides needed information on 

 ecological requirements for habitat management; rec- 

 ognition and protection of important habitats are 

 necessary for effective fisheries management. Similar- 

 ly, further descriptions of the different habitats are 

 required to adequately assess the relative importance 

 of habitat features to the different life-history stages 

 of rockfishes. This study was designed to provide a 

 quantitative comparison of habitat use for copper, quill- 

 back, and brown rockfishes on four habitat types com- 

 mon in Puget Sound. 



Materials and methods 



Study sites 



For each of four habitat types— high-relief rocky reef, 

 low-relief rocky reef, high-relief artificial reef, and 

 sand/eelgrass— two representative replicate study sites 

 were selected. The two high-relief natural rocky reefs 

 were characterized by steep vertical relief to 5 m off 

 the bottom, surface canopies of the annual bull kelp 

 Nereocystis leutkeana May through November, and 

 understories of the perennial kelps Agarum fimbria- 

 fun) and Pferygophora ralifnniicn. The high-relief 

 rocky reefs range in depth from 12-20 m (gauged from 

 mean lower low water). The Orchard Rocks high-relief 

 rocky reef (HRl) is located on the southeastern side 

 of Bainbridge Island (Fig. 1) approximately 600 m off- 

 shore in the middle of Rich Passage, which is swept 

 by high currents up to 8.1 km/hour (4.5 knots) (U.S. 

 Dep. Commer. 1987, current tables). The entire Or- 

 chard Rocks reef covers approximately 5 ha. The 

 portion of reef used as the study site was about 12-18 

 m in depth and consisted of large boulders and rocky 

 ledges that rise up to 5 m off the bottom. The second 

 high-relief reef (HR2), Blakely Point, is a series of rock 

 outcroppings separated by sand and shell gravel. The 

 outcroppings are oriented perpendicularly offshore 

 from the north entrance of Port Blakely Harbor on the 

 eastern side of Bainbridge Island. Transects extended 

 across the reef from 12-18 m in depth; each transect 

 covered a similar depth range. Similar to HRl , the HR2 

 reef consists of steep walls and crevices with vertical 

 relief of 5 m, but has minimal current. 



