232 



Fishery Bulletin 88(2). 1990 



Figure 7 



Mean percent of algal or eelgrass cover (O) compared with mean 

 number ( • . combination of 80-200 mm and >200 mm) of copper, 

 quillback. and brown rockfishes on the four habitat types in central 

 Puget Sound for winter 1 (wtrl), spring (sp), summer 1 (sul), fall 

 (fall), winter 2 (wtr2), and summer 2 (su2). Seasons are described 

 in Methods section. Density increase in high-relief rockfish (*) follow- 

 ed the influx of young-of-the-year rockfish. Percent eelgrass cover 

 was relative to maximum height (1.5 m) of eelgrass which occurred 

 during the summer. 



Small quillback rockfish were primarily observed on 

 the artificial reefs all seasons and were infrequently 

 observed on all other habitats (Figs. 3-5). Large 

 quillback rockfish were most common on the high-relief 

 rocky reefs and artificial reefs. Large quillback rockfish 

 were rarely observed on the low-relief reefs. Neither 

 small nor large quillback rockfish were observed on the 

 sand/eelgrass. 



Small brown rockfish were observed only on the high- 

 relief reefs and on one artificial reef (Figs. 3, 5). Large 

 brown rockfish were seen all seasons on the high-relief 

 reefs although highest numbers were observed at HRI 

 (Orchard Rocks) (Fig. 3). They were also seen during 

 the summer on low-relief reefs and sand/eelgrass (Figs. 

 4,6). 



YOY rockfish were observed on all four habitat types 

 (Figs. 3-6). On the high-relief low-relief reefs, and the 

 sand/eelgrass, they were first seen in the summer and 

 fall of 1987. YOY were observed year-round on Boe- 

 ing Creek artificial reef. YOY were not observed in the 

 summer or October of 1988 except at AR2. 



Macrophyte cover varied seasonally; the densest 

 cover was observed June through October on all reefs 

 (Fig. 7). The high-relief reefs had dense canopies of 

 Nereocystis leufkeuna and subcanopies o( Pterygophora 

 califomica, and Agaru m that during the summer cov- 

 ered 50-100% of the bottom along the transect lines. 

 The two low-relief reefs had 100'7o bullkelp and under- 

 story coverage June through October. The annual 

 bullkelp was gone November through May and only the 

 stipes of the understory perennial kelps remained; the 

 blades of the understory kelps had eroded or were 

 otherwise lost. There was no Nercocystis on the two 

 artificial reefs; however, understory kelps covered ap- 

 pro.ximately 0-20% of the transects, with peak growth 

 in the summer. Sand/eelgrass transects were always 

 covered with the perennial eelgrass throughout the 

 year, although the height varied seasonally. The height 

 peaked during the summer at apjjroximately 1 .5 m, and 

 during the winter many of the blades were gone and 

 the eelgrass was prostrate with little (0-0.5 m) vertical 

 structure. 



Monthly mean temperatures were highest August 

 through October (up to 13°C) and lowest (down to 

 7.1°C) in January and Februai-y (Fig. 8). There was 

 little qualitative difference in temperatures between 

 the different reefs, although de|)th ranges were 5-20 

 m along transect lines. 



on the high-relief reefs all seasons. In contrast, their 

 densities fluctuated seasonally on other habitats; they 

 were only observed during the summer and fall on the 

 low-relief reefs during all seasons, although in lower 

 densities during the summer on the artificial reefs, and 

 only during the summer on the sand/eelgrass. 



Discussion 



Seasonal habitat use 



Habitats that underwent seasonal vegetation and sub- 

 sequent structural changes had the most dramatic 



