Abstract.— Seasonal habitat use 

 of young-of-the-year, subadult, and 

 adult rockfishes (Sebastes caurinus, 

 S. maliger, andS. auriculatug) were 

 compared for four habitat types: high- 

 relief rocky reefs, low-relief rocky 

 reefs, high-relief artificial reefs, and 

 sand/eelgrass. Diving surveys con- 

 ducted December 1986 through Octo- 

 ber 1988 on two representative sites 

 of each habitat ty]3e revealed signifi- 

 cant seasonal changes in rockfish 

 densities and habitat use. Young-of- 

 the-year (YOY) recruitment varied 

 between the two survey years: YOY 

 were observed on all haliitat types in 

 the summer and fall of 1987, where- 

 as they were observed at only one 

 site (artificial reef) in a similar time 

 period of 1988. High-relief rocky 

 reefs had the most consistent den- 

 sities of the three rockfish species, 

 mostly fish > 200 mm TL. Adult and 

 YOY copper, quillback, and brown 

 rockfishes were observed on the low- 

 relief rocky reefs primarily in the 

 summer months coincident with 

 summer algal growth; when the kelp 

 died back in the fall, most rockfishes 

 left these reefs. The highest densities 

 of rockfishes, primarily 80-200 mm 

 quillback rockfish (up "to 420/90-nr'' 

 transect) and large copper rockfish 

 (up to 56.3/transect), were observed 

 on the artificial reefs. Here, also, 

 density fluctuations were dramatic; 

 copper rockfish densities peaked in 

 fall and winter and declined (to 

 0/transect) during the summer, and 

 quillback rockfish densities also 

 seasonally fluctuated. Sand/eelgrass 

 areas were the least-utilized habitat 

 type; only during July and August 

 wei , young-of-the-year and low den- 

 sities of adult copper and brown 

 rockfishes observed on one sand/eel- 

 grass site. Although all four habitats 

 were used, natural reefs may repre- 

 sent source habitats that are used by 

 and maintain rockfishes on less pro- 

 ductive sink (artificial reef) habitats. 

 Thus, the recent use of artificial reefs 

 as mitigation for the loss of natural 

 reefs could have negative impacts on 

 rockfish populations. 



A Comparative Study of Habitat Use 

 by Young-of-tFie-year, Subadult, and 

 Adult Rockfishes on Four Habitat 

 Types in Central Puget Sound* 



Kathleen R. Matthews 



Washington Department of Fisheries, 7600 Sand Point Way NE 

 Seattle. Washington 981 15-0070 



School of Fisheries WH-10, University of \A a^ytgn^JetogtCoWashington 98195 

 Present address: Pacific Biological Station, I )epartment ^(gif^pes and Oceans 

 Nanaimo, British Columbia, Canada V9li 5K6 



SEP 12 mo 



Rockfishes are a successful group of 

 marine fishes represented by about 

 100 species (Barsukov 1981), which 

 occupy a variety of habitats ranging 

 from the intertidal to the edge of the 

 continental shelf (Lea 1983). This 

 speciose and interesting group dis- 

 plays extremes in habitat use and 

 movement patterns: Some species 

 live deep (500 m) over sandy bottoms, 

 some make long-distance movements 

 (to 550 km), whereas others are pe- 

 rennially sedentary on shallow (<10 

 m) rocky reefs (Larson 1980, Love 

 1980, Culver 1987). One group of 

 rockfishes is solitary and demersal 

 and inhabits shallow reefs (Ebeling et 

 al. 1980a); in Puget Sound this group 

 of rockfishes is represented by cop- 

 per Sebastes caurinus, quillback S. 

 maliger, and brown S. auriculatus. 

 Copper, quillback, and brown rock- 

 fishes are common shallow-water 

 benthic species found along the Pacif- 

 ic coast of North America (Hart 

 1973). They are morphologically sim- 

 ilar to one another but differ in color- 

 ation. The three species have overlap- 

 ping geographic ranges; copper and 

 brown rockfishes are found from 

 Baja California to Alaska, whereas 

 quillback are found from central Cali- 

 fornia to Alaska (Hart 1973). All 

 three species occur in Puget Sound, 



Manuscript accepted 1 December 1989. 

 Fishery Bulletin, U.S. 88:223-239. 



'Contribution No, 804 of the School of Fish- 

 eries, University of Washington. 



Washington, and comprise approx- 

 imlflfSp^i^J-tePitheipecBeationkl bot- 

 romllah thatch in central Puget Sound 

 (Palsson 1988). These species inhabit 

 a variety of habitat types although 

 highest densities are reported on ar- 

 tificial reefs, natural rocky reefs, and 

 rock piles in water less than 30 m 

 (Moulton 1977, Buckley and Hueckel 

 1985). Usually these species are 

 found directly on the bottom closely 

 associated with rock, artificial sub- 

 strate, or vegetation (Patten 1973, 

 Moulton 1977). Although copper and 

 quillback rockfishes are common 

 throughout Puget Sound, the San 

 Juan Islands, and Strait of Juan de 

 Fuca, brown rockfish are more limited 

 in distribution and are found only 

 within central and south Puget 

 Sound (Moulton 1977). 



Rockfishes are viviparous (Boehlert 

 and Yoklavich 1984), undergoing in- 

 ternal fertilization and subsequently 

 releasing pelagic larvae. Little is 

 known regarding the length of time 

 that young rockfishes are pelagic 

 before they recruit to adult or tran- 

 sitional habitat. Parturition reported- 

 ly occurs April through June for the 

 three species in Puget Soimd (DeLacy 

 et al. 1964, Washington et al. 1979, 

 Dygert 1986). An influx of postlarval 

 or yoimg-of-the-year (YOY) rockfishes 

 into isolated areas in Puget Sound 

 has been observed (Patten 1973, 

 Gowan 1983); assessment of habitat 



223 



