Matthews Habitat use by rockfishes in central Puget Sound 



235 



reefs; Richards (1987) noted qiiOlback rockfish densities 

 were correlated with rehef, and highest densities were 

 found on complex habitats. The lack of large quillback 

 rockfish on low-relief and sand/eelgrass areas is pre- 

 sumably due to their preference for high relief and com- 

 plex habitats. 



Brown rockfish displayed the most restricted and 

 perplexing distribution, primarily being found on Or- 

 chard Rocks high-relief reef and the inshore low-relief 

 reefs during the summer, and rarely observed on arti- 

 ficial reefs or sand/eelgrass. Brown rockfish have been 

 observed on artificial reefs in south Puget Sound (Greg 

 Hueckel, Wash. Dep. Fish., Olympia, WA 98504, pers. 

 commun., summer 1988) and it is unclear why they did 

 not inhabit the artificial reefs in central Puget Sound. 

 Additionally, brown rockfish are relatively uncommon 

 on rocky reefs in northern Puget Sound and the San 

 Juan Islands (Moulton 1977). In California, brown rock- 

 fish are primarily found on sandy, low-relief areas (Mat- 

 thews 1985); their different habitat use in Puget Sound 

 could be due to local hybridization with congeners (L. 

 Seeb, Southern 111. Univ., Carbondale, IL 62901, pers. 

 commun., summer 1987). 



YOY were distributed differentially among all habitat 

 types. The sand/eelgrass was a temporary YOY habi- 

 tat, as YOY were observed in July and never again 

 seen. Either the YOY left the area or died. Similarly, 

 YOY were observed on the low-relief reefs but subse- 

 quently emigi'ated or suffered high mortality; their con- 

 tribution to recruitment on other reefs is unknown. On 

 the other hand, YOY were first observed on the tran- 

 sects on HR2 in August, although they were previous- 

 ly seen in July off the reef on adjacent (within 25 m) 

 sand/Agarum. The numbers of YOY increased over the 

 next few months, peaked in November, and initial set- 

 tlement was followed by an increase in the 80-200 mm 

 copper, quillback, and brown rockfishes, presumably, 

 the result of recruits staying and growing into the 

 larger size category. A similar pattern of YOY influx 

 was followed by an increase in the 80-200 mm group 

 on AR2, although two periods of YOY settlement were 

 observed, spring and fall. 



Parturition of these rockfishes reportedly occurs 

 April through June, as most female rockfishes captured 

 April and May near Bainbridge Island had embryos and 

 ovaries that were in the transitional stage during the 

 summer (DeLacy et al. 1964, Washington et al. 1979, 

 Dygert 1986). On SCUBA surveys, I saw pregnant 

 rockfish late April through late June. Therefore, the 

 YOY that were observed during the summer and fall 

 of 1987 on HR2 presumably were released between 

 April and July, spent some unknown amount of time 

 in pelagic regions or on some other habitat, and then 

 settled to a demersal existence in July and August. Ex- 

 aminations of the otolith microstructure of eight 45-60 



mm TL rockfish (M. Yoklavich, Natl. Mar. Fish. Serv., 

 Seattle, WA 98115, pers. commun., fall 1987) that I 

 collected 29 August 1987 on HR2 revealed approx- 

 imately 120-160 growth rings. Similar growth rings 

 have been shown to be deposited daily in black rockfish 

 (Yoklavich and Boehlert 1987). If the rings examined 

 on my rockfish were also daily, it would confirm that 

 parturition occurred around April. Additionally, these 

 fish appeared to grow quite quickly. When first ob- 

 served in July and August they were approximately 

 45-60 mm TL and by November were 90-100 mm TL 

 (fish wei'e captured to verify these measurements). This 

 scenario describes the parturition on the natural reefs 

 which was quite different from the YOY settlement on 

 Boeing Creek artificial reef. YOY were assumed to be 

 primarily quillback rockfish, as YOY settlement was 

 followed by an increase of 80-200 mm quillback 

 rockfish. They were observed in the spring and the fall 

 on Boeing Creek artificial reef. It is unclear when the 

 spring recruits were released or if there are possibly 

 two reproductive periods for quillback rockfish in 

 Washington as noted for some California rockfishes 

 (Wyllie Echeverria 1987). Brown rockfish sampled 

 from one location in north-central California had two 

 distinct seasons of larval extrusion, December and 

 June, and Wyllie Echeverria (1987) concluded that 

 rockfishes have a flexible reproduction system that 

 enables individuals to adaptively respond to environ- 

 mental factors. On the other hand, in my study young 

 quillback rockfish could arrive from another source- 

 northern Puget Sound, Strait of Juan de Fuca, or even 

 the outer coast of Washington— causing the second 

 pulse. 



On Vancouver Island, Haldorson and Richards (1987) 

 noted an infliLX of YOY (< 50 mm) copper rockfish dur- 

 ing August and September; the YOY utilized four 

 habitat types: (1) Nereocysfis leutkeana, (2) Agarum 

 slopes, (3) eelgrass, and (4) sand. They observed the 

 highest densities of young copper rockfish first in the 

 bullkelp canopies. Subsequently, the yoimg rockfish left 

 the kelp canopy and were found on the floor of the kelp 

 forest in September and October, coincident with fall 

 storms and the annual decomposition of the bullkelp. 

 After the initial association with the kelp canopy, the 

 YOY shifted their distribution to a demersal habitat 

 with the perennial macvo\>hyte?, Agarum and eelgrass. 

 Similarly, Carr (1983) first observed YOY copper rock- 

 fish in the upper canopy of giant kelp Macrocystis 

 pyrifera in central California kelp beds. The YOY cop- 

 per rockfish subsequently moved toward the bottom 

 over the following weeks. Carr (1983) and Haldorson 

 and Richards (1987) always observed YOY in close pro- 

 ximity to drift or attached kelp or eelgrass and sug- 

 gested that young rockfishes strongly associated with 

 plant cover to avoid predation and find food resources. 



