352 
Reproductive biology, 
growth, and natural mortality 
of Puget Sound rockfish, 
Sebastes emphaeus (Starks, 1911) 
Andreas T. Beckmann 
Prof. Hofmann Laboratory 
Department of Zoology and Parasitology 
Ruhr-University Bochum, ND 05-334, 44801 Bochum, Germany 
Donald R. Gunderson 
Bruce S. fVHSIer 
School of Fisheries 
University of Washington, Seattle, Washington 98195 
E-mail address (for Donald R. Gunderson, contact author) dgun@fish.washington.edu 
Raymond M. Buckley 
Washington Department of Fish and Wildlife 
University of Washington, Seattle, Washington 98 1 95 
Betty Goetz 
Alaska Fisheries Science Center 
National Marine Fisheries Service, NOAA 
7600 Sandpoint Way N.E., Seattle, Washington 98115 
In spite of being one of the most 
common rockfish in the rocky near- 
shore region of the Strait of Geor- 
gia, relatively little is known about 
the early life history, ecology, re- 
cruitment, and reproductive biology 
of Puget Sound rockfish, Sebastes 
emphaeus. 
In rockfish, fecundity at 50% 
maturity ranges from 2,000 (S. 
dalli ) to 417,000 (S. paucispinis) 
eggs per female (Haldorson and 
Love, 1991). Parental care in this 
genus is essentially lecithotrophic, 
characterized by primitive, unspec- 
ialized viviparity at an evolution- 
ary stage when eggs, embryos, and 
early larval stages are protected 
inside the female body rather than 
born live as fairly advanced young 
(Wourms, 1991). Although most 
other northeastern Pacific Sebastes 
release their young between Janu- 
ary and July (Westrheim, 1975), 
parturition occurs in August and 
September for Puget Sound rockfish 
(Moulton, 1975; Beckmann, 1995). 
The goals of this study were to 
delineate the spawning season 
more closely and to determine the 
age and length at first maturity, the 
growth and mortality rates, and the 
length-fecundity relationship for 
Puget Sound rockfish. 
Materials and methods 
A total of 362 Puget Sound rockfish 
older than age 0 were collected dur- 
ing 23 sampling trips in coastal 
waters of the San Juan Islands, 
from 26 June 1994 to 12 March 
1995 (Table 1). The fish were col- 
lected either by anglers using hook- 
and-line gear or by SCUBA divers 
using spears and hand nets. The 
average collection depth for these 
rockfish was 15 m to 21 m, with a 
maximum depth of 76 m. 
In addition, 19 collection trips 
were made with hand nets for 
young-of-the-year (YOY) speci- 
mens. These trips extended from 26 
February through 18 August 1994, 
and 424 YOY were obtained. 
The spawning period was defined 
as occurring from the time when 
the first females with spent ovaries 
were caught to the time when no 
females with embryos were ob- 
served. A total of 253 females older 
than age 0, collected between June 
1994 and March 1995, were classi- 
fied by maturity stage according to 
the criteria described in Finckh 
McDermott ( 1994). Nonlinear least 
square regression was used to fit 
the data to the logistic model: 
p - 1 , 
L l+e~ (a+pL) 
where P L = proportion mature at 
length L (mm FL); 
a. P = constants; and 
a 
~~n = length at which 50% of 
fish are mature ( =L () 5 ). 
Sagittal otoliths were removed 
from the fish and stored in 50% 
ethanol. Readings prepared by the 
break-and-burn method were taken 
either from left or right otoliths, 
following the international conven- 
tion of considering 1 January as the 
birth date. All final age determina- 
tions were made by the coauthor 
with extensive age-determination 
experience (B. Goetz), after exam- 
ining the results obtained by the 
senior author and then examining 
edge type and annulus formation 
for the entire collection. A sample 
of 59 otoliths was read twice (with 
six months between readings) and 
showed 66% agreement (to the ex- 
Manuscript accepted 7 August 1997. 
Fishery Bulletin 96: 352-356 (1998). 
