Love and Johnson: Life history of Sebastes rastrelliger and 5 auriculatus 



105 



F = aL\ 



where F = number of eggs in thousands; 



L = total length in centimeters; and 

 a and b = constants. 



The value of the parameters a and b were estimated 

 by fitting the linear function log F = log a + b Log L 

 by least squares. Estimated fecundity ranged from 

 80,000 eggs for a 26 cm TL individual to about 

 760,000 for one 46.5 cm long. 



Discussion 



al., 1990), although compared to many other groups, 

 their growth rates are quite low (Beverton and Holt, 

 1960). The largest species of rockfishes tend to grow 

 slowest (y^=0.05, rougheye rockfish, S. aleutianus) 

 and dwarf species exhibit relatively rapid growth 

 (k-OAb, halfbanded rockfish, S. semicinctus). How- 

 ever, between these extremes there is no relation 

 between maximum size and growth rate. Grass rock- 

 fish and brown rockfish growth rates are near the 

 mean for the genus (Love et al., 1990). However, what 

 was usual for the rockfishes was a lack of sexual di- 

 morphism in growth rates. In most species, females 

 grow faster than males, particularly after maturity. 



Compared with most other eastern Pacific rock- 

 fishes, both species are short-lived. Of the 38 species 

 for which we judge that fairly accurate maximum 

 ages are known, only eight had life spans that were 

 similar to or less than grass and brown rockfishes 

 (Love et al.^). Most species lived to more than 30 

 years, a majority to more than 40 years. Short-lived 

 species tend to be dwarf taxa, such as shortbelly (S. 

 jordani), Puget Sound (S. emphaeus), squarespot (S. 

 hopkinsi), and honeycomb (S. umbrosus) rockfishes. 



For brown rockfish, there appears to be little dif- 

 ference in age and length at 50% maturity throughout 

 much its range (Table 2). Although fish off central and 

 northern California are older and larger at 50% matu- 

 rity, those from Washington State and southern Cali- 

 fornia are almost identical. Latitudinal differences in 

 length or age of maturation, or both, occur in a number 

 of rockfish species (e. g. splitnose rockfish, S. diploproa; 

 widow rockfish, S. entomelas; yellowtail rockfish, S. 

 flavidus; black rockfish, S. melanops; bocaccio, S. 

 paucispinis) with fishes from higher latitudes gener- 

 ally maturing when larger or older or both (Wyllie 

 Echeverria, 1987; Love et al., 1990; Field, 1984). How- 

 ever, this difference does not occur in greenstriped rock- 

 fish, S. elongatus (Love et al., 1990). Although it is likely 

 that environmental parameters (e.g. water tempera- 

 ture, food availability, growth seasons) play a role in 

 this phenomenon, it is not yet clear how they interact. 



With 50% mature at age 4, both grass rockfish and 

 brown rockfish mature at a young age compared with 

 many rockfishes. Off California, most species reach 50% 

 maturity at between 4 and 8 years (Wyllie Echeverria, 

 1987; Love et al., 1990); thus these two species fall in 

 the younger part of that range. Dwarf species, such as 

 shortbelly rockfish iS. jordani), Puget Sound rockfish 

 (S. emphaeus) and stripetail rockfish (S. saxicola) ma- 

 ture earliest, often when 2 or 3 years old (Moulton, 1975; 

 Wyllie Echeverria, 1987; Love et al., 1990). At the other 

 extreme, the largest and more northerly species, such 



In the northeast Pacific, rockfish growth rates, as 

 measured by the term k, are quite variable (Love et 



* Love, M. S., M. Yoklavich, L. Thorsteinson, J. Butler. 1998. 

 guide to the rockfishes of the northeast Pacific. In prep. 



