918 



Fishery Bulletin 101(4) 



28 



24 



? 2° 

 S 16- 



^ 12 



S 



en 



-> 0,8 i, 



0.4 



00 



20 40 



60 80 100 

 Age (yr) 



120 140 160 



2.4 2.5 



Jaw length (cm) 



2.7 



Figure 2 



(A) Growth curve for jaws of red sea urchins from northern California, Oregon, and Washington usingTanaka parameters 

 and an initial jaw size of 0.44 cm, the approximate jaw size for a 1-year-old red sea urchin; (B) change in jaw size, Ajaw, 

 with Atime = 35 years starting with a final jaw length; Ajaw is the estimate of how much of the jaw would have to be 

 removed to expose prebomb calcite for sea urchins collected in 1992. 



Red sea urchins larvae spend at least two months in the 

 plankton (Strathmann, 1978) during which time they can 

 be carried far along the coast or out to sea. There is year- 

 to-year variation in settlement and recruitment and years 

 of zero success and greater variation at northern sites (Ber- 

 nard and Miller, 1973, Low, 1975,Tegner and Dayton, 1981, 

 Duggins, 1983, Pearse and Hines, 1987, Sloan et al., 1987, 

 Ebert et al., 1994). An important point, however, is that 

 these authors reported some recruitment at study sites 

 and so extreme longevity would at first seem unnecessary 

 for species survival. The important issue for evolution of 

 life histories, however, is not whether some individuals 



recruit to the population but how successful an individual 

 is each year in leaving offspring. The long life of adult red 

 sea urchins emphasizes the difficulties individuals have in 

 successfully having offspring that settle in suitable habitat 

 and survive to reproductive age. Many annual reproductive 

 episodes appear to be required to succeed and therefore red 

 sea urchins are classic bet hedgers that use resources to 

 promote annual survival of adults as well as to reproduce 

 (Stearns, 1992), 



Attributes of a long life span have consequences for 

 resource management. The implications for management 

 of the red sea urchin resource have been explored by us- 



