LABORATORY OBSERVATIONS ON THE EARLY GROWTH OF THE 



ABALONE, HALIOTIS SORENSENI, AND THE EFFECT OF TEMPERATURE 



ON LARVAL DEVELOPMENT AND SETTLING SUCCESS 



David L. Leighton^ 



ABSTRACT 



The influence of temperature on larval development rate and growth of juveniles of the 

 white or Sorensen's abalone, Haliotis sorenseni, was investigated using a thermal gradient 

 apparatus. While larvae developed most rapidly at 20°C, most settled juveniles at that 

 temperature did not survive. At 15-16 °C, however, the operculate veliger stage was 

 attained in 72 hr and settlement of advanced individuals occurred in 9 days. No settling 

 was observed at 10°C. Juveniles maintained at 15-19°C and provided mixed diatoms as 

 food showed marked variability in growth rate; at 130 days shell length ranged from 

 4.0 to 8.0 mm (average 5.5 mm). Two distinctly different patterns of shell pigment 

 distribution emerged with continued growth. Approximately 60% of the juveniles were 

 bicolored, red and yellow-green, while the remainder had an even tone of red-violet. 



The description by Carlisle (1962) of the troch- 

 ophore and early veliger stages of the red aba- 

 lone, Haliotis rufescens Swainson, has hereto- 

 fore been the only published information on lar- 

 val development of an eastern Pacific species of 

 Haliotis. No account of larval development 

 through settlement and juvenile growth of any 

 of the seven American species of abalones exists 

 in the literature. Details of larval morphogen- 

 esis and an estimate of growth during the first 

 year of life for the northeastern Atlantic H. tu- 

 berculata Linnaeus were given by Crofts (1929, 

 1937) . Japanese workers have reported obser- 

 vations on early development and growth in 

 several of their native species; H. gigantea 

 Chemnitz (Murayama, 1935), H. discus Reeve 

 and H. sieboldii Reeve (Ino, 1952) , and H. di- 

 versicolor supertexta Lischke (Oba, 1964). 



Recent interest in mass culture of commer- 

 cially important species in Japan and the United 

 States has prompted more critical studies of 

 growth and nutrition of abalones. Advances 

 by Japanese workers in the field of abalone cul- 

 ture were reported by Imai (1967) and Ryther 

 (1968). However, no comparable research in- 



^ Scripps Institution of Oceanography, University of 

 California, San Diego, La Jolla, CA 92037. 



Manuscript accepted December 1971. 

 FISHERY BULLETIN: VOL. 70, NO. 



2, 1972. 



formation has been published heretofore from 

 any abalone culture facility in California. This 

 work, done in conjunction with abalone culture 

 efforts of California Marine Associates, Cayu- 

 cos, Calif., describes early growth of the white 

 or Sorensen's abalone, Haliotis sorenseni 

 Bartsch. 



H. sorenseni exhibits an unusual pattern of 

 distribution. Common to southern California 

 and northern Baja California, it appears in 

 abundance along the mainland only at the north- 

 ern and southern extremes of its range (Santa 

 Barbara to Pt, Conception and Pta. Eugenia to 

 Pta, Abreojos, respectively). Elsewhere it is 

 islandic, occurring at Santa Cruz, Santa Bar- 

 bara, San Clemente, Santa Catalina, Los Cor- 

 onados, and Cedros Islands (Cox, 1962) , Adults 

 attain a shell length of about 25 cm and are 

 characterized by an orange-tan epipodium with 

 foliose epipodial papillae, brown cephalic tenta- 

 cles, and a deeply cupped, light-weight, and scar- 

 free shell. Respiratory apertures are strongly 

 fluted. The species is prized by commercial and 

 sport divers for its white and tender edible por- 

 tion, the right shell muscle. 



Sexually mature //. sorenseni have been dif- 

 ficult to obtain in good condition since this is a 

 relatively fragile species and losses in transit 



373 



