802 



Abstract.— The effect of maturation on 

 relative growth of somatic tissues was 

 investigated by measuring and compar- 

 ing monthly changes in dry weight of 

 somatic tissues and reproductive or- 

 gans. In both sexes, reproductive tis- 

 sues grew in relation to total body mass; 

 at maturity female reproductive tissue 

 was 16'7f of total dry body mass, 

 whereas male reproductive tissue was 

 2.6'7f. In females, the relative mass of 

 thfmantle and head decreased during 

 maturation, whereas the relative mass 

 of the viscera increased. In males, the 

 mass of the viscera increased with 

 maturation, but no decreases occurred. 

 The percentage composition of protein 

 in the mantle and head of females for 

 each maturity stage did not differ sig- 

 nificantly. For both sexes, the digestive 

 gland mass remained relatively con- 

 stant throughout the different maturity 

 stages and seasons, and analysis of 

 stomach fullness indicated that feeding 

 increased in the final maturity stages. 

 All observations support the hypothesis 

 that energy and nutrients for matura- 

 tion are supplied mainly by diet rather 

 than by stored resources, but that dur- 

 ing maturation there is a shift of em- 

 phasis from somatic growth to gonadal 

 development and vitellogenesis. Sepia 

 pharaonis, which appears to be an in- 

 termittent multiple spawner, does not 

 use protein from muscle tissue for de- 

 veloping and growing its reproduction 

 tissues. 



Reproductive versus somatic tissue growth 

 during the life cycle of the cuttlefish 

 Sepia pharaonis Ehrenberg, 183T 



Howaida R. Gabr 



Department of Marine Biology 

 Suez Canal University 

 Ismailia, Egypt 



Roger T. Hanlon 



Marine Biological Laboratory 

 Woods Hole, Massachusetts 02543 



E-mail address (for R T Hanlon, contact author) rhanlonidimbi edu 



Salah G. El-Etreby 



Mahmoud H. Hanafy 



Department of Marine Science 

 Suez Canal University 

 Ismailia, Egypt 



Manuscript accepted 16 November 1998. 

 Fish. Bull. 97:802-811 i 19991. 



Cephalopod mollusks have various 

 life history strategies, ranging from 

 typically semelparous (e.g. many 

 coleoids) to iteroparous (e.g. Nauti- 

 lus spp.X Boyle, 1983, 1987). Differ- 

 ent modes of semelparity may oc- 

 cur, and this diversity may be re- 

 lated in part to growth patterns 

 (Mangold et al., 199.3). Most cepha- 

 lopods that have been studied are 

 fast growing, and they generally 

 reproduce once and die (Calow, 

 1987). However, others have inter- 

 mittent growth (Boletzky, 1987; 

 Forsythe and Van Heukelem, 1987; 

 Jackson and Choat, 1992) and mul- 

 tiple spawning events (Harman et 

 al., 1989; Lewis and Choat, 1993). We 

 investigated the relation between re- 

 production and somatic growth in the 

 commercially valuable cuttlefish Se- 

 pia pharaonis Ehrenberg, 1831. 



For many marine invertebrates, 

 reproduction represents an enormous 

 energy investment, and achieving 

 the optimum balance between so- 

 matic and reproductive effort is 

 critical to an individual's lifetime 

 fitness (Calow, 1981). The varia- 

 tions in reproductive strategies usu- 

 ally correlate with variations in 



feeding and growth patterns. As- 

 sessing the cost of reproduction is 

 difficult, and although slowing of 

 somatic gi'owth may indicate the al- 

 location of energy to oocyte produc- 

 tion, an assessment of somatic tissue 

 may provide a better indicator of the 

 cost of reproduction (Calow, 1983). 



For example, in some benthic oc- 

 topuses, mantle protein is mobilized 

 to provide energy for egg develop- 

 ment; the subsequent depletion of 

 protein from body tissues probably 

 contributes to the death of some 

 octopus females (Tait, 1986; Pollero 

 and Iribarne, 1988). This would not 

 seem to be a sensible strategy for a 

 swimming cephalopod, such as 

 cuttlefish, which still requires func- 

 tional muscle to survive in the wa- 

 ter column. Sepia pharaonis. which 

 migrates to spawning grounds from 

 its feeding grounds (Gabr et al., 

 1998), would certainly need to 

 maintain swimming ability. 



Elucidation of patterns of energy 

 storage and utilization is important 

 in understanding the interaction 

 between organism and environment 

 ( Clarke et al., 1994 ). Although many 

 studies indicate that oocyte produc- 



