258 



Abstract— The carpenter seabream 

 (Argyrozona argyrozona) is an 

 endemic South African sparid that 

 comprises an important part of the 

 handline fishery. A three-year study 

 (1998-2000) into its reproductive biol- 

 ogy within the Tsitsikamma National 

 Park revealed that these fishes are 

 serial spawning late gonochorists. 

 The size at 50% maturity (L 50 ) was 

 estimated at 292 and 297 mm FL for 

 both females and males, respectively. 

 A likelihood ratio test revealed that 

 there was no significant difference 

 between male and female L 50 (P>0.5). 

 Both monthly gonadosomatic indices 

 and macroscopically determined ovar- 

 ian stages strongly indicate that A. 

 argyrozona within the Tsitsikamma 

 National Park spawn in the astral 

 summer between November and April. 

 The presence of postovulatory follicles 

 (POFs) confirmed a six-month spawn- 

 ing season, and monthly proportions 

 of early (0-6 hour old) POFs showed 

 that spawning frequency was highest 

 (once every 1-2 days) from December 

 to March. Although spawning season 

 was more highly correlated to photo- 

 period (r = 0.859) than temperature 

 (r = -0.161), the daily proportion of 

 spawning fish was strongly correlated 

 (r=0.93) to ambient temperature over 

 the range 9-22°C. These results indi- 

 cate that short-term upwelling events, 

 a strong feature in the Tsitsikamma 

 National Park during summer, may 

 negatively affect carpenter fecundity. 

 Both spawning frequency and dura- 

 tion (i.e., length of spawning season) 

 increased with fish length. As a result 

 of the allometric relationship between 

 annual fecundity and fish mass a 3-kg 

 fish was calculated to produce fivefold 

 more eggs per kilogram of body weight 

 than a fish of 1 kg. In addition to pro- 

 ducing more eggs per unit of weight 

 each year, larger fish also produce 

 significantly larger eggs. 



Manuscript submitted 22 September 

 2003 to the Scientific Editor's Office. 



Manuscript approved for publication 

 30 August 2004 by the Scientific Editor. 



Fish. Bull. 103:258-269 (2005). 



Reproductive biology of carpenter seabream 

 (Argyrozona argyrozona) (Pisces: Sparidae) 

 in a marine protected area 



Stephen L. Brouwer 



Marc. H. Griffiths 



Department of Marine and Coastal Management 



Private Bag X2 



Rogge Bay 8012, South Africa 



E-mail (for S. L. Brouwer): sbrouwer'5'deat gov 23 



The carpenter seabream (Argyrozona 

 argyrozona), known as "carpenter" 

 regionally, is an endemic South Afri- 

 can sparid found between St Helena 

 Bay and KwaZulu-Natal (Fig.l) (Smith 

 and Heemstra, 1986). Although the 

 third most important species in the 

 line-fishery in terms of landed mass, 

 catch per unit of effort (CPUE) on 

 traditional fishing grounds, declined 

 by 95% during the twentieth century 

 (Griffiths, 2000). Despite the impor- 

 tance of this resource, little research 

 attention has been given to this spe- 

 cies. The only previous study on the 

 reproductive biology of carpenter was 

 based on specimens collected towards 

 the western extreme of the distribu- 

 tion range (west of Cape Agulhas), 

 where most of the fish examined were 

 reproductively inactive (Nepgen, 1977). 

 As a result spawning seasonality was 

 not accurately delineated and sizes 

 at 50% maturity were not calculated. 

 Assuming carpenter to be determi- 

 nate spawners, Nepgen (1977) overes- 

 timated batch fecundity by counting 

 immature oocytes. 



The objective of the present study 

 was to provide information on spawn- 

 ing seasonality, size at maturity, and 

 annual fecundity of carpenter in the 

 Tsitsikamma National Park (TNP), 

 a 75-km no-take marine protected 

 area (MPA) that has existed for 38 

 years (Fig. 1). It was envisaged that 

 in conjunction with other studies on 

 carpenter (Brouwer and Griffiths 1 ) 

 in exploited areas this information 

 would assist in determining the af- 

 fects of fishing on the life history of 

 carpenter. 



Materials and methods 



Fish were caught from a research 

 vessel at depths between 20 and 90 m 

 by using handlines with baited hooks of 

 2/o-6/o in size. An attempt was made 

 to sample 60 fish per month between 

 March 1996 and June 1999, although 

 weather conditions did not always 

 allow this number. Sampling involved 

 measuring total and fork length (FL) 

 (mm), whole mass (g), gutted mass 

 (g), determining the sex of fish, and 

 removing the gonads. Gonads were 

 staged macroscopically according to a 

 seven-stage maturity index (Table 1) 

 and weighed to the nearest 0.1 g. The 

 whole gonads were preserved in 10% 

 neutrally buffered formalin or alter- 

 natively fixed in Bouin's solution for 

 48 hours and then stored in 60% etha- 

 nol. Preserved samples were processed 

 for histological analysis according to 

 the techniques described by Osborne 

 et al. (1999). 



Length at maturity was modelled 

 by using a 2-parameter logistic ogive 

 of the form 



Pi 



1 



1 + exp 



-<L,-L,„)/a 



where p, = the proportion of mature 

 fish in size class i, sam- 

 pled during the spawn- 

 ing season (November to 

 April); 



1 Brouwer, S. L., and M. H. Griffiths. In 

 prep. Stock separation and life history 

 of Argyrozona argyrozona (Pisces: Spari- 

 dae) on the South African east coast. 



