A PRELIMINARY INVESTIGATION OF THE MARINE ICHTHYOFAUNA IN THE TSITSIKAMMA COASTAL NATIONAL

Sixty-five species representing 29 families were recorded in a survey of the marine ichthyofauna of the Tsitsikamma Coastal National Pa rk . Visual aSsessments of the composition of the fish communities at three inshore reef types indicated differences in the species composition and size of fishes present. Areas wh ich are closed to fishing prOlect many species important to the South African linefishery whereas a recent seaward extension of the park boundary in 1983 will also include areas inhabited by species important to the demersal trawl fish-


Introduction
The Tsitsikamma Coastal National Park (TCNP) situated on the southern Cape coast between Nature's Valley (34°59'S, 23"34'E) and Oubosstrand (34"04'S ,24°t2 'E), covers approximately 60 km of coastline.For the duration of this study the marine sanctuary ex tended 0,8 km offshore but in September 1983, except for a short section on the western side , this boundary was increased to 5,6 km offshore (Fig. I) .Within this area public fishing is prohibited except for a 2 km stretch close to the rest camp where shore fi shing is allowed.
Published ichthyological research re lating to the TCNP includes analyses of handline and deme rsal catches (Crawford & Crous 1982; Crawford 1982)  and notes on sex reversal in the Roman Chrysoblephus loticeps (Penrith 1972) and the dageraad C. cristiceps (Robinson 1976).In addition a guide to the mari ne fi shes of the park has been published (Smith & Smith 1966).This paper presents a check list of marine species recorded in the park and preliminary observations o n the distribution and abundance of some suprabenthic species.especially those of commercial importance.The study forms part of a long-term investigat ion of the ichthyofauna aimed at a better understanding of the role of reserves as a means of conserving marine fish .To date underwater observations have been restricted to accessible reefs approximately 5 km on either side of the Storms River mouth.Although detailed benthic surveys have not been undertaken in the TCNP, for the purposes of this study three distinct reef types were recognised.The first , a shallow inshore zone extending subtidally from the coastline to about 10 m, consists of low reefs interspersed by extensive sandy flats.The reefs appea r to be dominated by calcareous algae, with only few echinoderms, octocorals, poriferans and ascidians present (Fig. 2) .
The second reef type found in water betwee n 10 and 25 m, is characterised by a rugged relief.Macroalgae typical of TYPE I reef are absent , but microalgal cover is evident (N.Jarman, Sea Fisheries Research Institute, pers.comm .).The ben thic fauna is rich in ascidians (particularly the redbait Pyura stofoni/era o n the reef crests), poriferans, octocorals, echinoderms and reef-building and encrusting bryozoans (Fig. 3).The relief, incorporating overhangs, caves and cracks, provides shelter for associated fish species.
A third reef type is found in water below 25 m.Similar in appearance to the TYPE 2 reef, but not as rugged , it differs mainly in depth , the absence of Pyura, and the presence of large stands of kelp Eckfonia bisperJorata (F;g.4).

Sampling methods
Information on the fish species composition was obtained from visual observations and rotenone collectio ns accumulated between June 1980 and July 1982 and was supplemented by handline fishing.The use of visual techniques for assessing fish populations has been well documented (Russel 1977;Keast & Harker 1977;Bohnsack & Talbot 1980;Craik 1981).These techniques have the advantage of providing a non-destructive method of sampling.This was particu larly attractive in the marine reserve context where killing of fis h was avoided as far as possible .Fish were identified and counted on a 10 m wide transect by two divers swimming from opposite ends of a 30 m line.Total fish lengths were istimated by comparison with a ruler and limited spearing of representative species.After each dive observations were pooled and averaged for each species.The method has disadvantages, including avoidance of SCUBA divers by certain species (Chapman, Johnstone, Dunn & Creasy 1974), under-estimation of the abundance of cryptic species (Brock 1982) and inability to sample at depths greate r than 30 m using SCUBA.Four rotenone stations were carried out between 10 and 30 m by releasing 24 litres of solutio n underwater in calm conditions.Dead fish were then collected by divers using hand-nets.The rotenone was made up from a solution of acetone , 400 ml of dry rotenone resin powder and 500 ml of teepa!.Handline fis hing was done over a variety of depth and substrate types using a number of baits including squid , pilchard, reef fish and redbait.Most of the fi shing took place over reefs as part of an ongoing investigation into the biology of reef fish important to the South African linefishery.) and probably did no t contribute to the ichthyofaun a associated with the TCN P prior to the exte nsion of the seaward boundary.In addition many o f the inclusions in Smith 's refere nce we re based on the known distributio nal ranges of species which would not normally be found in the park .These include the devilfish Mama biroslris, pompano Trae/rinolils blochii, marlins and other tropical vagrants.

Table 1 Species of fISh recorded in the Tsitsikamma Coastal National Park with a classification of prefered habit and sampling methods (C-cryptic, E-exposed, T-transect, R-rotenone, L-linefishing)
Visual assessment of the supra benthic species composition suggested differ• ences between the ichthyofauna of the three reef types studied.The relati ve abundance o f species found in shallow subtidal areas (TYPE I) is summa• .rised in Table 2.Although size at sexual maturity fo r most of these species is unknown , they were separated into small and large sizes with the inference that small fi sh represented juven iles o f the species.The area supported three distinct groups of fi sh.The first, typically shallow water species, incl uded zebra Diplodus cervinus, blacktail D. sargus, mullet MugU spp ., bronze bream Pachymetopon grande, Cape stumpnose Rlrabdosargus IrOlllbi, stre• pie Sarpa sa/pa and musselcracker Sparadon dllrbanensis.BOIh large and small specimens were present.Studies o n these fi sh suggest that their distribution may be attributed to feeding preferences (Christensen 1978 , April suggesting an infl ux of recruits ove r a sho rt period of time and hence a restricted breeding season fo r the species.The third group including white and sand steen bras Lithognathus lithognathus and L. morrnyrus, moony Monodactylus falciforrn is, red tjor•tjor Pagel/us "atalensis and piggy Porna• dasys olivaceum arc species associated with sandy substrates (Mehl 1973;Joubert & Hanekom 1980;Buxton, Smale, Wallace & Cockroft 1984).
The composition of suprabcnlhic species found on reefs al depths between 10 and 25 m (TYPE 2) is summarised in Table 3.The results show that Sarpa sa/pa, B. inornata, Pachymetopon aeneum and Spondyliosoma emargjnatum were the most numerous (93%) of the 27 species recorded .Significantly 15 of the remaining species were also of the fa mily Sparidae , which therefore forms 70% of the species found over reef TYPE 2. This domination by a si ngle fa mily diffcrs considerably from the diversi ty fou nd o n tropical reefs Depth , bottom time and poor visibility imposed severe restrictions on the visual assessment of deep reefs (TYPE 3) and as a result only 4 transects were successfully completed during the study period.Combi ning these resulls with incidental observations showed that these areas had a lower suprabenthic species diversity than shallower reefs.Boopsoidea inornota, S. emarginalum and Pachymetopon aeneum were still numerically important whereas Sarpa salpa were not recorded al all.Silverfish Argyrozona argyrozona and gnomefish Scomhrops dubius, species not recorded on shallower reefs, were important.Red sturnpnose Chrysoblephus gibbiceps were seen in greater numbers on these reefs compared to the shallower study sites.
Although the abse nce of many species may be explained by their preference for shallower water, the lack of C. cristiceps was unexpected as they are caught on line at this depth.This may be attributed to a tendancy to avoid divers , aggravated by poor visibility.This behaviour is also thought to bias the shallow water results as the ratio of C. cristiceps to C. laticeps is far greater in line catches than in the visual assessments.
The results presented in this study show th at a wide variety of important commercial species are afforded protection by the T CNP.Prior to the extension of the seaward boundary, the majority of the protected fishes were important to the linefishery.Clearly , the extended boundary will incorporate areas inhabited by a number of important trawl species (Crawford 1982), but whether this exte ntion will afford significant protection to trawl species needs further investigation.Shallow water trawling surveys «50 m) off the Cape south coast provided little evidence of an inshore nursery for the target species of the demersal trawl fishery (Wallace, Kok, Buxton & Bennet 1984;Smale 1984), whereas Hatanka et al.(1983) demonstrated that both adults and juveniles of species important to the demersal trawl fishery were most abundant on the Agulhas bank west of Mossel Bay well outside the TCNP .

Fig
Fig. I .Map of the Tsitsikamma Coastal National Park.

Table 1 (
com .)TableI).On the basis of habit and colouration the fish were subjective ly cl assifi ed as being cryptic or exposed.Although no attempt was made to quantify rotenone collections by encircling the reef wi th nets(Russel, Talbot , Anderson & Goldman 1978)it is clear that most of the cryptic species sampled using rote none (95%) we re overlooked during visual census.Conversely, many of the more mobile species, particularly sparids, were able to escape the effects o f rotenone .Some 153 species representing 64 famili es thought to occur in the TCNP(Smith & Smith 1966)were not recorded during this survey.This discrepency may be partially expl ained by the fa ct that depth limitations of this study «30m) omitted the many demer- (Botha 1980;ecies associated with the area .These include the sole Auslroglossus pectoralis, gurnards Chelidonichthys cape'lSis and C. kum ll, hake Merluccius capensis, kingklip X iphiurus capensis, monk Lophius piscarorus and snoek Thrysites atun(Crawfo rd 1982).Most arc associated with deep water(Botha 1980; Hatanka, Salo.Augustyn , Payne & Leslie 1983 Visual assessment of species found in shallow subtidal areas in the TeN P (xxx -abundant, xx-common, x-uncommon) .A pproximate sizes (total length in mm) of small fish are given and species important to the linefishery are asterisked water including fransmadam Boopsoidea illomato, dageraad ChrysobfefJllIIs cristiceps, Roman C. iaticeps, poenskop Cymatoceps ,ws wus, blue hottentot Pachymetopon aeneum, red steen bras Petrus rupestris and sleentjie Spondyiiosoma emargiflatum .These fi sh we re only present between December and Table 2

Table 3
Percemage comribution of species to all /ish observed on underwater transects and approximate total length rallges of {ISh observed on reef types 2 alld 3.
showed that fewer juveniles were present on the deeper reefs.This was particul arly true for important Iinefish species with the exceptio n of Petrus rupestris, juveniles ofwh.ich were more common in this depth ra nge.