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White stumpnose Rhabdosargus globiceps is the main target of the linefishery in Saldanha Bay. Increased fishing pressure over the last three decades, particularly by the recreational sector, has led to concerns regarding sustainability of the local white stumpnose stock. The fishery was exceptionally productive between 2006 and 2008, with an estimated annual catch of 141.2 tonnes (t). Only 3% of boat outings surveyed were commercial boats targeting white stumpnose, yet this sector accounted for 39.3 t (31%) of the average annual catch. The recreational boat sector accounted for most of the catch (70.0 t), and the recreational shore sector the least (31.9 t). Commercial boat catch per unit effort (CPUE; 3.7 fish angler–1 h–1) was more than 10 times that of recreational boats (0.3 fish angler–1 h–1). White stumpnose catch length-frequency differed significantly (p < 0.01) between the fishing sectors, with the commercial sector retaining larger fish (34.7 cm [SD 5.9]) than the recreational boat (33.9 cm [SD 5.9]) and shore (30.4 cm [SD 5.8]) sectors. A decline in commercial CPUE (2000–2015) of approximately 40% and a concomitant severe decline (>95%) in survey data for juvenile white stumpnose CPUE (2007–2016) indicate that the current rate of exploitation is not sustainable. Recovery of the white stumpnose stock will require a decrease in fishing mortality. Possible management regulations include sector-specific effort limitations, extending the ‘no take’ marine protected area, reducing the recreational-sector bag limit to 5 fish person–1 day–1, implementing a commercial-sector bag limit, and increasing the minimum size limit to 30 cm TL.Keywords: angling, annual yield, catch and effort, Langebaan Lagoon, linefish, recruitment survey, roving creel survey, temperate sparid

Slender baardman Umbrina robinsoni are an important component of recreational shore-angler and spearfisher catches along the eastern seaboard of South Africa. Stocks of U. robinsoni at three sites — False Bay, Stil Bay and the KwaZulu-Natal (KZN) coast — were modelled using a per-recruit approach. Total (Z) and fishing (F) mortality rates were estimated by catch-curve analyses using measures of individual size (length or weight) recorded by researchers, divers (log books) or during spearfishing competitions. Based on estimates of F during the period 2001–2003, spawner biomass per-recruit ratios were estimated to be either at or below the 25% threshold (False Bay SB/R = 21% SB/RF=0, Stil Bay SB/R = 25% SB/RF=0, and KZN SB/R = 21% SB/RF=0), suggesting that rates of F were too high. Reductions in F necessary to achieve target fishing mortality levels (FSB40) at the current minimum size limit (lc 40 cm total length) were 51% for Stil Bay and the KZN coast and 57% for False Bay. Based on the bag frequencies from 927 diver outings in KZN (1989–2003), a reduction in bag limit from the current five to two fish is predicted to reduce F in this region by approximately 25%. Increasing the lc to 50 cm is predicted to increase SB/R ratios to 36% SB/RF=0 in False Bay, 43% SB/RF=0 in KZN and 52% SB/RF=0 in Stil Bay, at current levels of F. Owing to the philopatric nature of U. robinsoni and the consequent existence of temporary refugia, catch curves are likely to underestimate fishing mortality. The reductions in F estimated to attain the target reference points are therefore probably conservative.Keywords: fishing mortality, growth rate, management, Sciaenidae, stock assessmentAfrican Journal of Marine Science 2010, 32(3): 511–523

The effect of temporal variation in growth rate on per-recruit model outputs was investigated by comparing biological reference points obtained using growth curves derived for Umbrina robinsoni populations from False Bay, on the south coast of South Africa, sampled 10 years apart (1991–1993 and 2001–2003), and applying the two different age–length keys to length frequency data collected over the period 1991–1993 (n = 1 389) for the estimation of total mortality (Z), fishing mortality (F)and spawner biomass per recruit (SB/R). The SB/R and yield per-recruit (Y/R) curves constructed using biological data collected during the two different time periods were very similar, with target and threshold reference points differing only moderately (11%). This suggests that for long-lived species, the frequency of age and growth studies can be at least the lifespan of a cohort if they are to be assessed with a per-recruit approach. The use of the more recent length-at-age data, however, resulted in lower estimates of F (0.61 y–1 vs 1.05 y–1) and a slightly higher spawner biomass per-recruit ratio (19.5% vs 14.5%) for the earlier period. The reduced estimate of F when using the more recent dataset was likely due to a bias towards older fish caused by small sample size, the philopatric nature of U. robinsoni, and possible recruitment collapse. This highlights the importance of having a large, representative sample of length-at-age data for construction of age–length keys.Keywords: growth rate variation, management, Sciaenidae, slender baardman, stock assessmentAfrican Journal of Marine Science 2010, 32(3): 633–636

Biological data for Umbrina robinsoni were obtained from fish sampled monthly during 2001–2002 by shore-angling in the warm-temperate De Hoop Marine Protected Area (MPA) (n = 312), and by means of spearfishing during three trips (May, September and January 2001–2002) in the Kosi Bay region of the subtropical Maputaland MPA (n = 354). Annuli in otolith sections were validated by means of marginal increment analyses and fluorochrome marking (oxytetracycline). Maximum ages recorded were 12 and 16 years at Kosi Bay and De Hoop respectively. Kosi Bay fish obtained a significantly greater asymptotic length than De Hoop fish and mean length-at-age (for ages 2–10 years) was significantly greater. The fitted von Bertalanffy growth equations for combined sexes were: Lt = 594 (1 - e-0.183 (t + 2.42)) for De Hoop and Lt = 875 (1 - e-0.151 (t + 2.49)) for Kosi Bay. Trends in mean monthly gonadosomatic indices and proportions of histologically validated macroscopic gonad stages indicated a summer spawning season (November–February) at De Hoop and year-round spawning at Kosi Bay. Relative condition peaked in both spring and autumn at De Hoop but showed little seasonal variation in the Kosi Bay region. Kosi Bay females attained 50% sexual maturity at a significantly larger size (48 vs 39 cm) but at younger age (2.8 vs 3.4 years) than those at De Hoop. Analysis of maturity schedules indicates that current sizes at maturity are plastic responses that maximise lifetime fecundity within local regimes of somatic growth and natural mortality. The instantaneous rate of natural mortality was substantially higher at Kosi Bay than at De Hoop (M = 0.35 vs M = 0.26).Keywords: age and growth; natural mortality; reproduction; SciaenidaeAfrican Journal of Marine Science 2010, 32(1): 37–53

Data collected by questionnaire and telephone surveys conducted during 1998 and 1999 are used to describe the socio-economic characteristics of inshore netfishers in the Western Cape. Approximately two-thirds of netfishers work or have worked in other fishing sectors and a further 6–50%, depending on the area surveyed, are retired. Very few (0–11%) permit-holders in most areas classified their occupations as netfishers and the majority claimed to make

Total catch and effort for the inshore net-fisheries in the Western Cape, South Africa, were estimated by means of face-to-face questionnaire, telephone and access point surveys, analysis of factory records and compulsory catch returns. In most areas, gillnet fishing effort was confined to summer, with highest average catch per unit effort during months of low effort. Records of monofilament gillnet sales show that approximately 180 illegal nets are sold annually (20% of all sales). During the period 1994–1999, only 26 illegal mesh size nets were confiscated annually (14% of those sold) on average, indicating that few illegal fishers are apprehended. Beach-seine fishers appeared to operate opportunistically throughout the year along the West Coast, whereas South-West Coast permitholders concentrate their activity during summer. Sources of survey error in effort and catch-rate estimation are discussed. Approximately 25 000 gillnet days and 3 200 beach-seine hauls made annually land around 6 000 tons of fish, substantially more than the mean annual reported catch of 1 369 tons. Comparison of observed or documented catches with compulsory catch returns confirmed that as little as 21% of the actual effort and only 8% of the fish caught are reported. Despite the fact that catches are much greater than those reported, the lower catch rates, smaller average size of fish caught and historical and anecdotal evidence suggest that the harder Liza richardsonii stock is regionally overexploited in areas with high fishing effort. It is concluded that the inshore net fishery in the Western Cape is oversubscribed in most regions and a reduction in latent and “recreational” effort is therefore recommended. A suitable reduction in total effort may allow the L. richardsonii stock to recover, reduce the ecosystem effects of the fishery by reducing the amount of bycatch and improve catch rates for bona fide commercial fishers. It would also facilitate improved monitoring and policing of the fishery and hopefully improve compliance with regulations. Keywords: beach-seine, catch-and-effort estimates, catch returns, gillnets, Liza richardsoniiAfrican Journal of Marine Science 2002, 24: 205–225

Two Umbrina species, U. canariensis Valenciennes 1843 and U. robinsoni Gilchrist and Thompson 1908, are recognised from southern Africa. The latter species was hitherto believed to be a synonym of Umbrina ronchus Valenciennes 1843 (type locality Canary Islands). U. canariensis is distributed along the South Africa eastern seaboard from Cape Point to Sodwana Bay and U. robinsoni is known from False Bay to Madagascar and Oman. African Umbrina taxonomy has, however, been hindered by geographic samples that were either too few or consisted of specimens of disparate length; and as a result the identification and distribution of South African Umbrina species was confused. Morphological comparison of a large number of South African Umbrina with specimens from the type locality (Canary Islands) confirmed the identity of South African U. canariensis and allowed for an expanded description of the species. However, differences between specimens of U. ronchus and those of the second South African species (n = 251) led us to resurrect U. robinsoni (Gilchrist and Thompson 1908) as a valid name for this species. U. robinsoni differs from U. ronchus in having a smaller supraoccipital crest and thus a less steep pre-dorsal profile; a shallower preorbital bone (13–21% head length [HL] vs 21% HL); and a shorter nostril-orbit distance (2.4–6.9% HL vs 7.8–8.5% HL). Colour patterns also differ between the two species, with U. ronchus lacking the oblique, wavy, white stripes evident on the flanks of U. robinsoni. U. ronchus does not occur in South African waters, and is an eastern Atlantic species occurring from Gibraltar to Angola. Specimens from the east coast of Africa (Moçambique to Gulf of Oman) that were previously identified as U. ronchus are U. robinsoni. Differences between U. robinsoni and U. canariensis include: a lower modal number of soft dorsal fin rays, (22–27 vs 24–30); less deep body depth, (26–36% standard length [SL] vs 33–39% SL); shorter pectoral fin length (15–21% SL vs 20–25% SL); longer caudal peduncle length (26–34% SL vs 21–28% SL) and snout length (27–38% HL vs 23–32% HL); and smaller orbit diameter (14–33% HL vs 23–34% HL). Otoliths of U. robinsoni differ from those of U. canariensis in being smaller, less elongate, lacking a massive post-central umbo and having a post-dorsal spine remnant. The body colour and nature of the striping pattern on the flanks differs markedly between the species: in U. robinsoni the oblique stripes are thin, wavy, white lines; in U. canariensis the oblique stripes are thicker, nearly straight and brown; U. robinsoni also lacks the triangleshaped mark on the outer operculum and the dark pigmentation of the inner operculum that is found on U. canariensis. Spatial analysis of South African specimens collected with a variety of gear revealed U. robinsoni to be a shallow-water species found from the surf-zone to 40m, whereas U. canariensis occurs predominantly from 40 to 100m depth. Although both species occur throughout the South African eastern seaboard, U. canariensis is most common west of the Kei River, where the shelf is wider. Examination of three specimens of U. steindachneri Cadenat 1950 confirmed the presence of a fourth sub-Saharan Umbrina species that is limited to tropical West African waters from Senegal to Angola. U. steindachneri differs from the other African Umbrina in having a high number of soft dorsal rays (28–29), a greater 3rd dorsal spine length (25–27% SL) and a very pronounced and convoluted striping pattern on the flanks. African Journal of Marine Science 2005, 27(1): 1–21