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The west coast rock lobster Jasus lalandii fishery is South Africa’s third-most-valuable fishery, although the stock is currently estimated at

Temporal trends in the size composition (length frequency) and length–weight (L–W) relationship of chokka squid Loligo reynaudii on the south coast of South Africa were assessed over periods spanning 22 years: length frequencies from 1996 to 2017 (with 15 years represented); and L–W relationships over 9 years between 1994 and 2016. To allow for comparison, identical data selection and processing was adopted for all years considered (i.e. identical period of 60 days in spring–summer; the same depths and areas; chokka with empty stomachs; and squid of the same maturity stage). Although there were no significant long-term temporal trends in the mean lengths, there was a significant short-term drop in the mean lengths over the years 2014–2017 (especially in females), which could not be attributed with certainty to any cause. A tentative explanation is that this drop might be linked to the introduction of an additional closed season in these years. The estimated parameters of the L–W relationship also revealed no trend over the years considered. Investigation of the caecum colour, which indicates the state of starvation (white: 8 h on average after food ingestion; yellow: 6 to 7 h after food ingestion), showed significantly more starving males than starving females. Starvation of males on the spawning grounds might be associated with the spawning behaviour of chokka.

In the past two decades, small, targeted artisanal shark fisheries have developed in the extreme north of Madagascar, largely in response to the shark fin trade. Few studies have been undertaken to assess the biological characteristics and impact of these fisheries. Here, we developed a profile of the fishery in the region of Antsiranana for the period 2001–2004. A total of 23 elasmobranch species were identified. Carcharhinidae accounted for 69% with Carcharhinus amblyrhynchos most commonly captured, followed by Carcharhinus sorrah, Loxodon macrorhinus and Triaenodon obesus. Sphyrnidae accounted for 24% of the catch, with Sphyrna lewini most commonly captured. The presence of gravid females in gillnet catches from shallow coastal waters, combined with the vulnerable conservation status of some of the primary catch species, as well as the heavy exploitation of shark resources, suggests that this level of fishing may be unsustainable. Urgent management intervention is required, but it must take into consideration the vulnerable social and economic status of the coastal communities in the area. Keywords: artisanal shark fisheries, livelihoods, sharksAfrican Journal of Marine Science 2013, 35(1): 9–15

Lichia amia is an important coastal recreational fishery species with a cosmopolitan distribution in the eastern Atlantic. In southern Africa, it is distributed from southern Angola to northern KwaZulu-Natal in South Africa. A recent biological survey revealed differences between Angolan and South African individuals suggesting that they may represent separate stocks. As fishery management decisions should be based on accurate knowledge of population structure, an initial survey of the genetic substructuring of L. amia was conducted on samples collected in southern Angola and South Africa. Assessment of genetic diversity and population structure was conducted using a fragment of the mitochondrial Control Region. Obtained genetic diversity levels were within the expected range for marine teleosts (h = 0.867, π = 0.007), and two deeply divergent (southern Angolan and South African) populations were identified (average φST = 0.78) across the Benguela Current system. These results suggest that Angolan and South African L. amia should be managed as two independent stocks. This work represents the first assessment of population genetic substructuring across the Benguela Current of a valuable coastal fishery resource, and has application for future fisheries management.Keywords: fisheries management, genetic diversity, leervis, mtDNA, population structureAfrican Journal of Marine Science 2012, 34(4): 585–591

Barnard’s dentexDentex barnardiis a relatively slow-growing, late-maturing species with an intermediate longevity (maximum recorded age = 13 years). The length and age structures of the population were similar for males and females; however, the sex ratio was female biased at 1:1.6. Growth was described by the three-parameter von Bertalanffy model as Lt = 332.14(1 e-0.14(t+3.97)). The species is a rudimentary hermaphrodite and the length- and age-at-50% maturity was calculated as 220 mm fork length and 3.7 years respectively. Reproductive activity in fish sampled in southern Angola was observed over an extended period during the austral summer (August–February) and a drop in water temperature is a possible ultimate cue for spawning activity in this species. The diet consisted mainly of teleost fish and mysid shrimps. The life-history characteristics of the species render it susceptible even to low levels of fishing pressure. Owing to the paucity of information on the fisheries for D. barnardi, and the current fisheries management situation in Angola, conventional management tools are not considered appropriate. The establishment of marine protected areas is suggested as the most appropriate management strategy for the species.Keywords: age and growth, feeding, life history, population structure, reproductionAfrican Journal of Marine Science 2012, 34(2): 223–231

Blacktail seabream Diplodus capensis were sampled from proximate (10 km apart) exploited and unexploited areas in southern Angola to compare their population structures and life-history parameters. Females dominated the larger size and older age classes in the unexploited area. In the exploited area the length and age frequency distributions were more equitable, but there was a lack of large and old individuals in this area due to the selective nature of fishing gear. Growth zone deposition rate was validated as being annual using mark-recapture of chemically injected (oxytetracycline) fish. In the unexploited area, females attained larger sizes and greater ages than males; however, growth and longevity were more equitable between the sexes in the exploited area. Length- and age-at-50% maturity were similar between the sexes in both areas. The sex ratio was heavily female-skewed (1:4.7) in the unexploited area but less so in the exploited area (1:2.2). Although the growth curves were significantly different for fish between areas, this was likely due to a reduction in longevity rather than a physiological change in growth. The length- and age-at-50% maturity was also similar between areas, indicating that this species either does not have the ability to respond to exploitation through physiological change in these life-history characteristics, or that the current level of exploitation is not high enough to elicit such a response. However, the female dominance in the smallest size class in the exploited area (compared to the unexploited area) indicated that a threshold may have been reached, and that this species responds to exploitation by increasing the relative number of fish that mature as females.Keywords: age and growth, blacktail seabream, maturity, sex ratio, subsistence fishingAfrican Journal of Marine Science 2011, 33(2): 191–201

The annual catch of octopus in the Rodrigues Lagoon, located east/north-east of Mauritius, has dropped by almost half since 1994. This has prompted concern over the resource and has initiated an assessment of the current status of the stock. The limited available biological information suggests that the main pulse of recruitment into the lagoon occurs in the first few months of the year, but that exact timing varies between years and additional staggered recruitment may occur throughout the year. Size frequency information suggests that the brooding period may be variable and extended, with a main peak between October and January. Catch-and-effort data were also limited, but a decreasing trend in catch per unit effort in two of the datasets examined allowed some preliminary withinseason assessment of population size (using a depletion model) at selected landing sites. The use of a migration bias correction formula suggested a net emigration from the lagoon, which might be indicative of adult movement into deeper waters. Depletion models seem to be useful as a management tool and should be tested further against more substantial monthly catch-and-effort data. In the interim, a precautionary approach of instituting a national seasonal closure for octopus fishing following periods of peak recruitment may have both economic and conservation benefits.Keywords: growth, management recruitment, Octopus cyanea, regulations, reproduction, stock assessmentAfrican Journal of Marine Science 2011, 33(1): 181–187

Ovarian atresia is described for the first time in cephalopods. Detailed histological examination of ovaries of Loligo vulgaris reynaudii in various stages of maturity revealed atresia in primary, previtellogenic and vitellogenicoocytes. These were analysed separately. Previtellogenic and vitellogenic oocytes could be subdivided into five clear stages, whereas primary atretic oocytes are given a general description. Follicular atresia lowers the number of maturing and mature eggs in the ovary, so previous fecundity estimates for cephalopods may have been too high. To correct potential fecundity estimates for losses arising from atresia, it is necessary to estimate the duration of each atresia stage in relation to the total spawning period.

The sparid Dentex macrophthalmus is a widespread, important fishery species along most of the West African coast from southern Namibia to the Mediterranean. In southern Angola it is an important artisanal species targeted predominantly by handline fishers. A biological and fisheries study was conducted on this species in southern Angola between June 2008 and July 2009. It was the dominant species in the artisanal fishery, accounting for 99% of the sparids captured and 67% (by mass) of the total catch. The life history of D. macrophthalmus was characterised by slow growth (females: Lt = 309[1 - e-0.06(t + 5.43)], males: Lt = 248[1 - e-0.16(t - 1.77)]), advanced age at maturity (females: 7.4 years, males: 6.0 years) and high longevity (females: 36 years, males: 38 years). The sex ratio was 1:1 male:female. The length- and age-frequency distributions and macroscopic observations suggested that the species is a late gonochorist. Males and females reached 50% maturity at 151 and 166 mm fork length respectively. Although individuals with ripe gonads were found during most of the year, the peak spawning period appeared to be in December and January. Despite a life history that renders D. macrophthalmus vulnerable to overexploitation, only 38% of artisanal fishers noticed a decline in the catches of this species. Potential reasons for this include: technology creep; limited pressure on the juvenile portion of the stock as a result of late recruitment (above the length of 50% maturity); the ‘basin affect’, whereby depleted areas are reseeded by areas (e.g. deeper water) inaccessible to the linefishery; and a deep-water reserve of large individuals. It is recommended that precautionary management strategies be implemented until the age estimates are revised by the countries in which this species forms significant fisheries.Keywords: growth, large-eye dentex, management, mortality, reproduction, SparidaeAfrican Journal of Marine Science 2010, 32(3): 601–611

The West Coast dusky kob Argyrosomus coronus is an understudied yet important fishery species in Angola. During a five-year study (2005–2009), the species was recorded in all fishery sectors, but was most important in the inshore recreational fishery in southern Angola (Cunene Estuary to Namibe). Early juveniles (870 mm TL) were captured in all fisheries as far north as Namibe, and shoals of large adult fish (>1 000 mm TL) were occasionally captured in the offshore purse-seine commercial fishery between the Cunene Estuary and Lucira. Because some Argyrosomus species are morphologically cryptic, a DNA barcoding method was used to confirm the taxonomic status of the biological samples used in this study. The male:female sex ratio of examined samples was 1:1.4 (n = 225). The length-at-50% maturity was 823 mm and 904 mm TL for males and females respectively. Age-at-50% maturity was 4.4 and 4.3 years for males and females respectively. The periodicity of otolith ring formation was confirmed to be one year using a marginal zone and a chemical marking analysis. Growth (in mm TL) was best described by: Lt= 1 826(1 – e-0.12(t + 1.60)). Argyrosomus coronus fed predominantly on fish, mainly Sardinella aurita (62% frequency of occurrence). Early juveniles appeared to frequent the offshore zone (50–100 m depth), moving into the inshore region at approximately 300 mm TL. Juveniles and subadults were resident (57% recaptured at the same site) and were particularly abundant around the mouth of the Cunene Estuary as well as in central and northern Namibia. Adults undertake migrations that correspond with the movement of the Angola–Benguela frontal zone, moving north as far as Gabon in winter and returning to southern Angola in spring, when spawning appeared to take place offshore. There are currently no catch restrictions on A. coronus in Angolan waters. However, declining catches and increasing fishing effort suggest that some management intervention is required, commencing with a proposed closure of the Cunene Estuary mouth region to fishing. Keywords: fisheries, growth, management, reproduction, SciaenidaeAfrican Journal of Marine Science 2010, 32(2): 247–258

The coastline of southern Angola is sparsely populated and, largely because of a protracted civil war, has very lightly exploited inshore fish stocks. This has provided the almost unprecedented opportunity to determine prefishing-state reference points and to implement management strategies at the early stages of exploitation. The leerfish Lichia amia is distributed from the Mediterranean Sea, along the west coast of Africa to the southern and eastern coasts of South Africa. Despite its importance in recreational catches in South Africa and Angola, there is little information on the biology of this species. The leerfish is one of the three most dominant recreational shore-fishery species in southern Angola, and a biological study on the species was conducted in that region between May 2005 and December 2006. The mean length of captured fish was 767 mm fork length (FL) and 6.8 kg, and the catch per unit effort was 0.13 fish angler–1 h–1 and 0.79 kg angler–1 h–1. The growth of the leerfish population (in mm) was described by: Lt = 1 137(1 – e0.22(t + 1.58)), and its total mortality was estimated to be 0.41 (±0.05). Female mortality (0.40 ± 0.06) was lower than that for males (0.44 ± 0.14), and the length and age-at-50% maturity was 623 mm FL and 2.4 years respectively. Female fish with ripe ovaries were found between June and November. The male:female ratio was 1:1.9. Leerfish fed exclusively on fish, mainly sardinella Sardinella aurita (62% frequency of occurrence). Based on this biological information, a theoretical Traffic Light Precautionary Management Framework is constructed for the species. Appropriate management regulations and potential future threats to the species are discussed. Keywords: Carangidae, growth, leervis, management, mortality, regulations, reproductionAfrican Journal of Marine Science 2008, 30(1): 113–121

In attempts to achieve sustainability, ecosystem-based approaches to fisheries management are becoming increasingly applicable. Indicators to assess the success of management measures are an important component of this approach. Data from a recreational linefishery are used to develop and propose a simple set of indicators to assess local fishery sustainability. The indicators have been organised within a framework based on the ecological, institutional and social sustainability domains and scored through a rapid assessment matrix. Results indicate that the estuarine, rock-and-surf (coastal) and skiboat-based fisheries in Plettenberg Bay on the south coast of South Africa are presently non-sustainable. The institutional domain had very low scores whereas the socio-economic domain had the highest scores. The validity and usefulness of the indicators as a tool for the development of local fishery management plans are discussed. Keywords: EAF; indicators; local management; Plettenberg Bay; rapid assessment matrix; recreational fisheries; South Africa; sustainabilityAfrican Journal of Marine Science 2007, 29(3): 511–525

The feasibility of a directed trap-fishery for panga Pterogymnus laniarius was investigated with special emphasis on minimising the bycatch. A total of 1 302 fish, representing 19 species, was captured in 59 trap deployments at three locations along the Eastern Cape coast of South Africa between September 2002 and July 2004. Panga comprised over 55% of the total catch, with an average of 12 panga per trap haul. Depth and substrate type had a significant effect on the species composition of the catch. Panga comprised 77% of the catch in depths >50m, whereas other commercially important species contributed 11% to the total catch in water >50m. No kingklip Genypterus capensis were captured in the traps and shallow-water Cape hake Merluccius capensis accounted for only 0.2% of the total catch composition. The findings suggest that trap-fishing provides a new fishing opportunity in South Africa with a high catch per unit effort for the target species and a low level of bycatch. Keywords: bycatch, mesh selectivity, panga, Pterogymnus laniarius, soak time, trap-fisheryAfrican Journal of Marine Science 2007, 29(3): 465–472

No Abstract.African Journal of Marine Science Vol.29(2) 2007: pp.259-270

The movement behaviour of adult Roman Chrysoblephus laticeps (Sparidae) was investigated using mark-and-recapture techniques in the Goukamma Marine Protected Area (GMPA) and the Tsitsikamma National Park (TNP) on the South African temperate south coast. The study was designed to improve the spatial resolution of previous studies on Roman that suggested residence behaviour, but which could not estimate home range size. A combination of conventional barbed dart tags and visible implant fluorescent elastomer (VIFE) tags were used to tag Roman from a skiboat in the GMPA. Roman were tagged with dart tags from the shore in the TNP. Of the recaptures, 61% were within 50m of the tagging position, confirming that Roman are very resident. A few fish, independent of size and sex, moved distances up to 4km. A model was developed to quantify the degree of residence, by accounting for tag loss, mortality and the distribution of recovery effort. The probability of a Roman remaining within an area of 1ha is 0.91 (GMPA) and 0.94 (TNP) — such a small home range suggesting that individual Roman would benefit from small MPAs. Keywords: Chrysoblephus laticeps; dart tags; mark and recapture; maximum likelihood; MPAs; site fidelity; VIFE tagsAfrican Journal of Marine Science 2007, 29(1): 93–103

Six early, post-cleavage embryonic stages for chokka squid Loligo vulgaris reynaudii eggs that were developed in an aquarium are identified and described, expanding the embryonic stages for this species from 14 to 20. The influence of water temperature on embryonic development is described. At temperatures 15&#176C, high percentages of morphological abnormalities were observed in embryonic development. Gross forms are described and illustrated.Keywords: abnormalities, aquarium, embryonic development, chokka squidAfrican Journal of Marine Science 2002, 24: 379–382

The availability of resources and their suitability for subsistence and small-scale commercial fishers in South Africa were assessed and appropriate options for the management of resources recommended. Assessment of current resource utilization and recommendations for future subsistence and/or small-scale commercial use were based on information gathered during a nationwide survey of 144 subsistence fishing communities in South Africa and a review of relevant published and unpublished literature. Current patterns of resource use in three regions of the coast (West, South and East coasts) revealed that most true subsistence fisheries occur in the eastern half of the country. These fisheries are primarily focused on invertebrate species found on intertidal rocky shores and sandy beaches, or in estuaries. Fish are harvested by rod or handline, netting or traditional fishing methods (fishtraps, spearing, baited baskets). No “new” or previously underutilized resources were identified as suitable for subsistence fishing in any of the three regions. The potential for several new small-scale commercial fisheries was identified, but the need to retain certain resources for subsistence fisheries (rather than converting them to small-scale commercial fisheries) was evident in certain areas. Resources with high commercial value were not considered suitable for subsistence fishing, but rather for the introduction of small-scale commercial fisheries. The overall management strategy for the subsistence sector, which is currently in the process of being developed, must ensure sufficient flexibility to be able to take into account regional and site-specific requirements. It will also need to develop co-management structures, protect traditional fishing practices, avoid user conflict and provide for no-take areas, all within the framework of sustainable resource utilization.Keywords: estuarine resources, fisheries management, intertidal resources, subsistence fisheries, subtidal resourcesAfrican Journal of Marine Science 2002, 24: 489–501