S. J. Lamberth

A survey of the South African shore-angling fishery

Roving creel surveys and aerial surveys of shore-angling were undertaken as part of a national investigation into linefishing in South Africa. Shore patrols utilized a random stratified sampling procedure to collect catch-and-effort data, and a questionnaire provided information on fishing effort, angler demographics, economics and attitudes towards current regulations. A total of 1 677 patrols, covering 19 616 km, was conducted between April 1994 and February 1996, during which period 9 523 anglers had their catches checked and 4 490 were interviewed. A further 16 497 km were covered by aerial surveys, when 22 609 anglers were counted. From the aerial surveys, angler densities were highest on the KwaZulu-Natal coast (4.65 anglers·km−1), followed by the Southern Cape coast (2.29 anglers·km−1), the Eastern Cape coast (0.36 anglers·km−1) and the West Coast (0.12 anglers·km−1). Catch rates varied from 1.5 kg·angler−1·day−1 on the Southern Cape coast to 0.45 kg·angler−1·day−1 on the KwaZulu-Natal coast. Total...

An economic valuation of the South African linefishery

Economic data collected during 1995 and 1996 in a national survey of shore-anglers and skiboat fishermen is used to provide an economic assessment of aspects of recreational, subsistence and commercial linefishing on the South African coastline. Results show that more than 90% of shore-anglers have incomes which lie in the highest two quintiles of the distribution of incomes, and that <5% of rock-and-surf anglers were members of a household that was in poverty. Estimated mean income of commercial skiboat operators also fell into the upper 40% of incomes, but the estimated incomes earned by their crew barely exceeded the poverty line. A low income elasticity of demand was estimated for fishing trips by recreational anglers, predicting that the growth in demand for recreational fishing trips will slow with economic growth. The price elasticity of demand was also estimated to be low, indicating that the levying of an annual licence fee will not be effective in reducing effort. The macroeconomic importance of...

An evaluation of attitudes and responses to monitoring and management measures for the South African boat-based linefishery

The boat-based linefishery in South African waters was investigated between 1994 and 1996. Methods involved a combination of access point and questionnaire surveys to collect catch and effort data, and to assess responses to management measures by the commercial and recreational fishing sectors. Compulsory catch returns submitted from commercial vessels were validated from direct observations. Results revealed substantial errors in compulsory catch returns; where over-reporting was high, it was not possible to quantify these statistically because of the high variance obtained when combining these data with both nil returns and under-reporting. Where over-reporting was negligible, statistical assessment was possible for some key species and areas. These were calculated to be under-reported by an overall factor of 2.87±0.94. The inclusion of the recreational component of the overall catch provides the most comprehensive coverage of that sector to date. The results indicate that increased attention should be...

An evaluation of participation in and management of the South African spearfishery

An evaluation of participation and management of the South African spearfishery was undertaken by analysing spearfishing catch and effort data stored on the National Marine Linefish System (NMLS) and by conducting a creel and questionnaire survey. Results indicated that the spearfishery is the smallest sector of the linefishery, with an estimated 7 000 participants and an annual compounded growth rate of 6.14%. Regional comparisons of catch composition and catch-per-unit-effort (cpue) were made, although spearfishing data stored on the NMLS were biased in favour of KwaZulu-Natal. Analysis of the data from KwaZulu-Natal showed little evidence of a decline in cpue or significant changes in species composition between 1984 and 1995. However, considerable overlap was noted between catches of spearfishermen and those made by other sectors of the linefishery. Of the 950 postal questionnaires sent to KwaZulu-Natal licence-holders, 152 (16%) were returned. A further 38 personal interviews and 74 creel inspections...

Characteristics and value of the Thukela Banks crustacean and linefish fisheries, and the potential impacts of changes in river flow

This study describes the Thukela Banks crustacean and linefish fisheries and investigates the potential impacts of reduced flow from the Thukela River on the value of these fisheries. Data were obtained from published and unpublished material, key informants and government records. The crustacean fishery employs about 300 people, and comprises an inshore and offshore fishery. Inshore catches and effort are strongly seasonal, peaking in April to June. The probability of fishing in any particular month is positively correlated with catch per unit effort. Average overall annual catch (inshore and offshore) was estimated to be in the region of 700 tonnes for 1992–2002 with a gross output of about R36.7 million per annum, and a gross value added (net output) of R13.8 million (1 US

First documented southern transatlantic migration of a blue shark Prionace glauca tagged off South Africa

= R6.40; 2003). Inshore prawns were estimated to contribute R8.5 million of the gross output. The Thukela Banks was estimated to contribute R4.5 million and R35 million (rand value in 2003) to the gross output of the commercial linefishery and boat-based recreational angling fishery respectively. Freshwater reduction scenarios yielded 0.7–11% reductions in prawn catches, which translated into only a 1–2% drop in the annual value of the fishery. The latter was attributed to the fisherys diversity (predominantly the buffering effect of bycatch) and the fact that the stocks of the species targeted by the offshore component are largely independent of flow. Catches and value of the recreational boat-based linefishery were predicted to remain fairly constant irrespective of any changes in flow. The commercial linefishery was the most responsive, with a 20% decline in total catch and 17% value predicted for the most extreme flow reduction scenario.

The current status and management of South Africa's chondrichthyan fisheries

The first documented recapture of a South African-tagged juvenile blue shark Prionace glauca off Uruguay lends weight to the hypothesis of a single blue shark population in the South Atlantic. The presence of neonate blue sharks with umbilical scars and females with post-parturition scars, as well as the high frequency of small juveniles in research longline catches, confirm the existence of a parturition and nursery area off South Africa. The final positions of three tagged sharks suggest that large-scale movement patterns in the South Atlantic are a mirror image of movements in the North Atlantic, with sharks using the north-westerly Benguela Drift to migrate into the tropics and ultimately across into South American waters. The confirmed existence of a parturition and nursery area off the south coast of South Africa and the movement of sharks into both adjacent ocean basins suggest that the southern African blue sharks are part of a single stock that straddles the South Atlantic and Indian oceans, and possibly the entire Southern Hemisphere.

Assessment of the effectiveness of South Africa's marine protected areas at representing ichthyofaunal communities

Chondrichthyans (sharks, skates, rays and chimaeras) are captured in many marine fisheries. Management and research efforts directed at chondrichthyan fishing are often neglected because of low product value, taxonomic uncertainty, low capture rates, and harvesting by multiple fisheries. In South Africas diverse fishery sectors, which include artisanal as well as highly industrialised fisheries, 99 (49%) of 204 chondrichthyan species that occur in southern Africa are targeted regularly or taken as bycatch. Total reported dressed catch for 2010, 2011 and 2012 was estimated to be 3 375 t, 3 241 t and 2 527 t, respectively. Two‑thirds of the reported catch was bycatch. Regulations aimed at limiting chondrichthyan catches, coupled with species‑specific permit conditions, currently exist in the following fisheries: demersal shark longline, pelagic longline, recreational line, and beach‑seine and gillnet. Limited management measures are currently in place for chondrichthyans captured in other South African fisheries. Catch and effort dataseries suitable for stock assessments exist for fewer than 10 species. Stock assessments have been attempted for five shark species: soupfin Galeorhinus galeus, smoothhound Mustelus mustelus, white Carcharodon carcharias, spotted ragged‑tooth Carcharias taurus, and spotted gully Triakis megalopterus. Fishery‑independent surveys and fishery observer data, which can be used as a measure of relative abundance, exist for 67 species. Compared with most developing countries, South African shark fishing is relatively well controlled and managed. As elsewhere, incidental capture and bycatch remain challenges to the appropriate management of shark species. In 2013, South Africas National Plan of Action for the Conservation and Management of Sharks (NPOA‑Sharks) was published. Implementation of the NPOA‑Sharks should help to improve chondrichthyan management in the near future.

Genetic analyses reveal declining trends and low effective population size in an overfished South African sciaenid species, the dusky kob (Argyrosomus japonicus)

SUMMARY National and international policies have encouraged the establishment of a representative network of marine protected areas (MPAs) in South Africa, with the aim of protecting marine biodiversity. The extent to which these marine and estuarine protected areas (EPAs) represent marine fish species and communities was assessed by comparing their species compositions with those of exploited areas, as sampled using four fishing techniques. Seven hundred fish species were sampled, representing one-third of South Africa’s marine fishes. MPAs in coastal habitats scored c. 40% on the Bray-Curtis measure of similarity for species representativeness, but this score declined markedly for offshore ‘trawlable’ fishing grounds. The combined effects of sampling error, temporal variation and the effects of fishing on relative abundance suggest that 80% similarity would be the maximum achieveable. Forty-nine per cent of all fish species that were recorded were found in the 14 MPAs sampled. Redundancy in the MPA network was low, with fish species most commonly being represented in only one MPA or absent. There was greater redundancy in the 33 EPAs, with 40% of species being found in two or more EPAs, but many of these estuaries were adjacent to each other and embedded in large MPAs. Deep water fish communities (>80 m deep) and communities located on the west and south-east coasts of South Africa were most poorly represented by MPAs. Routine fishery surveys provide a robust and repeatable opportunity to assess species representativeness in MPAs, and the method used could form the basis of an operational definition of ‘representative’. In contrast to an assessment based on presence-absence data, this analysis of quantitative data presents a more pessimistic assessment of protection.

Identification of naturally occurring hybrids between two overexploited sciaenid species along the South African coast

Overfishing has led to the collapse of many marine fish stocks along the South African coast, particularly species characterised by predictable distribution patterns and vulnerable life-history traits. Dusky kob (Argyrosomus japonicus) is an estuarine-dependent sciaenid fish that has been severely depleted by overfishing and is currently managed by suboptimal management measures aggravated by poor enforcement and compliance to regulations. The present study utilised microsatellite markers to evaluate levels of genetic diversity and population structuring of dusky kob along the South African coast, including five estuarine areas. Results showed signatures of bottlenecking, low and declining trends of effective population size and weak differentiation among samples collected along 2000km of coastline, indicating that dusky kob continues to be subject to the detrimental influence of fishing pressure. Additionally, because dusky kob is a key species in the emerging South African aquaculture sector, parentage analyses were used to successfully identify the origin of first-generation (F1) individuals from a commercial hatchery, hence allowing traceability of farmed products and discrimination between wild and farmed fish. Findings from the present study provided essential information to aid future management of wild populations, as well as to establish sustainable fish farming.