FAO Fisheries Circular No. 920 FIRM/C920
REVIEW OF THE STATE OF WORLD FISHERY RESOURCES: MARINE FISHERIES
Marine Resources Service,
Fishery Resources Division,
FAO, Rome, Italy
7. SOUTHEAST ATLANTIC
FAO Statistical Area 47
This section deals with the three countries with coastlines on the Southeast Atlantic (Figure B7.1): Angola, Namibia and South Africa. Included in the catches of the last-named are some taken from the western Indian Ocean. However, discounting the Agulhas Bank, which is now considered a part of the Benguela upwelling system, these landings form a very small part of the total for the region. The rest of the region is dominated by the Benguela upwelling system which, through the injection of cold nutrient-rich water into the surface waters, supports relatively high production along much of the coastline of these three countries. The northern border of the Benguela upwelling system occurs at the marked thermal front with the warm Angola Current, between about 15S and 17S in southern Angola.
This area is marked by productive and well established fisheries that have a general history of good management in recent decades after periods of over-exploitation, particularly in the 1950s and 1960s. Despite the level of management intervention, however, a number of fisheries are in a tenuous state, apparently largely because of environmental influences. The pelagic fisheries in the region are being affected by declines in sardine abundance in the north and anchovy abundance in the south, while the trawl fishery in Namibia and Angola is being affected by a decline in hake abundance in their waters. Research activities in this area are mainly undertaken by the Instituto de Investigacao Pesqueira, Angola, the National Marine Information and Research Centre, Namibia and the Sea Fisheries Research Institute, South Africa, who are thanked for providing invaluable data and information for this section.
PROFILE OF CATCHES
Total catches from the region increased rapidly in the 1950s and 1960s, primarily due to fishing by distant-water fleets. Since the early 1960s the pattern in total catches has been almost entirely due to catches of species within ISSCAAP Groups 32, 34 and 35 (Figure B7.2). The total catch declined in the late 1980s and subsequently fluctuated around 1.4 million tonnes in the early 1990s. The largest national landings in 1994 were made by South Africa, with a total catch of over half a million tonnes, followed by Namibia (300 000 t) and Angola (71 000 t, Table B7.1). However, some foreign fishing also takes place in Namibian and Angolan waters and, for example, in 1994 nearly 230 000 t of Cape horse mackerel was caught, mainly by the Russian Federation, Ukraine and Estonia, as well as approximately 30 000 t of Cape hakes Merluccius paradoxus and M. capensis, mainly by Spain.
Landings made by the fisheries of Angola, Namibia and South Africa in 1994, in '000 t
The pelagic fisheries in the area are dominated by the Southern African pilchard and anchovy (Figure B7.3), with catches of Whitehead's round herring having been the third most abundant species in recent years (Table VII). Sardinella spp are caught mainly in Angolan waters. These species all fall into ISSCAAP Group 35, which accounted for the highest mass of landings in the fisheries of this region in 1994 (Table VII). Catches by the pelagic fisheries of the sub-region, generally making use of purse-seine nets, were dominated by the Southern African pilchard until the early 1970s, when over-fishing, probably coupled with adverse environmental conditions, caused a drastic decline in abundance. Hence, anchovy were caught in increasing numbers during this period of sardine decline, particularly in the southern parts of the sub-region, and thereafter became the dominant species in the South African pelagic fishery. In recent years, however, the pilchard has shown encouraging increases, while anchovy has been highly variable but with an overall decline in landings since 1988.
The ISSCAAP Group contributing the second highest landings, by weight, from the region in 1994 was group 34 (Jacks, mullets, sauries, etc.). Landings of species within this group amounted to nearly 400 000 t in 1994. Of this, over 280 000 t was Cape horse mackerel and another 100 000 t of Cunene horse mackerel. The Russian Federation recorded the bulk of these landings, accounting for 50% and 70% of the Cape and Cunene horse mackerel landings respectively. Of the countries within the region, Namibia landed the most Cape horse mackerel (34 000 t) and Angola the most Cunene horse mackerel (29 000 t). Cape horse mackerel landings increased rapidly in the 1970s (Figure B7.4), probably as a result of a redirection of effort in response to declining landings of hakes and sardine, possibly associated with the entry of several strong year classes into the population. Landings have subsequently shown a general decline since the early 1980s, while those of Cunene horse mackerel have been variable but not shown a sustained increase or decrease over the same period.
The third highest landings in the region in 1994 came from ISSCAAP Group
32 (Cods, hakes, haddocks, etc.) with landings of approximately 266 000 t.
Within this group, Cape hakes accounted for the highest catch mass from the
fisheries of the sub-region, with a total catch in 1994 of 266 000 t. The
range of the two species within this catch group, M. capensis and M.
paradoxus, extends over South Africa and Namibia, with the shallow water
Cape hake, M. capensis also extending into Angola. Catches in Namibia
and on the Agulhas Bank on the southern tip of Africa, are dominated by M.
capensis, while along the West Coast of South Africa M. paradoxus
is the dominant component of catches. The large eye Dentex is an important
demersal species in Angola and supported landings of over 2 000 t in 1993
and 1994. The landings of hakes in the region reflect the very heavy exploitation
of the 1960s and 1970s (Figure B7.4).
|Figure B7.5||Figure B7.6|
RESOURCE STATUS AND MANAGEMENT
The pelagic fisheries are particularly important in Namibia and South Africa within region 47, and the stocks are closely monitored in both countries, making extensive use of hydroacoustic surveys. In November 1994, hydroacoustic survey results suggested that sardine (597 000 t) was more abundant than anchovy (476 000 t) in South African waters for the first time since such surveys were started there in 1984. This reversal persisted in November 1995, but the estimated sardine biomass had decreased marginally to 580 000 t over the year. However, during this period the northern component of the sardine population, occurring in Namibia and Angola, has been estimated to have declined from approximately 800 000 t in 1992 to less than 100 000 t at the end of 1995. At the same time, it has contracted towards the warm frontal zone in Angola. As a result of this shift, Namibian vessels were licensed to fish in Angolan waters for the first time in 1995. The decline in sardine abundance in the northern Benguela has also been associated with the unusually anoxic state of the coastal marine environment.
A secondary result of the shift of the northern sardine stocks into Angola, described above, was a similar shift northwards of the Cape fur seal, causing concern in Angola of adverse impacts on the local fish resources through increased predation. This movement of seal northwards followed reported incidences of starvation-induced mortality of seal pups in 1994, followed by high incidences of abortion of foetuses and of adult mortality. Clearly, the Benguela system in the region of Namibia and southern Angola has been suffering a severe environmental anomaly.
Both stocks of Cape hakes were heavily depleted in the 1960s and 1970s (as reflected in the catches described above), before more conservative management approaches were instituted. Since then the stocks are estimated to have recovered somewhat and, in Namibia, to have recovered particularly after independence, when foreign fleets were prevented from fishing in the country and conservative TACs were introduced. Within South African waters, there have been no major anomalies in the population trends detected in recent years and the hake stocks are generally considered to be either stable or to have increased to some extent since the over-exploitation of two decades ago. However, Namibian surveys in their own waters have suggested substantial declines in the abundance of M. capensis hake stocks since 1993, possibly as a result of unusually low oxygen levels along the coast. The total allowable catches for the species group have been set at 150 000 t 1996 in both South Africa and Namibia.
The status of the Cape rock lobster stock is cause for concern, and catches for the sub-region have declined virtually continually since the 1950s (described above), despite conservative management approaches in both Namibia and South Africa, where catches are taken. There was some apparent growth of the biomass in South Africa in the mid 1980s, possibly in response to a reduction in the TAC from 5 600 t in the 1970s to 3 600 t in 1981. However, the population was struck by very low somatic growth rates in the late 1980s and, despite reductions in the TAC to a low of 1 500 t in 1995/96, the population appears to have continued to decline. The catches in Namibia and South Africa in 1994 were 134 t and 2198 t respectively. The other major contributor to the landings of Group 43 is the Southern spiny lobster. Landings of this species had been maintained at approximately 1 000 t since 1990 but have been reduced slightly since 1994 as a result of new estimates of the productivity of the stock.
Since the peak landings of abalone in the 1960s, more conservative management approaches have been implemented and, under TAC control, the recorded landings have been relatively constant at approximately 600 t in recent years. There is some concern over the status of the stock, however, particularly in the light of unknown but suspected high, levels of illegal catch. Mariculture has had a pronounced impact on the production of molluscs from the region, and culture of the Mediterranean mussel, started in 1985, has risen to 2 300 t, with another 400 t of unidentified mussels in 1994. Between approximately 500 and 600 t per year of Pacific cupped oyster has also been produced by mariculture since approaching a plateau in 1989.
A growing fisheries management issue in the area is the rapidly increasing interest in fisheries for deepwater species including orange roughy Hoplostethus atlanticus and Patagonian toothfish Dissostichus eleginoides. The former has been found within the continental EEZs of the three countries and is suspected to be a straddling stock, extending outside the EEZs as well. The Patagonian toothfish occurs within South Africa's EEZ around Prince Edward Island in the Southern Ocean and also extends into international waters. The countries of the region are currently discussing the establishment of one or more multilateral organizations to oversee management of these multilateral stocks. There is a strong desire to avoid a rapid depletion of the slow-growing stocks and to manage them in a responsible and sustainable manner.