Habitat and Biology
Climatic zone: Tropical; Temperate; Polar.
The environmental conditions range from typically tropical in the north to sub-Antarctic in the south. Towards the northern part of Area 41, the marine environmental conditions are dominated by the South Equatorial Current. This current flows from the coast of Africa until it hits the South American coast. There, it branches into the North Brazil Current, which flows along the north Brazilian coast, and the Brazil Current, which flows south along the central and southern Brazilian coast. The northern part of Area 41 is further influenced by the great flow of freshwater from the Amazon River. Further south, the marine environment is dominated by the warmer southward-flowing Brazil Current and then by the colder northward-flowing Falkland Current (Malvinas Current). These currents merge into an offshore flow of subtropical convergence just off the Plate River. This is a region where there is also a large flow of freshwater into the coastal ecosystems (Emílsson, 1959; Hempel, 1971; Dias Neto and Mesquita, 1988; Bakun and Parrish, 1991; Bakun, 1993; Castro and Miranda, 1998).
Water Area Overview
Area 41 covers a total surface of 17.65 million km2 off the east coast of South America, between latitudes 05°00’N off northern Brazil and 60°00’S off southern Argentina, and includes a total shelf area of 1.96 million km2 (Figure B6.1). In the north, the continental shelf may extend as far as 160 nm (320 km) offshore from the Amazon River, where the bottom is mostly river deposits and debris. As one moves south away from the influence of the Amazon River, the shelf becomes narrow, coralline and mostly unsuitable for trawling. The shelf is also narrow and mostly rocky further south off central and southern Brazil. Closer to the southern extent of Area 41, it widens and becomes more suitable for trawling. The best and largest areas for trawling are found around the Plate River and over the Patagonian shelf and the area of the Falkland Islands (Malvinas). In these regions, the shelf extends well beyond the 200‑nm limit (more than 370 km) off the coastline. This makes this region the largest area of continental shelf in the Southern Hemisphere.
The variety and abundance of fishery resources and types of fisheries in Area 41 are determined by a combination of physical and environmental characteristics. Shrimps and lobsters, and to a lesser extent reef fishes and other tropical demersals, tend to be of particular relevance towards the northern part of Area 41. Further south, important populations of small pelagics are found in nutrient-rich coastal regions where water masses mix off central Brazil and off Uruguay–northern Argentina. This mostly occurs around the Plate River. Coastal demersals are particularly important off southern Brazil and in the vicinity of the Plate River. Whereas mid-water and deepwater demersals tend to dominate over most of the continental shelf in the vicinity of the Plate River, the Patagonian shelf and the Falkland Islands (Malvinas). The region of the Falkland Islands (Malvinas) is also important for squids. Large pelagics are mostly caught off central Brazil and the Plate River.
|Figure B6.1 The Southwest Atlantic (Area 41) |
Considered a single stock: No
PROFILE OF CATCHES
Most capture fish production from Area 41 comes from demersals and squids. This is one of the FAO Statistical Areas where capture fisheries grew rapidly until the late 1990s. In the last decade, total catches from Area 41 have stabilized, although with marked interannual fluctuations. In 1950, the total catch for the whole of Area 41 was only 172 000 tonnes. At that time, most of the known fish stocks were only lightly or moderately exploited, and several important stocks were still virtually unexploited.
A number of new fisheries have developed since, and total annual catches increased steadily at an average rate of 7.4 percent per year to reach a maximum of 2.4 million tonnes in 1987. There was an exceptional spike in catches between 1966 and 1968, with a peak catch of 599 000 tonnes in 1967 caused by an intense pulse of fishing for hake and probably other demersals by the then Soviet Union fleet (Figure B6.2). Catches declined after 1987, to a low 2.0 million tonnes in 1990 and 2.1 million tonnes in 1994. A new maximum was reached in 1997 at 2.8 million tonnes. Since then, catches have been fluctuating between 2.0 and 2.5 million tonnes (Figure B6.2 and Table D6).
Demersal species in ISSCAAP Group 32 (cods, hakes, haddocks) and molluscs in Group 57 (squids, cuttlefishes, octopuses) are the major contributors to the catches from this region. The next most-important catch groups are the coastal species in Group 33 (miscellaneous coastal fishes such as croakers and weakfishes), the small pelagics in Group 35 (herrings, sardines, anchovies), and other demersals in Group 34 (miscellaneous demersal fishes such as toothfish and cusk-eel) and Group 38 (sharks, rays, chimaeras). The dominant species in the demersals of Group 32, in terms of volume, are the Argentine hake (Merluccius hubbsi), the Patagonian grenadier (Macruronus magellanicus), and the southern blue whiting (Micromesistius australis). Among the other groups, the Argentine shortfin squid (Illex argentinus) in Group 57, and the Brazilian sardinella (Sardinella brasiliensis) in Group 35 contributed the largest catches.
|Figure B6.2 Annual nominal catches by ISSCAAP Groups in the Southwest Atlantic (Area 41) |
The Argentine hake sustains one of the most important fisheries in the region of the Plate River and over most of the Patagonian shelf. Total catches of this species steadily increased from 1950 to 102 000 tonnes in 1965. Catches were at first all taken by the coastal States (Argentina, Brazil and Uruguay). Following the exceptionally high catches of hake reported by the then Soviet Union in 1967 (513 000 tonnes), catches declined to 70 000 tonnes in 1969. The total catch from this region then increased steadily to 462 000 tonnes in 1979, and then gradually increased to a record high of 682 000 tonnes in 1996. Since then, total catches of Argentine hake rapidly declined to a record low of 243 000 tonnes in 2000 and have fluctuated since. Reported catches in 2009 were 331 000 tonnes (Figure B6.3).
The Argentine hake is mostly exploited by Argentine and Uruguayan fleets. Both fleets increased in the 1980s to the early 1990s, and the Argentine fleet continued to increase in the 1990s. Other deepwater demersals in Group 32 that make a significant contribution to the total fish production in Area 41 are the Patagonian grenadier and the southern blue whiting (Figure B6.3). These species produced 135 000 tonnes and 32 000 tonnes, respectively, in 2009. They are particularly abundant in the southern Patagonian shelf and slope, where they are exploited by long-range fleets from the region as well as by distant-water fleets.
|Figure B6.3 Annual nominal catches of selected species in ISSCAAP Group 32, Southwest Atlantic (Area 41) |
The miscellaneous demersals in Group 34 (Figure B6.4) that contribute most to total fish production in Area 41 are the pink cuskeel (Genypterus blacodes) and Patagonian toothfish (Dissostichus eleginoides), with 21 000 tonnes and 5 000 tonnes, respectively, in 2009. These species are exploited by both coastal and long-range fleets from the region and from other FAO Statistical Areas. Coastal demersal species within Group 33 also produce significant catches within Area 41, particularly the Argentine croaker (Umbrina canosai), the striped weakfish (Cynoscium striatus), the whitemouth croaker (Micropogonias furnieri), and other weakfishes (Cynoscion spp.). These species have reported relatively high and stable catches in the past few years, with a total of 140 000 tonnes for the four species in 2009. These species are all exploited by coastal fleets.
|Figure B6.4 Annual nominal catches of selected species in ISSCAAP Groups 33 and 34, Southwest Atlantic (Area 41) |
The main small pelagic species within Group 35 are the Brazilian sardinella (S. brasiliensis) and the Argentine anchovy (Engraulis anchoita). After the record catches of 228 000 tonnes of Brazilian sardinella reported in 1973, total catches of this species declined. The total catch of Brazilian sardinella hit a low of 17 000 tonnes in 2000. Since then catches have been steadily increasing, reaching 83 000 tonnes in 2009 (Figure B6.5). Catches of Argentine anchovy reached a maximum of 44 000 tonnes in 2005 and 2006, declining to 28 000 tonnes in more recent years. Catches of tunas and other large pelagics in Group 36 have been more or less stable at 50 000–70 000 tonnes per year, after reaching a maximum of 74 000 tonnes in 1996.
|Figure B6.5 Annual nominal catches of selected species in ISSCAAP Groups 35, 36, Southwest Atlantic (Area 41) |
Another very important fishery in Area 41 is that for squids (Group 57). The main species is the Argentine shortfin squid (Illex argentinus). It represented 87 percent of the squid catches and 14 percent of total marine catches in Area 41 in 2009. The overall abundance and actual catches of Argentine shortfin squid have been very variable since the fisheries started in the late 1970s. After reaching 638 000 tonnes in 1993, total catches of this species declined to 506 000 tonnes in 1994, before increasing to a record high of 1.1 million tonnes in 1999. From 2000 to 2009, catches fluctuated widely between 179 000 tonnes and 955 000 tonnes. Catches in 2009 (261 000 tonnes) were among the lowest catches in the last two decades (Figure B6.6). Although less abundant, total catches of Patagonian squid (Loligo gahi) also fluctuated between a maximum of 89 000 tonnes in 1989 and a low of 22 000 tonnes in 1997. In 2009, the total catch of this species was 35 000 tonnes. Another squid species caught occasionally is the seven-star flying squid (Martialia hyadesi). Catches are usually low, ranging between 0 and 1 000 tonnes/year in most years. The exception was a record high catch of 24 000 tonnes in 1995. This exceptional catch was followed by catches of 3 800 tonnes and 8 300 tonnes in 1996 and 1997. Catches of other non-identified squids has declined sharply in recent years, suggesting great improvements in the identification at species level of squid catches from Area 41.
|Figure B6.6 Annual nominal catches of selected species in ISSCAAP Group 57, Southwest Atlantic (Area 41) |
Shrimps, prawns, lobsters, crabs and other crustaceans in Groups 42, 43 and 45 also sustain important local fisheries throughout Area 41 from the tropics to the sub-Antarctic zone. Altogether, these species groups have yielded total catches of more than 100 000 tonnes since 2000 (Figure B6.7). These are important volumes considering their relatively high market value. The single crustacean species yielding the largest catches is the Argentine red shrimp (Pleoticus muelleri). It has highly variable catches ranging from 3 000 to 50 000 tonnes/year since the fishery started in the 1980s. The highest record catch of 79 000 tonnes was reported in 2001. In 2009, the total catch of this species was 54 000 tonnes. About 3 percent of the total catches in Area 41 (55 779 tonnes in 2009) are reported as “not identified marine fishes” in the official FAO statistics. These species are grouped under ISSCAAP Group 39 (marine fishes not identified). These mostly come from smallscale fisheries, particularly in Brazil, where the variety of species and landing sites makes the recording of catches by species a difficult task.
|Figure B6.7 Annual nominal catches of selected species in ISSCAAP Groups 42, 43 and 45, Southwest Atlantic (Area 41) |
Management unit: No
International fisheries research, stock assessment and fisheries management activities in Area 41 are mostly dealt with through bilateral arrangements. Argentina and Uruguay cooperate mainly through the Joint Technical Commission for the River Plate Maritime Front (CTMFM, http://ctmfm.org). This organization was established in 1973 to promote bilateral cooperation between neighbouring Argentina and Uruguay regarding the assessment and management of shared stocks in the River Plate Maritime Front. In so doing, the CTMFM has been organizing or coordinating joint research surveys and other research activities in its convention area. It has also actively promoted scientific publications and meetings of regional and international relevance. At these meetings, various stock assessment and fisheries management issues of interest to the two member countries and other stakeholders are addressed. While very active in the 1980s and 1990s, the activities of this regional commission have decreased, particularly in relation the wider regional or international significance of their scientific activities. However, in November, the CTMFM signalled the start of a new, more active era by holding a scientific symposium. This symposium, titled “The ecosystem approach and its implementation in fisheries management in the Fisheries Common Zone of Argentina and Uruguay”, was the first in a decade and was attended by more than 100 scientists from more than 20 institutions. Argentina and the United Kingdom of Great Britain and Northern Ireland also cooperate in the assessment of fish stocks and management of fisheries in the region of the Falkland Islands (Malvinas). In November 1990, the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland signed a joint statement on the conservation of fisheries. This statement led to the establishment of a South Atlantic Fisheries Commission, composed of delegations from both States. The South Atlantic Fisheries Commission met regularly and provided a forum for the exchange of information on marine living resources. It discussed the implementation of measures to improve the conservation and management of commercially important fish stocks in the Southwest Atlantic, particularly those around the Falkland Islands (Malvinas). However, it has been less active in recent years. Brazil has about ten technical working groups (Grupos Permanentes do Estudos), which have had variable degrees of activity over the years. In certain circumstances, these groups have been instrumental in coordinating research work. They have also provided technical advice on the assessment and management of important fisheries in Brazil, such as tunas, shrimps, lobsters, sardines and coastal demersals. Through some of these working groups covering the northernmost part of Area 41, there is active cooperation with the WECAFC covering Area 31 regarding the study and assessment of fish stocks in the Guyana–Brazil region.
Most of these fisheries are under some kind of management scheme with specific management measures varying from one country to another and from one fishery to another. However, enforcement is not always as effective as desired. Only a few fisheries are under an open-access regime, and these are mostly coastal small-scale fisheries. In most cases, there is a limited-access scheme for which a fishing licence is required. These licensing requirements are usually combined with other fishing effort and total catch restrictions to keep fishing mortality under control. In addition, regulations on the size at first capture and seasonal and area closures are used to protect juveniles and spawners. In particular, Argentina and Uruguay, and their subregional organization,the Frente Marítimo, have been compelled to adopt more severe restrictive regulations, combining TAC limits, size-at-first-capture limits, and seasonal and area closures to address the critical situation of the Argentine hake stock.
Biological State and Trend
To access all FIRMS State and Trend summaries available for this Area, please look at: Status and Trend Summaries (extracted from reports)
Until the early 1980s, Area 41 was among the few major fishing regions of the world still with a large potential for expansion. Until that time, there were abundant and potentially valuable fishery resources that were still being reported as underexploited or lightly exploited (FAO, 1979, 1981, 1983; Otero et al., 1982, 1983; Csirke, 1987; Dias Neto and Mesquita, 1988). Several coastal and mostly industrialized long-range fisheries have developed since. Most of the fish stocks are now considered to be fully exploited, while some are, or have been, severely overexploited in recent years (Bezzi, Akselman and Boschi, 2000; Dias Neto, Saccardo and Bernardino, 2001; FAO, 1997, 2002; MMA, 2006). The status of commercial fish stocks is shown in Table D6.
Most of the reported expansion in production in Area 41 in the last three decades has been due to the increased catches of hake and other demersals as well as squids on the Patagonian shelf and slope. There are two well-known species of hake in this region, the Argentine hake (Merluccius hubbsi) and the Patagonian or southern hake (M. australis). A third hake species (M. patagonicus, sp. nov, Lloris and Matalallanas, 2003) has also recently been described.
The distribution and fishing grounds of Argentine hake tends to overlap with that of the other hakes in the outer Patagonian shelf and slope, and the species are difficult to identify correctly. Given the higher abundance and rela tive importance of the Argentine hake, it is likely that at least some of the southern hake catches are reported as Argentine hake. Reported catches of southern hake have been well under 10 000 tonnes per year in recent years, while those of Argentine hake have been in the range of 243 000–682 000 tonnes per year.
There seem to be at least two stocks of Argentine hake (M. hubbsi), with some authors proposing the existence of three or four or even up to five stocks (Otero and Kawai, 1981; Bezzi and Perrotta, 1983; Otero, Giangiobbe and Renzi, 1986; Perrotta and Sanchez, 1992; Bezzi, Verazay and Dato, 1995). However, the possible presence of two or more stocks is not taken into account in the official annual catch statistics. They are also not always taken into account in the assessment and management of the hake fishery within the common Argentine–Uruguayan fishing zone and in the remaining area around the Patagonian shelf. The assessments available indicate that, until the 1980s and early 1990s, the stocks of Argentine hake were fully exploited. However, this soon developed into a state of overexploitation by the mid-1990s and stock depletion (FAO, 1983; Csirke, 1987; Bezzi, Verazay and Dato, 1995; Consejo Federal Pesquero, 1998; Aubone et al., 1998; Bezzi, Aubone and Irusta, 1999; Aubone, 2000; Bezzi, Akselman and Boschi, 2000; Tringali and Bezzi, 2001; Arena and Rey, 2003; Irusta and D’Atri, 2010). At first, the overexploitation of the hake stocks was mainly caused by growth overfishing. This soon developed into recruitment overfishing, with a serious depletion of the SSB. The hake resource was declared to be in a state of emergency. Both main fishing countries, Argentina and Uruguay, had severe restrictive measures imposed in 1998. The restrictive measures are still in force and include reduced TACs and extensive seasonal and zonal closures to protect juveniles and spawners. While some signs of increased recruitment are being reported, the restrictive measures adopted so far do not seem to have reduced fishing pressure sufficiently for a more rapid long-lasting recovery of the Argentine hake stocks in Area 41.
In comparison with the Argentine hake, the southern hake (M. australis) stock is much smaller and is distributed further south in the southern part of the Patagonian shelf and slope. There is also evidence of a possible connection with a larger stock of southern hake in Area 87, off the southern coast of Chile (Tingley et al., 1995). The stock of southern hake is considered to be fully exploited and current catches are within the recommended TAC for this species.
Patagonian grenadier and Southern blue whiting
The Patagonian grenadier (Macruronus magellanicus) is usually found in deeper waters in the southern Patagonian Shelf. According to recent analyses, Patagonian grenadier is considered to be moderately exploited, with catches in recent years under the estimated TACs (Giussi and Wohler, 2009). The other main fish stock in Group 32 is the southern blue whiting (Micromesistius australis), which is also found in deeper waters in the southern Patagonian shelf and slope, particularly around the Falkland Islands (Malvinas). While this stock was considered to be moderately to fully exploited until the mid-1990s, more recent studies suggest that, at current catch rates, the stock of southern blue whiting is being overexploited (Bezzi, Akselman and Boschi, 2000; Cordo and Wöhler 2000; Wöhler, 2000; Consejo Federal Pesquero, 2002; Giussi and Wohler, 2010). Stock abundance has declined since 1992, reaching the lowest level in 2007, with a slight recovery in 2008 and 2009 (Giussi and Wohler, 2010).
Other demersal fish stocks in Group 34
Other demersal fish stocks in Group 34, such as the Patagonian toothfish (Dissostichus eleginoides) and the pink cusk-eel (Genypterus blacodes) are also considered overexploited.
Several stocks of coastal demersal species in Group 33
There are several stocks of coastal demersal species of Group 33 throughout the region. The main species in this ISSCAAP group are the Atlantic croaker (Umbrina canosai), stripped whitefish (C. striatus), various species of weakfishes (Cynoscium spp.) and the whitemouth croaker (Micropogonias furnieri). Most of these stocks are fully exploited, while some local stocks are showing clear signs of overexploitation (Otero and Ibañez, 1986; Arena, 1990; Dias Neto and Dornelles, 1996; Arena and Rey, 1999; Bezzi, 2000; Bezzi, Akselman and Boschi, 2000; Vasconcellos and Haimovici, 2006; MMA, 2006; Lorenzo and Scavino, 2011; Chiesa et al., 2011).
Brazilian sardinella off Central Brazil
The Brazilian sardinella (Sardinella brasiliensis) is one of the main small pelagics in ISSCAAP Group 35 being exploited in Area 41. It is found over the shallower continental shelf off central Brazil between 22° and 29°S. After the record high catches of 228 000 tonnes taken in 1973, catches of this species dropped and then varied between 100 000 tonnes and 150 000 tonnes until 1986, when a further period of decline occurred. The total biomass of Brazilian sardinella declined from an estimated 350 000 tonnes in 1977 to 80 000 tonnes in , and there have been no signs of stock recovery since then (Saccardo and Rossi-Wongtschowski, 1991; Rossi-Wongtschowski, Saccardo and Cergole, 1995, 1996; Matsuura, 1998; Vasconcellos, 2001; MMA, 2006). The causes of the severe decline and lack of recovery of this sardine stock is a source of great interest and active debate among fisheries scientists and administrators (Saccardo 1983; Saccardo and Rossi-Wongtschowski, 1991; Rossi-Wongtschowski, Saccardo and Cergole, 1996; Dias Neto, Saccardo and Bernardino, 2001; Vasconcellos, 2003). All available evidence seems to indicate that the Brazilian sardine is also exposed to decadal cycles of favourable and unfavourable environmental conditions, similar to other stocks of sardines in other parts of the world. These environmental cycles drive the population size up and down more or less independently of fishing pressure. These effects comes in addition to the effects of heavy fishing, which seems to have maintained this sardine stock under a state of overexploitation almost continuously since the first recorded large catch more than four decades ago. In this respect, it has already been suggested that excessive fishing pressure could exacerbate biomass declines and delay or compromise potential natural recoveries.
Argentine anchovy, Southwest Atlantic
Another small pelagic fish stock particularly abundant in the Southwest Atlantic is the Argentine anchovy (Engraulis anchoita). This anchovy is usually found off southern Brazil, Uruguay and northern Argentina. In some years, it has also been reported as far north as central Brazil, in regions usually inhabited by Brazilian sardine (Lima and Castello, 1994). This is one of the few cases worldwide of a highly abundant, wellknown commercial fish stock that still remains underexploited. Total catches are in the lower tens of thousands tonnes per year, while the potential for their entire distribution is more than 100 000 tonnes. The total estimated biomass of Argentine anchovy varies widely. Most estimates have been well over 1 million tonnes, with maximum estimates close to 10 million tonnes in some years (Ciechomski and Sánchez, 1988; Hansen and Madirolas, 1999; Hansen, 2004). This is a stock that clearly could support a much higher fishing pressure. However, it is clear that, as the species is close to the base of the food web of the northern Patagonian and Plate River system, any significant increase in fishing pressure on this stock could have negative impacts on other fish species feeding on it.
Tuna and other large pelagics
Catches of tunas and other large pelagics have been more or less stable in recent years. Most stocks seem to be fully exploited, although some potential for limited expansion exists. Total catches of sharks, rays and chimaeras have remained more or less stable or increased slightly in the last decade, with 83 000 tonnes reported for this species group in 2009. Although some stocks are not subject to direct fishing, they might still be moderately or fully exploited as bycatch in other more intensive demersal fisheries in Area 41. Because of their low fecundity and other life history characteristics, there is some concern about the effect of this indirect fishing on shark, ray and chimaera populations. The excessive fishing mortality will probably be unsustainable. In extreme cases, it may lead to population depletion even when these species are not targeted by any particular direct fishery. More studies are needed in this respect, particularly in the context of the FAO International Plan of Action for the Conservation and Management of Sharks (IPOA-Sharks).
Among the crustaceans, the most abundant single species producing the highest yield is the Argentine red shrimp (Pleoticus muelieri) in the central Patagonian shelf (Boschi, 1989; Bezzi, Akselman and Boschi, 2000). At present, this stock is considered to be fully exploited.
Argentine shortfin squid
Another main stock is the Argentine shortfin squid (Illex argentinus), which is distributed along the shelf and slope from 22° to 54°S. It is exploited by long range fleets from Area 41 as well as from distant areas. Several studies have been conducted on the shortfin squid stock in the Patagonian shelf and slope (Koronkiewicz, 1980, 1986; Brunetti, 1981; Otero et al., 1982; Hatanaka, 1986, 1988; Csirke, 1987; Haimovici and Perez, 1990; Haimovici et al., 1998; Bakun and Csirke, 1998). Some work has been done to distinguish possible population groups or stocks in Area 41 by analysing differences in reproductive seasonality and distribution of early and older life stages. At least three main spawning stocks are described, the summer-spawning stock, the south Patagonia stock and a Bonaerensis-north Patagonia stock. There is a possible fourth stock in southern Brazil that could well be an extension of the Bonaerensis-north Patagonia stock.
In the first years of rapid development of this fishery, there was great uncertainty and concern regarding the state of this stock and the risk of overexploitation. This concern was addressed through the joint and coordinated research and management actions undertaken by Argentina and the United Kingdom of Great Britain and Northern Ireland within the South Atlantic Fisheries Commission. The results of these studies have contributed to improved assessment, monitoring and control of fishing operations of local and long-range fleets. Regardless of the high year-to-year variability in abundance and resulting catches, the Argentine shortfin squid as well as the Patagonian squid are considered fully exploited (Csirke, 2005; Maguire et al., 2006).
Source of information
Marine and Inland Fisheries Service, Fisheries and Aquaculture Resources Use and Conservation Division. FAO Fisheries and Aquaculture Department “Review of the state of world marine fishery resources” FAO FISHERIES AND AQUACULTURE TECHNICAL PAPER.
No. 569. Rome, FAO. 2011. http://www.fao.org/docrep/015/i2389e/i2389e.pdf
The bibliographic references are available through the hyperlink displayed in "Source of Information".