Four hundred years in the history of pinniped colonies around Mar del Plata, Argentina

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS

Aquatic Conser6: Mar. Freshw. Ecosyst. 8: 721–735 (1998)

Four hundred years in the history of pinniped coloniesaround Mar del Plata, Argentina

DIEGO RODRIGUEZa,b,* and RICARDO BASTIDAa,b

a Consejo Nacional de In6estigaciones Cientıficas y Tecnicas (CONICET), Fundacion Mundo Marino, Argentinab Departamento de Ciencias Marinas, Facultad de Ciencias Exactas y Naturales,

Uni6ersidad Nacional de Mar del Plata, Dean Funes 3350, (7600) Mar del Plata, Argentina

ABSTRACT

1. Historical records show the area of Mar del Plata (38°05% S/57°32% W, Argentina) as inhabitedby extensive seal colonies; the present study describes the evolution of their size and location fromthe 16th century to the present.

2. Southern sea lion (Otaria fla6escens Shaw 1800), South American fur seal (Arctocephalusaustralis Zimmerman 1783) and southern elephant seal (Mirounga leonina Linnaeus 1758) colonies,which consisted of between 80000 and 165000 animals, were subject to no commercial harvest, andonly small local catches were performed by transient aboriginal groups.

3. During the second half of the 19th century coastal zones were rapidly colonized by man andby the turn of the century, the pinniped rookeries finally disappeared. Such a dramatic decline wasnot only due to spatial competition with man, but also to the indirect effect of pinnipedover-exploitation in other areas of the south-western Atlantic.

4. No seal colonies were recorded in Mar del Plata during the 20th century until the mid sixties,when small non-breeding groups of sea lions and fur seals established themselves in the area.

5. The seal rookeries decline in Mar del Plata provides an interesting example of how humanactivity may severely affect the conservation of pinniped colonies, even with no direct actionthrough massive catches.© 1998 John Wiley & Sons, Ltd.

KEY WORDS: pinnipeds; Argentina; commercial exploitation; historical records; conservation; spatial competi-tion; Otaria fla6escens ; Arctocephalus australis ; Mirounga leonina

INTRODUCTION

The intensive exploration of the southern hemisphere during the 17th and 18th centuries resulted in thediscovery of antarctic and subantarctic areas that were inhabited by high concentrations of pinnipeds,mainly fur seals (Arctocephalus spp. Geoffroy Saint-Hilaire and Cuvier 1826) and southern elephant seals(Mirounga leonina Linnaeus 1758). For more than two centuries massive and uncontrolled sealingexpanded to austral areas and the stocks of seals were dramatically reduced; with only a few exceptionsthe populations of most of the southern species of pinnipeds are minimal compared to historical ones.

* Correspondence to: Casilla de Correos 43, (7600) Mar del Plata, Argentina. E-mail: [email protected]

CCC 1052–7613/98/060721–15$17.50© 1998 John Wiley & Sons, Ltd.

Received 15 March 1997Accepted 27 July 1998

D. RODRIGUEZ AND R. BASTIDA722

Recently, some studies (e.g. Hindell and Burton, 1988) have focused on the historical evolution of sealstocks, in order to assess the initial status of pinniped populations prior to commercial harvests. In thecase of South America, the knowledge of marine mammal populations is restricted to the 20th century,mainly due to the particular characteristics of human colonization and the recent delimitation ofcountries. The only historical records available were those related to commercial harvest of seals inUruguay (Vaz Ferreira, 1960, 1982; Vaz Ferreira and Ponce de Leon, 1987), South Georgia (Bonner,1958, 1968; Godoy, 1963; Laws, 1973; Payne, 1977, 1978; McCann and Doidge, 1987), the JuanFernandez Islands (Hubbs and Norris, 1971; Laws, 1973; Aguayo, 1979; Torres, 1987) and the recentanthrolopogical studies on seal hunting by Tierra del Fuego natives (Schiavini, 1987; Vidal and Winograd,1987; Orquera and Piana, 1990).

The present paper reports the historical evolution of seal rookeries in the area of Mar del Plata(Argentina) during the last four centuries, characterizing the basic features of the former colonies andanalysing the most probable causes for their disappearance. As no commercial harvests were conductedin this area, this case provides an interesting example of how human activities severely affect theconservation of seal colonies even with no direct action through massive catches.

NATURAL CHARACTERISTICS OF THE AREA AND INITIAL STAGES OF HUMANESTABLISHMENT

Social organization of breeding populations in seals is basically terrestrial, and the availability of suitablecoastal habitats is essential for parturition, copulation and safe weaning of pups. On the northern coastof Argentina (38° and 38°06% S, 57°30% and 57°32% W), cuarcitic (Eopaleozoic) substrates of the TandiliaSystem are exposed as rocky points, defining shallow sandy bays. This area, where Mar del Plata city isnow located, has the only suitable terrain available for eared seal colonies in more than 600 km of flatsandy beaches (Figure 1).

Terrestrial predation is a limiting factor for breeding activity in pinnipeds (Bartholomew, 1970; Stirling,1983), and carnivores are an important cause of natural mortality, essentially in northern phocids (Smith,1976, 1980; Best, 1977; Stirling and Archimbald, 1982; Stirling and Calvert, 1982; King, 1983; Riedman,1990). However, man proved to be a major predator of many pinniped populations around the world. Inorder to understand the historical evolution of seal colonies in a particular area, it is essential to know thenature of human presence and the development of urban settlements near the rookeries.

In the area of Tandilia, human activity is recorded from at least the Pleistocene. Early human groupswere technologically simple and their food items were mainly deer, guanacoes, vizcachas, fishes,armadillos, rhea’s eggs, frogs and marine snails (Flegenheimer, 1986a,b; Mazzanti et al., 1991). Studies inprogress suggest that paleoindian communities of the coastal area occasionally exploited pinnipeds (J.Lorenzini, personal communication). The recent aboriginal groups that inhabited the inland area(Pampas, Guenaken and later Araucanians) bred wild cattle and their territories were temporary andhighly mobile (Canals Frau, 1953; Mandrini, 1984; Austral, 1986).

With the exception of Juan de Garay’s expedition in 1581 (Gascon, 1942), there was no further interestin this area until Jesuit monks established three settlements between 1740 and 1751 (Cova, 1968, 1973a)(Figure 1). From 1820 onwards, the new independent government decided to expand the territories to thesouth, offering land to establish permanent settlements. As a consequence of this, the original Mar delPlata town was established in 1856 (Cova, 1968). Due to the increasing military campaigns, the northernlimit of indian territories rapidly moved south, resulting in the total extermination of the aboriginalcommunities between 1878 and 1885 (Figure 1).

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THE HISTORY OF PINNIPED COLONIES AROUND MAR DEL PLATA, ARGENTINA 723

EARLY RECORDS OF SEALS IN MAR DEL PLATA

Due to its distinctive topography, the area of Mar del Plata was recorded by Spanish and Britishexpeditions that reached South American coasts.

Francis Drake, in 1578, characterized Cabo Corrientes by the great number of seals, and 3 years laterJuan de Garay explored the area of Punta Mogotes and Punta Cantera, where he found huge seal colonies(Gascon, 1942) (Figure 2).

Vignati (1956) reported that eight survivors of the Wager wreck in Chile were abandoned in the areaof Mar del Plata in January of 1742. The group, headed by Isaac Morris and part of Commodore Anson’sfleet, stayed there for about 1 year feeding exclusively on pinnipeds, which they reported to be extremelyabundant and the only resource available.

The Jesuit monks, during their stay in this region, made detailed descriptions of the area. In 1744Falkner characterized Punta Iglesia, Punta Piedras and Cabo Corrientes as inhabited by seals, referringto these locations as Sea-wol6es hills (Figure 2). The nearby 400 km of coastal area between ArroyoClaromeco (38°50% S/60°05% W) and Punta Rasa (36°18% S/56°47% W) was surveyed by Cardiel in 1748. Heconfirmed only the location of the rookeries at Punta Mogotes, Punta Cantera, Cabo Corrientes, PuntaPiedras and Punta Iglesia. This situation was also confirmed by Sanchez Labrador a few years later. In1772 Pedro Pablo Pabon also found seals in this area, as reported in his expedition logbook (Pabon,1837).

The first topographic measurements of the area were made by Senillosa in 1826, who saw a greatnumber of sea lions sleeping in Punta Iglesia, Punta Piedras and Cabo Corrientes (Ayesa, personalcommunication), and a few years later D’Orbigny described these rocky shores as inhabited by seals(Valette, 1940).

Figure 1. Coastal area of Buenos Aires Province (Argentina), with a detail of the northern limits of native territories and JesuitMonk settlements during the 18th and 19th centuries.

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D. RODRIGUEZ AND R. BASTIDA724

Figure 2. Original coastline of Mar del Plata (Argentina) and location of seal colonies.

Urban settlements were established in Mar del Plata in 1856, a small pier being constructed in PuntaIglesia in 1865 (Figure 2). The founder of Mar del Plata, Patricio Peralta Ramos, described the greatconcentration of pinnipeds found close to the town in 1873, very probably referring to Cabo Corrientes.The last reference to seals inhabiting this area was in 1895, when tourist groups visited Punta Mogotes forsport shooting of seals, promoted by newspaper advertising.

Fernando Lahille surveyed the entire Buenos Aires coastal area in 1897, but he was unable to findpinniped rookeries (Lahille, 1898). The results of this survey are important because the absence of sealswas confirmed by one of the pioneers of marine mammalogy in South America. In the photographs of his

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THE HISTORY OF PINNIPED COLONIES AROUND MAR DEL PLATA, ARGENTINA 725

report, Punta Cantera was free of animals, a situation later reconfirmed by Florentino Ameghino in 1907for the whole region (Ameghino, 1909).

PINNIPED SPECIES INHABITING THE AREA

Mar del Plata is located within the breeding range of the southern sea lion (Otaria fla6escens Shaw 1800)and the South American fur seal (Arctocephalus australis Zimmerman 1783), and the 16th through 19thcentury colonies may have been formed by either species. Although their distributions overlapped, thesespecies breed on topographically different areas: the sea lions tend to concentrate in flat rocky areas orsandy beaches whereas fur seals are found in stepped rocky shores (Carrara, 1952; Vaz Ferreira, 1965).

Morris (in Vignati, 1956) Cardiel (1930) and Sanchez Labrador (1936) described seals with maximumlengths reaching 2.4 to 2.5 m, whose males not only were larger than females, but also developed anoticeable neck with a prominent mane, resembling terrestrial lions. As these animals were found lying onflat areas, they were undoubtedly southern sea lions.

Some sectors of the rocky shores of Mar del Plata and their crevices are more suitable for fur seals thanfor sea lions, and almost all fur seal vagrants are actually recorded along these stepped shores (Bastidaand Rodrıguez, 1994). Both species are difficult to distinguish by casual observers, with the exception ofsouthern sea lion adult males. Due to their smaller size (Table 1), fur seals are frequently mistaken forjuvenile or female sea lions, so probably the fur seals could have been considered sea lions by the earlyobservers, and no species distinction made.

Falkner (1911) also reported the presence of the sea lions described by Commodore Anson for the JuanFernandez Archipelago. In his logbook Anson (1748) reported that these sea lions:

...are in size, when they arri6ed to their full growth, from twel6e to twenty feet in length, and from eight to fifteenin circumference... They ha6e a distant resemblance to an o6ergrown seal, though in some particulars there is amanifest difference, especially in the males, who ha6e a large snout or trunk hanging down fi6e or six inches belowthe end of the upper jaw; this particular the female has not, and this renders the countenance of the male and femaleto be distinguished from each other, and besides, the males are of a much larger size....

Undoubtly Anson’s sea lions were southern elephant seals, which were also described by Morris in Mardel Plata as extremely fat, 14 feet long seals.

Allen (1899) and Harrison Matthews (1929), suggested that elephant seals formerly inhabited vast areasin Patagonia and Tierra del Fuego, but there were no records of colonies established in northern areassuch as Buenos Aires Province.

ESTIMATED SIZE OF THE EARLY COLONIES

It is difficult to estimate the early population sizes from the available information, although all thedescriptions referred to very abundant colonies. Not withstanding this, a gross estimation could be made

Table 1. General features of southern sea lions (Otaria fla6escens) and South American fur seals(Arctocephalus australis)

Sea lions Fur seals

Feature Males Females Males Females

Maximum length (cm) 266 204 189 143118Length at maturity (cm) 210 142 15749Maximum weight (kg) 350 145 160

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Table 2. Characteristics of rocky shores in Mar del Plata (Argentina); locations are in Figure 2.Surface estimations were assessed from aerial photographs using an AOTT KEMPTEN

Planometer

Area Topography Surface (m2)

Punta Iglesia Flat 19 000Punta Piedras Flat-step 42 000Cabo Corrientes Flat-step 52 000Punta Cantera Flat 40 000Punta Mogotes Flat 30 000

Total Flat 89 000Flat-step 94 000Combined 183 000

Table 3. Estimation of maximum number of sea lions and fur seals that inhabited rocky shores inMar del Plata (Argentina)

Theoretical occupation Estimated maximum numbers Total

Flat areas Flat-step areas Sea Lions Fur Seals

SL SL 79 000–88 000 — 79 000–88 000SL SL-FS 58 500–66 000 21 000–42 000 79 500–108 000SL-FS SL-FS 39 300–43 000 41 200–82 300 80 500–125 300SL FS 38 500–43 000 42 000–84 000 80 500–127 000SL-FS FS 19 100–21 400 62 300–126 000 81 400–147 400FS FS — 82 400–164 800 82 000–164 800

if the approximate size of the area available is related to density values recorded in similar colonies of thesame pinniped species.

The general characteristics of Mar del Plata rocky shores are summarized in Table 2. The approximatedensity of southern sea lions in breeding colonies is 0.43 to 0.45 animals per m2 (Campagna, 1985; Crespo,1988), while Vaz Ferreira and Ponce de Leon (1987) recorded 0.45 to 0.90 South American fur seals perm2 in Uruguay.

Table 3 summarizes the different possibilities of theoretical population sizes in Mar del Plata, withmaximum values ranging roughly from 80000 to 165000 animals for both otariid species for the wholearea. Due to the topography of the rocky areas, a combined occupation by sea lions and fur seals is themost probable, a situation recorded both in Cabo Blanco (Argentina) and Uruguay (Vaz Ferreira, 1956,1965; Vaz Ferreira and de Soriano, 1963; Vaz Ferreira, 1975a).

In the case of Mirounga leonina, the only data on density and beach occupation for areas withtopography and environmental conditions comparable to Mar del Plata, are the approximate 168 animalsper km of sandy beach front reported by Campagna and Lewis (1992) for Penınsula Valdes. Varying withcoastal erosion, the area of Mar del Plata has 10 to 15 km of sandy beaches, an area that could have beeninhabited by 1700 to 2500 southern elephant seals. It should be remembered that sandy beaches coverednearly 600 km in Buenos Aires Province, an area that could have also been colonized by elephant seals.

WHY AND WHEN DID THE SEALS DISAPPEAR?

Reviewing the chronology of seal records in Mar del Plata during the last four centuries, two main periodscan be clearly defined (Figure 3). First, an extended period of stability, for which the oldest available

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THE HISTORY OF PINNIPED COLONIES AROUND MAR DEL PLATA, ARGENTINA 727

Figure 3. Historical evolution of seal colonies in Mar del Plata (Argentina) since the 16th century. Horizontal bars indicate thepresence of seals in each area.

records were during the 16th century, and a second period that began approximately between 1855 and1860 marking the beginning of a sharp decline in the colonies, a process that ended with the extinctionof the rookeries by 1895–1900. With the information available, it is difficult to define the exact causes ofsuch a dramatic decline, but the effect of local human disturbance and the direct exploitation in otherareas of the south-western Atlantic are likely to have been important.

The Indians that occasionally visited this area hunted small numbers of animals for their pelts (Falkner,1911; Cardiel, 1930), but as this was not a very frequent activity, it apparently caused no alterations tothe pinniped colonies. The situation dramatically changed when humans began to permanently inhabit thecoastal area. For several years after its establishment in 1856, Mar del Plata was only a tiny village, butin the 1880s it began to transform into an important tourist centre, with a rapid increase in the residentand tourist populations after a railway service from Buenos Aires was installed in 1886 (Cova, 1973b;Figure 4). Competition for space with seal colonies surely ended in direct action against the animals and,although there are no records of commercial harvests in Mar del Plata, the possibility of small localharvests or extermination attempts should not be discarded; ‘sport shooting’ in rookeries may also haveaffected the animals.

During the last decade of the 19th century there were no restrictions on human presence on rockyshores near the town, possibly due to the absence of seals. By 1890 urban development increased in PuntaIglesia and the photographs show an area free of seals. It is not known whether the other nearest colonies(Punta Piedras and Cabo Corrientes) still existed, but the southward expansion of the early city may havealso affected these colonies. The southernmost colonies, Punta Cantera and Punta Mogotes, were affectedlater than the northern ones, but by the turn of the century they finally disappeared.

The seal colonies around Mar del Plata were surely affected not only by direct spatial competition, butby indirect effects of seal over-exploitation in other areas of South America.

Sealing activities began in Uruguay in the 16th century, but commercial harvests in the southernsouth-western Atlantic began later, at the end of the 18th century, as a consequence of the results of the

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first sealing in the Malvinas (Falkland) Islands (Allen, 1899; Vaz Ferreira, 1960; Bastida, 1962; Hofmanand Bonner, 1985; Vaz Ferreira and Ponce de Leon, 1987). Between 1775 and 1800, massive commercialharvests of southern elephant seals, fur seals and sea lions extended to Patagonia, Tierra del Fuego,Malvinas (Falkland) Islands and South Georgia. Some years later, the Spanish Government was forcedto create the Royal Company of Fisheries to protect their interests in South America, because the colonieswere commonly exploited by British, French and American sealers.

The 19th century was characterized by intensive exploitation, and the different stocks showed earlysigns of depletion. Fur seal and sea lion populations were over-exploited during the first half of thecentury all around the south-western Atlantic. A similar situation occurred with the southern elephantseal colonies in northern Patagonia. Despite a few decades of recovery, the uncontrolled harvests duringthe last quarter of this century put almost all populations near extinction. Allen (1899) reported that bythe turn of this century the small number of seals in the south-western Atlantic would not be able tosustain profitable commercial harvests.

Although the beginning of the 20th century marked the end of massive harvests and the first attemptsat legal protection (Hofman and Bonner, 1985), controlled local harvests were conducted during thiscentury on South Georgia (southern elephant seals), Malvinas (Falkland) Islands (southern sea lions andsouthern elephant seals), Uruguay (fur seals and sea lions) and Patagonia (southern sea lions and southernelephant seals). With the exception of Uruguay, these activities ceased during the sixties and earlyseventies, and the different species were legally protected. As a consequence of these controlled anduncontrolled catches, at least 3 million animals were killed in the south-western Atlantic over the last 200years (Table 4).

Mar del Plata was never a sealing area, but the colonies were not isolated and were surely affected bythe over-exploitation of the rest of the South American pinniped populations. The situation of Mar delPlata seems to be similar to that of California and Oregon (USA). There, the stability of marine mammal

Figure 4. Human settlement in Mar del Plata (Argentina).

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Table 4. Records of seal exploitation in the south-western Atlantic since the 18th century

Species Area Period Record (years) Animals killed

Mirounga leonina South Georgia 1775–1820 45 \35 0001910–1964 54 260 000Total 99 295 000

Otaria fla6escens Patagonia and Tierra del Fuego 1917–1953 36 500 000Malvinas (Falkland) Islands 1928–1952 15 \45 000Uruguay 1910–1976 66 203 000

Total 66 748 000

Arctocephalus gazella South Georgia 1790–1822 32 1 200 000

Arctocephalus australis Uruguay 1873–1983 88 754 000

Sources: Weddell, 1825; Harrison Matthews, 1929; Cabrera and Yepes, 1960; Carrara, 1952; Laws, 1953, 1973; Godoy, 1963;Strange, 1972; Vaz Ferreira, 1982; Vaz Ferreira and Ponce de Leon, 1987.

populations until the 19th century may have been due to the small effect of prehistoric hunting, while themore recent (19th and early 20th centuries) abandonment of the area by Steller and California sea lions,northern fur seals and sea otters was a direct or indirect effect of commercial sealing during the 19thcentury (Bonnot, 1928, 1951; Rowley, 1929; Cass, 1985; Lyman, 1988).

THE EVOLUTION OF SEAL COLONIES DURING THE 20th CENTURY

The general characteristics of Mar del Plata region dramatically changed during the 20th century. Theformer colonies’ terrain was occupied by man and the coastline modified by the new harbour builtbetween 1915 and 1917. Coastal fisheries rapidly increased, and Mar del Plata became the most importantfishery harbour in Argentina. The region became isolated from the seal breeding colonies of Uruguay andnorthern Patagonia, and only small non-breeding groups of southern sea lions remained in the southernareas of Bahıa Blanca (39°14% S, 62° 15% W) and Bahıa San Blas (40°24% S, 62°15% W).

The local harbour offered two new benefits for pinnipeds: man-made areas suitable for seal concentra-tion and a great amount of fish discarded as by-catch. This new habitat also caused increased pollution,restricted access to new terrain and potential aggression by fishermen.

During the 1960s, after sealing activities ceased in Patagonia, sea lions gradually began to establishthemselves inside the harbour. In the early 1980s, the permanent colony consisted of about 100–150pre-reproductive males which fed almost exclusively on discarded fish (Baldas et al., 1987; Figure 5). Since1985 there has been a noticeable increase in size of the colony to 600–700 individuals, mainly due to thenew terrain becoming available (Rodrıguez, 1990, 1996; Rodrıguez et al., 1992). The occasional presenceof small sea lion groups inside fishery harbours is quite common in the south-western Atlantic, but noneof them have the size and stability of the Mar del Plata colony. Colonies of both non-breeding bachelorsand non-territorial bulls, commonly known by the sealers’ term hauling ground, have been recorded forOtaria fla6escens (Vaz Ferreira, 1973, 1975a,b; Vaz Ferreira and de Soriano, 1963; Ximenez, 1976; Lewisand Ximenez, 1983; Crespo, 1988). In Mar del Plata both gregariousness and the prolonged pre-reproduc-tive period in southern sea lion males surely favoured this concentration.

The presence of resident fur seal groups was ignored until the recent discovery of a seasonalconcentration of animals in shallow waters near Punta Mogotes (Bastida and Rodrıguez, 1994; Figure 5).The occurrence of this group since 1978 has been confirmed, although there are no accurate records of itspresence earlier in this century. Fur seals may have never definitively abandoned Mar del Plata, but may

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have taken refuge in an inaccessible area such as Punta Mogotes. Alternatively this area may have beenrecently colonized as a consequence of the population increase. The absence of fur seals inside thepolluted waters of the harbour may be a result of the effect of oil on the pelts of fur-bearing pinnipeds.When oiled, air bubbles cannot form an insulative barrier and pelt conductivity is drastically increased,resulting in severe thermal stress (Oritsland, 1975; Smith and Geraci, 1975; Kooyman et al., 1976, 1977;Hurst and Oritsland, 1982; Siniff et al., 1982; Geraci and St Aubin, 1985).

In the case of the southern elephant seal, no group established in Mar del Plata during this century. Thepresent distribution in continental Argentina is restricted to Penınsula Valdes and adjacent areas,

Figure 5. Actual location of seal colonies in Mar del Plata (Argentina).

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THE HISTORY OF PINNIPED COLONIES AROUND MAR DEL PLATA, ARGENTINA 731

although vagrants are commonly recorded far from their breeding colonies in Argentina, Uruguay andBrazil (Smith, 1927; Cabrera and Yepes, 1960; Ximenez, 1964; Vaz Ferreira, 1965; Daciuk, 1973;Carvalho, 1975; Castello, 1984; Pinedo, 1990; Rodrıguez, 1996; Rodrıguez et al., 1996).

Mar del Plata’s colonies are located midway between northern Patagonia and Uruguay, and theirbreeding populations of seals actually show very different trends. In Uruguay, sea lions are declining andfur seals are increasing (Vaz Ferreira and Ponce de Leon, 1987), whereas in northern Patagonia the sealion colonies have been stable for many years (Crespo, 1988; Crespo and Pedraza, 1991) and elephant sealcolonies are increasing (Scolaro, 1976; Vergani et al., 1987; Campagna and Lewis, 1992). Competitionwith coastal fisheries and/or global environmental changes may contribute to the current populationtrends. However, the lack of historical environmental or biological information make this analysis veryspeculative in the case of the former colonies of Mar del Plata.

CONCLUSIONS

The historical location of seal rookeries near Mar del Plata (Argentina) was determined from records ofearly voyagers that explored this area since the 16th century. The animals were formerly concentrated inthe rocky areas between 38°00% S and 38°06% S, and very probably the main concentration was found inthe area between Punta Iglesia and Cabo Corrientes. Historical records of pups are frequent and confirmthese rookeries as breeding colonies.

This area was inhabited by southern sea lions, South American fur seals, and southern elephant seals.Considering the terrain available in relation to seal density values recorded in similar habitats (Uruguayand northern Patagonia), this area could have been inhabited by 1700–2500 elephant seals, 19000–88000sea lions and 21000–165000 fur seals.

Prior to the first half of the 19th century, the rookeries probably remained at the same size and locationas in the 18th century, and it is quite probable that they were in a similar situation to that of the 16thcentury. The establishment of permanent human settlements near the rookeries marked the beginning ofthe seals’ decline, which coincided with the southward expansion of the early town. The final disappear-ance of the colonies during the second half of the 19th century is closely related not only to the sharpincrease in human population in Mar del Plata, but also to noticeable signs of over-exploitation inpinniped colonies of the south-western Atlantic.

During this century, the presence of established groups of non-breeding seals in Mar del Plata has beenrecorded since 1960, and currently a permanent male southern sea lion colony is located inside Mar delPlata harbour and a seasonal concentration of South American fur seals is found in shallow waters nearPunta Mogotes.

The former rookeries were colonized by a new species, Homo sapiens, and transformed into tourist andsport fishing resorts, restaurants, pubs, parks and roads. These ‘new colonies’ are extremely well-adaptedto changing environments and successfully established in coastal areas so, unfortunately, we will probablynot have the opportunity to see breeding seals again in the rocky shores of Mar del Plata.

ACKNOWLEDGEMENTS

In our efforts to link pinniped biology with recent history, we needed the help of many people. Arq. Roberto Covaand Mr. Felix de Ayesa kindly clarified many aspects of Mar del Plata history. Dr. Anita McConnell (The RoyalInstitution of Great Britain, UK) reviewed the original Lord Anson’s logbook. Dr. Claudio Campagna (CentroNacional Patagonico, Argentina), Dr. R. Lee Lyman (University of Missouri at Columbia, USA) and twoanonymous reviewers made helpful comments on the manuscript. Dr. R. Lee Lyman and Dr. Rowland H. Taylor(Landcare Research Ltd., New Zealand) provided bibliography unavailable in Argentina. Mrs. Carmen Milloc, Mrs.Carolina Lupiano and Mrs. Nora Carzon (Gabinete de Cartografıa y Dibujo, Universidad Nacional de Mar del

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Plata, Argentina) drew the maps. Partial funds were obtained from Consejo Nacional de Investigaciones Cientıficasy Tecnicas (CONICET), Fundacion Mundo Marino and Universidad Nacional de Mar del Plata (EXA 03/94). Wegratefully acknowledge all of them.

Finally we would like to express our special gratitude to the late Dr. W. Nigel Bonner. With a friendly andenthusiastic manner he reviewed early drafts of the manuscript and made helpful suggestions for its improvement.This paper, the final version of which he was unable to read, is dedicated to his memory.

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Islands of the North Pacific Ocean, Part 3 (XII), Government Printing Office, Washington, DC, USA, 307–319.Ameghino, F. 1909. ‘Las formaciones sedimentarias de Mar del Plata y Chapalmalan’, Anales del Museo Nacional de

Buenos Aires, III, 343–429.Anson, G. 1748. A Voyage Round the World (Compiled by R. Walter), Royal Geographical Society, London,

122–124.Austral, A.G. 1986. Esbozo antropologico preliminar de la historia del poblamiento de la Pro6incia de Buenos Aires,

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