The Guano Islands of Peru: the Once and Future Management of a Renewable Resource

The Guano Islands of Peru: the Once and Future Management of a Renewable Resource

The guano islands of Peru: the once and future management of a renewable resource DAVID C. DUFFY SUMMARY Anchoveta populations remained low for a decade and the remaining fishery switched to sardina S ardinops T h e Peruvian coastal guano islands and headlands have o cellata, a slightly larger fish that could be canned. Fish­ been among Ihc world’s best and worst managed of ing pressure continued on the anchoveta, supposedly to seabird nesting areas. The islands contained enormous keep it from recovering and ouicompeting the sardina, deposits of seabird excreta or guano which was mined but in reality because fishmeal could be sold for hard for fertilizer in the nineteenth century. In the early twen­ currency on the international market, whereas sardina tieth century, with guano deposits exhausted and bird was sold domestically. Following the collapse of the populations almost exterminated by the exploiters, the anchoveta stock, seabird numbers only partially recov­ Peruvian government nationalized the islands and be­ ered and the guano industry abandoned many islands gan to manage them as a sustainable resource, protect­ and headlands. Money for management sharply de­ ing the birds, im proving their nesting sites, and taking creased as the government has struggled to pay for Pe­ only (he annual accumulations of guano. ru ' s international debt and for a protracted conflict with Populations of the three pnnctpal guano-producing two guerrilla movements. Hyperinflation has further species, the Guanay Cormorant Phalacrocorax eroded the government’s ability to manage its natural bougainvilli, Peruvian Booby Sula variegata, and Pe­ resources. ruvian Brown Pelican Pelecanus ( occidentalis) Ihagus The situation is extremely unpromising, but there recovered sufficiently so that their nesting colonies be­ are three elements that provide hope. First, guano is the came space-limited. The Peruvians responded by fenc­ ideal organic fertilizer and could be sold overseas for ing coastal headlands with predator-proof walls and the hard currency to the large and growing organic farming guano bird population increased ever further. In the muvement, as is being done with Namibian guano. Sec­ 1960s, a commercial fishmeal industry developed for ond, private and local efforts, such as those working to the anchoveta Engraulis ringens, the main food o f the preserve Punta San Juan, a major penguin nesting area seabirds, leading to competition with the guano indus­ in southern Peru, provide a model for non-governmen­ try. Guano harvests fell to low levels. By 1972, the fish­ tal management and protection of nesting areas. Finally, ery hud a vast excess capacity of boats and fishmeal if Peru can overcome its political and security problems, plants and began to collapse because of low returns on it w ill again be a major destination for the nature tour­ investment. The collapse was accelerated by fishing ism industry. The guano islands, only one o f which is during the 1972 El Niño, an oceanographic anomaly presently visited by a tourist boat, could become an im­ linked to reproductive failure of the anchoveta. portant component of such tourism. HE eastern boundary currents of the world's agement o f natural resources in such areas is subject oceans are among the most productive o f ma­ to conflicting needs by different exploiters (Schaefer Trine environments, originally supporting rich 1970, Butter worth et al. 1988) and to complex inter­ and diverse marine communities (Hutchinson 1950, actions between exploited species (MacCall 1984). Cushing 1971). More recently, these ecosystems have The Peruvian Coastal Current or Humboldt been severely over-exploited by humans, resulting upwelling is an excellent example of the problems in [he collapse of exploited fishery populations. Man­ facing such ecosystems. O riginally endowed with HirHI ife C onservation Sorieb d QcWl no. 1 : Guano Islands of Peru enormous stocks of marine birds, mammals and fish, ‘guano islands’ , those islands sufficiently large and the upwelling’ s resources were over-exploited, leav­ frequently used by the main guano-producing ing an impoverished resource base that makes a seabirds to merit protection, and ‘ non-guano’ islands, greatly diminished contribution to the national which are either very small or larger, higher, and more economy compared with previously (Schweigger disturbed than most of the guano islands (e.g. El 1964). In addition, the El Niño phenomenon, a tem­ Fronton, a prison island in Callao harbour at Lima; porary collapse of the upwelling’s productivity San Lorenzo, also in Callao harbour; and San Galian, (Walsh 1977), has made management o f resources o ff Paracas). Lobos de Tierra and Lobos de Afuera, d ifficu lt because of the year-to-year uncertainty and both o ff northern Peru, and La Vieja south o f Paracas its damage to the national infrastructure (Caveides also have relatively few guano birds relative to their 1975, del Solar 1983, Am tz 1986). total area, but guano production has been sufficient to merit protection by guards. ISLAND TYPE AND DESCRIPTION_______ Terrain, habitats and community Island types With the exception of the larger islands, most of the The islands o f Peru have been discussed by Murphy islands do not have beaches and are cliff-bound, some (1925), Vogt (1942) and Hutchinson (1950), among requiring elaborate gantries to allow access. In other others. There are at least 84 islands (Anon. 1962). as cases, the shores are less vertical but are rendered welt as countless small offshore stacks (Figure 1). inaccessible by oceanic waves and swell. A few is­ Combined with the coastal headlands used by guano lands such as Lobos de Tierra, two o f the Chincha birds, the total nesting area available for birds is 8,116 Island group and one o f the Ballestas have low-en­ ha (Gonzalez 1952), The islands can be divided into ergy sand or pebble beaches. Many of the less dis­ turbed beaches are presently occupied by sea-lions 84° BCT ^ 76° Otaria flavescens. Isolated rock ledges and seacaves are often occupied by southern fu r seals A rcto­ cephalus australis. The surrounding waters are usu­ ally very deep, dropping o ff to hundreds o f metres. ZONES n PAITA V PERU The islands themselves are mostly o f andésite, I 1V2 extensively undercut on their lower portions with fre­ 3 . 4 - y s quent seacaves and tunnels. The upper portions of II 6-11 CHIMBOTE the islands were formerly covered with thick depos­ 12-\.13 its of guano (Hutchinson 1950). A ll o f the original guano beds have been removed, leaving bedrock and oV'SpGÄLLAÖ 21-23 --24 gravel and at most two or three years of guano. IV 26-29 (»» Except for Isla Lobos de Tierra in the far north 30,31*.32 where a single Prosopis chilensis tree occurred PACIFIC 333 ? SAN ju a n (Murphy 1925) until about 1978 when it was cut 35” OCEAN II J-x down (pers. obs.) and the high islands o f San Galian, VI 3 8 'V jt-O 39 ^ La Vieja and San Lorenzo where ‘loma’ fog-zone 0 200 40 km vegetation occurs at upper elevations, the islands are ___ i______________ i—.—-—I---- ------- i ----------1—„1------------1--------------- —j ____ 1_________I L virtually devoid of vascular plants (a few exist where 84* SO0 75r 72> w planted and maintained by humans). The food chains Figure 1. Distribution of Peruvian seabird guano is­ are relatively short: detritivores and parasites exploit lands and headlands by zones (after Tovar and the birds or their by-products. The detritivores are Cabrera 1985): Zone I: I. Lobos de Tierra (1 ), Lobos eaten by predatory arthropods including scorpions, de Afuera (2), I. Macabí (3); Zone II: 1. Guñape S. (4), 1. Guñape N. (5), I. Chao (6), 1. Corcovado (7), I. Santa spiders and a lizard, w ith ants being almost com­ (B), I. Blanca N. (9), I. Ferroi (10), I. Tortuga (11); Z one pletely absent (Murphy 1921, Duffy 1983a, 1991). ill: Pta Culebra (12), Pta Colorado (13), Pta Liera (14), The parasites include mallophaga, hippoboscid flies I. Don Martin (15), Pta Salinas (1 6), I. Huampanu (1 7), and ticks (Murphy 1921 ). The argasid tick Ornitho- I. Mazorca (18), I. Pescadores (19), I. lsleta(20);ZONE doros amblus reaches sufficiently high levels o f in ­ IV: I. La Cruz (21 ), I. Palominos (22), I. Cavinzas (23), festation to force birds to abandon their nests and I. Pachacamac (24), 1. Asia (25), I. Chincha N. (26), I. Chincha C. (27), I. Chinea S. (28), I. Ballestas (29); young, and can inhibit breeding altogether (D uffy Zone V: 1. La Vieja (30), I. Sta Rosa (31 ), Pta Lomrtas 1983a). A lizard was introduced to several islands to (32), Pta San Juan (33), Pta Lomas (34); Z one VI: Pta control the ticks (Vogt 1939), but this may be inef­ Atico (35), Pta La Chira (36), Pta Islay (37), Pta Jesus y fective because the breeding seabirds are aggressive Cocotea (38), Pta Coles (39), Morro Sama (40). to lizards and exclude them from the colonies (Duffy 69 D. C. Duffy 1983a). Cats and rats arc known to occur on a number ‘ Saturnalia’ (Murphy 1981), as guano was used to o f islands, but their effect on seabirds is unknown. maintain the productivity of farms feeding the in­ dustrializing cities of Europe and North America. Seabird species and recent changes Guano was mined and the young birds were fed to There are 18 species of seabirds nesting on guano the workers (Murphy 1981). The removal of the islands or along the coast in the upwclling area of guano substrate probably greatly reduced numbers coastal Peru (M urphy 1936). The most important of Peruvian Diving-petrels and Inca Tcms (Hutch­ numerically are the Guanay Cormorant Phalacro­ inson 1950).

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