The Peruvian Coastal Upwelling System
241
El Nifio events have both negative and positive effects on many commercially exploited species, with substantial economic implications for the
economies of the region. During El Nifio events (1972-1973, 1976,
1997-1998) with up to 8 oc temperature increase, anchovy changed from a
wide distribution along the entire Peruvian coast to a dispersed, asymmetric distribution at the southern Peruvian littoral, whereas pilchards
migrated from 5°S (Paita) to the central-southern coast (Niquen et al.
1999). Pelagic fisheries, which are mostly monospecific for anchovy, became multispecific because a large number of tropical and oceanic fish
migrated into the pelagic zone of Peruvian-Chilean upwelling areas. Dolphinfish ( Coryphaena hippurus ), yellowfin tuna ( Thunnus albae ares),
picuda (Sphyraena ensis), and Pacific mackerel (Scomber japonicus) were
the first to invade the area, followed by samasa (Anchoa nasus), machete de
hebra (Opisthonema libertate), penaeid shrimps, skipjack (Katsuwonus
pelamis), and Myctophidae (i.e., Bregmaceros bathymaster). Other invading species were ayamarca ( Cetengraulis mysticetus), fine jack mackerel
(Decapterus macrosoma), big-eye jack mackerel (Caranx hippos), ribbonfish (Desmodema polysticta), and swimming crabs, mainly Euphylax sp.
Some, like dolphinfish, frigate tuna (Auxis rochei, A. thazard), flying
fish (Hirundichthys rondeletii, Cheilopogon heterurus, Exocoetus volitans),
and pampanito (Stromateus stellatus) are reliable indicators of El Nifio
conditions.
During the strong 1982-1983 El Nifio event, part of the anchovy and
pilchard shoals migrated from the warmer epipelagic zone to remaining
nearshore upwelling cells with cold, nutrient-rich water (Arntz 1986). The
increase in density led to exceptional catches ( 170,000 tons of anchovy in
1 day) at the beginning of El Nifio (1972). Another part of anchovy and
pilchard shoals migrated to deeper waters (>100m) and a third group
migrated southward where pelagic fisheries off northern Chile benefited
from recruitment (Alheit and Bernal 1993). Also, the silverside (Odontesthes regia regia), which sustains artisanal drift net fisheries, virtually
disappeared from Peruvian water, possibly owing to migration into deeper
waters or coastal areas off Chile. As a result of the different migrations, the
pelagic food web collapsed and the withdrawal of pelagic fish shoals from
areas almost devoid of food was reflected in reduced spawning and reproduction of anchovy and pilchard. Other important shoaling fish of the
Humboldt upwelling, like the jack mackerel and Pacific mackerel, approached the shore between Ecuador and Chile ( 45°30'S) but were little
affected by limited food resources.
Also, the shallow-water ichthyofauna reveals the impact of El Nifio. More
than 50 species (i.e., Opisthonema spp., Cetengraulis mysticetus, Etrumeus
teres, Scomberomorus sierra, Mycterop erca x enarcha) that normally live
241
El Nifio events have both negative and positive effects on many commercially exploited species, with substantial economic implications for the
economies of the region. During El Nifio events (1972-1973, 1976,
1997-1998) with up to 8 oc temperature increase, anchovy changed from a
wide distribution along the entire Peruvian coast to a dispersed, asymmetric distribution at the southern Peruvian littoral, whereas pilchards
migrated from 5°S (Paita) to the central-southern coast (Niquen et al.
1999). Pelagic fisheries, which are mostly monospecific for anchovy, became multispecific because a large number of tropical and oceanic fish
migrated into the pelagic zone of Peruvian-Chilean upwelling areas. Dolphinfish ( Coryphaena hippurus ), yellowfin tuna ( Thunnus albae ares),
picuda (Sphyraena ensis), and Pacific mackerel (Scomber japonicus) were
the first to invade the area, followed by samasa (Anchoa nasus), machete de
hebra (Opisthonema libertate), penaeid shrimps, skipjack (Katsuwonus
pelamis), and Myctophidae (i.e., Bregmaceros bathymaster). Other invading species were ayamarca ( Cetengraulis mysticetus), fine jack mackerel
(Decapterus macrosoma), big-eye jack mackerel (Caranx hippos), ribbonfish (Desmodema polysticta), and swimming crabs, mainly Euphylax sp.
Some, like dolphinfish, frigate tuna (Auxis rochei, A. thazard), flying
fish (Hirundichthys rondeletii, Cheilopogon heterurus, Exocoetus volitans),
and pampanito (Stromateus stellatus) are reliable indicators of El Nifio
conditions.
During the strong 1982-1983 El Nifio event, part of the anchovy and
pilchard shoals migrated from the warmer epipelagic zone to remaining
nearshore upwelling cells with cold, nutrient-rich water (Arntz 1986). The
increase in density led to exceptional catches ( 170,000 tons of anchovy in
1 day) at the beginning of El Nifio (1972). Another part of anchovy and
pilchard shoals migrated to deeper waters (>100m) and a third group
migrated southward where pelagic fisheries off northern Chile benefited
from recruitment (Alheit and Bernal 1993). Also, the silverside (Odontesthes regia regia), which sustains artisanal drift net fisheries, virtually
disappeared from Peruvian water, possibly owing to migration into deeper
waters or coastal areas off Chile. As a result of the different migrations, the
pelagic food web collapsed and the withdrawal of pelagic fish shoals from
areas almost devoid of food was reflected in reduced spawning and reproduction of anchovy and pilchard. Other important shoaling fish of the
Humboldt upwelling, like the jack mackerel and Pacific mackerel, approached the shore between Ecuador and Chile ( 45°30'S) but were little
affected by limited food resources.
Also, the shallow-water ichthyofauna reveals the impact of El Nifio. More
than 50 species (i.e., Opisthonema spp., Cetengraulis mysticetus, Etrumeus
teres, Scomberomorus sierra, Mycterop erca x enarcha) that normally live