Complete issue

Latin American Journal of Aquatic Research, 2012

Changes in abundance and distribution of anchovy and other species of pelagic fish of the Northern Humboldt Current System (NHCS) are driven by environmental forcing variations in different time and spatial scales between the coastal 'cold' ecosystem and the 'warm' oceanic one. Data to study these fluctuations have come mostly from the fishery to show how anchovy (Engraulis ringens) increases when sardine (Sardinops sagax) declines and vice versa. However, using acoustic data on latitudinal biomass we show that other species as mackerel (Scomber japonicus) and jack mackerel (Trachurus murphyi) also follow the same opposed trend, then the fishery data hides the true dimension of the balance of abundance among species. Based on Hovmoller diagrams we scrutinized the changes in interannual latitudinal acoustic biomass, landings and influence of El Niño events from 1966 to 2009 in order to describe: 1) how the anchovy decadal distribution pattern moved from south to north since the 1960's; 2) how there have been produced concomitant changes in the latitudinal abundance and distribution of other species such as sardine, jack mackerel and mackerel before, during and after El Niño events; and 3) what was the overall effect of the succession of El Niño events on all these pelagic species. We concluded that: a) every El Niño event has had an effect on the expansion or contraction of pelagic species distribution and abundance, with different latitudinal effects; and b) the El Niño 1997-98 did not trigger but accelerated a decline phase on the abundance of sardine, jack mackerel and mackerel by a reduction of their ideal habitat due to an expansion of the coastal ecosystem caused by a shallower location of the upper limit of the Oxygen Minimum Zone (OMZ) These findings observed using past data might be taken into consideration for fishery management purposes when considering future scenarios.

Fisheries Oceanography, 2018

Oceanographic and hydroacoustic data were obtained by the Instituto del Mar del Peru (IMARPE) during 72 cruises off the Peruvian coast between 1985 and 2017 to determine the ranges of the abiotic parameters influencing the anchovy (anchoveta) distribution and to observe the effect of the 1997-1998 El Niño event. The hydroacoustic data show a high seasonal variability in anchoveta distribution related to differences of environmental parameters as well as changes in distribution after the very strong El Niño event in 1997-1998. Geostatistic variograms were used to describe the seasonal variability and generalized additive models (GAMs) with a Tweedie distribution were applied to study the relationships between anchoveta and oceanographic parameters. The dependent variable was the value for anchoveta obtained from echosounder (nautical area scattering coefficient [NASC] of anchoveta) and the tested covariates were temperature, salinity, and dissolved oxygen at the sea surface; distance to the coast; year, latitude-longitude; and Oceanic Niño Index 1 + 2. The results show a high variability of anchoveta with seasonal differences in its distribution. Preferred abiotic conditions (temperature, salinity, oxygen)

Mathematical Modelling, 1985

Peruvian anchovy industry grew at a compound rate of 42 percent between 1956 and 196.5, making Peru the largest fish producer in the \vor!d. Berxveen 1967 and 1971 annual catches averaged 10.5 million metric tons. However. in 1972 the anomalous ocean current known as El Nino combined with over-exploitation to decimate the anchovy stock. Anchovy harvests fell by 55 percent in 1972 and another 5 1 percent in 1973. Despite the efforts of the Institutio de1 Mar de1 Peru, an incomplete understanding of the anchovy's behavior and imperfect management practices led to severe economic hardship. This paper presents an anchovy population dynamics model implemented as a computer simulation. It incorporates aspects of several general population models in the literature, the peculiar characteristics of the anchovy ecosystem. and Peru's specific economic needs. Our goal was to find the optimal management policy that can be practically implemented and to develop a methodology that can be apphed to other situations. The model indicated that Peru should limit fishing to the springtime and use quotas that favor large modern purse seiners.

2009

During the BIC Humboldt, Olaya y SNP2 0209-11 cruise, the hydroacoustic evaluation method was used. The sampling was done according to the methodology established by the IMARPE. The Peruvian anchoveta (7,433.429 t) was the most abundant species; it showed a coastal distribution, continuous from Paita to San Juan, and dashed towards the south of this locality, reached the greater abundance off Paita to Punta La Negra and off Cerro Azul to Tambo de Mora. The vinciguerria (5,790.910 t), widely distributed in the area evaluated was more frequent off Punta Infiernillos and Ilo, and more abundant from Chala to Ilo. The carrot lobster (2,418.569 t) was the second most abundant species in cold coastal waters (CCW), it was found continuous off Pucusana to Chicama and discontinuous off Pisco to Morro Sama. Jack mackerel (446,782 t) and Pacific mackerel (66,246 t); were scarce; the reduction of these two species has been recorded since September 1998. The longnose anchovy (28,606 t) was found ...

Ciencias Marinas

In this paper we analyze the standardized monthly anomalies of time series of the gonadosomatic index (GSI, 1986–2008), spawning fraction (SF, estimated by histological analysis of gonads, 1992–2008), and condition factor (1986–2008) of the Peruvian anchovy Engraulis ringens. Statistical analysis using filters showed, according to their mode of variability, the existence of three distinct periods for GSI (1986–1989, 1990–2000, and 2001–2008) and two for SF (1995–2001 and 2002–2008). Based on this, we built monthly GSI and SF patterns for each period, which showed marked and prolonged seasonal reproductive activity. The patterns found have been interpreted as changes in reproductive strategy. The condition factor showed no significant differences throughout the study period. We discuss changes in these periods and their implications for fisheries management measures.

PeerJ, 2019

Background Small fishes play fundamental roles in pelagic ecosystems, channelling energy and nutrients from primary producers to higher trophic levels. They support globally important fisheries in eastern boundary current ecosystems like the Humboldt Current System (HCS) of the SE Pacific (Chile and Peru), where fish catches are the highest in the world (per unit area). This production is associated with coastal upwelling where fisheries target small pelagic fishes including the Peruvian anchovy (Engraulis ringens). The elevated biomass attained by small pelagics is thought to reflect their low trophic position in short/simple food chains. Despite their global importance, large gaps exist in our understanding of the basic ecology of these resources. For instance, there is an ongoing debate regarding the relative importance of phytoplankton versus animal prey in anchovy diet, and ecosystem models typically assign them a trophic position (TP) of ∼2, assuming they largely consume phyto...

1999

Progress in Oceanography, 2008

Paleontological and historical stock abundance estimates indicate that pelagic fish populations inhabiting upwelling ecosystems undergo large interdecadal variations in abundance with amplitudes equal to, if not larger than, the interannual variability. The interdecadal variability is characterized by periods of high and low abundance, termed ''pseudo-cycles", because of their irregular periodicity. Fisheries targeting small pelagic fish suffer from overall overcapitalization, like many other fisheries, but also from an additional overcapitalization problem: a phase displacement between rapid fish population decreases and a slower disinvestment which follows. This lag produces economic hardship.

Deep Sea Research Part II: Topical Studies in Oceanography, 2018

Temporal changes in mesoscale aggregations and spatial distribution scenarios of the Peruvian anchovy (Engraulis ringens),

Fisheries Oceanography, 2007

Three indexes of spatial aggregation are developed and used to examine the aggregation pattern of sardine (Sardinops sagax) and anchovy (Engraulis ringens) in the Peruvian Humboldt Current System, determined from 36 acoustic surveys conducted from 1983 through 2003 by the Peruvian Marine Institute (IMARPE). Each index assesses a different aspect of aggregation: the concentration, the percent occupancy of space and the clustering of high-fish abundance. Both time-series correlation and tree-based clustering-regression method, classification and regression trees (CART), were used to relate each of the indexes to environmental variables (season, temperature anomaly and year). Additionally, a measure of onshore-offshore distribution, the average distance from the coast, and abundance variables (the average acoustic backscatter per occupied sampling unit, and the acoustically estimated total abundance of sardine and anchovy from IMARPE) were related to environmental factors by using CART. We show that the 1983-2003 time series can be divided into three different periods: with shifts in 1992 and in 1997-98. Sardine and anchovy showed large differences in both abundance and aggregation among these periods. Although upwelling ecosystems support dramatic and sudden changes in environmental conditions, fish responses are sometimes smoother than usually suggested and there are transition periods with concomitant high biomasses of anchovy and sardine, but with different spatial aggregation patterns. Observed relationships between environmental proxies and aggregation patterns support the habitat-based hypothesis that environmentally mediated alterations in range lead to population changes.