Three-dimensional structure and avoidance behaviour of anchovy and common sardine schools in central southern Chile

Gerlotto, François; Castillo, Jorge; Saavedra, A. Gaye; Barbieri, María Ángela; Espejo, M.; Cotel, Pascal

doi:10.1016/j.icesjms.2004.07.017

Cited by 74 publications

(54 citation statements)

References 16 publications

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“…8). This finding is in agreement with observations by Gerlotto et al (2004), who proposed that internal structures are stable while external morphologies are variable. Therefore monospecific schools could correspond to various echo types and a single echo type could correspond to several fish species.…”

Section: Schooling Behavioursupporting

confidence: 94%

“…In this study, to determine whether these results are relevant to other communities, we performed a comparative analysis of schooling behaviours of similar fish assemblages from different geographical areas. Following definitions by Gerlotto et al (2004), we studied school 'morphology', represented by external and global school characteristics (e.g. overall dimensions) and school 'structure', defined by the internal arrangement of individual fish inside schools, e.g.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Schooling behaviour of small pelagic fish: phenotypic expression of independent stimuli

Brehmer¹,

Gerlotto²,

Laurent³

et al. 2007

Mar. Ecol. Prog. Ser.

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We compared echo sounder measurements of fish schools on Venezuelan and Senegalese coastal shelves. In both areas Sardinella aurita was the predominant aggregative species; the stocks are known to be genetically independent. Persistent school typology is described by analysing 7 acoustic surveys in Venezuela and comparing with pioneer observations in Senegal. The echo types encountered in both countries were comparable, with S. aurita and their associated species having comparable schooling behaviour. School morphology appears to be more related to species than to global characteristics of their ecosystems, as fish school descriptors were similar for both stocks. Nevertheless, S. aurita may adopt different school morphologies. Differentiation between day and night fish schools was mainly due to morphological variables, as determined by fractal dimension. Echo types were different between day and night in both Venezuela and Senegal. This analysis shows that several independent parameters can influence school morphology. However, although schooling behaviour is temporally highly variable, it shows several constant, typical 2D morphological structures, i.e. echo types. The observation of small pelagic fish schools occurring during the night is not unusual according to the literature, although a strict diurnal schooling behaviour, with scattering during the night, is often reported. Schooling behaviour appears to be a phenotypic expression depending on biotic and abiotic stimuli, intrinsic characteristics and motivation.

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Section: Schooling Behavioursupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Schooling behaviour of small pelagic fish: phenotypic expression of independent stimuli

Brehmer¹,

Gerlotto²,

Laurent³

et al. 2007

Mar. Ecol. Prog. Ser.

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show abstract

“…and (2) fish avoid the vessel. In the case of the Peruvian anchovy, vertical avoidance is minor, ~5 m, and horizontal avoidance is absent (Gerlotto et al 2004). So from the original depth measurement, we would normally add echo sounder depth and subtract avoidance depth.…”

Section: Prey Distributionmentioning

confidence: 99%

Foraging in Guanay cormorant and Peruvian booby, the major guano-producing seabirds in the Humboldt Current System

Weimerskirch¹,

Bertrand²,

Silva³

et al. 2012

Mar. Ecol. Prog. Ser.

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The Humboldt Current System is the most productive upwelling system globally in terms of fish and sustains huge populations of guano-producing birds as well as the world's largest single-species fishery targeting the Peruvian anchovy Engraulis ringens. Peruvian boobies Sula variegata and Guanay cormorants Phalacrocorax bougainvillii are the most abundant seabird species in the system and feed mainly on anchovies. By using high precision GPS and time−depth recorders, we compared the horizontal and vertical movements of the 2 species to examine whether segregation occurs between their foraging areas and whether there is any evidence for prey depletion close to large colonies. A simultaneous acoustic cruise in the foraging area of the 2 bird species estimated the vertical and horizontal distributions of anchovy schools. During the study period in austral spring 2008, the 2 bird species foraged in the same area, at relatively short distance from the colony (average, 19 to 20 km). Both species foraged at similar times of the day, although Peruvian boobies tended to leave earlier in the morning and return later in the evening than did the cormorants. Foraging trips were similar in duration, distance covered and range. Peruvian anchovies were abundant and schools occurred at shallow depths (median, 7 m; range, 3 to 34 m), mainly to the north and west of the colony where foraging bouts of the 2 species overlapped extensively. Cormorants are mainly pelagic surface divers, diving at shallow depths (median, 4 m) but reaching up to 32 m depth, and are thus able to track all the depths at which anchovies occurred during the study period. Peruvian boobies are plunge divers able to reach occasionally 10 m (median, 2 m), and are thus able to reach only shallow anchovy schools. No sexspecific differences in horizontal or vertical movements occurred between males and females in the 2 species. We suggest that the absence of significant differences between horizontal movements of boobies and cormorants, the relative short duration of their trips and the high number of chicks fledged were probably explained by the high abundance and accessibility of anchovies. Differences may be exacerbated during years of low anchovy abundance or accessibility, especially El Niño years. KEY WORDS: Peruvian anchovy · Telemetry · Phalacrocorax bougainvillii · Sula variegataResale or republication not permitted without written consent of the publisher

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“…This identical reproductive strategy is not a surprise since both species co-occur and are mixed in several types of aggregations (Gerlotto et al 2004), and they have similar biological characteristics such as the same spatial distribution, growth rate, natural mortality, reproduction time, and spawning area (Cubillos et al 2001, Castillo-Jordán et al 2007). Cubillos and Claramunt (2009) buen indicador del potencial reproductivo.…”

Section: Discussionmentioning

confidence: 99%

“…iteróparas, con desarrollo ovocítico asíncrono, fecundidad indeterminada, y desoves parciales. No es de sorprender esta idéntica estrategia reproductiva dado que ambas especies concurren y se mezclan en varios tipos de agregaciones (Gerlotto et al 2004), y tienen características biológicas similares como distribución espacial, tasa de crecimiento, mortalidad natural, época roproductiva y zona de desove (Cubillos et al 2001, Castillo-Jordán et al 2007). Cubillos y Claramunt (2009) documentaron que el ciclo estacional reproductivo era afectado por el tamaño de las hembras.…”

Section: Para Sardina Pilchardusunclassified

Spatial and temporal changes in batch fecundity of common sardine and anchovy off central and southern Chile (2002–2007)

et al. 2011

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Anchovy Engraulis ringens and common sardine Strangomera bentincki are two small pelagic fish that co-occur in the same reproductive habitat off central and southern Chile and have a similar reproductive strategy. Interannual and spatial changes in the batch fecundity of both fish were analyzed with the purpose of detecting variability in the parameters and inferring different reproductive tactics that could affect the reproductive potential. Samples were obtained from adult surveys carried out to estimate spawning biomass by the Daily Egg Production Method, from 2002 to 2007, off Chile. The study area was divided into two zones: central and south. The batch fecundity was linearly related to ovary-free female body weight for each year. For anchovy, the slope was not different across years and zones, while for sardine, changes in intercept and slopes varied significantly among years, but not between zones. The average weight of mature females tended to be higher in the south zone for both species, and average batch fecundity ranged from 4,283 to 8,903 eggs per mature female anchovy, and from 5,901 to 10,414 eggs per mature female sardine. Although the anchovy and sardine reproductive strategy is similar, differences in batch fecundity seemed to be the main distinction between the species in the central and southern spawning sites off Chile, with implications for the reproductive potential.

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Three-dimensional structure and avoidance behaviour of anchovy and common sardine schools in central southern Chile

Cited by 74 publications

References 16 publications

Schooling behaviour of small pelagic fish: phenotypic expression of independent stimuli

Schooling behaviour of small pelagic fish: phenotypic expression of independent stimuli

Foraging in Guanay cormorant and Peruvian booby, the major guano-producing seabirds in the Humboldt Current System

Spatial and temporal changes in batch fecundity of common sardine and anchovy off central and southern Chile (2002–2007)

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