Decadal-scale variability in populations

Alheit, Jürgen; Roy, Claude; Kifani, Souad

doi:10.1017/cbo9780511596681.007

Cited by 49 publications

(45 citation statements)

References 8 publications

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“…Sardine catches present decadal cycles such as many environmental variables (Alheit, Roy, & Kifani, ). In the late 1990s, Iberian sardine stock entered a second consecutive negative period (Garrido et al., ; Guisande, Vergara, Riveiro, & Cabanas, ) from which it has not yet recovered.…”

Section: Introductionmentioning

confidence: 99%

Study of sardine (Sardina pilchardus) regime shifts in the Iberian Atlantic shelf waters

Cabrero

González-Nuevo

Gago

et al. 2018

Fisheries Oceanography

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Sardine fisheries in the Iberian Atlantic shelf (36°N–44.5°N) show decadal‐scale cycles. In the late 1990s, a positive phase in sardine stock was expected; on the contrary, catches have declined until now. Regime shifts in climatic and oceanographic variables on different scales (as forcing factor) and shifts in sardine stock (as result) have been used with the aim of identifying the physical variables that explain most of the sardine population variance in the region. Circa 1998, when last sardine regime shift was detected, the main patterns of large‐scale atmospheric circulation in the Northern Hemisphere with influence in the study area namely Northern Atlantic Oscillation (NAO) and East Atlantic (EA) pattern changed and coupled in a combination that led to a rise in sea surface temperature and a decline in the coastal upwelling intensity. Several years with a downwelling situation in average in the main spawning and feeding Iberian sardine areas would have affected the stock abundance, averting the return to the projected positive regime. The sardine negative regime shift was detected first in the regions of the study located further north. The regional variable latent heat flux that groups a set of environmental processes related to the ocean–atmosphere heat exchanges and so with the turbulence manages to explain the 72% of sardine recruitment.

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Section: Introductionmentioning

confidence: 99%

Study of sardine (Sardina pilchardus) regime shifts in the Iberian Atlantic shelf waters

Cabrero

González-Nuevo

Gago

et al. 2018

Fisheries Oceanography

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“…Anchovy ( Engraulis encrasicolus ) and sardine ( Sardinops sagax ) are small pelagic fish species of ecological and socio‐economic importance in the southern Benguela ecosystem because they are the main prey of numerous predators and support large fisheries that employ a significant number of people (Hutchings et al ., 2009). These fish species are characterized by a relatively low position in the marine foodweb, a short lifespan (2–3 yr for anchovy and 4–7 yr for sardine) and a reproductive strategy of producing large quantities of pelagic eggs over an extended spawning season (Fréon and Misund, ; Fréon et al ., ; Alheit et al ., ), all of which make them very susceptible to environmental variability (Bakun, ). Armstrong and Thomas () defined the period of spawning for anchovy from October to November, with a maximal intensity in November.…”

Section: Introductionmentioning

confidence: 99%

Have the spawning habitat preferences of anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax) in the southern Benguela changed in recent years?

Mhlongo¹,

Yemane

Hendricks³

et al. 2015

Fisheries Oceanography

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This paper examines whether the ranges of occurrence of anchovy and sardine eggs have changed off the South African coast in recent years, and whether this could be linked to changes in sea surface temperature (SST). We used a single parameter quotient analysis with randomization to estimate the preferred and tolerated SST ranges of the spawning habitats of anchovy and sardine in the southern Benguela over the period 1988–2009. Previous studies have reported long‐term change in SST off the South African coast, and our analysis was aimed at determining whether spawning habitat selection by these small pelagic fish tracked such change. The analysis used data on egg occurrence collected concurrently with in situ SST data during annual surveys of pelagic fish biomass conducted along the South African coast. Results show that anchovy typically, but not always, spawn in warmer waters (17.0–23.0°C) than sardine do (16.0–22.0°C), and sardine almost always showed a wider SST tolerance range than did anchovy, over the time‐series. The analysis further suggests evidence of an increase in the surface temperature conditions along the South African coast recently; the spawning patterns of anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax) appear to track these changes through time. Therefore, the spawning habitat preferences of anchovy and sardine in the southern Benguela have changed in recent years, but this is unlikely to be due to warming alone.

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“…Species replacements may take place, mainly between sardine and anchovy but sometimes involving less abundant species of pelagic ecosystems like chub mackerel in the Pacific (e.g. Alheit et al 2009). An illustrative example is that of the pelagic ecosystem off the Japanese waters: Pacific sardine and anchovy have shown dramatic out-of-phase fluctuations in abundance since the 1940s, leading to an anchovy period up to the late 1960s and a sardine period in the 1980s, with another shift in the 1990s (Yatsu et al 2005, Watanabe 2009).…”

Section: Introductionmentioning

confidence: 99%

Changes in the abundance and spatial distribution of the Atlantic chub mackerel (<i>Scomber colias</i>) in the pelagic ecosystem and fisheries off Portugal

Martins¹,

Skagen²,

Marques³

et al. 2013

Sci. Mar.

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SUMMARY: This study describes changes in abundance and spatial distribution of Atlantic chub mackerel in the Portuguese waters and the Spanish waters of the Gulf of Cadiz using data from acoustic surveys from 1995 to 2010 and data from the fishery since 1958. The distribution and dynamics of chub mackerel and sardine (Sardina pilchardus) are compared and species interactions are discussed. From 2007 to 2009, chub mackerel biomass, as measured acoustically, ranged between 69000 and 238000 t concentrated off the western coast (~50%) and in the Gulf of Cadiz (~30%). Portuguese landings have varied with periods of high landings around 1970 and in recent years. Since 1986 landings have been between 4000 and 23000 t. Both survey catches and commercial landings are taken mainly off the southwestern coast and one-to two-year-old individuals (20-24 cm) predominate in both. Scarcity of larger individuals may be a consequence of their deeper distribution and avoidance of fishing gear, migration of older individuals or a combination of both. In years with high abundance, the fishery expands to the northwestern areas of the Iberian Peninsula. The expansion appears to be caused by improved recruitment although other factors might have contributed (such as targeting to compensate for low sardine catches and the appearance of new markets). The complementary spatial distribution of chub mackerel and sardine and the inverse correlations between their frequency of occurrence, landings and recruitment indices suggest some interaction between the dynamics of the two species, possibly associated with climatic variation.Keywords: Chub mackerel, sardine, Portugal, pelagic ecosystem, purse seine fishery. RESUMEN: Cambios en la abundancia y distribución espacial del estornino del Atlántico (Scomber coliaS) en el ecosistema pelágico y pesquerias de Portugal. -Este estudio describe los cambios en la abundancia y distribución espacial del estornino del Atlántico en las aguas portuguesas y aguas españolas del golfo de Cádiz a partir de datos de las prospecciones acústicas 1995-2010 y datos de la pesquería desde 1958. La distribución y la dinámica del estornino y de la sardina (Sardina pilchardus) se comparan y se analiza la interacción de las especies. Durante 2007-2009, la biomasa del estornino medida acústicamente osciló entre 69 y 238 mil t y se concentró frente a la costa occidental (~50%) y en el golfo de Cádiz (~30%). Los desembarques portugueses han variado con períodos de altas capturas alrededor de 1970 y en los últimos años. Desde 1986 los desembarques han sido entre 4 y 23 mil t. Ambas capturas de campañas y desembarques comerciales se toman principalmente en la costa sur occidental y individuos de 1-2 años edad (20 a 24 cm) predominan en ambos. La escasez de individuos más grandes puede ser una consecuencia de su distribución más profunda y la evitación de las artes de pesca, la migración de los individuos mayores o una combinación de ambos. En los años de mucha abundancia, la pesquería se expande a las áreas occidentales norte d...

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Decadal-scale variability in populations

Cited by 49 publications

References 8 publications

Study of sardine (Sardina pilchardus) regime shifts in the Iberian Atlantic shelf waters

Study of sardine (Sardina pilchardus) regime shifts in the Iberian Atlantic shelf waters

Have the spawning habitat preferences of anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax) in the southern Benguela changed in recent years?

Changes in the abundance and spatial distribution of the Atlantic chub mackerel (<i>Scomber colias</i>) in the pelagic ecosystem and fisheries off Portugal

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