Fine-scale spatial variability of different stages of pelagic fish eggs over the western Agulhas Bank, South Africa

Dopolo, MT; Drapeau, Laurent; Lingen, CD van der; Moloney, Coleen L.

doi:10.2989/ajms.2008.30.1.13.463

Cited by 3 publications

(1 citation statement)

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“…Extensive research effort has been made to understand the factors determining anchovy and sardine habitat in upwelling areas where fish habitat expands or shrinks, largely determined by the intensification of the upwelling. In southern African waters anchovy spawns from midshelf to the offshore area of the shelf, within waters of intermediate temperature (17–21°C) and high salinity [9] , [50] , [51] clearly separating its niche from adult sardine [52] . In south Australia anchovies spawn in productive waters (Chl-α concentration up to 4.5 mg m –3 ) and temperatures ranging from 15.5 to 23.5°C but anchovies tend to expand their distribution to shelf waters only when sardine abundance is low [53] , [54] .…”

Section: Discussionmentioning

confidence: 99%

Habitat Selection Response of Small Pelagic Fish in Different Environments. Two Examples from the Oligotrophic Mediterranean Sea

et al. 2014

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A number of scientific papers in the last few years singled out the influence of environmental conditions on the spatial distribution of fish species, highlighting the need for the fisheries scientific community to investigate, besides biomass estimates, also the habitat selection of commercially important fish species. The Mediterranean Sea, although generally oligotrophic, is characterized by high habitat variability and represents an ideal study area to investigate the adaptive behavior of small pelagics under different environmental conditions. In this study the habitat selection of European anchovy Engraulis encrasicolus and European sardine Sardina pilchardus is analyzed in two areas of the Mediterranean Sea that largely differentiate in terms of environmental regimes: the Strait of Sicily and the North Aegean Sea. A number of environmental parameters were used to investigate factors influencing anchovy and sardine habitat selection. Acoustic surveys data, collected during the summer period 2002–2010, were used for this purpose. The quotient analysis was used to identify the association between high density values and environmental variables; it was applied to the entire dataset in each area in order to identify similarities or differences in the “mean” spatial behavioral pattern for each species. Principal component analysis was applied to selected environmental variables in order to identify those environmental regimes which drive each of the two ecosystems. The analysis revealed the effect of food availability along with bottom depth selection on the spatial distribution of both species. Furthermore PCA results highlighted that observed selectivity for shallower waters is mainly associated to specific environmental processes that locally increase productivity. The common trends in habitat selection of the two species, as observed in the two regions although they present marked differences in hydrodynamics, seem to be driven by the oligotrophic character of the study areas, highlighting the role of areas where the local environmental regimes meet ‘the ocean triad hypothesis’.

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