Abstract
We recorded seasonal changes in the paralarval cephalopod communities collected off the southwestern coast of Baja California Sur, Mexico, during 2003. Simultaneous surface and oblique trawls were carried out with CalCOFI-type nets and CTD casts during spring and autumn 2003 on board the R/V Río Suchiate (Secretaría de Marina), at 85 sampling stations (Magdalena Bay to Cape San Lucas). The paralarval cephalopod community predominantly showed tropical affinity in both seasons. During autumn, 11 tropical taxa, 2 cosmopolitan taxa, and one temperate taxon were incorporated to the paralarval community recorded previously in spring and were associated with the decrease in Subarctic Water and the entrance of warm water masses to the study region, modifying the community indexes between seasons. The canonical correspondence analysis showed 2 groups significantly correlated with chlorophyll a concentrations and zooplankton volumes. Oblique tows provide better information on the paralarval cephalopod community, while surface tows can be an efficient method for monitoring and evaluating the hatching areas of the jumbo Pacific squid Dosidicus gigas through their paralarvae, which are included in the Sthenoteuthis oualaniensis–Dosidicus gigas complex (SD complex).
 Key words: paralarvae, community structure, SD complex, Baja California Sur.
Highlights
Simultaneous surface and oblique trawls were carried out with CalCOFI-type nets and CTD casts during spring and autumn 2003 on board the R/V Río Suchiate (Secretaría de Marina), at 85 sampling stations (Magdalena Bay to Cape San Lucas)
Oblique tows provide better information on the paralarval cephalopod community, while surface tows can be an efficient method for monitoring and evaluating the hatching areas of the jumbo Pacific squid Dosidicus gigas through their paralarvae, which are included in the Sthenoteuthis oualaniensis–Dosidicus gigas complex (SD complex)
The Sthenoteuthis oualaniensis–Dosidicus gigas complex (SD complex) is a frequent and abundant component of paralarval communities off the Pacific coasts of Mexico. This species complex is formed by paralarvae, measuring ≤3.0–4.0 mm mantle length (ML), that cannot be morphologically differentiated to species (Staaf et al 2011, De Silva-Dávila 2013)
Summary
In Mexico, mainly off northwestern Mexico and off the Gulf of Tehuantepec, the effects of the regional oceanography and of some physical, chemical, and biological variables on paralarvae distribution have been analyzed at different temporal and spatial scales. The Sthenoteuthis oualaniensis–Dosidicus gigas complex (SD complex) is a frequent and abundant component of paralarval communities off the Pacific coasts of Mexico This species complex is formed by paralarvae, measuring ≤3.0–4.0 mm mantle length (ML), that cannot be morphologically differentiated to species (Staaf et al 2011, De Silva-Dávila 2013). Biweekly satellite images (resolution: 4 km2) during each sampling season (http://coastwatch.pfeg.noaa.gov/erddap/ index.html) were used for both matrices
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