Age, growth, and mortality of Loligo vulgaris wild paralarvae: implications for understanding of the life cycle and longevity

Abstract

González, Á. F., Otero, J., Pierce, G. J., and Guerra, Á. 2010. Age, growth, and mortality of Loligo vulgaris wild paralarvae: implications for understanding of the life cycle and longevity. – ICES Journal of Marine Science, 67: 1119–1127. Age, growth, and mortality were estimated for the first time in wild paralarvae of the common squid, Loligo vulgaris, by examining growth increments in the statoliths of 273 animals collected off the Ría de Vigo (NW Spain, NE Atlantic). Hatching was all year round for the period 2003–2005, with a peak during late spring and a secondary peak during early autumn. Paralarvae varied from 1260 to 7580 µm, and their abundance decreased abruptly as they grew. Statolith increments were clearly visible without grinding in almost all material, allowing reliable estimation of age. Paralarvae are planktonic for at least 3 months. Growth in dorsal mantle length (DML) during that period fitted an exponential equation. The instantaneous relative growth rates were 2.11, 2.15, and 1.82% DML d−1 for 2003, 2004, and 2005, respectively, and there were no significant differences in size-at-age between the 3 years. Taking into account the growth rates estimated for the whole cycle of L. vulgaris, we suggest that the lifespan may previously have been underestimated by 3 months, because the proximity of the rings deposited during paralarval and early juvenile stages would prevent accuracy in enumerating the number of growth increments in later stages. The estimated instantaneous rate of total mortality during the first 90 d of a paralarva life was 9.6, 5.3, and 4.8% d−1 for 2003, 2004, and 2005, respectively. Eye diameter was a reliable and rapid way of estimating DML and age.

Sepiolid paralarval diversity in a regional upwelling area of the NE Atlantic

“…Additionally, four diurnal surveys were conducted, one in summer and the others in early autumn in both 2012 and 2013. For each survey, sampling was conducted along four transects following González et al (2010), (Fig. 1a).…”

Field estimates of planktonic larval duration in a marine invertebrate

“…Unfortunately, the majority of marine invertebrate larvae do not have an equivalent 'time-keeper' (though see e.g. Laptikhovsky et al 1993, Villanueva et al 2003, Gonzalez et al 2010, so estimating planktonic durations for most marine invertebrates is much more difficult. Despite the difficulties, estimates of planktonic durations are essential for understanding and managing marine populations.…”

Determination of age and growth of the horned octopus <em>Eledone cirrhosa</em> (Cephalopoda: Octopoda) using stylet increment analysis

“…In the future, the results of the present study will need further validation, not only because the deposition rate of growth rings could have a different periodicity to a day, but also because stylet formation and growth processes remain unknown during embryonic development and early life stages and, as observed in other structures such as statoliths (González et al 2010), the central area of the stylet may undergo compaction during early growth. That would make it harder to estimate the number of rings in this area and could bias the results on estimated age.…”