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Marine Ecology Progress Series

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MEPS 253:197-208 (2003)  -  doi:10.3354/meps253197

Embryonic life of the loliginid squid Loligo vulgaris: comparison between statoliths of Atlantic and Mediterranean populations

R. Villanueva1,*, A. Arkhipkin2, P. Jereb3,8, E. Lefkaditou4, M. R. Lipinski5, C. Perales-Raya6, J. Riba1, F. Rocha7

1Institut de Ciències del Mar (CSIC), Passeig Marítim 37-49, 08003 Barcelona, Spain
2Falkland Islands Government Fisheries Department, PO Box 598, Stanley, Falkland Islands
3Istituto di Ricerche sulle Risorse Marine e l'Ambiente, Consiglio Nazionale delle Ricerche (IRMA-CNR), Via Luigi Vaccara 61, 91026 Mazara del Vallo, Italy
4Institute of Marine Biological Resources (IMBR), Aghios Kosmas, 16604 Helliniko, Greece
5Marine and Coastal Management, DEAT, Private Bag X2, Roggebaai 8012, South Africa
6Centro Oceanográfico de Canarias, Instituto Español de Oceanografía, Carretera de San Andrés s/n, 38120 Santa Cruz de Tenerife, Spain
7Instituto de Investigaciones Marinas (CSIC), Eduardo Cabello 6, 36208 Vigo, Spain
8Present address: Istituto Centrale per la Ricerca Scientifica e Tecnologica Applicata al Mare (ICRAM), Via di Casalotti 300, 00166 Roma, Italy

ABSTRACT: Egg masses of the loliginid squid Loligo vulgaris Lamarck, 1798 are attached to hard substratum or branched sessile organisms on the sea bottom. Embryonic development lasts from a few weeks to a few months, depending on the environmental water temperature. Because embryonic statolith growth of L. vulgaris is very sensitive to temperature under laboratory conditions, we analyzed the possibilities of determining past events in the squid¹s early life from analysis of the embryonic area of statoliths of wild squid populations. The relationship between egg-incubation temperature and daily growth of embryonic statoliths under laboratory conditions was determined by tetracycline markings at 10 incubation temperatures ranging from 12 to 24.7°C. In addition, the mean width of embryonic increments in statolith collections of wild L. vulgaris from the Eastern Atlantic (Saharan Bank and NW Iberian Peninsula) and the Mediterranean Sea (Central and Eastern) was calculated. The temperature inferred from the embryonic increment widths of the statoliths of wild squid indicates that embryonic development of L. vulgaris in the regions sampled is likely to occur at temperatures ranging from 12 to 17°C. Mediterranean squid have wider embryonic increments than Atlantic squid, reflecting the slightly higher water temperatures in the Mediterranean Sea during the development of the egg masses. Eggs of L. vulgaris spawned off the NW Iberian Peninsula were estimated, on average, to remain at sea for 47 d, 1 wk longer than Mediterranean eggs (nearly 1 mo longer when comparing minimum and maximum ranges). A longer incubation time for egg masses attached to the sea bottom increases mortality risks. Conversely, slow development at a lower temperature can improve yolk conversion, producing larger hatchlings, and increased hatching competence is expected from such squid. Therefore, a compromise between longer-versus-shorter incubation time and related characteristics does exist.

KEY WORDS: Cephalopods · Spawning sites · Embryonic development · Eggs · Larvae · Growth · Statoliths

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