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In the present paper, a normalization technique to scale data that exhibit an allometric growth is presented and the way it has to be used is described. It is shown how the method has been derived from the theoretical equations of allometric growth. Consequently, the method completely removes all the information related to size, not only scaling all individuals to the same size, but also adjusting their shape to that they would have in the new size according to allometry. In the particular case of isometry when the measures are of identical dimension, this normalization coincides with ratios (one of the most popular methods but only valid in this particular case). This procedure is a theoretical generalization of the technique used by Thorpe (1975, Biol. J. ̧inn. Soc. 7, 27}43; 1976, Biol. Rev. 51, 407}452) which was recorded as one of the most e$cient methods in the empirical evaluation done by Reist (1985, Can. J. Zool. 63, 1429}1439).

Keywords: Lipids; Fatty acids; Cephalopods; Octopus; Squid; Cuttlefish.

We report here the main lipid classes and the fatty acid composition from the total lipids of hatchlings of three cephalopod species: Sepia officinalis, Loligo Íulgaris and Octopus Íulgaris, as well as the lipid composition of two selected crustaceans that have been used previously with success as food resource for rearing cephalopod hatchlings: zoeae of Pagurus prideaux and the mysidacean Acanthomysis longicornis. Additionally, we report the lipid class and fatty acid composition of two cultures of O. Íulgaris paralarvae reared with enriched Artemia juveniles, and with enriched Artemia juveniles plus a prepared pelleted diet. From their lipid composition and that of their natural food, it can be deduced that cephalopod paralarvae and juveniles must require a food rich in polyunsaturated fatty acidsPUFA., phospholipids and cholesterol and with a moderate content in neutral lipids. There was a clear influence of the lipid composition of the food on the lipids of cultured octopus paralarvae both at the level of lipid class and fatty acid composition. The cultured octopus paralarvae showed a lower content of PUFA as compared with the newly hatched individuals. Co-feeding techniques based on the use of polar lipid and PUFA enriched Artemia together with palatable pellets seemed to be a possible way to improve paralarval and juvenile cephalopod culture beyond the experimental scale. q2000 Elsevier Science B.V. All rights reserved.

It is possible to mark octopus (Octopus vulgaris) paralarvae on a massive scale (up to 3500 paralarvae l−1) with 100% marking reliability using alizarin complexone (ALC). The whole statolith is marked and the best results obtained were with concentrations of 60-300 mg l−1 and bath duration of 3-24 h. Taking into account the quality of marking, mortality and ALC costs suggest using from 60 to 200 mg l−1 for 3-6 h. The only treatments causing significant mortalities were 300 mg l−1 over 6 and 24 h.

Prey size is one of the major factors involved in prey selection of fish larvae, and is closely related to their foraging abilities and mouth size. This study examines the feeding habits of 6 coexisting fish larvae species of the order Myctophiformes in the western Mediterranean. The Myctophiformes are the dominant teleosts of the open oceans worldwide, and their larvae are characterized by high morphological variability. In the present study, size of ingested prey increased through larval development for all species examined, but at different rates. Niche breadth (i.e. range of sizes of ingested prey, estimated as the standard deviation of log-transformed prey sizes) was constant throughout growth. The larvae actively selected certain prey sizes; selection changed during development, and varied between species. This variability appears to be related to interspecific morphological differences, and may constitute a strategy to optimize the utilization of trophic resources in the oligotrophic open-ocean habitat.

Keywords: fisheries impacts, mud communities, disturbance..

We report the findings of an experiment conducted in the northwestern Mediterranean to evaluate the short-term effects of otter trawling on a muddy-sediment infaunal community. A commercial fishing vessel, using conventional otter trawling gear, fished two waylines repeatedly until each had been disturbed entirely either once or twice. Infaunal samples were collected from replicate sites located within the fished and adjacent undisturbed control areas. Univariate analyses of species richness and diversity indicated that the infaunal community did not alter during the first 102 h after fishing in the area that was trawled once. However, the abundance of a number of species decreased significantly on the unfished line compared with the fished line 150 h after fishing. No differences were detected on the line that was fished twice, but this part of the experiment was terminated after 72 h. Multivariate analyses revealed that the communities in both fished and unfished areas changed in a similar manner through time and that there was no apparent effect of fishing until 150 h after fishing. These short-term changes are discussed in the light of recent studies of infaunal changes in other habitats.

Over the past decade, statolith interpretation has resulted in a major advance in our knowledge of squid population-dynamics, but the way in which environmental conditions affect the statolith increment-de-position ratio remains virtually unknown. The object of the present study was to determine the effect of temperature on this process, usingtetracycline marks to validate statolith growth in Loligo vulgaris Lamarck, 1798 under rearing conditions equivalent to severe winter (11 °C) and summer (19 °C) temperature regimes. Tetracycline marking was performed every 10 d (at 10, 20, 30, 40, 50 and 60 d of age). The newly hatched squid paralarvae were slightly smaller in summer than those hatched in winter. Survival rates were similar in both cultures, but growth rates (wet mass) of summer squids were double those in winter. At hatching, statoliths were already longer in the summer squids, and growth rates were 2% d)1 as opposed to 0.9% d)1 for winter statoliths. For the dorsal dome area of the statolith, where more increment counts were made, statolith growth was of 3.25 lm d)1 in summer, and daily increment deposition was confformed in 87% of the statoliths. The slow growth of statoliths at winter temperatures yielded a mean growth of 1.1 lm d)1 ± insufficient to discern the increments using light microscopy. Subsequent SEM observation enabled only 21% of the winter statoliths to be read; these also indicated a deposition rate of one increment d)1. Since the life span of L. vulgaris is '1 yr, squids will experience at least one winter during their life cycle, and this might be visible on the statolith.