Task 3. Biological variation
Sub-task 3.1: Development of new tools for statolith image processing
New radial processing software was developed, in order to improve the age estimation process of Cephalopod statoliths. Based on the various image profile trajectory programming, local estimators working by data integration or by data interpolation were developed.
The assessment of the main reading difficulties was carried out and the statolith preparations gathered were used for the constitution of a statolith image database. The database is composed of 300 statolith images for Loligo forbesi, Loligo vulgaris, Sepia hierredda, and Sepia officinalis samples.
The recourse to the mosaics of images was regarded as a tool essential to the analysis of the statoliths by digital imaging. An algorithm of mosaic construction was developed on the basis of a search of the shift between two contiguous images in their overlapping zone.
The imaging tools don?t solve all the cephalopod age estimation problems. Although, curved and combined trajectories enable to collect information precisely where it is located and the interpolation enables to process samples where ring sequences are locally not visible, allowing for instance to back-calculate hatching dates and with this, to temporally align growth patterns.

Sub-task 3.2: Assessment and application of new statolith ageing tools
Age-reading precision was tested on known-age Sepia officinalis statolith samples. Precision was high, especially for individuals of less than 200 days old.
The application of these tools has started on a comparative study of Loligo vulgaris growth patterns of specimens captured to different seasons along the Portuguese coasts. The distribution of statolith radius at 100 days showed a trend in the winter-hatched individuals with a higher variability in their growth, than spring-hatched individuals.
The image analysis tools were developed, tested and are currently available near various users, before to be commercially distributed. Complementary tools for image mosaic construction and a database were also developed. This tool set thus represents currently a coherent whole, enabling to assist the user since image acquisition until their most advanced treatment.
Future work on computer-assisted cephalopod age estimation should be focused on the improvement of image quality of statolith images by filtering radial structures but also to the increasing of the standardisation of the preparation techniques.

Sub-task 3.3: Growth and reproduction - new analysis of existing data
A substantial amount of historical commercial fishery and research vessel survey information on Loligo forbesi and Loligo vulgaris and more restricted information for cuttlefish and some ommastrephid species across its biogeographic range was obtained during the European-funded FAR, AIR and FAIR projects (1990 - 99). As a result, we now have one of the largest cephalopod databases in existence. This database is now structured with a user interface to extract selected sub-sets of the original data, to view or print charts or to export to other software. Users can select data for specific species, ICES subdivisions, years, months, sample types etc.
The spatial and temporal trends in Loligo forbesi (1990-1999) was analysed for recruitment, sex ratios, maturation and spawning in Azores, English Channel, French, Faroese, Irish, Portuguese, Scottish and Spanish waters.
The analysis of spatial and temporal biological patterns in Loligo vulgaris (1991 to 1995) in North France, Northwest Spain, Northwest and South Portugal and the Saharan Bank showed geographical biological variation in most biological indices.

Sub-task 3.4: Growth and reproduction - data from new sampling
Limited new sampling for cephalopod species throughout the range of the study was made and information on population structure, growth and reproduction were collected. The accuracy of official fishery statistics has been assessed by comparison between market observers and reported catches.
Biological variation of Loligo forbesi, Sepia officinalis, Octopus vulgaris, Loligo vulgaris and Illex coindetii was analysed in relation to geographic and oceanographic variables Results showed that biological variation between geographic areas is more pronounced in benthic than in pelagic species. This variation is also often found between the Eastern Atlantic and Eastern Mediterranean populations.
The relationship between SST and biological parameters was evaluated by correlation of moving averages. Inter-annual variation in biological indices of Loligo vulgaris is more clearly related with inter-annual variation in Sea water temperature, showing negative correlation with levels of recruitment (% recruits) and spawning (% mature, GSI) and positive correlation with size and weight indices, i.e. somatic growth. The correlation of SST with Octopus vulgaris biological indices was in general higher with shifts in the data series. Biological indices related to growth didn?t show any significant correlation with SST.
PCA was used in biological indices of Illex coindetii and Spearman?s rank correlation coefficient used to test for any relationship between the scores of the first two PC axes and SST values in each one of the studied areas. Average SST values were found to be weakly correlated with both PC axes, indicating that many other environmental variables may affect the life-cycle of the species. Additional rank correlation tests were performed to detect any significant relationship between life-cycle indices and average SST values indicating some negative correlation mainly with length and weight related indices in the Atlantic and positive correlation in the Mediterranean. Chl-a values in the Greek Seas, were found to be negatively correlated with most biological indices.
Biological data collected during opportunistic research cruises was used to locate recruitment and spawning areas of the target species and their relation to environmental variables. Main spawning and recruitment areas of Loligo spp. showed some relation to lower SST areas, although paralarvae distribution was more related with areas of highest food availability. Main spawning of Illex coindetii and Todaropsis eblanae and Sepia officinalis occur in areas with SST below 17ºC, but Ommastrephid paralarvae were found mainly close to warmer areas. Octopus vulgaris spawning and recruitment areas didn?t present any relation with the environmental variables analysed.