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Cephalopods are highly sensitive to environmental conditions and changes at a range of spatial and temporal scales. Relationships documented between cephalopod stock dynamics and environmental conditions are of two main types: those concerning the geographic distribution of abundance, for which the mechanism is often unknown, and those relating to biological processes such as egg survival, growth, recruitment and migration, where mechanisms are sometimes known and in a very few cases demonstrated by experimental evidence. Cephalopods seem to respond to environmental variation both 'actively' (e.g. migrating to areas with more favoured environmental conditions for feeding or spawning) and 'passively' (growth and survival vary according to conditions experienced, passive migration with prevailing currents). Environmental effects on early life stages can affect life history characteristics (growth and maturation rates) as well as distribution and

Although Chaceon affinis is practically unknown to Canarian fishermen, relatively abundant quantities of deep-sea red crab C. affinis have been found in all trap surveys conducted around the Canary Islands in the last 10 yr, in which waters deeper than 550 m have been examined. From July 1994 to May 1996, monthly samples were taken from north-eastern waters off Tenerife using a variety of trap designs. Crabs were caught at depths ranging from 550 to 1200 m on muddyrocky bottoms. A variety of measurements were taken from each specimen, and most of these showed linear and isometric growth relative to carapace width (CW). Male chela width (ChW) and female abdomen width (AW) did not show such evident allometry as other crab species. Changes in growth of these features, considered as secondary sexual characters, were used to discriminate morphometrically immature crabs from mature crabs, using hierarchical cluster analysis. Different morphometric groups were distinguished, for both males and females, and male ChW and female AW were plotted against CW. Regressions were calculated separately for each cluster to test the discrimination statistically. Morphometric size at maturity was initially estimated and compared with data on gonad stage. This comparison revealed a high correlation in males between morphometric and sexual maturity, which is reached at about 129 mm CW. However, most females become morphometrically mature before their ovaries mature and before copulation (at sizes of ~99, 108 and 113 mm CW, respectively). KEY WORDS: Biology · Maturity · Chaceon affinis · Geryonidae · Canary IslandsResale or republication not permitted without written consent of the publisher

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