Biology ofPlesionika narval(Crustacea, Decapoda, Pandalidae) Around the Canary Islands (Eastern Central Atlantic)

The biology ofPlesionika narval(Fabricius, 1787) (Crustacea, Decapoda, Pandalidae) around the Canary Islands (Eastern Central Atlantic) was studied, based on a total of 41 679 shrimps of size range 2–30 mm carapace length (CL) collected over a 20-year period. This species carries out seasonal migrations; shrimps concentrate in deep waters in the autumn, move to shallower waters during winter and spring, and return to deep waters in summer. The growth parameters of males wereL0nfin;=29•47 mm CL andk=0•54 year−1, and of females wereL0nfin;=31•90 mm CL andk=0•66 year−1, with size generally increasing gradually with depth. Carapace length/wet weight relationships showed negative allometry. Ovigerous females occur year round but a spawning peak was determined from April to June when the population is found in shallower waters (26–175 m). Ovigerous females decrease in number as the depth increases. The size at maturity in females was 11•96 mm CL. The study of the sex ratio by depth and the seasonal migrations, as well as the sex differences in growth, confirm that this species conforms to the reproductive pattern of tropical pandalids, in which dioecy occurs.