First description of spawning in a deep water loliginid squid, Loligo forbesi (Cephalopoda: Myopsida)

Despite being an exploited and economically important species, little is known about the reproductive behaviour of Loligo forbesi. During a captive trial performed in a closed seawater system in the Azores, three spawning events were directly witnessed. An account of their main behavioural aspects is given. A number of behavioural components are described for the first time in this species: ‘pair formation’, ‘mate guarding’, ‘egg holding’, ‘egg touching’, ‘white arms’, ‘red accessory nidamental glands’, ‘accentuated testis’, and ‘jockeying and parrying’. The chromatic, locomotor and postural components were very similar to other coastal loliginids observed on spawning grounds. From egg masses recovered on octopus traps, we show that in the Azores spawning activity occurs at least between 25 and 144 m, but greater depths might be expected. We suggest that this squid preferentially deposits egg masses on hard structures probably hiding them in cracks and crevices of volcanic substrata. The existence of spawning aggregations is supported by several factors: (i) these spawning grounds may coincide with the fishing spots, where the exploitation seasonally takes place, given that most individuals caught by fishermen are usually mature (more than 80%); and (ii) mate guarding and jockeying/parrying by males was observed, which is a common feature of spawning aggregation areas, where sperm competition occurs. Furthermore, our results, combined with available published and non-published data further confirm L. forbesi as an intermittent spawner. We estimate that throughout their short life cycle, females of L. forbesi are able to perform up to six spawning events, each composed of an average of ≈2300 eggs.