The jumbo squid Dosidicus gigas is an ecologically and commercially important species whose northernmost geographic limit is the Gulf of California. However, over the last decades this species has extended its geographic distribution polewards, with associated impacts on the ecosystem. The origin of range-shifting individuals is poorly understood; therefore, we aimed to identify and characterize the northernmost spawning habitat of this species. Implications of the location and oceanographic conditions of the spawning habitats, migration capacity and life history characteristics of D. gigas are also discussed to elucidate its migration pattern. The northernmost spawning area was located between the biological activity centres (BACs) around the Gulf of Ulloa at the west coast of southern Baja California Peninsula during winter, summer and autumn 2005. Generalized linear models indicated that the interaction of sea surface salinity and thermocline depth, and the effect of latitude and sea surface temperature explained most of the variability in paralarval presence, whereas chlorophyll a and latitude explained paralarval abundance. Simulations indicated that paralarvae were dispersed towards the southwest or temporarily remained between BACs. The northwards incursion of D. gigas may be favoured by BACs and upwelling events along the coast of the northeastern Pacific. In warm years, D. gigas is likely to spawn off the Baja California Peninsula, it may actively migrate as far north as Alaska (USA) tracking BACs and upwelling conditions in search of feeding grounds, and it may return from different areas along the northeastern Pacific to spawn off the Baja California Peninsula.

The common Sydney octopus Octopus tetricus has undergone range extension along the east coast of Australia, associated with regional warming and the strengthening and southward extension of the East Australian Current (EAC). Its historical range of distribution is from southern Queensland to southern New South Wales, but it is now also found off north-east Tasmania, where it may affect local ecosystem dynamics due to changes in trophic interactions. This study aims to identify the prey and trophic level of O. tetricus from specimens collected off Tasmania to anticipate potential ecological, economic, and conservation effects in the range-extended area. The stomach contents of 18 O. tetricus individuals captured off north-east Tasmania in 2011 were characterised using DNA metabarcoding. Sixteen families of prey were identified; crustaceans (Alpheidae, Calcinidae, Diogenidae, and Galatheidae) were the most frequently detected prey, followed by fishes and bivalves. Prey species of commercial importance included blue-throated wrasse Notolabrus tetricus and the scallop Pecten fumatus. O. tetricus was found to have an intermediate trophic level of 3.66, participating in the transfer of energy from lower to upper trophic levels. Predation by O. tetricus could present competition to local fishers for resources and additional pressure on local fishery stocks, and may alter estimates of natural mortality used by fisheries management. The present study may be useful to scientists, fishery managers, and conservationists because it provides a preliminary assessment of the diet of O. tetricus, with potential ecological, economic, and conservation implications in the range-extended area.