Cephalopod fauna of South Pacific waters: new information from breeding New Zealand wandering albatrosses

Abstract

Cephalopods play an important ecological role in the Southern Ocean, being the main prey group of numerous top predators. However, their basic ecology and biogeography is still poorly known, particularly in the lightly sampled Pacific sector of the Southern Ocean. We collected and analysed information on cephalopods in that area, using Antipodean and Gibson's wandering albatrosses (Diomedea antipodensis antipodensis and D. antipodensis gibsoni, respectively) breeding at Antipodes Islands and Auckland Islands, respectively, in the New Zealand subantarctic islands as samplers, as they are known from tracking studies to cover huge areas of the Pacific sector of the Southern Ocean (Antipodean wandering albatrosses mostly forage east of New Zealand, whereas Gibson's wandering albatrosses forage west of New Zealand). A total of 9111 cephalopod beaks, from 41 cephalopod taxa, were identified from boluses (voluntarily regurgitated items by chicks). The families Histioteuthidae (e.g. Histioteuthis atlantica) and Onychoteuthidae (e.g. Moroteuthis robsoni) were the most important cephalopods numerically and by reconstructed mass, respectively, in both wandering albatross species. Combining this information with previously gathered data on cephalopods in the Atlantic and Indian sectors of the Southern Ocean, we provide evidence from predators of the circumpolar distribution of numerous key cephalopod species in the Southern Ocean, and provide new information on poorly known cephalopods (i.e. relevance in the diet of wandering albatrosses, sizes consumed, biodiversity in the South Pacific, assemblages according to predator breeding sites) in one of the most remote ocean areas in the planet.

Genetic analysis reveals historical and contemporary population dynamics in the longfin squid Doryteuthis gahi: implications for cephalopod management and conservation

“…Cephalopods are considered highly susceptible to overfishing as their annual or sub-annual life histories mean there is little opportunity to adjust fishing strategies during the lifetime of a single cohort (Pierce et al, 2008). Some cephalopod fisheries have already declined with such declines expected to have wide ranging impacts on the marine ecosystems within which the species occupy important roles as predators and prey (Xavier et al, 2014). A fundamental requirement for the sustainable management of commercially harvested taxa is an accurate understanding of patterns and processes of population connectivity.…”

Cephalopod prey of two demersal sharks caught in the Aegean Sea (eastern Mediterranean)

“…The reason for this is that several cephalopods, particularly the pelagic ones, are not widely fished and conventional gears, used in monitoring other pelagic taxa, usually collect juveniles, since adult specimens generally avoid being captured (Clarke, 1996; Piatkowski et al ., 2001). Therefore, diet composition analysis of various top predators, such as cetaceans, seabirds, sharks and large pelagic finfish, is a standard technique that provides valuable information on their ecology, geographic distribution, abundance and seasonal fluctuations (Clarke, 1986; Xavier et al ., 2014).…”

Using seabirds to map the distribution of elusive pelagic cephalopod species

“…Wandering albatrosses are cephalopod predators, which specialize in feeding on a wide range of oceanic squid and octopod species in subtropical waters in the north to Antarctic waters in the south (Xavier & Croxall 2005). During the chick-rearing period, wandering albatrosses adults may provide almost 60 different cephalopod species to their chicks (Xavier et al 2014). According to our analysis, oceanic squid were caught by wandering albatrosses in all water masses (i.e.…”

“…Distribution data of most marine groups is absent in remote marine areas, such as the vast Southern Ocean (considered in this study, as south of the subtropical front; (Xavier et al 2014). Information on fast swimming oceanic prey, such as squid, is particularly difficult as they appear rarely in scientific nets (Xavier et al 2006).…”