Spawning cycle of onychoteuthid squids in the southern Indian Ocean:new information from seabird predators

Abstract

Cephalopods play an important role in the trophic web of the Southern Ocean, but little information is available on their biology. The 2 largest sub-Antarctic seabirds, the king penguin Aptenodytes patagonicus and the wandering albatross Diomedea exulans, feed primarily on squids during the austral winter at the Crozet Islands. We examined a large number of accumulated cephalopod beaks in the stomach of these birds together with some undigested items; first, to understand how these 2 predators share the squid resource during winter, a period of supposed low food availabhty, and, second, to use a diving and a flying seabird as biological samplers of Southern Ocean cephalopods. Individuals of the fanuly Onychoteuthidae formed the bulk of the squid diet, accounting for 72.6 and 57.0% of the number of lower beaks in samples from king pengulns and wandering albatrosses, respectively. Seven different species were identified, the 3 main squids being Kondakovia longimana (38.8 and 28.0% by number for penguins and albatrosses, respectively), Moroteuthis ingens (13.5 and 26.2%) and Ivf. knipovitchi (20.1 and 2.3 %). Both seabirds preyed upon the same cephalopod species, but penguins primarily took small-to medium-sized juveniles (99.0% of the onychoteuthids) and albatrosses preyed on larger adult specimens (96.0%). Fresh remains indicated that adult K. longimana and M. ingens were mature ~ndividuals which, as shown by satellite tracking of albatrosses, were taken over the slope and nearby oceanic waters surrounding the archipelago. The present study indicates that matinglspawning of K. longimana and M. ingens occurs in Crozet waters during the winter months. It also extends the biogeography of K. longimana to north of the Antarctic Polar Front, in the Polar Frontal Zone, where it has not previously been recorded.

Diet of the squid Moroteuthis ingens (Teuthoidea: Onychoteuthidae) in the upper slope waters of the Kerguelen Islands

“…The 2 size classes of Moroteuthis ingens in Kerguelen waters were similar to those found at the Falkland Islands over the year (Jackson et al 1998a) and in the diet of seabirds from Crozet Islands (Cherel & Weimerskirch 1999). The co-occurrence of mature males and maturing females in upper-slope waters is also in agreement with the population structure elsewhere, with mature females descending to greater depths to spawn (Jackson 1997).…”

“…Onychoteuthids are major prey items for many species of top predators, including fishes, seabirds and marine mammals (Clarke 1983, Cherel & Weimerskirch 1999. However, little is known about their basic biology, including their food and feeding ecology and thus, trophic relationships in the marine ecosystems.…”

“…There, M. ingens is a main food for the commercially important Patagonian toothfish (authors' unpubl. data), large seabirds such as the king penguin Aptenodytes patagonicus and wandering albatross Diomedea exulans (Cherel et al 1996, Moore et al 1998, Cherel & Weimerskirch 1999, and the southern elephant seal Mirounga leonina (Green & Burton 1993). A better knowledge of subantarctic marine ecosystems therefore requires determining the prey and trophic level of this abundant and voracious feeder that potentially consumes in excess of 10% of its body mass per day (Jackson et al 1998b).…”

Variacion Latitudinal Y Estacional en La Dieta De Dissostichus Eleginoides Smitt, 1898 (Perciformes: Nototheniidae) en Ambientes Profundos De La Costa Centro-Sur De Chile

“…En efecto, se ha reportado la migración de la principales especies de cefalópodos presa del "bacalao de profundidad" con fines reproductivos en la época invernal. Así, Cherel & Weimerskirch (1999), indican que los onicotéutidos K. longimana y M. ingens, presentes en las islas Crozet, desovan en los meses de Invierno. En otras áreas, como islas Malvinas y Nueva Zelanda se confirma el desove de Invierno de M. ingens, cuyas hembras realizan migraciones desde la plataforma continental hacia aguas más profundas para desovar en esta estación del año (Jackson 2001).…”

Stable isotopes, beaks and predators: a new tool to study the trophic ecology of cephalopods, including giant and colossal squids

“…Predators included penguins, albatrosses, sleeper sharks and the Patagonian toothfish (Cherel & Weimerskirch 1999;Cherel et al 2002;unpublished data). Cephalopods were first identified from the morphology of their beaks; second, lower rostral length (LRL) of squid beaks and lower hood length (LHL) of octopus beaks were measured and, finally, allometric equations were used to estimate their dorsal mantle length (ML) from their LRL or LHL .…”