Distribution and abundance of the early life stages of squid, primarily Gonatidae (Cephalopoda, Oegopsida), in the northern North Pacific (Part 2)

All member of the family Gonatidae do not occur uniformly across the Subarctic Pacific; we have here attempted to demonstrate the geographic distribution of each specie and its size clases. Gonatus berryi seems to be limited to the eastern portion of the northern north Pacific and the southernmost Bering Sea (Figs. 4A- C). No individuals were taken further west than 176°E. Adolescent (>20mm DML) occurred over the entire range, but the larvae (<10mm DML) occurred only in nearshore waters off the American coast. Post-larval individuals occurred at both limits of the distribution, off the American coast and south of the central Aleutians. This type of distribution suggests a spawning area localized in the California Current

A New Species of Bobtail Squid, Euprymna megaspadicea, from Okinawa, Japan

Euprymna megaspadicea n. sp. collected from Nago Bight, Okinawa Island, Japan, is described. This species is characterized by its small size compared with its congeners, and by having four rows of suckers on all arms, arm II longer than the other arms and a hectocotylized left arm I in males. Modification of the hectocotylus affects almost the whole length of the arm, and is characterized by the fusion of all sucker pedicels giving the arm a peculiar massive, wavy and twisted appearance

Distribution and abundance of the early life stages of squid, primarily Gonatidae (Cephalopoda, Oegopsida), in the northern North Pacific (Part 2)

All member of the family Gonatidae do not occur uniformly across the Subarctic Pacific; we have here attempted to demonstrate the geographic distribution of each specie and its size clases. Gonatus berryi seems to be limited to the eastern portion of the northern north Pacific and the southernmost Bering Sea (Figs. 4A- C). No individuals were taken further west than 176°E. Adolescent (>20mm DML) occurred over the entire range, but the larvae (<10mm DML) occurred only in nearshore waters off the American coast. Post-larval individuals occurred at both limits of the distribution, off the American coast and south of the central Aleutians. This type of distribution suggests a spawning area localized in the California Current

Young squids collected with 10-foot Ikpt net during the Jare-28 cruise, 1987

Fifty young squids were obtained from the samples collected with 8 oblique tows of the 10-foot IKPT in the Antarctic and Indian Oceans during February-March, 1987 on the JARE-28 cruise. Seven species were identified among which Alluroteuthis antarcticus was the dominant. The distribution patterns differ by species and they are correlated with oceanographic domains. The Antarctic endemic species tended to be abundant in near coastal water suggesting the importance of mixing waters of Antarctic Circumpolar Current (ACC) and coastal water for their reproduction

Observations of wild hunting behaviour and bioluminescence of a large deep-sea, eight-armed squid, Taningia danae

Our newly developed underwater high definition video camera system took the first live images of adults of the mesopelagic large squid, Taningia danae, between 240 and 940 m deep off Ogasawara Islands, western North Pacific. The resulting footage includes attacking and bioluminescence behaviours, and reveals that T. danae is far from the sluggish neutrally buoyant deep-sea squid previously suspected. It can actively swim both forward and backward freely by flapping its large muscular triangular fins and changes direction quickly through bending its flexible body. It can attain speeds of 2–2.5 m s−1 (7.2–9 km h−1) when attacking bait rigs. They emitted short bright light flashes from their large arm-tip photophores before final assault, which might act as a blinding flash for prey as well as a means of measuring target distance in a dark deep-sea environment. They also emitted long and short glows separated by intervals while wandering around the double torch lights attached to the bait rig, suggestive of potential courtship behaviours during mating

Diet and mitochondrial DNA haplotype of a sperm whale (Physeter macrocephalus) found dead off Jurong Island, Singapore

Despite numerous studies across the large geographic range of the sperm whale (Physeter macrocephalus), little is known about the diet and mitochondrial DNA haplotypes of this strongly female philopatric species in waters off Southeast Asia. A female sperm whale found dead in Singapore waters provided the opportunity to study her diet and mitochondrial DNA haplotype. Here we report on the identification of stomach contents and mitochondrial DNA haplotype of this individual, and we include coastal hydrodynamic modelling to determine the possible geographic origin of the whale. At least 28 species of prey were eaten by this adult female whale, most of which were cephalopods. The mesopelagic squids Taonius pavo, Histioteuthis pacifica, Chiroteuthis imperator,and Ancistrocheirus lesueurii made up over 65% of the whale’s stomach contents. Plastic debris was also found in the whale’s stomach. Based on the diet, genetics, and coastal hydrodynamic modelling that suggest an easterly drift of the whale carcass over several days, the dead sperm whale in Singapore probably originated from a pod in the Southern Indian Ocean. This study provides an increase in the understanding the diet and natural history of the sperm whale in Southeast Asia. The combined analyses of stomach contents, DNA, and hydrodynamic modeling could provide a context to future studies on the sperm whale strandings, and have broader applicability for other marine mammals in the region

Distribution and abundance of squids caught in surface gillnets in the subartic Pacific, 1977-1981

Memoirs of the Faculty of Fisheries. Vol. 30 No. 1/2 (1983

Stereotypical diel movement and dive pattern of male sperm whales in a submarine canyon revealed by land-based and bio-logging surveys

Male sperm whales are under pressure to grow larger in order to increase their mating opportunities, which could lead them to more efficiently forage in high latitude feeding grounds. Movement patterns of male sperm whales in Nemuro Strait, Japan, were investigated horizontally and vertically using land-based observation and bio-logging methods to determine how they facilitate foraging in the narrow submarine canyon. Eleven tagged whales showed the distinct diel pattern for dive depth, as it was deeper at night than during the day. Five-year data of land-based observation and GPS data from six tagged whales revealed the tendency of whales to change the north-south direction of their horizontal movement every 4–6 h, and this movement direction was not related to the direction of the current. Their periodic heading change is thought to be a consequence of the whales making two round trips each day within the foraging area, one during the day to shallow layers and one during the night to deep layers. These tactics may help the whales to search for prey in this narrow submarine canyon efficiently. Most whales changed their direction of movement in a similar manner, which is probably due to the whales’ tendency to stay close enough to each other to obtain information about the prey environment using the echolocation clicks of other whales. The results emphasize the ability of male sperm whales to adapt their foraging tactics according to the prey environment of their habitat and intense pressure to grow faster may be the drive for this ability. The importance of social cohesion among foraging male sperm whales was also suggested