Japanese Flying Squid Todarodes Pacificus Research Articles

Current state of resources for japanese flying squid Todarodes pacificus in the northwestern Tatar Strait (Japan Sea)

Data on commercial catches of japanese flying squid Todarodes pacificus in the northwestern Tatar Strait in 2003–2019 are analyzed. To assess the resours status in the study area, the relative number (individuals per jigger winch per hour) and biomass (kilograms per vessel per day) marks recognized to be the most applicable winch per hour or the catch in kg per vessel per day. The average CPUE value was 35.6 ± 3.6 ind./winch/hour; increasing trend of CPUE is observed (α = 1.5 ± 0.6, r2 = 0.3, p < 0.03). The squid abundance decreased slightly in the last 2 years, with CPUE decreasing to 28 ind./winch/hour in 2019, though the squid biomass was relatively stable (average CPUE 582.0 ± 45.8 kg/vessel/day) — decreased number of caught individuals was compensated by individual body weight increasing. Long-term tendency to the body weight increasing was noted: the average body weight was 205.0 ± 4.0 g in 2004, 256.0 ± 3.5 g in 2012, and 297.0 ± 6.3 g in 2019. Possible climate change influence on the squid population was discussed. Because of warming in the reproductive area of T. pacificus in the southern Japan Sea, SST in the spawning period reached 20–25 оC and exceeded the value optimal for reproduction and larvae development (15–23 оC), so the squid abundance decreased. On the contrary, in the northern Japan Sea (in the Tatar Strait) the warming caused better conditions for the squid feeding: the higher zooplankton biomass in this area was observed under SST 13–18 оC that is reached every year recently. On the other hand, the Tsushima Current intensifying promoted active migrations of T. pacificus to the northwestern Tatar Strait. These factors of climate warming ensure favorable environments for northward migrations of T. pacificus and forming of dense feeding aggregations in the northwestern Tatar Strait that allows to expect good conditions for the squid fishery in this area in the nearest future.

Changes in the strategy of a small-scale jigging fishery for Japanese flying squid Todarodes pacificus off northeastern Japan

Long-term fluctuations in the strategy of a small-scale squid jigging fishery for Japanese flying squid Todarodes pacificus off northeastern Japan were evaluated based on time series data for nine variables derived from the catch obtained by Iwate’s fishing boats, the total catch and the income from the waters off Iwate, the number of licenses issued by Iwate Prefecture, and crude oil prices from 1970 to 2008. Upon applying principal component and change-point analyses, the first three principal components were found to explain 80.4% of the total variance, and eight temporal change points were detected. A multiple sequential t-test analysis of regime shifts detected significant shifts in the time series for each variable. A decrease in the total catch obtained by Iwate’s fishing boats was delayed with respect to the decline in catch from off Iwate in the 1970s, which can be explained by adaptive migration, as the fishers shifted grounds to exploit more abundant resources. In the 1980s, the number of licenses for fishing boats from Iwate remained high as the fishers again adapted to better exploit the reduced resources available without migrating to different fishing grounds. In the 1990–2000s, the number of licenses for fishing boats from Iwate declined for economic reasons (high running costs and low squid prices), but the remaining fishers adapted yet again in the mid-2000s to increase the catch off Iwate by operating in daylight.

Orientation Patterns of Japanese Flying Squid Todarodes pacificus Embryos within Egg Masses and Responses of Paralarvae to Light.

Squid embryos develop in the perivitelline fluid inside the chorion, which is an envelope secreted by the ovarian follicle. The onset of hatching initiates local dissolution of the chorion when the hatching gland enzyme facilitates the release of the developed paralarvae. In the present study, we investigated the pre-hatching behavioral patterns of Todarodes pacificus embryos and their responses to light after hatching. Observations of orientation were conducted using embryos developing inside chorions embedded within intact egg masses, while phototactic experiments were conducted on paralarvae that hatched from these egg masses. Within the restricted chorion and along the animal-vegetal axis, the embryos demonstrated a variety of orientation patterns that were categorized as swirls, glides, and somersaults. The contributions of these orientations to enhance oxygen diffusion and stimulate paralarval swimming immediately after hatching are discussed. Paralarvae exhibited normal diel vertical migration and responded positively to light sources. Vertical migration and phototaxis in T. pacificus paralarvae could have great adaptive significance because they hatch in neritic environments and are transported by ocean currents during their planktonic life.

Male copulatory behavior interrupts Japanese flying squid Todarodes pacificus female spawning activity

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 551:277-281 (2016) - DOI: https://doi.org/10.3354/meps11776 NOTE Male copulatory behavior interrupts Japanese flying squid Todarodes pacificus female spawning activity Pandey Puneeta1,*, Dharmamony Vijai1,3, Jun Yamamoto2, Yasunori Sakurai1,4 1Department of Marine Bioresources and Ecology, School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate 041-8611, Japan 2Field Science Center for Northern Biosphere, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan 3Present address: Oceanography Division, Tohoku National Fisheries Research Institute, 25-259 Shimo-mekurakubo, Samemachi, Hachinohe, Aomori 031-0841, Japan 4Present address: Hakodate Cephalopod Research Center, Fisheries and Oceans Hakodate, Benten-cho 20-5, Hakodate, Hokkaido 040-0051, Japan *Corresponding author: puneeta83@gmail.com ABSTRACT: Batch spawning, intermittent spawning and multiple spawning represent common reproductive strategies among cephalopods. These flexible spawning strategies are also common in fishes, and are thought to be a female trait that is programmed depending on environmental parameters. The ommastrephid squid Todarodes pacificus, being a terminal spawner, is considered to have a single spawning event, extruding one large egg mass and dying soon thereafter. Females that are interrupted by males exhibiting mating behavior, while extruding the egg mass, spawn multiple egg masses over the course of 2-3 d instead of dying soon after spawning the first egg mass. We demonstrate that male mating behavior causes ‘forced’ intermittent spawning by females (i.e. more than one spawning event). We hypothesize that in T. pacificus, some males use this strategy to mate with females unable to repel advances while spawning, thus providing the male with the opportunity to contribute sperm and enhance gene flow. KEY WORDS: Batch spawning · Spawning interruption · Multiple paternity · Egg mass · Oceanic squid Full text in pdf format Supplementary material PreviousCite this article as: Puneeta P, Vijai D, Yamamoto J, Sakurai Y (2016) Male copulatory behavior interrupts Japanese flying squid Todarodes pacificus female spawning activity. Mar Ecol Prog Ser 551:277-281. https://doi.org/10.3354/meps11776Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 551. Online publication date: June 09, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Male copulatory behavior interrupts Japanese flying squid Todarodes pacificus female spawning activity

Male copulatory behavior interrupts Japanese flying squid Todarodes pacificus female spawning activity

Physiological response of the eye to different colored light-emitting diodes in Japanese flying squid Todarodes pacificus

To effectively introduce light-emitting diode (LED) lights into Japanese flying squid Todarodes pacificus fisheries, information is required regarding how LED lights affect physiological responses of the squid eye. In order to examine the effects of LED emission-color on squid eyes, we observed the pupillary constriction and migration of black-screening pigment in the retina. The pupils constricted in all squid after exposure to LED lights; the pupils gradually opened and pigment migration occurred. Both of the physiological responses to LED light were affected by blue, green, and white lights, which have wavelengths close to the visual pigment sensitivity peak in T. pacificus (482 nm). However, response rates were much lower under red colored LED, which comprises wavelengths that are far from the visual pigment sensitivity peak. Thus, the eyes of squid responded sensitively to light which included the wavelengths close to the visual pigment sensitivity peak of T. pacificus and responded little to the light which did not include these wavelengths. These results suggest that the eyes of T. pacificus react in different ways to various LED light colors, where the first reaction to a lighting change is the pupillary response, and pigment migration occurs only if the illumination continues.

A Hypothesis of Capture Process of Squid Jigging Fisheries Estimated from Behavioral Reaction of Japanese Flying Squid Todarodes pacificus to the Light

A Hypothesis of Capture Process of Squid Jigging Fisheries Estimated from Behavioral Reaction of Japanese Flying Squid Todarodes pacificus to the Light

Water-Soluble and Lipid-Soluble Arsenic Compounds in Japanese Flying Squid Todarodes pacificus

Water-soluble and lipid-soluble arsenic compounds in Japanese flying squid Todarodes pacificus were analyzed. Regardless of the tissues, the major water-soluble arsenic compound was identified as arsenobetaine by LC/ESI-MS analysis, as reported for a number of marine animals. Lipid-soluble arsenic compounds were found at relatively high levels in liver and testis. LC/ESI-MS analysis of water-soluble arsenic compounds released from liver phospholipids by either chemical hydrolysis or phospholipase D hydrolysis demonstrated that the major arsenolipids are dimethylarsinic acid (DMA)-containing glycerophospholipid (phosphatidyldimethylarsinic acid) and DMA-containing sphingomyelin where the choline moiety of sphingomyelin is replaced by DMA. This is the first work to report the presence of DMA-containing phospholipids in marine invertebrates.