Yoshioki Oozeki

• Doctor of Philosophy
• Senior Advisor at Japan Fisheries Research and Education Agency

Transportation of Pacific saury Cololabis saira larvae from spawning to nursery grounds was examined based on datasets from larval distribution surveys during winter seasons 1990–2011. In the surveys, a neuston net was towed for 10 minutes over broad areas off the southern Pacific coast of Japan. Transport trajectories of saury larvae and temperatu...

Patchiness structure and mortality rates of Pacific saury Cololabis saira larvae were estimated in the frontal area of the Kuroshio Extension in spring 2000 and 2001. Drogued GPS buoys, which were used as Lagrangian reference points, were deployed to mark dense patches of saury larvae and a series of samplings was conducted using a neuston net arou...

The out-of-phase population oscillations between anchovy and sardine have been attributed to climate changes. However, the biological processes causing these species alternations have remained unresolved. Here we propose a simple "optimal growth temperature" hypothesis, in which anchovy and sardine regime shifts are caused by differential optimal t...

Small pelagic fish have exhibited cyclic population dynamics in complex marine ecosystems worldwide. These fish regime shifts have been associated with ocean regime shifts; however, the biological mechanisms have remained unresolved and have been considered to depend mainly on multi-step processes through food webs. In the present study, we focus o...

Early life survival is critical to successful replenishment of fish populations, and hypotheses developed under the Growth-Survival Paradigm (GSP) have guided investigations of controlling processes. The GSP postulates that recruitment depends on growth and mortality rates during early life stages, as well as their duration, after which the mortali...

Remote sensing is essential for monitoring fisheries. Optical sensors such as the day–night band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) have been a crucial tool for detecting vessels fishing at night. It remains challenging to ensure stable detections under various conditions affected by the clouds and the moon. Here, we dev...

While most research has focused on the legality of global industrial fishing, unregulated fishing has largely escaped scrutiny. Here, we evaluate the unregulated nature of global squid fisheries using AIS data and nighttime imagery of the globalized fleet of light-luring squid vessels. We find that this fishery is extensive, fishing 149,000 to 251,...

At-sea transshipment, transfer of catch from a fishing vessel to a carrier vessel is largely practiced in distant water fisheries. In the Convention Area (CA) of the North Pacific Fisheries Commission (NPFC), major portions of catches are known to be transshipped from fishing vessels to carrier vessels. To achieve proper stock assessment and manage...

A paradigm of proportionality between spawning stock biomass (SSB) and total egg production (TEP) has been largely untested at multidecadal scales mainly because of difficulty in estimating annual TEP. Recently, this paradigm was directly tested for sardine (Sardinops melanostictus) and anchovy (Engraulis japonicus) at a multidecadal scale to revea...

Illegal, unreported, and unregulated fishing threatens resource sustainability and equity. A major challenge with such activity is that most fishing vessels do not broadcast their positions and are “dark” in public monitoring systems. Combining four satellite technologies, we identify widespread illegal fishing by dark fleets in the waters between...

Sustainable development is being promoted in numerous fields, including the seafood industry. Policymakers, stakeholders, and the general population are also expected to contribute to implementation of this development. Seafood eco-labeling has been receiving growing attention for its key role in enhancing consumer-driven sustainable development. T...

Understanding of density‐dependent effects is key to achieving sustainable management of self‐regulating biological resources such as fish stocks. Traditionally, density‐dependent effects on population abundance in fish have been considered to occur from hatching to recruitment, based on the paradigm of proportionality between spawning stock biomas...

Variability of swept area by horizontal tows of a neuston net at the sea surface was examined based on a data set of flow-meter revolutions from larval surveys for Pacific saury off the Pacific coast of Japan in winter during 2003 to 2016 (total of 1566 tows). The swept area rate was defined as the realized swept area by the actual net tow relative...

Synchrony of species alternations in the northern Humboldt (NHCS) and Kuroshio (KCS) Current systems was examined by comparing time series data of landings and population statistics of major small pelagic fish species along with climate indices from 1960 to 2015. Target species were anchovy Engraulis ringens, sardine Sardinops sagax, jack mackerel...

A paradigm of fisheries science holds that spawning stock biomass (SSB) is directly proportional to total egg production (TEP) of fish stocks. This “SSB–TEP proportionality” paradigm has been a basic premise underlying the spawner–recruitment models for fisheries management and numerous studies on recruitment mechanisms of fish. Studies on maternal...

To understand the processes linking environmental variability to fish population dynamics in marine ecosystems, the dynamics of lower trophic levels including zooplankton as fish prey resources needs to be studied. Furthermore, the spawning habitat is the place connecting the life history of spawning adults and offspring and thus reflects the physi...

To establish an estimation procedure for reliable catch amount of illegal, unreported and unregulated (IUU) fishing, light-gathering fishing operations in the northwestern Pacific were analyzed based on the Visible Infrared Imaging Radiometer Suite (VIIRS) day/night band (DNB) data provided by the Suomi National Polar Partnership (SNPP) satellite....

In situ filtering rate variability was examined for vertical tows of plankton nets in egg and larval surveys off the Pacific coast of Japan, based on a data set pooled over large spatial and temporal scales (76,444 sampling tows from 1978 to 2013). The filtering rate showed unimodal distributions and was highly variable for the four net types: Long...

Growth variability was examined for Pacific saury Cololabis saira larvae under contrasting environments across the Kuroshio axis, based on samples collected during the winter spawning season in 2013 and 2014. The growth rate index (residual of the otolith marginal 3-day mean increment width from the linear regression on knob length) of larvae was c...

Restricting human access to a specific wildlife species, community, or ecosystem, i.e., input control, is one of the most popular tools to control human impacts for natural resource management and wildlife conservation. However, quantitative evaluations of input control are generally difficult, because it is unclear how much human impacts can actua...

Growth and survival are tightly coupled in early life stages of fish. Larger and/or faster growing individuals (or populations) are more likely to survive than smaller and/or slower growing conspecifics. This “growth–survival” paradigm was given much attention in studies on recruitment dynamics of fish. However, predicting year-class strength from...

We present evidence indicating that day closures are successful management measures in some Japanese purse seine fisheries. A pelagic species of Pacific chub mackerel Scomber japonicas that was heavily exploited during the 1990s and early 2000s began to recover in the late 2000s following the introduction of management measures by the Japanese Fish...

Since formalin-preserved eggs of Japanese jack mackerel Trachurus japonicus have been considered difficult to identify, egg abundance of this species has not been estimated, and subsequently information on their spawning habitat is limited. The present study provides a practical identification of Japanese jack mackerel eggs from formalin-preserved...

The occurrence and density of Pacific saury Cololabis saira larvae and juveniles were examined in relation to environmental factors during the winter spawning season in the Kuroshio Current system, based on samples from extensive surveys off the Pacific coast of Japan in 2003–2012. Dense distributions of larvae and juveniles were observed in areas...

Particle-tracking experiments were performed to infer the distribution of larvae of the Japanese sardine (Sardinops melanostictus) and to detect effects of transport environment on sardine recruitment, using the output of a high-resolution ocean general circulation model and observed data of sardine spawning grounds during 1978–2004. By the 60th da...

A new autonomous multiple codend opening/closing system was constructed to be attached to a midwater trawl net, and the layer discrimination ability of this new system attached to the Matsuda–Oozeki–Hu Trawl (MOHT, mouth area 5 m2) was demonstrated through comparison with the Multiple layer Opening/Closing MOHT (MOC–MOHT), which was equipped with a...

The distribution pattern and biomass of the Japanese anchovy Engraulis japonicus in the offshore region of the western North Pacific (north of 35°N and west of 170°E) were studied using a quantitative echosounder. This is the first attempt at such a study in this region. Data were collected in summer from 2004 to 2007. The biomass was estimated usi...

Effect of the depth-dependent target strength (TS) on biomass estimation of Japanese ahcovy was examined by using following four TS models: (1) TS = 20logL t-71.9, (2) TS = 20logL t-72.5, (3) TS = 20logL t-(20/3)log(l+z/10)-67.6 and (4) 7S = 20logL t-(20/3)log( 1 +z/10)-64.7, where L t and z represent total length (cm) and depth (m), respectively....

Production of larvae in the hatching size-class of Pacific saury (Cololabis saira) was highest in autumn 1990-1994, implying that spawning activity was highest in this season. Growth and mortality rates were stable in the winter-spawned cohorts in Kuroshio waters (south of Honshu); variable rates were found in the autumn- and spring-spawned cohorts...

A benchmark evaluation was carried out on scientific publications in fisheries sci- ence and related disciplines from the Japanese Fisheries Research Agency (FRA) and inter- national research institutions. Data for the period 2000－2009 were obtained from the Web of Science. A total of 2,678 scientific papers were published by the FRA. Research ins...

In order to validate daily increment formation in otoliths of immature and adult Japanese anchovy Engraulis japonicus, three rearing experiments using chemical marking of otoliths were conducted on adult anchovy in summer 2004 and immature anchovy in summer 2005 and in winter 2006. In the two experiments conducted in summer, the number of otolith m...

We tested whether the predation dynamics of chub mackerel Scomber japonicus and spotted mackerel S. australasicus on young anchovy Engraulis japonicus relates to individual growth characteristics of the prey and could account for the growth-selective survival predicted by recruitment hypotheses. Juvenile and adult mackerel were sampled along with t...

We investigated the relationships between stock biomass, distribution area and mean density of sardine and anchovy populations off California, Peru, South Africa and Japan. Our objective was to elucidate whether their ecological responses to habitat availability and use would support the possibility of them developing synchronic, alternating biomas...

This book details the effects of climate variability on small pelagic fish and their ecosystems and fisheries. Particularly abundant in coastal upwelling regions off the west coasts of the Americas and Africa, off Japan, and in the NE Atlantic, the stocks of these fish fluctuate greatly over the timescale of decades, with large ecological and econo...

The assessment and management of small pelagic fish (SPF) stocks is particularly difficult and uncertain because their short life expectancy, characteristic aggregative behavior, rapid response to climate and environmental signals and large and variable natural mortality make them less tractable through traditional population dynamic models and ass...

Spatial and temporal spawning overlaps in Japanese anchovy Engraulis japonicus and sardine Sardinops melanostictus were examined using a long-term data set (1978 to 2004) of monthly egg and larval surveys (total of 102613 vertical tow samples) off the Pacific coast of Japan. Egg abundance was estimated in 15' latitude x 15' longitude squares, and s...

Relationships between otolith and somatic sizes were examined for Japanese anchovy Engraulis japonicus and sardine Sardinops melanostictus larvae collected broadly in the western North Pacific, based on a substantial data set derived from a previous paper. Allometric formulae showed close fits to the relationships between otolith radius and standar...

Anchovy and sardine are both abundant small pelagic fish that have exhibited out-of-phase population oscillations in both the western boundary current region off Japan and the eastern boundary current upwelling region off California. These species alternations could indicate approximately synchronous patterns (with some variations in timing between...

We analyzed sea surface temperature, salinity, and depth in the spawning grounds of three small pelagic fishes, Japanese sardine (Sardinops melanostictus), Japanese anchovy (Engraulis japonicus), and Pacific round herring (Etrumeus teres), to compare species-specific characteris- tics of spawning based on a long-term dataset of egg sur- veys off Ja...

Predator-specific growth-selective predation on larval Japanese anchovy Engraulis japonicus was demonstrated by comparing growth rates between the larvae ingested by predators and the larvae from the corresponding original populations through otolith microstructure analysis, based on original data and reanalyzed data from previous studies. Ingested...

Since there have been practically no surveys of the eggs of Pacific saury (Cololabis saira) in the western North Pacific (WNP), its spawning ground (SG) distribution has been poorly resolved, based mainly on the larval distribution. This means of estimating SG distribution is imprecise because saury eggs drift for more than a week before they hatch...

Batch fecundity and spawning frequency data for Japanese anchovy Engraulis japonicus, as well as sea surface temperature (SST) data, derived from the recent literature, were compared between inshore samples (Sagami Bay) and offshore samples (western North Pacific) of anchovy. The offshore anchovy were heavier in body weight and had heavier ovaries...

Daily changes in otolith increment widths from the core to the edge in 0+ Pacific saury, Cololabis saira, were examined. There appeared a first peak of increment width at 22.9 ± 9.6 (73) [mean ± SD (sample number)] days old, followed by the bottom of the first trough [88.6 ± 25.3 days old (73)] and a second peak [143.8 ± 24.6 days old (62)]. The ag...

A fish bioenergetics model coupled with an ecosystem model was developed to reproduce the growth of Pacific saury. The model spatially covers three different oceanographic spatial domains corresponding to the Kuroshio, Oyashio, and interfrontal (mixed water) regions. In this coupled model, three (small, large, and predatory) zooplankton densities w...

Environmental factors affecting larval growth of the Pacific saury, Cololabis saira, were analyzed from specimens sampled in the northwestern Pacific Ocean in winter, spring and autumn, 1992–94. Body length at 5 days before sampling was individually estimated by back-calculation from otolith increment widths and recent growth rate was determined. R...

The 'growth-selective predation' hypothesis was revisited for larval Japanese anchovy Engraulis japonicus, focusing on larval cannibalism by juveniles and larval predation by skipjack tunas Katsuwonus pelamis, in offshore waters. Larval anchovy and predators were captured simultaneously in June 1997 and in May 2000 in the western North Pacific. Gro...

A newly designed frame trawl with a 5 m2 mouth area was constructed for quantitative sampling of larval and juvenile pelagic fishes and its performance was tested in the ocean. Towing depth of the trawl was easily controlled by adjusting the warp length, and the stability at depth increased with decreasing weight of the net in water. Larval and juv...

We examined the species composition and horizontal distribution of myctophid fish larvae in the transition region of the western North Pacific during the early summer. In total, 4,760 myctophid larvae were collected at 44 stations; 18 species of myctophids from 15 genera were collected, and the 8 most abundant species accounted for >95% of larvae....

We assessed the ability to discriminate local stocks of walleye pollock Theragra chalcogramma based on data from five elements (Na, K, P, Ca and Sr) using electron probe micro analyzer (EPMA) from the otoliths of 26 adult fish (standard length 339–576 mm) caught at four sites (Rausu, Kushiro, Minami-kayabe and Musashi Bank) around Hokkaido, Japan i...

Growth rate time series of Pacific saury, Cololabis saira, larvae in the Kuroshio waters were constructed using a previously reported relationship between early life stage growth rates and environmental factors in winter (January to March) 1971–2000, including sea surface temperature, chlorophyll a concentration and copepod density. Pacific saury h...

Growth and mortality rates of larval and early juvenile Pacific saury Cololabis saira were estimated for spring and autumn spawning seasons in the Kuroshio-Oyashio transitional waters and for winter spawning season in the Kuroshio waters in 9 years from 1990–1998, based on quantitative fish sampling and otolith daily ring readings. Growth and morta...

Naupliar copepods were distributed at similar concentrations over the waters inshore and offshore of the Kuroshio Current off central Japan in early spring 1993 and 1994, overlapping with the distribution of early feeding larvae of Sardinops melanostictus. Although N, P, Si and chlorophyll a concentrations were higher in the waters inshore of the K...

Relations between the long-term variations in numbers of Japanese sardine and in ocean/climate were studied. We examined long-term records of the spring air temperature on the north-western coast of North America (ATNA; 40–50°N, 130–110°W) reconstructed from tree rings, and the sardine catch records inferred from documents dating from 1600 to 1990....

A new midwater sampling trawl was designed to collect pelagic larval and juvenile fish. It has a rigid square frame of 2.25 m2, with a 12.5 m high strength polyethylene net. The cambered V-type depressor with a camber ratio of 15%, aspect ratio of 6.0, and dihedral angle of 20° was hung to the bottom of the frame with four slings based on the princ...

The otolith microstructure of 48 Pacific saury, Cololabis saira, were observed under light microscope (LM) and under scanning electron microscope (SEM). Daily-like increments, that appeared to have been produced on a daily basis, within the whole opaque zone were observable for all otoliths (100%) under LM, whereas for only 14 otoliths (29%) under...

To develop an efficient depressor for sampling midwater trawl, a cambered V-type depressor was designed with the camber ratio of 15%, aspect ratio of 6.0 and dihedral angle of 20°. An experiment was carried out using a 1/5 scale model in a circulating water tank. The sinking force, drag and pitching moment were measured with a six-component balance...

The relationship between somatic growth and incremental growth of otoliths of Pacific saury, Cololabis saira (Brevoort), larvae under different temperature conditions was studied in the laboratory for three age groups (0 to 9, 10 to 20 and 20 to 30 d posthatch). Larvae were incubated from hatching to 9 d at 24, 20, and 16 °C. Further, larvae initia...

Catch efficiencies were compared between the surface ring net ( 1.3 m mouth diameter, 0.45 mm mesh) and the Manta net (0.65 m wideX0.15 m high, 0.33 mm mesh) for larvae and juveniles of Pacific saury, Co/olabis saira. The nets were towed alternately three times across a total of 11 stations during 8-28 February 1995. Five stations were sampled duri...

Without Abstract

Growth rates of the Japanese sardine, Sardinops melanostictus, sampled at various stations along the Kuroshio Current, were estimated from otolith increments. Hatch date composition varied among stations along the Kuroshio Current. Growth trajectories of individual larvae were estimated by the Biological Intercept Method and the recent growth rate...

Activities of digestive enzymes trypsin, amylase and lipase in laboratory-reared walleye pollock, Theragra chalcogramma, were measured from hatching to Day 39 (just before notochord flexion) in 1993. All measurements were conducted individually or semi-individually (groups of two larvae of the same standard length). Close relationships between dige...

Oxygen consumption rates of larval Japanese whiting, Sillago japonica, were examined at various developmental stages from hatching (Day 0) to just before the juvenile stage (Day 28). The oxygen consumption rate per larva increased exponentially with larval age throughout development. The weight-specific oxygen consumption rate increased with age fr...

Designing a feeding schedule for fish larvae according to their food preference will improve their survival and growth in the hatchery. The feeding schedule is currently determined speculatively by the development of the mout parto and actually as a results of mass rearing trials at seed production stations. 2 > A model feeding schedule should take...

Larval development of laboratory reared Japanese whiting,Sillago japonica, was described according to morphological and histological observations of the development of organ systems. The development of larvae from hatching to the early phase of the juvenile period was classified into ten stages. These ten stages were grouped into three phases that...

The larvae of the saury, Cololabis saira (BREVOORT), deficient in pigmentation on the dorsal part of the head were observed under breeding conditions, one hour to three days after hatching. The dorsal part of the head showed no histological difference between the larvae with and without head pigmentation 15 hours after hatching. Also no histologica...

Experiments were conducted on larvae of Mugil cephalus to determine onset of feeding, temporal changes in food selectivity, initial stocking density of larvae, rotifers and phytoplankton, and the effectiveness of enriching food organisms. Larvae were observed to possess rotifers in their gut at 70 h posthatch. A significant (P < 0.01) difference in...

Introductions of aquatic organisms into Japan are controlled only on the basis of the Convention on International Trade in Endangered Species (CITES) of Wild Fauna and Flora and the quarantine acts. Up to 1986 more than 120 exotic species have been introduced, of which only 36 were made prior to 1945. Introductions are classified into four basic ca...

Starvation tolerance of laboratory-reared larval stone flounder, Kareius bicoloratus, was examined at different temperatures and salinities during the winters of 1984, 1985 and 1986. Starvation tolerance decreased with increased temperature and exhibited low values with high salinities. The highest starvation tolerance observed at low salinity was...

The use a buffered 2.5% glutaraldehyde solution as a fixative for red sea bream larvae was investigated. Morphometric data were obtained from live larvae 3, 12, 18, and 25 days old. These were then fixed for a period of 6 months and were remeasured. The only significant changes between live and preserved specimens were in body and muscle depth in 3...

The transport mechanism of larvae of stone flounder, Kareius bicoloratus was investigated from January 23th to February 17th, 1986 in the mouth of Matsukawaura inlet, Fukushima prefecture. The number of larvae peaked on January 27th and decreased gradually then after. A diurnal peak of occurrence was observed at the turning point of the tide (flood...

Changes in the egg quality of the Japanese whiting, a multiple-spawning fish, were examined throughout its spawning season. Fertilization and hatching rates were constantly high and the optimum temperature and salinity for hatching (26.00C, 32.5 ppt) did not vary much. Oxygen consumption was constant at each developmental stage and linearly increas...

The purpose of the present investigation is to describe the effects of short-term temperature changes on the development and survival of eggs of the Japanese whiting Sillago japonica. Before the measurement of thermal tolerance, the normal developmental stages from fertilization to hatching were described and divided into 27 stages. Temperature cha...