Japanese Spanish Mackerel Scomberomorus Niphonius Research Articles

Otolith biogeochemistry reveals possible impacts of extreme climate events on population connectivity of a highly migratory fish, Japanese Spanish mackerel Scomberomorus niphonius

Otolith biogeochemistry reveals possible impacts of extreme climate events on population connectivity of a highly migratory fish, Japanese Spanish mackerel Scomberomorus niphonius

Interannual variability in otolith biogeochemical signatures of Japanese Spanish mackerel in the Yellow Sea

Fishes often use multiple habitats to complete their life cycles, leading to their unique otolith biogeochemical signatures. Interannual variability in otolith biogeochemical signatures is expected as fish respond to annual environmental variations in their distribution areas. In this study, we focus on Japanese Spanish mackerel Scomberomorus niphonius, an abundant commercial species in the Yellow Sea. As highly migratory fish that undergo their entire migratory cycle in a year, S. niphonius is susceptible to environmental variations. Consequently, they are believed to exhibit discernibly distinct migration patterns and varying timings of ontogenetic events across different years. Otolith biogeochemical signatures of 1-year-old spawning adults S. niphonius caught in the Yellow Sea from 2016 to 2018 were measured from core to edge using laser ablation inductively coupled plasma mass spectrometry (LAICP-MS). We hypothesized that the year-specific chemical signature could be found in 2016 as a strong El Niño Southern Oscillation event happened. From 2016 to 2018, converse ontogenetic changing patterns was observed for Sr/Ca and Ba/Ca, with Sr/Ca being positively correlated with sea surface salinity while Ba/Ca being negatively. As expected, the year-specific effect was identified for 2016 cohort but it was only significant on Ba/Ca. During this year, a stronger variation of elemental concentration and an earlier downward shift of Ba/Ca were found. These results provide evidence that otolith biogeochemical signatures have useful applications as natural tags, helping understand the interannual variability in migration of marine fish species.

Water temperature induced interannual variation in spawning of Japanese Spanish mackerel Scomberomorus niphonius in the northern Yellow Sea

Water temperature induced interannual variation in spawning of Japanese Spanish mackerel Scomberomorus niphonius in the northern Yellow Sea

Development of a prey-predator species distribution model for a large piscivorous fish: A case study for Japanese Spanish mackerel Scomberomorus niphonius and Japanese anchovy Engraulis japonicus

One of the major challenges of species distribution models (SDMs) is incorporating the influence of prey on the predator. An ensemble modeling approach, the prey-predator species distributabion model (PPSDM), uses environmental variables (sea surface temperature, bathymetry, sea surface salinity, and sea surface current) and a biotic variable (predicted prey distribution: Japanese anchovy) to predict a piscivorous fish (Japanese Spanish mackerel) habitat in the China Seas. PPSDM comprised selected preferable single algorithms from nine algorithms, including tree-based models, machine learning models, regression models, an envelope-style method, and a classification model. Compared with that obtained when using habitat without the Japanese anchovy distribution, the regression models, machine learning models and a classification model have significant improvements. However, tree-based models have only slightly improved. The PPSDM results well reflected the ontogenetic migration of Japanese Spanish mackerel. We found that the wintering ground was distributed in regions with temperatures between 11 and 17 °C and salinities between 33.6 and 34.1. The bottom topography was also closely correlated with Japanese Spanish mackerel, and the suitable habitat was at 50–100 m isobaths as topography determined the position of isotherms (11, 17 °C), salinity isolines (33.6, 34.1), and fronts (temperature, salinity) in winter. The relationships among different climatic indices, temperature, and Japanese Spanish mackerel were analyzed. We found that the East Asian monsoon significantly influenced the Japanese Spanish mackerel habitat by affecting temperature variation. In the future, the suitable habitat of Japanese Spanish mackerel is projected to decrease by 21%, 28%, 36%, and 42% under RCP2.6, RCP4.5, RCP6.0, and RCP8.5, respectively. The Japanese Spanish mackerel in the northern Yellow Sea is projected to experience the ‘cul de sac’ effect, which would drive this species toward local extinction. The Japanese Spanish mackerel in the China Seas will probably shift northeastward through the Tsushima Strait, and the Sea of Japan may form the main habitat at the end of the century.

High-temperature and starvation tolerances of juvenile Japanese Spanish mackerel Scomberomorus niphonius

Japanese Spanish mackerel Scomberomorus niphonius is a target species for stocking, but its biological characteristics at the juvenile stage are not well understood. Here, we investigated the high-temperature and starvation tolerances of hatchery-reared juveniles in captivity. We used juveniles of approximately 40 mm standard length, the size of juveniles released into the field. The upper incipient lethal temperature (50% lethal water temperature) was estimated to be 31.8 °C, higher than the maximum sea surface temperature in the field (approximately 29 °C). The critical thermal maximum was 34.8 °C, whereas it was 36.1 °C when juveniles were preliminarily acclimated to 31 °C for 24 h. Juveniles died from 3 to 11 days under nonfeeding conditions at 20 °C, but from 2 to 7 days at 27 °C. This information is expected to contribute to the development of the production of juvenile Japanese Spanish mackerel.

Effect of hot smoking treatment in improving Sensory and Physicochemical Properties of processed Japanese Spanish Mackerel Scomberomorus niphonius.

Japanese Spanish Mackerel (JSM) Scomberomorus niphonius (Cuvier 1832) is an important commercial fish species in South Korea. The postharvest handling, preservation, and storage of JSM have not been clearly understood, and therefore, it is very often oxidized to produce off‐flavor while marketed as the raw or frozen state. To overcome these problems, the present study was designed to adapt the hot smoke processing technique for improving the sensorial, physicochemical, and microbial qualities of JSM with extended shelf life. The hot smoking (70°C) with different sawdusts at the different smoke times (0, 20, 25, and 30 min) was applied to process JSM fillet. The smoked JSM obtained higher sensory attributes (appearance, odor, taste, color, texture, and overall preferences) and suppressed bacterial growth, pH, volatile base nitrogen, thiobarbituric acid‐reactive species, and trimethylamine N‐oxide at an optimum smoking time of 25 min using oak sawdust. Moreover, it possessed higher nutritional value and beneficial polyunsaturated fatty acids such as docosahexaenoic acid (DHA), 4.19 g/100 g, and eicosapentaenoic acid (EPA), 1.82 g/100 g. The smoked JSM product extended shelf life up to 42 days at 10°C storage temperature. The overall findings indicate that the hot smoking technology with JSM could be effective in achieving good sensorial, nutritional, and functional attributes to the consumer.

Molecular characterization of kisspeptin 2 dodecapeptide in sixteen species of Scombridae

Kisspeptin is an endogenous ligand that modulates gonadotropin-releasing hormone (GnRH) secretion and plays an essential role in the reproduction of mammals. In fish, two subtypes of kiss genes (kiss1 and kiss2), which encode kisspeptins, have been reported. Our previous study showed that kisspeptin 2 receptor (KissR2) is highly expressed in the vicinity of GnRH1 neurons, and that centrally administered Kiss2, but not Kiss1, significantly increased gonadotropin synthesis in chub mackerel Scomber japonicus. The results of this latter study suggested that the kisspeptin system plays an important role in chub mackerel reproduction, and that Kiss2 in particular plays a dominant role in the regulation of the central reproductive axis. In the present study, we identified the functional form of Kiss2 peptide in 16 species of Scombridae. All the species possessed kiss2, and the deduced mature peptide had 12 amino acids, all of which were very highly conserved, except for the second amino acid from the N-terminal end that was found to vary across species. However, species specificity of the second residue did not affect signal transduction in chub mackerel KissR2, bluefin tuna Thunnus orientalis KissR2, or Japanese Spanish mackerel Scomberomorus niphonius KissR2. Therefore, the importance of the Kiss2 system, shown in studies of chub mackerel reproduction, may be relevant across all species of Scombridae.

Stock Structure Analysis of the Japanese Spanish Mackerel Scomberomorus niphonius (Cuvier, 1832) Along the China Coast Based on Truss Network

The Japanese Spanish mackerel Scomberomorus niphonius (Cuvier, 1832) is widely distributed in the subtropical and temperate waters of the northwestern Pacific Ocean, supporting one of the most important commercial fisheries in China. However, ignoring the potential population structure changes induced by fishing pressure and climate change may undermine the population stability under the current management strategy. In this study, the population structure of the Japanese Spanish mackerel was investigated based on a morphometric truss network system. A total of 534 individuals were randomly collected from commercial gill nets spanning eight major spawning grounds in the Bohai, Yellow, and East China Seas during the peak spawning seasons respectively. A total of 17 measurements (including eye diameter) were conducted in each specimen and subjected to principal component analysis (PCA) and discriminant function analysis (DFA). The results of PCA indicated that the first two factors cumulatively caused 78.38% of the total morphometric variation and observable differences, primarily fin the caudal and trunk areas. The results of DFA revealed that the eight spawning groups can be divided into three stocks, i.e. , southern, middle, and northern stocks, with 68.7% of total accuracy. In contrast to previous studies, the spawning groups of the Japanese Spanish mackerel demonstrated a tendency to disperse to northern regions. In conclusion, this study found that to maintain the stability of the population structure and the total production of Japanese Spanish mackerel S. niphonius (Cuvier, 1832), a newly revised management method should be developed and implemented.

Population structure of Japanese Spanish mackerel Scomberomorus niphonius in the Bohai Sea, the Yellow Sea and the East China Sea: evidence from random forests based on otolith features

In this study, the population structure of Japanese Spanish mackerel Scomberomorus niphonius were investigated based on the geographical variation of otolith features, and the concept of random forests was introduced as a classifier. Samples were collected from eight main spawning grounds using commercial gill nets, covering the distribution range along the coast of China. Otolith shape was described by the shape variables and principle components of Fourier coefficients. Every possible combination of otolith variable was tested to search for an optimal variable combination. An intermediate number of variables (8 out of 13) produced the most discriminating signal, and then the eight grounds were divided into three stocks with 64.5 % global accuracy. The discriminant result provided phenotypic evidence for the common migration trajectory, and further confirmed the existence of a metapopulation in Japanese Spanish mackerel at a larger scale.

Age Composition of Japanese Spanish Mackerel Scomberomorus niphonius (Cuvier 1832) Caught off Hyogo Prefecture, South-western Sea of Japan, as Determined by the Otolith Cross-section Method

Age Composition of Japanese Spanish Mackerel Scomberomorus niphonius (Cuvier 1832) Caught off Hyogo Prefecture, South-western Sea of Japan, as Determined by the Otolith Cross-section Method

サワラ仔魚における耳石透明帯と不透明帯の形成時間

飼育下のサワラ仔魚について 24 時間にわたって 3 時間ごとに標本のサンプリングを行い，扁平石の透明帯と不透明帯が形成される時間帯を調べた。初生輪は 5 日齢に形成され，摂餌開始日と一致していた。透明帯の形成は 05:00～08:00 の間に始まり，日中から夜間にかけて継続し，不透明帯はその後夜間に形成された。この結果は耳石の最外縁に観察される日周輪の読み取り精度を向上させるための有効な情報であり，天然で採集されたサワラ仔魚の耳石日周輪解析を行う際に採集時間を考慮することによって，より正確な判断が可能となる。

Deformity of the inter-nostril epidermis in artificially raised Japanese Spanish mackerel Scomberomorus niphonius juveniles

Deformity of the inter-nostril epidermis in artificially raised Japanese Spanish mackerel Scomberomorus niphonius juveniles

Mitochondrial DNA variation in the East China Sea and Yellow Sea populations of Japanese Spanish mackerel Scomberomorus niphonius

Japanese Spanish mackerel Scomberomorus niphonius is a commercially important species in the East China Sea and Yellow Sea, but there is limited knowledge of its genetic population structure. In order to detect its genetic structure, sequence variation of the first hypervariable segment of the control region was analyzed among eight populations of S. niphonius from the East China Sea and Yellow Sea. A total of 119 polymorphic sites were detected in the 505-bp segment of the control region among 134 individuals of S. niphonius, defining 112 haplotypes. Mean haplotype diversity and nucleotide diversity for the eight populations were 0.9963 ± 0.0017 and 0.0236 ± 0.0119, respectively. As expected, analysis of molecular variance detected no significant differences at all hierarchical levels, and most of the conventional population ΦST statistics were negative, indicating that no significant population genetic structure exists in the East China Sea and Yellow Sea. Moreover, the exact test of differentiation supported the null hypothesis that S. niphonius within the East China Sea and Yellow Sea constitutes a panmictic mtDNA gene pool. Neutrality tests and mismatch distribution revealed that S. niphonius underwent population expansion in the late Pleistocene. Strong dispersal capacity of larvae and adults, long-distance migrations, and ocean currents in the studied area could be the reasons for genetic homogeneity in this species in the East China Sea and Yellow Sea. Insufficient time to accumulate genetic variation might be another explanation for the lack of genetic structure in the East China Sea and Yellow Sea.

資源計画のためのシミュレーションモデル:瀬戸内海東部海域のサワラを例として

資源計画のためのシミュレーションモデル:瀬戸内海東部海域のサワラを例として

Growth-selective survival in piscivorous larvae of Japanese Spanish mackerel Scomberomorus niphonius: early selection and significance of ichthyoplankton prey supply

Scombrid fishes are considered to have adopted a survival strategy characterized by fast growth and the ability to consume large prey at an early age. Variability in feeding condition can significantly affect larval growth as early as the post first-feeding stage and may control growth-related survival during the early larval stage. Through otolith microstructure analysis, growth-selective survival was demonstrated for post first-feeding larvae of Japanese Spanish mackerel Scomberomorus niphonius, which exhibit exclusive piscivory, a high growth rate, and low tolerance to starvation. Larvae and juveniles were repeatedly collected in the Seto Inland Sea in June and July from 1997 to 1999. Growth trajectory back-calculated using otolith microanalysis was compared between the survivors (SV) captured in July and the presumed original population (OP) captured in June. Selection for fast-growing larvae was evident during the 5 d after first feeding (Days 5 to 10). More than 90% of the SV had a mean growth rate during Days 5 to 10 (G 5-10 ) > 0.8 mm d -1 , and those with G 5-10 < 0.8 mm d -1 rarely survived the period. Intensity of selection differed among 3 years. A less intense selection was observed in 1999 when the larval cohort experienced higher prey concentrations and G 5-10 . Laboratory experiments demonstrated that 1 to 2 d starvation retarded the larval growth during the following larval period, and supported the conclusion that fluctuation in ichthyoplankton prey abundance alters larval survival probability by affecting the larval growth rate within a short period subsequent to first feeding.

瀬戸内海東部海域におけるサワラの種苗放流への取り組み

瀬戸内海東部海域におけるサワラの種苗放流への取り組み

Daily ration and prey size of juvenile piscivore Japanese Spanish mackerel

Daily ration of juvenile Japanese Spanish mackerel Scomberomorus niphonius(32·1–33·1 mm standard length, LS) was estimated at three temperatures (18·6, 19·5 and 21·2° C) in the laboratory. Gastric evacuation rate ranged between 0·398 (18·6° C) and 0·431 (21·2° C). Diel change in instantaneous consumption rate indicated that juvenile Japanese Spanish mackerel are daylight feeders. The estimated values of the daily ration ranged between 66·1%(18·6° C) and 82·6%(21·2° C) of body mass. These per cent values of daily ration were converted to daily consumption in mg (28 mg at 18·6° C to 34 mg at 21·2° C) using the mean dry body mass of juvenile Japanese Spanish mackerel of 30 mm (42·1 mg). Stomach content analysis of wild specimens collected in the Seto Inland Sea, south‐western Japan, revealed that the majority of wild Japanese Spanish mackerel larvae and juveniles ingested fish larvae with a body size &gt;50% of the predator LS. Based on the predator‐prey size relationship, the daily consumption of a Japanese Spanish mackerel juvenile of 30 mm was equivalent to 5·1 (18·6° C) to 6·4 (21·2° C) Japanese anchovy Engraulis japonicus larvae which was the dominant prey organism in stomachs of the wild Japanese Spanish mackerel.

Effect of prey concentration on growth of piscivorous Japanese Spanish mackerel Scomberomorus niphonius larvae in the Seto Inland Sea, Japan

Summary Japanese Spanish mackerel, Scomberomorus niphonius, larvae feed almost exclusively on fish larvae from the first-feeding stage. The relationship between the growth of S. niphonius larvae and concentration of major prey organisms of the larvae, clupeid larvae, was investigated in the Sea of Hiuchi, the central Seto Inland Sea, Japan, from 28 to 29 May 1997. Water temperature, salinity, and the concentration of clupeid larvae had no significant effect on the S. niphonius larval concentration. Mean growth rate of S. niphonius larvae varied between 0.38 and 0.64 mm day−1. The temperature and salinity had no significant effect on the mean larval growth rate while there existed prey concentration-dependent growth at lower prey concentration. The relationship between the mean larval growth rate (Gm) and concentration of clupeid larvae (CC) was expressed by a logarithmic equation: Gm = 0.037 log CC + 0.441 (n = 16, r2 = 0.519, P < 0.01).

Susceptibility to starvation by piscivorous Japanese Spanish mackerel Scomberomorus niphonius (Scombridae) larvae at first feeding

The hypothesis that prey abundance and larval growth rate are related to recruitment was tested in Japanese Spanish mackerel in the central Seto Inland Sea, Japan. The relationships among larval abundance, growth rate, prey fish (clupeiform larvae) abundance, and the catch per unit fishing effort (CPUE) of the subsequent 1-year-old fish were examined from 1995 to 1999. A significant, positive correlation was found between the larval growth rate and the CPUE, but not between the larval abundance and the CPUE. There also existed a significant positive correlation between the abundance of clupeiform larvae and the larval growth rate, which varied from 0.4 to 1.0mm/day. Both the larval growth rate and the CPUE were higher in 1995 and 1999, when the period of peak occurrence of clupeiform larvae timed well with that of the mackerel larvae. It has been concluded that the prey abundance during the early larval period is one of the most important determinants of the growth and recruitment of Japanese Spanish mackerel.

Daily ration of Japanese Spanish mackerel Scomberomorus niphonius larvae

SUMMARY: Diel successive samplings of Japanese Spanish mackerel Scomberomorus niphonius larvae were conducted throughout 24 h both in the sea and in captivity in order to estimate their daily ration. Using the Elliott and Persson model, the instantaneous gastric evacuation rate was estimated from the depletion of stomach contents (% dry bodyweight) with time during the night for wild fish (3.0–11.5 mm standard length) and from starvation experiments for reared fish (8, 10, and 15 days after hatching (DAH)). Japanese Spanish mackerel is a daylight feeder and exhibited piscivorous habits from first feeding both in the sea and in captivity. Feeding activity peaked at dusk. The estimated daily ration for wild larvae were 111.1 and 127.2% in 1996 and 1997, respectively; and those for reared larvae ranged from 90.6 to 111.7% of dry bodyweight. Based on the estimated value of daily rations for reared fish, the total number of newly hatched red sea bream Pagrus major larvae preyed by a Japanese Spanish mackerel from first feeding (5 DAH) to beginning of juvenile stage (20 DAH) in captivity was calculated to be 1139–1404.