Oxygen and carbon isotope ratios（δ^（18）O and δ^（13）C） in otoliths were used to identify the stock structure of small yellow croaker,Larimichthys polyactis.Otoliths were collected from fish at five locations ac...Oxygen and carbon isotope ratios（δ^（18）O and δ^（13）C） in otoliths were used to identify the stock structure of small yellow croaker,Larimichthys polyactis.Otoliths were collected from fish at five locations across the Yellow Sea and the Bohai Sea representing most of their distributional range and fisheries areas.The significant differences in the isotopic signatures showed that the five locations could be chemically distinguished and clearly separated,indicating stock subdivision.Correlation of δ^（18）O and δ^（13）C values suggested that population of L.polyactis could be divided into the Bohai Sea group,the southern Yellow Sea group and the central Yellow Sea group.Discriminant analysis of δ^（18）O and δ^（13）C values demonstrated a high significant difference with 85.7% classification accuracy.The spatial separation of L.polyactis indicated a complex stock structure across the Yellow Sea and the Bohai Sea.These results indicate that optimal fisheries management may require a comprehensive consideration on the current spatial arrangements.This study has provided further evidence that measurement of the stable isotopes ratios in otolith can be a valuable tool in the delineation of fishery management units.展开更多
The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate a...The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate and tropical waters. Changes of the microincrements growth pattern and otolith shape are described in relation to larval, hatching and metamorphosis stages have similar patterns for Ps. georgianus and Charnpsocephalus gunnari, reflecting similar habitats in their early life. Width of larvae-postlarvae daily increments are： （1.0-1.6）×10-3 SSI, （1.8-2.8）×10-3 SG1 and （1.5-2.4）×10-3 ANI. They were search and chosen automatically from density profiles of otolith tissues. Tissues were prepared by new saving time and materials way--one time up to 40 ones per microscopic glass. Age of fish estimated from microincrements was alike to that inferred from the body length distribution, otoliths mass （age （years） = 140.82 OM （g） ＋ 0.8546） and otolith shape changes--large in length and surface on medial plane. Those parameters create age groups of close neighbours. They have different environments. C. aceratus due to its adaptation to cold water, attain rapidly large body according to a growth equation： Lt= 75.1 ×10-3 （1-e-0.26（t-0.51）. Among large fishes there were only females.展开更多
Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT a...Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT and stomach content data are insufficient for trophic level(TL)data of past fi shes which is important for the changes of marine fi shery resources over long time scales.To determine the correlation betweenδ^(15) N_(oto) and fi sh WMTδ^(15) N(δ^(15) N_(wmt))and the feasibility of usingδ^(15) N_(oto) in characterizing the TLs of marine fi shes,we conducted nitrogen stable isotope analysis(SIA)in the otolith and WMT of 36 marine fi sh species sampled from the Yellow Sea and northern East China Sea in 2011-2014.Bothδ^(15) N_(oto) andδ^(15) N_(wmt) were analyzed using an elemental analyzer coupled with an isotope ratio mass spectrometer(EA-IRMS).Multiple otoliths were combined to make each otolith measurement and were analyzed as-is without a carbonate dissolution pre-processing step.δ^(15) N_(oto) andδ^(15) N_(wmt) comparisons for species in the Yellow Sea and northern East China Sea are currently lacking and would be helpful for both regional studies and for increasing the number of species for whichδ^(15) N_(oto) andδ^(15) N_(wmt) have been compared.Additionally,to determine the relative accuracy of trophic level calculated usingδ^(15) N_(oto),we compared TL calculated fromδ^(15) N_(oto) to traditional trophic level metrics calculated usingδ^(15) N_(wmt).The results showed a positive and highly signifi cant correlation(R=0.780,P<0.001)betweenδ^(15) N_(oto) andδ^(15) N_(wmt).Trophic level estimation using WMT(TL wmt)and otolith(TL oto)showed congruence in our study,which is not entirely surprising given thatδ^(15) N_(oto) was regressed againstδ^(15) N_(wmt) and the resulting regression coefficient was used to convertδ^(15) N_(oto) toδ^(15) N_(wmt) prior to calculating TL oto.This conversion was required in order to be consistent with previousδ^(15) N_(wmt)-based calculations of TL for comparison.TL oto calculations resulted in TL values that were largely within 5%-10%of TL values calculated withδ^(15) N_(wmt).Our fi ndings show thatδ^(15) N_(oto) is a feasible technique for characterizing the TLs of marine fi sh and can also assist in food web and marine ecosystem studies.展开更多
This study examined the right and left otoliths of 174 individuals of Pseudotolithus senegalensis from the Porto-Novo lagoon, Lake Nokoué and the Atlantic coast. The results show a significant variation in the po...This study examined the right and left otoliths of 174 individuals of Pseudotolithus senegalensis from the Porto-Novo lagoon, Lake Nokoué and the Atlantic coast. The results show a significant variation in the population according to geographic location. Mixed-effects linear analysis showed no significant variation by site, side or sex (p > 0.05). Analysis of otolith shape using ANOVA showed significant differences for length, width and area (p 0.05). Canonical discriminant analysis revealed significant differences between sites (p < 0.05). Finally, shape analyses showed significant differences between sites (p = 0.0001) and between right and left sides (p = 0.007), but no difference by sex (p = 0.395). The study of otolith morphology is therefore proving to be a valuable tool for differentiating stocks and understanding ecological variations.展开更多
Objective The macula lagena in birds is located at the apical end of the cochlea and contains many tiny otoliths. The macula lagena is innervated and has neural projections to the brainstem, but its physiological func...Objective The macula lagena in birds is located at the apical end of the cochlea and contains many tiny otoliths. The macula lagena is innervated and has neural projections to the brainstem, but its physiological function is still unclear. It remains disputable that it is because otoliths in the lagena are rich in elements Fe and Zn that birds can obtain geomagnetic information for homing. To clarify this issue, we carried out a study to determine whether or not otoliths in the lagena of homing pigeons are richer in magnetic elements than those in the saccule and the utricle. Methods The contents of ferromagnetic elements （Fe, Co, Ni） and other metal elements in lagenal otoliths of adult homing pigeons were precisely analyzed with inductively coupled plasma mass spectrometry （ICP-MS） of high sensitivity, and then they were compared with those in saccular and utricular otoliths （all the contents were normalized to Ca）. Results In adult homing pigeons, the contents of ferromagnetic elements （Fe, Co, Ni） in lagenal otoliths were less than 0.7% （normalized to Ca element） and were the same order in magnitude as those in saccular and utricular otoliths. The content of Fe in lagenal otoliths was not significantly different from that in utricular otoliths and was even lower than that in saccular otoliths. The content of Co in lagenal otoliths was lower than that in saccular otoliths and higher than that in utricular otoliths. The content of Ni in lagenal otoliths was not significantly different from that in saccular otoliths and was higher than that in utricular otoliths. The contents of other metal elements Na, Mg, K, Al, Mn and Pb in lagenal otoliths were not significantly different from those in utricular and saccular otoliths. The contents of metal elements Zn, Ba and Cu in lagenal otoliths were lower than those in saccular otoliths. Conclusion The contents of magnetic elements in lagenal otoliths of homing pigeons are not much higher than those in utricular and saccular otoliths, which does not support the hypothesis that birds depend on high contents of Fe and Zn in lagenal otoliths for sensation of geomagnetic information. Similarities in morphology, element ingredient and element content between lagenal otoliths and utricular otoliths suggest that the two types of otolithic organs may play similar roles in sensing gravitational and acceleration signals.展开更多
Otoliths are biogenic carbonate minerals whose microstructure and microchemistry have been used for age determination, stock identification, life history and environmental tracing. Using X-ray diffraction （XRD） and ...Otoliths are biogenic carbonate minerals whose microstructure and microchemistry have been used for age determination, stock identification, life history and environmental tracing. Using X-ray diffraction （XRD） and Fourier transform infrared （FTIR） spectroscopy, we have determined the mineral types and crystalline characteristics of three pairs of otoliths from naked carp Gymnocypris przewalskii, the predominant fish in Lake Qinghai. The results indicate that the mineral of both lapillus and sagitta of the naked carp is aragonite, and that of asteriscus is vaterite. The aragonite of lapillus has prefect crystallization. Given the shape of lapillus and the sensitivity of its aragonite to water chemistry, lapillus was used to analyze temporal Sr/Ca ratios along the maximal growth axis by an electron probe microanalyzer （EPMA）. Consistent variations of Sr/Ca ratios with a range of 1.0x10-3-5.0~10-3 on the long and short radii indicate that Sr/Ca ratios of lapillus potentially respond to the chemical compositions of the host waters during the period of the naked carp＇s growth and migration. Discontinuous （dark） zones of lapillus were formed during fall and winter when the naked carp grows slowly in Lake Qinghai, resulting in similar low Sr/Ca ratios to lake water, whereas incremental zones with higher St/Ca ratios respond to its migratory river waters during spring and summer. Various Sr/Ca ratios of incremental zones suggest that the migratory pattern of the naked carp may be much more flexible, rather than in a single river. Therefore, high-resolution otolith microchemistry of the naked carp can be used to trace its migratory behavior, which is of significance for determining its migratory pattern and life history of this precious species inhabiting the Tibetan Plateau.展开更多
Two basic questions must be solved in age determination of the early life stage of the eel, Anguilla japonica, in daily precision: (i) recognizing the initial increment in otolith and determining the timing of the ini...Two basic questions must be solved in age determination of the early life stage of the eel, Anguilla japonica, in daily precision: (i) recognizing the initial increment in otolith and determining the timing of the initial increment formation; (ii) confirming the deposition rate of the increment. A clear understanding of the first question in the otolith of larvae and glass eel, Anguilla japonica, has not been got, such as how to confirm the initial increment in age determination of glass eel, determine the timing of hatch check formation and validate the microstructure in the otolith of the early life stage of Anguilla japonica.展开更多
Atlantic halibut(Hippoglossus hippoglossus,Linnaeus,1758)are a data-poor stock within the waters of the United States.This study evaluated the use of otolith measurements to back-calculate lengths of Atlantic halibut ...Atlantic halibut(Hippoglossus hippoglossus,Linnaeus,1758)are a data-poor stock within the waters of the United States.This study evaluated the use of otolith measurements to back-calculate lengths of Atlantic halibut at previous ages.Back-calculations have proven useful for estimating length at age and growth rates of other species.To the best knowledge of the authors,this study is the first to document the use of this method for Atlantic halibut.Otolith back-calculations rely on a few key assumptions,such as proportionality of fish length and otolith length,which are not always met.This study shows that backcalculations using the Fraser-Lee method can provide reasonable estimates of Atlantic halibut length at previous ages,especially when samples from young halibut are included to improve estimates of the intercept of the linear regressions.Based on back-calculated estimates,female and male halibut in the Gulf of Maine showed different growth rates after age five.There was no evidence of changes in growth rates over an approximately 15 year time period.Halibut caught in the Gulf of Maine and on the neighboring Scotian Shelf showed some differences in growth rates;however,the results did not support strong conclusions about differences between the two regions as the direction of the differences was not consistent between the sexes and previous tagging studies have shown extensive movement between the two areas.The finding of reasonably accurate back-calculated lengths at previous ages is important for this data-poor species,as back-calculations increase the amount of information that can be obtained from otoliths.展开更多
The estuarine tapertail anchovy(Coilia nasus)is a high-value commercial fish.Estimating the spawning site or hatchery origin and habitat is essential for its conservation.This study aimed to determine the habitat use ...The estuarine tapertail anchovy(Coilia nasus)is a high-value commercial fish.Estimating the spawning site or hatchery origin and habitat is essential for its conservation.This study aimed to determine the habitat use and life history characteristics of C.nasus from the Changjiang River Estuary.We investigated the environmental signatures of strontium(Sr)and calcium(Ca)in the otoliths of the collected specimens using electron probe microanalysis;additionally,we examined their gonadal maturity stage.Our results indicate that the 31 adult C.nasus specimens used in this study could be classified into two types based on their otolith Sr:Ca concentration ratios and their gonadal maturity stage.The long freshwater early life history type(Type LF)had wider central region in the otolith with low Sr:Ca concentration ratios ranging from 1.24±0.62 to 1.92±0.78 and a bluish pattern of low Sr content level.These fish are of riverine origin and had a relatively long early life history in freshwater and low gonadal maturation when captured.The short freshwater early life history type(Type SF)had a shorter central region in the otolith with low Sr:Ca concentration ratios ranging from 1.35±0.5 to 2.82±0.97 and a correspondingly bluish pattern.These fish also had a relatively short-term early life history in freshwater and high gonadal maturation when captured.The results of the otolith microchemical analysis indicated that Type LF and Type SF originated in spawning/hatching sites far from and close to the estuary,respectively.The mature gonads of Type SF fish indicated that they may breed in areas close to the estuary,whereas the immature gonads of Type LF fish indicated that they may breed in areas far from the estuary.This study is the first to reveal that the Changjiang River Estuary contains stocks of anadromous C.nasus originating in different spawning sites during the same season.The estuarine habitat plays a critical role in the connectivity between freshwater recruitment and the marine resources available to adult spawners of this commercially valued species.From a conservation perspective,this study provides important information for identifying anadromous C.nasus stocks originating in different spawning sites in the Changjiang River Basin.展开更多
Information on survival and growth during the early life stage is essential to understand the mechanism of interannual variations in fish recruitment.Chub mackerel Scomber japonicus is a commercially important pelagic...Information on survival and growth during the early life stage is essential to understand the mechanism of interannual variations in fish recruitment.Chub mackerel Scomber japonicus is a commercially important pelagic fish widely distributed in the northwestern Pacific.Its catch showed large fluctuations with changes in distribution and migration under climate change and strong fishing.We determined the hatch dates and growth rates of young-of-the-year of chub mackerel through otolith microstructure using samples collected in the Oyashio water in autumn 2018.Results show that the ages of young chub mackerel ranged between 120 and 180 d,and the estimated hatch date lasted from midJanuary to late May with a peak from mid-March to mid-April.Average otolith daily increment width during the early life stages(from hatching to 25 d)showed an increasing trend.Chub mackerel grows slowly in the first 10 d,and then grows faster during the 10thto 25thd.Three groups with dissimilar growth histories and migration routes were identified using unsupervised random forest clustering analysis,but all eventually converge on the same nursery ground.The faster growth of young-of-the-year chub mackerel leads to better recruitment due to the hypothesis of growth-dependent mortality.Most chub mackerels hatched in March and April,the spawning period is longer and earlier,which could lead to strong year classes.These findings on population composition and life history traits of young-of-the-year of chub mackerel provide valuable information on its recruitment processes during the period of stock recovery.展开更多
Japanese Spanish mackerel Scomberomorus niphonius is a pelagic,neritic species that occurs in the Yellow Sea in high commercial value.The spawning period of this fast-growing species is controlled by water temperature...Japanese Spanish mackerel Scomberomorus niphonius is a pelagic,neritic species that occurs in the Yellow Sea in high commercial value.The spawning period of this fast-growing species is controlled by water temperature.Based on microstructural analysis of otoliths from 145 young-of-the-year(YoY)S.niphonius collected by trawl in 2017,2018,and 2020,and the temporal variation in the spawning period in the northern Yellow Sea,and its relationship to water temperature were examined.We found that the spawning lasted from late April to late June but differed in year:in 2017 it occurred from April 23 to June 1 and peaked in early May,in 2018 it extended later from May 7 to June 29,and in 2020 from May 6 to June 22 and peaked later from late May to mid-June.The highest temperature in 2017 corresponds with the earliest end of the spawning period and a lower growing degree-day(GDD,℃·day)of 383℃·day.In 2018,slower warming corresponds with a longer spawning period,and a GDD spawning period of 506℃·day.Rapid warming in late 2020 corresponds with a spawning peak,and a GDD spawning temperature of 448℃·day.Despite differences in spawning period,the water temperature when spawning commenced was 10-12℃.Therefore,water temperature is the major determinant of the spawning period,affecting both the starting and the ending of spawning.This study improved our understanding of the spawning dynamics and environmental adaptation of S.niphonius,and how these might change in environments subject to increased warming.展开更多
Background: The utricular macula is located on the floor of the utricle, approximately in the plane of the lateral semicircular canal, and is oriented to respond best to lateral tilts and side-to-side or fore-and-aft ...Background: The utricular macula is located on the floor of the utricle, approximately in the plane of the lateral semicircular canal, and is oriented to respond best to lateral tilts and side-to-side or fore-and-aft translations of the head. However, the details of the otolith ocular reflex are unknown. Pathophysiology of transient direction-changing geotropic positional nystagmus is a canalolithiasis in the lateral semicircular canal. The principle of affected-ear-up 90° maneuver is moving debris from a long arm to the utricle, therefore debris stimulates the utricular macula in the sitting position after the treatment. Objective: To clarify whether nystagmus occurs by the stimulation to the macula of the utricle. Methods: The subjects were 10 patients with lateral semicircular canal canalolithiasis. After the diagnosis, we performed affected-ear-up 90° maneuver immediately. We observed eye movements in the sitting position (chin-down 30°) just after the treatment. Results: No one showed nystagmus in the sitting position after the treatment. In all patients, positional nystagmus disappeared within 7 days after the treatment. Conclusion: Nystagmus does not occur by the stimulation to the macula of the utricle. Hence, we cannot assess the function of the utricle by the analysis of eye movements, and ocular counter-rolling is considered to be a semicircular canal ocular reflex.展开更多
Background: We have been performing a canalith repositioning procedure for benign paroxysmal positional vertigo. When we adopted the Epley maneuver for posterior semicircular canal type, and affected-ear-up 90° m...Background: We have been performing a canalith repositioning procedure for benign paroxysmal positional vertigo. When we adopted the Epley maneuver for posterior semicircular canal type, and affected-ear-up 90° maneuver for lateral semicircular canal type, we noticed that no nystagmus occurred in the sitting position just after treatment. Despite direct excitation to the utricle by the pathological debris, none of the subjects complained of dizziness. Thus, we hypothesized that nystagmus and dizziness do not occur by stimulation of the otolith organs. Objective: The aim of the study was to observe and record the eye movements induced by the otolith organs to confirm our hypothesis. Materials and Methods: Twelve healthy humans were tested. In the sitting position, the head was tilted to the right ear by 45° and vice versa. Afterward, the head was bent forward by 90° (nose-down), and the subject’s seat was reclined to the head-hanging position. Each position was kept for five seconds. We interviewed the subjects to assess their dizziness. Results: None of the subjects showed nystagmus and complained of dizziness in every position. Conclusions: Nystagmus does not occur by the stimulation to the otolith organs;therefore, ocular counter-rolling is a semicircular canal ocular reflex.展开更多
Black rockfish Sebastes schlegelii juveniles （30-40 mm total length） were immersed in a range of calcein （CAL） solutions at concentrations ranging from 50 to 250 mg/L and alizarin red S （ARS） solutions at concen...Black rockfish Sebastes schlegelii juveniles （30-40 mm total length） were immersed in a range of calcein （CAL） solutions at concentrations ranging from 50 to 250 mg/L and alizarin red S （ARS） solutions at concentrations ranging from 100 to 500 mg/L in filtered seawater （salinity 30） for 24 h. Fluorescent marks were detected in otoliths （sagittae, asteriscus）, scales, fin rays （dorsal, pectoral, ventral, anal, and caudal fin rays）, and fin spines （dorsal, ventral, and anal fin spines） after a 60-d growth experiment. With the exception of 50-100 rng/L CAL, acceptable marks were produced in the otoliths and fin spines by all concentrations of CAL and ARS. In particular, marks were clearly visible under normal light in the sagittae, asteriscus, and fin spines offish immersed in 200 500 mg/L, 300-500 rag/L, and 200-500 mg/LARS, respectively. Scales and fin rays had acceptable marks at much higher concentrations （≥50 mg/L CAL, ≥300 mg/L ARS for scales and ≥50 mg/L CAL,≥200 mg/L ARS for fin rays）. The mark quality was highest （i.e., acceptable marks were observed in all sampled structures after immersion marking） in fish immersed in 150-250 mg/L CAL or 300-500 mg/LARS. In addition, there was no significant difference in survival and growth of marked fish compared with controls 60 d post-marking （P〉0.05）.展开更多
We tested the utility of chemical marking techniques in the juvenile black rockfish Sebastes schlegelii. Juveniles （30-40 mm total length） were immersed in a range of tetracycline hydrochloride （TC） solutions at c...We tested the utility of chemical marking techniques in the juvenile black rockfish Sebastes schlegelii. Juveniles （30-40 mm total length） were immersed in a range of tetracycline hydrochloride （TC） solutions at concentrations ranging from 300 to 500 mg/L, and alizarin complexone （ALC） solutions at concentrations ranging from 200 to 400 mg/L in filtered sea water （salinity of 30） for 24 h, respectively. Otoliths （sagittae, asteriscus）, scales, fin rays （dorsal, pectoral, ventral, anal, and caudal fin rays）, and fin spines （dorsal, ventral, and anal fin spines） were sampled and used to detect fluorescent marks after a 60-day growth experiment. With the exception of 300 mg/L TC, acceptable marks were produced in the otoliths and fin spines by all concentrations of TC and ALC. In particular, we observed clearly visible marks in the sagittae, asteriscus, and fin spines under normal light at concentrations of200~00 mg/L, 250-400 mg/L, and 250-400 mg/L ALC, respectively. Scales and fin rays had acceptable marks at much higher concentrations （_〉350 mg/L TC, 〉250 mg/L ALC for scales and _〉350 mg/L TC, 〉300 mg/L ALC for fin rays）. The best mark quality （i.e., acceptable marks were observed in all sampled structures after immersion marking） were obtained following immersion in TC at between 350-500 rag/L, and ALC between 300-400 mg/L. In addition, there was no significant difference in survival and growth of TC and ALC marked fish compared to their controls up to 60 days post-marking （P〉0.05）.展开更多
Objective:To study the potential role of subjective visual vertical(SVV)as a prognostic marker for canalith repositioning maneuver(CRM)in patients with posterior canal benign paroxysmal positional vertigo(PC-BPPV)for ...Objective:To study the potential role of subjective visual vertical(SVV)as a prognostic marker for canalith repositioning maneuver(CRM)in patients with posterior canal benign paroxysmal positional vertigo(PC-BPPV)for the Indian population.Methods:SVV was examined in 30 patients with PC-BPPV before and after canalith repositioning maneuver and after complete resolution of PC-BPPV.Study parameters included the mean of 10 angular tilt readings and direction of deviation,which were compared before and after CRM and following complete resolution of PC-BPPV.Results:The angle of SVV tilt was greater and deviated towards the affected ear before CRM in all patients,which decreased significantly shortly after CRM and continued to decrease after complete resolution of PC-BPPV(p<0.0001).Conclusions:SVV can be used to test utricular dysfunction in PC-BPPV.The angle of tilt improves in response to CRM,which may be used as a prognostic marker in patients with PC-BPPV receiving CRM.展开更多
The migratory history of the engraulid fish Coilia nasus in the Rokkaku and Chikugo River estuaries of the Ariake Sea, Japan was assessed using otolith strontium（Sr） X-ray intensity maps and strontium：calcium（Sr...The migratory history of the engraulid fish Coilia nasus in the Rokkaku and Chikugo River estuaries of the Ariake Sea, Japan was assessed using otolith strontium（Sr） X-ray intensity maps and strontium：calcium（Sr：Ca） ratio life history transects by an electron probe microanalyzer（EPMA）. The results showed that seven of the ten specimens from the Rokkaku River Estuary（LJC） and all 15 specimens collected in the Chikugo River Estuary（ZHC） had low Sr：Ca ratios（≤3） at the central otolith area, indicating their riverine origin and initial freshwater residence. After the first regime shift adjacent to natal regions, the Sr level mapping displayed a wide variety of color patterns, and the Sr：Ca ratios obtained by the line transect analysis could be divided into one to six significantly different phases indicative of gradual life history transition. The other three specimens from the Rokkaku River Estuary had high Sr：Ca ratios（3–6.7） at the central otolith area but showed alternating changes between low and high values outside the natal region, suggesting that estuarine-origin individuals occurred in the Rokkaku River Estuary. The two-dimensional maps of the Sr level and average of the otolith Sr：Ca ratios along the life-history transects could be used as effective tools for reconstruction of past habitat use of the tapertail anchovy in estuaries of the Ariake Sea, Japan.展开更多
Although chub mackerel （Scomberjaponicus） is a primary pelagic fish species, we have only limited knowledge on its key life history processes. The present work studied the age and growth of chub mackerel in the East...Although chub mackerel （Scomberjaponicus） is a primary pelagic fish species, we have only limited knowledge on its key life history processes. The present work studied the age and growth of chub mackerel in the East China and Yellow Seas. Age was determined by interpreting and counting growth rings on the sagitta otoliths of 252 adult fish caught by the Chinese commercial purse seine fleet during the period from November 2006 to January 2007 and 150 juveniles from bottom trawl surveys on the spawning ground in May 2006. The difference between the assumed birth date of 1st April and date of capture was used to adjust the age determined from counting the number of complete translucent rings. The parameters of three commonly used growth models, the von Bertalanffy, Logistic and Gompertz models, were estimated using the maximum likelihood method. Based on the Akaike Information Criterion （AIC）, the yon Bertalanffy growth model was found to be the most appropriate model. The size-at-age and size-at-maturity values were also found to decrease greatly compared with the results achieved in the 1950s, which was caused by heavy exploitation over the last few decades.展开更多
基金The National Basic Research Program(973 Program)of China under contract Nos 2015CB453300 and 2010CB428900
文摘Oxygen and carbon isotope ratios（δ^（18）O and δ^（13）C） in otoliths were used to identify the stock structure of small yellow croaker,Larimichthys polyactis.Otoliths were collected from fish at five locations across the Yellow Sea and the Bohai Sea representing most of their distributional range and fisheries areas.The significant differences in the isotopic signatures showed that the five locations could be chemically distinguished and clearly separated,indicating stock subdivision.Correlation of δ^（18）O and δ^（13）C values suggested that population of L.polyactis could be divided into the Bohai Sea group,the southern Yellow Sea group and the central Yellow Sea group.Discriminant analysis of δ^（18）O and δ^（13）C values demonstrated a high significant difference with 85.7% classification accuracy.The spatial separation of L.polyactis indicated a complex stock structure across the Yellow Sea and the Bohai Sea.These results indicate that optimal fisheries management may require a comprehensive consideration on the current spatial arrangements.This study has provided further evidence that measurement of the stable isotopes ratios in otolith can be a valuable tool in the delineation of fishery management units.
文摘The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate and tropical waters. Changes of the microincrements growth pattern and otolith shape are described in relation to larval, hatching and metamorphosis stages have similar patterns for Ps. georgianus and Charnpsocephalus gunnari, reflecting similar habitats in their early life. Width of larvae-postlarvae daily increments are： （1.0-1.6）×10-3 SSI, （1.8-2.8）×10-3 SG1 and （1.5-2.4）×10-3 ANI. They were search and chosen automatically from density profiles of otolith tissues. Tissues were prepared by new saving time and materials way--one time up to 40 ones per microscopic glass. Age of fish estimated from microincrements was alike to that inferred from the body length distribution, otoliths mass （age （years） = 140.82 OM （g） ＋ 0.8546） and otolith shape changes--large in length and surface on medial plane. Those parameters create age groups of close neighbours. They have different environments. C. aceratus due to its adaptation to cold water, attain rapidly large body according to a growth equation： Lt= 75.1 ×10-3 （1-e-0.26（t-0.51）. Among large fishes there were only females.
基金Supported by the National Key Basic Research Development Program of China(973 Program)(No.2015CB453303)the National Science Foundation for Young Scientists of China(No.41606195)。
文摘Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT and stomach content data are insufficient for trophic level(TL)data of past fi shes which is important for the changes of marine fi shery resources over long time scales.To determine the correlation betweenδ^(15) N_(oto) and fi sh WMTδ^(15) N(δ^(15) N_(wmt))and the feasibility of usingδ^(15) N_(oto) in characterizing the TLs of marine fi shes,we conducted nitrogen stable isotope analysis(SIA)in the otolith and WMT of 36 marine fi sh species sampled from the Yellow Sea and northern East China Sea in 2011-2014.Bothδ^(15) N_(oto) andδ^(15) N_(wmt) were analyzed using an elemental analyzer coupled with an isotope ratio mass spectrometer(EA-IRMS).Multiple otoliths were combined to make each otolith measurement and were analyzed as-is without a carbonate dissolution pre-processing step.δ^(15) N_(oto) andδ^(15) N_(wmt) comparisons for species in the Yellow Sea and northern East China Sea are currently lacking and would be helpful for both regional studies and for increasing the number of species for whichδ^(15) N_(oto) andδ^(15) N_(wmt) have been compared.Additionally,to determine the relative accuracy of trophic level calculated usingδ^(15) N_(oto),we compared TL calculated fromδ^(15) N_(oto) to traditional trophic level metrics calculated usingδ^(15) N_(wmt).The results showed a positive and highly signifi cant correlation(R=0.780,P<0.001)betweenδ^(15) N_(oto) andδ^(15) N_(wmt).Trophic level estimation using WMT(TL wmt)and otolith(TL oto)showed congruence in our study,which is not entirely surprising given thatδ^(15) N_(oto) was regressed againstδ^(15) N_(wmt) and the resulting regression coefficient was used to convertδ^(15) N_(oto) toδ^(15) N_(wmt) prior to calculating TL oto.This conversion was required in order to be consistent with previousδ^(15) N_(wmt)-based calculations of TL for comparison.TL oto calculations resulted in TL values that were largely within 5%-10%of TL values calculated withδ^(15) N_(wmt).Our fi ndings show thatδ^(15) N_(oto) is a feasible technique for characterizing the TLs of marine fi sh and can also assist in food web and marine ecosystem studies.
文摘This study examined the right and left otoliths of 174 individuals of Pseudotolithus senegalensis from the Porto-Novo lagoon, Lake Nokoué and the Atlantic coast. The results show a significant variation in the population according to geographic location. Mixed-effects linear analysis showed no significant variation by site, side or sex (p > 0.05). Analysis of otolith shape using ANOVA showed significant differences for length, width and area (p 0.05). Canonical discriminant analysis revealed significant differences between sites (p < 0.05). Finally, shape analyses showed significant differences between sites (p = 0.0001) and between right and left sides (p = 0.007), but no difference by sex (p = 0.395). The study of otolith morphology is therefore proving to be a valuable tool for differentiating stocks and understanding ecological variations.
基金supported by the National Natural Science Foundation of China(No.30470560 and 30730041)the National Basic Research Program of China (No.2007CB512306)the Knowledge Innovation Project of Chinese Academy of Sciences (No.KSCX1-YW-R-36)
文摘Objective The macula lagena in birds is located at the apical end of the cochlea and contains many tiny otoliths. The macula lagena is innervated and has neural projections to the brainstem, but its physiological function is still unclear. It remains disputable that it is because otoliths in the lagena are rich in elements Fe and Zn that birds can obtain geomagnetic information for homing. To clarify this issue, we carried out a study to determine whether or not otoliths in the lagena of homing pigeons are richer in magnetic elements than those in the saccule and the utricle. Methods The contents of ferromagnetic elements （Fe, Co, Ni） and other metal elements in lagenal otoliths of adult homing pigeons were precisely analyzed with inductively coupled plasma mass spectrometry （ICP-MS） of high sensitivity, and then they were compared with those in saccular and utricular otoliths （all the contents were normalized to Ca）. Results In adult homing pigeons, the contents of ferromagnetic elements （Fe, Co, Ni） in lagenal otoliths were less than 0.7% （normalized to Ca element） and were the same order in magnitude as those in saccular and utricular otoliths. The content of Fe in lagenal otoliths was not significantly different from that in utricular otoliths and was even lower than that in saccular otoliths. The content of Co in lagenal otoliths was lower than that in saccular otoliths and higher than that in utricular otoliths. The content of Ni in lagenal otoliths was not significantly different from that in saccular otoliths and was higher than that in utricular otoliths. The contents of other metal elements Na, Mg, K, Al, Mn and Pb in lagenal otoliths were not significantly different from those in utricular and saccular otoliths. The contents of metal elements Zn, Ba and Cu in lagenal otoliths were lower than those in saccular otoliths. Conclusion The contents of magnetic elements in lagenal otoliths of homing pigeons are not much higher than those in utricular and saccular otoliths, which does not support the hypothesis that birds depend on high contents of Fe and Zn in lagenal otoliths for sensation of geomagnetic information. Similarities in morphology, element ingredient and element content between lagenal otoliths and utricular otoliths suggest that the two types of otolithic organs may play similar roles in sensing gravitational and acceleration signals.
基金supported by National Basic Research Program of China (Grant No. 2010CB833400)National Natural Science Foundation of China (Grant No. 40873082)
文摘Otoliths are biogenic carbonate minerals whose microstructure and microchemistry have been used for age determination, stock identification, life history and environmental tracing. Using X-ray diffraction （XRD） and Fourier transform infrared （FTIR） spectroscopy, we have determined the mineral types and crystalline characteristics of three pairs of otoliths from naked carp Gymnocypris przewalskii, the predominant fish in Lake Qinghai. The results indicate that the mineral of both lapillus and sagitta of the naked carp is aragonite, and that of asteriscus is vaterite. The aragonite of lapillus has prefect crystallization. Given the shape of lapillus and the sensitivity of its aragonite to water chemistry, lapillus was used to analyze temporal Sr/Ca ratios along the maximal growth axis by an electron probe microanalyzer （EPMA）. Consistent variations of Sr/Ca ratios with a range of 1.0x10-3-5.0~10-3 on the long and short radii indicate that Sr/Ca ratios of lapillus potentially respond to the chemical compositions of the host waters during the period of the naked carp＇s growth and migration. Discontinuous （dark） zones of lapillus were formed during fall and winter when the naked carp grows slowly in Lake Qinghai, resulting in similar low Sr/Ca ratios to lake water, whereas incremental zones with higher St/Ca ratios respond to its migratory river waters during spring and summer. Various Sr/Ca ratios of incremental zones suggest that the migratory pattern of the naked carp may be much more flexible, rather than in a single river. Therefore, high-resolution otolith microchemistry of the naked carp can be used to trace its migratory behavior, which is of significance for determining its migratory pattern and life history of this precious species inhabiting the Tibetan Plateau.
基金Project supported by the National Natural Science Foundation of China.
文摘Two basic questions must be solved in age determination of the early life stage of the eel, Anguilla japonica, in daily precision: (i) recognizing the initial increment in otolith and determining the timing of the initial increment formation; (ii) confirming the deposition rate of the increment. A clear understanding of the first question in the otolith of larvae and glass eel, Anguilla japonica, has not been got, such as how to confirm the initial increment in age determination of glass eel, determine the timing of hatch check formation and validate the microstructure in the otolith of the early life stage of Anguilla japonica.
基金This research was funded by Maine Sea Grant(grant number NA10OAR4170081)the Maine DMR(through the Halibut Fund established under 12 M.R.S.Sec.6039).
文摘Atlantic halibut(Hippoglossus hippoglossus,Linnaeus,1758)are a data-poor stock within the waters of the United States.This study evaluated the use of otolith measurements to back-calculate lengths of Atlantic halibut at previous ages.Back-calculations have proven useful for estimating length at age and growth rates of other species.To the best knowledge of the authors,this study is the first to document the use of this method for Atlantic halibut.Otolith back-calculations rely on a few key assumptions,such as proportionality of fish length and otolith length,which are not always met.This study shows that backcalculations using the Fraser-Lee method can provide reasonable estimates of Atlantic halibut length at previous ages,especially when samples from young halibut are included to improve estimates of the intercept of the linear regressions.Based on back-calculated estimates,female and male halibut in the Gulf of Maine showed different growth rates after age five.There was no evidence of changes in growth rates over an approximately 15 year time period.Halibut caught in the Gulf of Maine and on the neighboring Scotian Shelf showed some differences in growth rates;however,the results did not support strong conclusions about differences between the two regions as the direction of the differences was not consistent between the sexes and previous tagging studies have shown extensive movement between the two areas.The finding of reasonably accurate back-calculated lengths at previous ages is important for this data-poor species,as back-calculations increase the amount of information that can be obtained from otoliths.
基金The National Natural Science Foundation of China under contract No.31602159the Agricultural Finance Special Project under contract No.CJDC-2017-22the Scientific Research Foundation of Wuxi City for Returned Oversea Chinese Scholars under contract No.CZ2019231400.
文摘The estuarine tapertail anchovy(Coilia nasus)is a high-value commercial fish.Estimating the spawning site or hatchery origin and habitat is essential for its conservation.This study aimed to determine the habitat use and life history characteristics of C.nasus from the Changjiang River Estuary.We investigated the environmental signatures of strontium(Sr)and calcium(Ca)in the otoliths of the collected specimens using electron probe microanalysis;additionally,we examined their gonadal maturity stage.Our results indicate that the 31 adult C.nasus specimens used in this study could be classified into two types based on their otolith Sr:Ca concentration ratios and their gonadal maturity stage.The long freshwater early life history type(Type LF)had wider central region in the otolith with low Sr:Ca concentration ratios ranging from 1.24±0.62 to 1.92±0.78 and a bluish pattern of low Sr content level.These fish are of riverine origin and had a relatively long early life history in freshwater and low gonadal maturation when captured.The short freshwater early life history type(Type SF)had a shorter central region in the otolith with low Sr:Ca concentration ratios ranging from 1.35±0.5 to 2.82±0.97 and a correspondingly bluish pattern.These fish also had a relatively short-term early life history in freshwater and high gonadal maturation when captured.The results of the otolith microchemical analysis indicated that Type LF and Type SF originated in spawning/hatching sites far from and close to the estuary,respectively.The mature gonads of Type SF fish indicated that they may breed in areas close to the estuary,whereas the immature gonads of Type LF fish indicated that they may breed in areas far from the estuary.This study is the first to reveal that the Changjiang River Estuary contains stocks of anadromous C.nasus originating in different spawning sites during the same season.The estuarine habitat plays a critical role in the connectivity between freshwater recruitment and the marine resources available to adult spawners of this commercially valued species.From a conservation perspective,this study provides important information for identifying anadromous C.nasus stocks originating in different spawning sites in the Changjiang River Basin.
基金Supported by the National Natural Science Foundation of China(No.41930534)the Third Institute of Oceanography through the National Program on Global Change and Air-Sea Interaction(No.GASI-02-PACYDaut)。
文摘Information on survival and growth during the early life stage is essential to understand the mechanism of interannual variations in fish recruitment.Chub mackerel Scomber japonicus is a commercially important pelagic fish widely distributed in the northwestern Pacific.Its catch showed large fluctuations with changes in distribution and migration under climate change and strong fishing.We determined the hatch dates and growth rates of young-of-the-year of chub mackerel through otolith microstructure using samples collected in the Oyashio water in autumn 2018.Results show that the ages of young chub mackerel ranged between 120 and 180 d,and the estimated hatch date lasted from midJanuary to late May with a peak from mid-March to mid-April.Average otolith daily increment width during the early life stages(from hatching to 25 d)showed an increasing trend.Chub mackerel grows slowly in the first 10 d,and then grows faster during the 10thto 25thd.Three groups with dissimilar growth histories and migration routes were identified using unsupervised random forest clustering analysis,but all eventually converge on the same nursery ground.The faster growth of young-of-the-year chub mackerel leads to better recruitment due to the hypothesis of growth-dependent mortality.Most chub mackerels hatched in March and April,the spawning period is longer and earlier,which could lead to strong year classes.These findings on population composition and life history traits of young-of-the-year of chub mackerel provide valuable information on its recruitment processes during the period of stock recovery.
基金Supported by the National Natural Science Foundation of China(NSFC)(No.41930534)。
文摘Japanese Spanish mackerel Scomberomorus niphonius is a pelagic,neritic species that occurs in the Yellow Sea in high commercial value.The spawning period of this fast-growing species is controlled by water temperature.Based on microstructural analysis of otoliths from 145 young-of-the-year(YoY)S.niphonius collected by trawl in 2017,2018,and 2020,and the temporal variation in the spawning period in the northern Yellow Sea,and its relationship to water temperature were examined.We found that the spawning lasted from late April to late June but differed in year:in 2017 it occurred from April 23 to June 1 and peaked in early May,in 2018 it extended later from May 7 to June 29,and in 2020 from May 6 to June 22 and peaked later from late May to mid-June.The highest temperature in 2017 corresponds with the earliest end of the spawning period and a lower growing degree-day(GDD,℃·day)of 383℃·day.In 2018,slower warming corresponds with a longer spawning period,and a GDD spawning period of 506℃·day.Rapid warming in late 2020 corresponds with a spawning peak,and a GDD spawning temperature of 448℃·day.Despite differences in spawning period,the water temperature when spawning commenced was 10-12℃.Therefore,water temperature is the major determinant of the spawning period,affecting both the starting and the ending of spawning.This study improved our understanding of the spawning dynamics and environmental adaptation of S.niphonius,and how these might change in environments subject to increased warming.
文摘Background: The utricular macula is located on the floor of the utricle, approximately in the plane of the lateral semicircular canal, and is oriented to respond best to lateral tilts and side-to-side or fore-and-aft translations of the head. However, the details of the otolith ocular reflex are unknown. Pathophysiology of transient direction-changing geotropic positional nystagmus is a canalolithiasis in the lateral semicircular canal. The principle of affected-ear-up 90° maneuver is moving debris from a long arm to the utricle, therefore debris stimulates the utricular macula in the sitting position after the treatment. Objective: To clarify whether nystagmus occurs by the stimulation to the macula of the utricle. Methods: The subjects were 10 patients with lateral semicircular canal canalolithiasis. After the diagnosis, we performed affected-ear-up 90° maneuver immediately. We observed eye movements in the sitting position (chin-down 30°) just after the treatment. Results: No one showed nystagmus in the sitting position after the treatment. In all patients, positional nystagmus disappeared within 7 days after the treatment. Conclusion: Nystagmus does not occur by the stimulation to the macula of the utricle. Hence, we cannot assess the function of the utricle by the analysis of eye movements, and ocular counter-rolling is considered to be a semicircular canal ocular reflex.
文摘Background: We have been performing a canalith repositioning procedure for benign paroxysmal positional vertigo. When we adopted the Epley maneuver for posterior semicircular canal type, and affected-ear-up 90° maneuver for lateral semicircular canal type, we noticed that no nystagmus occurred in the sitting position just after treatment. Despite direct excitation to the utricle by the pathological debris, none of the subjects complained of dizziness. Thus, we hypothesized that nystagmus and dizziness do not occur by stimulation of the otolith organs. Objective: The aim of the study was to observe and record the eye movements induced by the otolith organs to confirm our hypothesis. Materials and Methods: Twelve healthy humans were tested. In the sitting position, the head was tilted to the right ear by 45° and vice versa. Afterward, the head was bent forward by 90° (nose-down), and the subject’s seat was reclined to the head-hanging position. Each position was kept for five seconds. We interviewed the subjects to assess their dizziness. Results: None of the subjects showed nystagmus and complained of dizziness in every position. Conclusions: Nystagmus does not occur by the stimulation to the otolith organs;therefore, ocular counter-rolling is a semicircular canal ocular reflex.
基金Supported by the Special Fund for Agro-scientific Research in the Public Interest(No.201003068)the National Natural Science Foundation of China(Nos.31172447,41176117)
文摘Black rockfish Sebastes schlegelii juveniles （30-40 mm total length） were immersed in a range of calcein （CAL） solutions at concentrations ranging from 50 to 250 mg/L and alizarin red S （ARS） solutions at concentrations ranging from 100 to 500 mg/L in filtered seawater （salinity 30） for 24 h. Fluorescent marks were detected in otoliths （sagittae, asteriscus）, scales, fin rays （dorsal, pectoral, ventral, anal, and caudal fin rays）, and fin spines （dorsal, ventral, and anal fin spines） after a 60-d growth experiment. With the exception of 50-100 rng/L CAL, acceptable marks were produced in the otoliths and fin spines by all concentrations of CAL and ARS. In particular, marks were clearly visible under normal light in the sagittae, asteriscus, and fin spines offish immersed in 200 500 mg/L, 300-500 rag/L, and 200-500 mg/LARS, respectively. Scales and fin rays had acceptable marks at much higher concentrations （≥50 mg/L CAL, ≥300 mg/L ARS for scales and ≥50 mg/L CAL,≥200 mg/L ARS for fin rays）. The mark quality was highest （i.e., acceptable marks were observed in all sampled structures after immersion marking） in fish immersed in 150-250 mg/L CAL or 300-500 mg/LARS. In addition, there was no significant difference in survival and growth of marked fish compared with controls 60 d post-marking （P〉0.05）.
基金Supported by the Special Fund for Agro-Scientific Research in the Public Interest(No.201003068)the National Natural Science Foundation of China(Nos.31172447,41176117)
文摘We tested the utility of chemical marking techniques in the juvenile black rockfish Sebastes schlegelii. Juveniles （30-40 mm total length） were immersed in a range of tetracycline hydrochloride （TC） solutions at concentrations ranging from 300 to 500 mg/L, and alizarin complexone （ALC） solutions at concentrations ranging from 200 to 400 mg/L in filtered sea water （salinity of 30） for 24 h, respectively. Otoliths （sagittae, asteriscus）, scales, fin rays （dorsal, pectoral, ventral, anal, and caudal fin rays）, and fin spines （dorsal, ventral, and anal fin spines） were sampled and used to detect fluorescent marks after a 60-day growth experiment. With the exception of 300 mg/L TC, acceptable marks were produced in the otoliths and fin spines by all concentrations of TC and ALC. In particular, we observed clearly visible marks in the sagittae, asteriscus, and fin spines under normal light at concentrations of200~00 mg/L, 250-400 mg/L, and 250-400 mg/L ALC, respectively. Scales and fin rays had acceptable marks at much higher concentrations （_〉350 mg/L TC, 〉250 mg/L ALC for scales and _〉350 mg/L TC, 〉300 mg/L ALC for fin rays）. The best mark quality （i.e., acceptable marks were observed in all sampled structures after immersion marking） were obtained following immersion in TC at between 350-500 rag/L, and ALC between 300-400 mg/L. In addition, there was no significant difference in survival and growth of TC and ALC marked fish compared to their controls up to 60 days post-marking （P〉0.05）.
文摘Objective:To study the potential role of subjective visual vertical(SVV)as a prognostic marker for canalith repositioning maneuver(CRM)in patients with posterior canal benign paroxysmal positional vertigo(PC-BPPV)for the Indian population.Methods:SVV was examined in 30 patients with PC-BPPV before and after canalith repositioning maneuver and after complete resolution of PC-BPPV.Study parameters included the mean of 10 angular tilt readings and direction of deviation,which were compared before and after CRM and following complete resolution of PC-BPPV.Results:The angle of SVV tilt was greater and deviated towards the affected ear before CRM in all patients,which decreased significantly shortly after CRM and continued to decrease after complete resolution of PC-BPPV(p<0.0001).Conclusions:SVV can be used to test utricular dysfunction in PC-BPPV.The angle of tilt improves in response to CRM,which may be used as a prognostic marker in patients with PC-BPPV receiving CRM.
基金The National Natural Science Foundation of China under contract No.31372533China Central Governmental Research Institutional Basic Special Research Project from Public Welfare Fund under contract No.2016PT01the“948”Program of the Ministry of Agriculture under contract No.2014-S6
文摘The migratory history of the engraulid fish Coilia nasus in the Rokkaku and Chikugo River estuaries of the Ariake Sea, Japan was assessed using otolith strontium（Sr） X-ray intensity maps and strontium：calcium（Sr：Ca） ratio life history transects by an electron probe microanalyzer（EPMA）. The results showed that seven of the ten specimens from the Rokkaku River Estuary（LJC） and all 15 specimens collected in the Chikugo River Estuary（ZHC） had low Sr：Ca ratios（≤3） at the central otolith area, indicating their riverine origin and initial freshwater residence. After the first regime shift adjacent to natal regions, the Sr level mapping displayed a wide variety of color patterns, and the Sr：Ca ratios obtained by the line transect analysis could be divided into one to six significantly different phases indicative of gradual life history transition. The other three specimens from the Rokkaku River Estuary had high Sr：Ca ratios（3–6.7） at the central otolith area but showed alternating changes between low and high values outside the natal region, suggesting that estuarine-origin individuals occurred in the Rokkaku River Estuary. The two-dimensional maps of the Sr level and average of the otolith Sr：Ca ratios along the life-history transects could be used as effective tools for reconstruction of past habitat use of the tapertail anchovy in estuaries of the Ariake Sea, Japan.
基金the Program for New Century Excellent Talents in University (NCET-06-0437)Shanghai Leading Academic Discipline Project (No T1101)
文摘Although chub mackerel （Scomberjaponicus） is a primary pelagic fish species, we have only limited knowledge on its key life history processes. The present work studied the age and growth of chub mackerel in the East China and Yellow Seas. Age was determined by interpreting and counting growth rings on the sagitta otoliths of 252 adult fish caught by the Chinese commercial purse seine fleet during the period from November 2006 to January 2007 and 150 juveniles from bottom trawl surveys on the spawning ground in May 2006. The difference between the assumed birth date of 1st April and date of capture was used to adjust the age determined from counting the number of complete translucent rings. The parameters of three commonly used growth models, the von Bertalanffy, Logistic and Gompertz models, were estimated using the maximum likelihood method. Based on the Akaike Information Criterion （AIC）, the yon Bertalanffy growth model was found to be the most appropriate model. The size-at-age and size-at-maturity values were also found to decrease greatly compared with the results achieved in the 1950s, which was caused by heavy exploitation over the last few decades.
