Elemental signatures in the vertebral cartilage of the round stingray, Urobatis halleri, from Seal Beach, California

Although numerous studies have utilized elemental analysis techniques for age determination in bony fishes, little work has been conducted utilizing these procedures to verify age assessments or temporal periodicity of growth band formation in elasmobranchs. The goal of this study was to determine the potential of laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) to provide information on the seasonal deposition of elements in the vertebrae of the round stingray collected from Seal Beach, California. Spatially resolved time scans for elements across the round stingray vertebrae showed peaks in calcium intensity that aligned with and corresponded to the number of seasonal growth bands identified using standard light microscopy. Higher signals of calcium were associated with the wide opaque bands while lower signals of calcium corresponded to the narrow translucent bands. While a close alignment between the numbers of calcium peaks and annual growth bands was observed in round stingray samples aged 5 years or younger, this relationship was less well defined in vertebral samples from round stingrays over 11 years old. To the best of our knowledge, this is the first study of its kind to utilize ICP-MS to verify age assessments and seasonal band formation in an elasmobranch. The results from this preliminary study indicate that LA-ICP-MS elemental analysis of the vertebral cartilage of the round stingray may have potential to independently verify optically derived age assessments and seasonal banding patterns in elasmobranch vertebrae.     

Age structure and multi-model growth estimation of longnose stingray Hypanus guttatus (Dasyatidae: Myliobatoidei) from north-east Brazil

We collected 729 Hypanus guttatus from the northern coast of the state of Rio Grande do Norte (RN), of which 196 were used to estimate age and growth. Ninety-five were male (12.7 to 57.0 cm disc width; W_D) and 101 were female (13.0 to 88.5 cm W_D); females were significantly larger than males. Cross sections of vertebrae showed band-pairs ranging from 0 to > 14 in females and from 0 to 9 in males. New-borns presented an opaque edge at birth in vertebrae without a birthmark. The average percentage of error (APE; %E) for the entire sample provided evidence that ages were repeatable. The mean monthly marginal increment (I_M) indicates annual band-pair formation from August to November. The annual cycle model for one band-pair deposition provided the best fit to data based on the AIC, with peaks between August and October, similar to that found in the I_M analysis, suggesting an annual formation pattern. A multi-model approach that included four models based on the observed mean W_D at age indicated a modified von Bertalanffy growth model as the best for describing the species growth: W₀ (W_D at birth) = 14.6 cm for both sexes; females W_∞ = 98.61 cm (95% CI = 87.34–114.61 cm); k = 0.112 year⁻¹ (CI = 0.086–0.148 year⁻¹); males W_∞ = 60.22 cm (CI = 55.66–65.35 cm); k = 0.219 year⁻¹ (CI = 0.185–0.276 year⁻¹). The age-at-maturity in males and females is 5 years and 7 years, respectively. The age composition shows that most (84%) specimens were aged 0 to 2 years. The information provided here is essential for analytical assessments of H. guttatus, which is subject to significant fishing pressure mainly on new-borns and juveniles.     

Population genetic structure of the round stingray Urobatis halleri (Elasmobranchii: Rajiformes) in southern California and the Gulf of California

The round stingray, Urobatis halleri, is a viviparous elasmobranch that inhabits inshore, benthic habitats ranging from the western U.S.A. to Panama. The population genetic structure of this species was inferred with seven polymorphic microsatellite loci in samples collected at three sites in coastal southern California, one near Santa Catalina Island, California and one in the eastern Gulf of California. Urobatis halleri is relatively common, but little is known of its movement patterns or population structure. Small F_ST values (?0·0017 to 0·0005) suggested little structure among coastal populations of southern and Baja California. The population sampled at Santa Catalina Island, which is separated by a deep‐water channel from the coastal sites, however, was significantly divergent (large F_ST, 0·0251) from the other populations, suggesting low connectivity with coastal populations. The Santa Catalina Island population also had the lowest allele richness and lowest average heterozygosity, suggesting recent population bottlenecks in size.     

Movement patterns of the round stingray Urobatis halleri(Cooper) near a thermal outfall

Fine‐scale movements and site fidelity of round stingrays Urobatis halleri at Seal Beach California, U.S.A., were examined using acoustic telemetry. Actively tracked fish generally exhibited limited nearshore movement, with greater distances travelled at night when the tide was ebbing than during the day with ebbing tides. Increases in round stingray activity were associated with increases in ambient temperature. Passively tracked fish showed seasonal patterns in their presence at Seal Beach. Males left Seal Beach during the autumn, returned the following spring, and remained in the area until the following autumn. Females spent far less time at Seal Beach, remaining in the area for a few weeks during June and July. Passively tracked round stingrays were recorded more often in the warm waters of the San Gabriel River mouth (the location of a thermal outfall from an electric‐generating station) than adjacent beaches, with fish often returning to Seal Beach after periods of absence. Anthropogenic effects resulting from coastal development may have created environmental conditions ( i.e . warmer water and finer sediments) that influence the movements and site fidelity of round stingrays.     

Photoperiod and water temperature regulation of seasonal reproduction in male round stingrays (Urobatis halleri)

This study characterizes the seasonal reproductive cycle of male round stingrays (Urobatis halleri) in Seal Beach, California. Mature round stingrays were collected monthly by beach seine near the San Gabriel River outfall from August 2004–September 2006, and rays were assessed for gametogenesis and steroid hormone levels. Male round stingrays exhibit a seasonal pattern of increased gonadosomatic index (GSI), spermatogenesis, and production of testosterone (T) and 11-ketotestosterone (11-KT). Based on GSI, the male reproductive cycle was broken into three distinct phases. TUNEL positive staining was only observed in the Sertoli cells of mature spermatocysts during the degenerative testicular phase, suggesting that Sertoli cell death potentially plays a role in testicular degeneration and the regulation of sperm release. GSI, T, and 11-KT were all inversely correlated with daylength, while only T was inversely correlated with temperature. Captive male round stingrays subjected to water temperatures of 25 °C showed a significant decrease in plasma testosterone concentrations, but the same males exposed to ambient water temperatures (18 °–20 °C) exhibited T concentrations observed in wild male round stingrays during the recrudescent phase. Together, these findings suggest that temperature plays an important role in the regulation of testosterone, and may serve as an ultimate cue for reproduction in male round stingrays.     

Observations of the mating behavior and dentition of the round stingray,Urolophus halleri

Synopsis The mating behavior and dentition ofUrolophus halleri, the round stingray was examined. Males frequently bite females during the mating period but most male biting does not result in copulation. In bites that do not lead to copulation, males bite the posterior (or occasionally the medial) portion of the females' disc but females often free themselves from these bites. In bites that precede copulation, males bite the anterior portion of the females' disc and females do not struggle to free themselves. Thus, females may exert some form of choice when they are bitten. Mature males have sexually dimorphic dentition that may aid in holding females. A principal component analysis (PCA) showed that in juvenile males, the relative size of the teeth decrease while the relative thickness of the disc increases as body size enlarges; adult males displayed no clear pattern. In adult females, there is a relative decrease in tooth size and increase in relative disc thickness as body size enlarges. The relative increase in females disc thickness in areas where they are bitten may function to minimize the amount of damage due to non-copulatory biting. There is no indication that biting functions to induce female receptivity but it may allow females and males to acquire information about potential mates. Thus, copulatory biting functions to maintain contact during copulation while the function of non-copulatory biting is less clear.     

Clasper control in the round stingray,Urolapkus halleri lower sensor motor pathways

Synopsis The innervation of the clasper has been studied in the round stingray,Urolophus halleri. Several large myelinated nerves (diameters approx. 0.7 mm; # 60–64 counting from the vagus) innervate the clasper muscles and skin. Low level electrical stimulation (<100A) of the nerves evokes clasper movements including: elevation, medial and lateral extension, rotation and opening. Stimulation of the spinal cord in the area of the roots of the clasper nerves also evoked the movements (<100A). Retrograde labeling of the clasper nerves using either cobalt-lysine or horseradish peroxidase (HRP) confirmed that motor neurons and sensory components of the nerves are at the levels indicated by stimulation. The motor neurons have large multipolar cell bodies (50–70) and occupy a discrete segment of the spinal cord.     

Enhanced anaerobic bioremediation of groundwater contaminated by fuel hydrocarbons at Seal Beach, California

Enhanced anaerobic biodegradation of groundwater contaminated by fuel hydrocarbons has been evaluated at a field experiment conducted at the Naval Weapons Station, Seal Beach, California. This experiment included the establishment of three different remediation zones in situ: one zone was augmented with sulfate, one was augmented with sulfate and nitrate, and the third was unaugmented. This enables a comparison of hydrocarbon biodegradation under sulfate-reducing, sequential denitrifying/sulfate-reducing, and methanogenic conditions, respectively. In general, the results from the field experiment are: (1) Certain fuel hydrocarbons were removed preferentially over others, but the order of preference is dependent upon the geochemical conditions; and (2) In the zones that were augmented with sulfate and/or nitrate, the added electron acceptors were consumed quickly, indicating that enhancement via electron acceptor injection accelerates the biodegradation process. More specifically, in the sulfate-reducing zone, sulfate was utilized with an apparent first-order rate coefficient of approximately 0.1 day^-1. In the combined denitrifying/sulfate-reducing zone, nitrate was utilized preferentially over sulfate, with an apparent first-order rate coefficient of 0.1–0.6 day^-1. However, the data suggest that slow sulfate utilization does occur in the presence of nitrate, i.e., the two processes are not strictly sequential. With regard to the aromatic BTEX hydrocarbons, toluene was preferentially removed under intrinsic conditions; biodegradation of benzene was slow if it occurred at all; augmentation with sulfate preferentially stimulated biodegradation of o-xylene; and ethylbenzene appeared recalcitrant under sulfate-reducing conditions but readily degradable under denitrifying conditions.     

Occurrence of pelagic stingray Pteroplatytrygon violacea (Bonaparte, 1832) in the North Sea

A mature male pelagic stingray Pteroplatytrygon violacea (99 cm total length, 33·5 cm disc length and 42 cm disc width; 2·5 kg) was caught by commercial Nephrops trawl in the North Sea (at c . 54º49' N; 0º57' W) on 14 November 2005. Records of P. violacea in the north-east Atlantic are reviewed, with only two vagrant specimens known from the North Sea, representing the most northerly records of this species in the Atlantic Ocean.     

Biological notes on the reef stingray,Urobatis concentricus,an endemic species of Mexico

This study found that the reef stingray Urobatis concentricus presents a matrotrophic aplacental viviparous reproduction with yolk sac and trophonemata formation. Growth of ovarian follicles occurs asynchronously and continuously with fecundity of three embryos per female. A maximum size of 58·4 cm total length and 37·6 cm disc width was recorded, corresponding to a mature female of 3 or 4 years of age.     

Age and growth of Anguilla anguilla in the Camargue lagoons

Age and total length ( L _T) data from a 11 year monitoring of the Anguilla anguilla eel population of the Camargue lagoons (Rhône delta, southern France) were collected for glass, yellow and silver eels. Three distinct models were calibrated to describe the growth process of undifferentiated eels, females and males, respectively. Uncertainty of parameter estimates was evaluated by bootstrapping. Females were characterized by larger asymptotic body size ( L _T) than males (580 ± 50 v . 388 ± 13 mm) and faster growth, whilst the Brody growth coefficient was larger for males than for females (means ±  s . d . 3·00 10⁻³ ± 1·68 10⁻³ v . 1·73 10⁻³ ± 0·50 10⁻³). Sexual differentiation was estimated to begin at 204 ± 38 mm mean ±  s . d ., i.e . at the end of the second year in the lagoons, well before the L _T at which macroscopic differentiation became possible ( c . 300 mm). Males probably leave the lagoon or die (due to either natural or fishing mortality) within the first 3 years, whilst females can remain up to 5 years. Sexual differentiation and maturation have a major role in shaping the L _T structure of the population. The L _T and mass ( M ) data were fitted by allometric curves     . The calibration of distinct curves for data from different years indicated that the allometric coefficient a was subject to wider interannual fluctuations than the allometric exponent b . A negative correlation linked the average L _T and the allometric exponent ( r  = −0·58, P  < 0·01).     

Age and growth of albacore Thunnus alalunga in the North Pacific Ocean

The age and growth of North Pacific albacore Thunnus alalunga were investigated using obliquely sectioned sagittal otoliths from samples of 126 females and 148 males. Otolith edge analysis indicated that the identified annulus in a sagittal otolith is primarily formed during the period from September to February. The assessments of the fish age at first annulus formation indicated that the first annulus represents an age of <1 year. This study presents an age estimate (0·75 years) for the formation of the first annulus. The oldest fish ages observed in this study were 10 years for females and 14 years for males. The von Bertalanffy growth parameters of females estimated were L(∞) = 103·5 cm in fork length (L(F) ), K = 0·340 year(-1) and t(0) = -0·53 years, and the parameters of males were L(∞) = 114·0 cm, K = 0·253 year(-1) and t(0) = -1·01 years. Sexual size dimorphism between males and females seemed to occur after reaching sexual maturity. The coefficients of the power function for expressing the L(F) -mass relationship obtained from sex-pooled data were a = 2·964 × 10(-5) and b = 2·928.     

Age and growth of Neotrygon picta, Neotrygon annotata and Neotrygon kuhlii from north-east Australia, with notes on their reproductive biology

Vertebral band formations were used to define age and growth in three Neotrygon species caught regularly as by-catch in prawn trawl fisheries in north-east Australia. Centrum edge and marginal increment ratio analyses were used to validate annual band formations. Age estimates ranged from 1 to 18 years, with the von Bertalanffy growth function considered to have the best fit to Neotrygon picta (males, W(D∞) = 271 mm, k = 0·12; females, W(D∞) = 360·5 mm, k = 0·08) and Neotrygon kuhlii (males, W(D∞) = 438·6 mm, k = 0·08; females, W(D∞) = 440·6 mm, k = 0·08) disc width (W(D))-at-age data. The Gompertz growth function had the best fit to Neotrygon annotata W(D)-at-age data (males, W(D∞) = 230·4 mm, k = 0·20; females, W(D∞) = 265·5 mm, k = 0·31). Age at sexual maturity ranged from 3 to 6 years, with N. picta having the smallest size at birth (100 mm W(D)), smallest W(D) at 50% maturity (W(D50): male, 172 mm, female, 180·7 mm) and lowest age at sexual maturity (3-4 years). This study helps redefine and improve the accuracy of fisheries-based risk assessments for these small species with relatively conservative life-history variables.     

北江侧条光唇鱼的年龄与生长特征

于2007年7月至2009年6月间,在北江中上游地区采集了358尾侧条光唇鱼(Acrossocheilus parallens)样本,以鳞片作为年龄鉴定材料,对其年龄与生长特征进行了研究。侧条光唇鱼鳞片上年轮结构清晰,前区主要为疏密型,而侧区主要为切割型;鳞片的边缘生长率显示,其年轮的主要形成期为2~3月份。样本中的雌性由1+~5+龄5个龄组组成,优势龄组为1+~3+龄;而雄性由1+~4+龄4个龄组组成,优势龄组为1+~2+龄。雌鱼的体长(L,cm)范围为5.7~14.8 cm,集中于7.0~13.0 cm之间;体重(W,g)范围为4.75~108.40 g,集中于10.00~30.00 g之间。雄鱼的体长范围为5.7~12.6 cm,集中于7.0~11.0 cm之间;体重范围为4.40~61.50 g,主要集中于10.00~20.00 g之间。体长与体重的关系为W=0.017L3.167、W♀=0.017L3.198、W♂=0.023L3.025,协方差分析表明,雌、雄个体在体长与体重关系上,差异显著。体长(L,cm)与鳞径(R,mm)呈线性关系,L♀=3.126R+1.869、L♂=2.875R+2.152。拟合出Von Bertalanffy生长参数,雌性L∞=17.143 5 cm,k=0.270 5,W∞=150.347 4 g,t0=﹣0.614 6龄;雄性L∞=17.236 5 cm,k=0.226 9,W∞=126.468 6 g,t0=﹣0.921 5龄。雌鱼体重生长的拐点年龄为3.68龄,拐点体长约为11.8 cm,体重约为45.26 g;雄鱼的拐点年龄为3.96龄,拐点体长约为11.5 cm,体重约为37.60 g。作为渔业对策,建议起捕年龄3龄以上或体长10 cm以上的个体。     

Age and growth of Mediterranean albacore

Estimated ages of 1136 individual albacore Thunnus alalunga (57–92 cm L F) from the Aegean and Ionian Sea ranged from 1⁺ to 9 years. Males grew faster and reached a greater size and age than females. No significant differences were found in the mean lengths at estimated ages between the two sampling areas. The von Bertalanffy growth model was fitted to mean lengths of estimated ages of individual fish and estimated growth parameters for the combined sexes were: L _∞=94·7 cm, K =0·258, to=–1·354 years. Significant differences were found when the Mediterranean albacore growth parameters were compared with those determined for Atlantic Ocean albacore. It is not possible to determine if the differences in growth rates for the two populations are phenotypic or genotypic at the present time.     

Age validation and growth of three commercially important hemiramphids in south-eastern Australia

The method of using sectioned otoliths to estimate age in three species of garfishes (family Hemiramphidae) was validated by: (1) staining fishes with the vital stain alizarin complexone (ALC) and periodically examining their otolith growth, and (2) marginal increment analyses. Staining fishes with ALC indicated that opaque zones were formed during winter and spring, but did not become visible on the otolith edge until late spring and summer. Hyporhamphus australis were found to be similar to the hemiramphids of the Atlantic in having fast growth rates and a maximum observed age of 4+ years old. Hyporhamphus regularis ardelio and Arrhamphus sclerolepis krefftii were found to be more similar to the southern sea garfish, Hyporhamphus melanochir , in being moderately long-lived, with maximum observed ages of 7+ years old for both species. Females grew faster and attained greater fork lengths than males for each species. Sectioned otoliths showed large variation in the appearance of opaque zones between the three species studied, with those from the wide-ranging, oceanic H. australis appearing inconsistent and diffuse when compared to the estuarine H. r. ardelio and A. s . krefftii . This variation was also apparent from fishes kept in aquaria, suggesting that the appearance of opaque zones in otoliths of these species is largely influenced by physiology, rather than by environmental conditions.     

Age,growth, reproduction and status of resource development of Ptychidio jordani,a critically endangered freshwater fish in the Hongshui River,China

The age, growth, reproduction and resource development status of Ptychidio jordani, as a critically endangered freshwater fish in the Hongshui River, China, was studied in this work. A total of 525 specimens were collected monthly using the cages and gillnets from October 2021 to September 2022 in the Hongshui River. The scale was used for age determination, and the maximum age for both female and male was estimated to be 5 years and 3 years, respectively. Female and male P. jordani showed different growth patterns, which were expressed as L_t = 261.3 (1-e^{−0.4885(t−0.1476)}) and L_t = 251.2 (1-e^{−0.4758(t+0.9643)}), respectively. The overall sex ratio was 1:0.47 (female:male). Female attained sex maturity at 2.34 years (192 mm body length). Month variation of the gonad somatic index indicated that the spawning period occurred from April to October. The absolute fecundity was estimated at 9046 ± 3434 eggs per individual, and the relative fecundity was 38.08 ± 15.77 eggs per gram. The exploitation rate of female and male was 0.233 and 0.495, which indicated that P. jordani was not overfishing. This study provided data on the key life-history traits of P. jordani, which has not been known previously and is essential for conservation strategy and policy development.     

基于内壳的西非乌贼日龄与生长特性

乌贼主要分布在北大西洋东部及非洲沿岸海域,是拖网渔业的重要捕捞对象,也是大西洋乌贼科最重要的商业种.本研究根据2015年7-8月西非沿岸采集的乌贼样本,测量了 283尾乌贼内壳外部形态参数,结合内壳日龄信息,对不同性别乌贼生长特性进行了研究.结果表明:不同性别乌贼胴长和体重存在显著差异.通过读取内壳日龄,发现雌雄性优势...