Comparison of pelvic fin rays, scales and otoliths for estimating age and growth of bull trout, Salvelinus confluentus

Abstract  The suitability of three anatomical structures to determine age and growth of bull trout, Salvelinus confluentus (Suckley), was assessed. Scales and pelvic fin rays collected from recaptured bull trout 96–265 mm TL were used to validate annulus formation and assess the accuracy and precision of back calculation. Ageing precision and agreement of assigned ages were compared among scales, fin rays and otoliths from bull trout 52–711 mm TL. Annulus formation was validated for 88% (14 of 16 fish) of recaptured bull trout using pelvic fin rays and 68% using scales (15 of 22 fish). Annulus formation in fin rays occurred between late April to early June, and the hyaline (non-growth) band began forming in late August. Back-calculated length was not significantly different from measured length at initial capture either for fin rays or scales ( P  ≥   0.19), and absolute percent error was 7.2 ± 1.2 (mean ± SE; n  =   14) for fin rays and 8.7 ± 1.9 ( n  =   15) for scales. Consistency of back-calculated lengths at age between tag and recapture samples for individual fish was similar for fin rays (mean absolute difference = 8.2% ± 0.9; n  =   33) and scales (9.4% ± 1.4; n  =   40). However, fin rays (87% precision) and otoliths (90%) provided notably higher ageing precision than scales (68%) and closer agreement of assigned ages, particularly for fish older than age 4. Pelvic fin rays appear to offer more accurate and precise age and growth determinations than scales and a non-lethal alternative to otoliths, but further work is needed to validate the accuracy and precision of ageing large, migratory bull trout.     

Comparative Annulus Formation on Anatomical Structures of the White Sucker, Catostomus commersoni (Lacépède)

Of 32 structures examined in the white sucker, annulus formation is potentially suited for age determination only on the dermethoid, frontal, lacrimal and rib bones, pectoral fin rays and body scales. Ages assigned by annulus counts on each of the above-noted structures, except scales, were in total agreement. Scale annulus counts were accurate determinants of age in slow-growing riverine stocks, but not in faster-growing lake fish using the same river for reproduction. A linear correlation (r=+0.978) between pectoral fin ray radii and standard length regardless of growth rate, and confirmed by tag-recovery data, permits the accurate back-calculation of white sucker growth using annuli formed on this structure.     

Comparison of age estimates from scale, opercular bone, otolith, vertebrae and dorsal fin ray in Labeo rohita (Hamilton), Catla catla (Hamilton) and Channa marulius (Hamilton)

The present study was undertaken with a view to compare the precision and reliability of the age readings obtained from different bony structures of some important freshwater teleosts viz., Labeo rohita (Hamilton), Catla catla (Hamilton) and Channa marulius (Hamilton). Standard procedures were followed to prepare and study the age structures. In L. rohita and C. marulius percent agreement between reader's age estimates was highest for scales, i.e. 96.3% and 90.5%, respectively and in C. catla percent agreement was highest (93.3%) for opercular bone. When scale ages were compared with other alternative structures viz., otoliths, opercular bone, vertebral centra and dorsal fin rays, percent agreement was found highest between scale and opercular bone age estimates (77.8%) in L. rohita and between scale and otoliths (94.8%) in C. marulius. In case of C. catla highest percent agreement was found between opercular bone and scale age estimates. In L. rohita each of the ageing structure showed significant (P < 0.05) underestimation of age in comparison to scales. In C. catla mean age estimates from opercular bone were comparable (P > 0.05) to the values obtained from all other structures except dorsal fin rays. In C. marulius mean age estimates from scales were comparable (P > 0.05) to those from all other structures except from dorsal fin rays. Results indicated scales to be the most suitable structure for ageing L. rohita and C. marulius and opercular bone for C. catla. However, in C. catla also scales may be used as a non-destructive method of age estimation with satisfactory results.     

Blue sucker stock characteristics in the upper Yazoo River basin, Mississippi, USA

Blue sucker Cycleptus elongatus (L.) in the upper Yazoo River basin, Mississippi, USA was studied using overnight hoop net sets (n = 4093) during 1988 and 1990–1998 to determine the influence of channel dredging. There were 264 blue suckers captured, ranging from 3 to 11 years of age. Length ranged from 265 to 700 mm and weight from 120 to 4700 g. Concurrent studies with smaller mesh hoop nets failed to capture any juvenile blue suckers. Catch‐per‐unit‐effort (CPUE: fish net^?1) declined throughout the study in the Yalobusha River, a river subjected to channel dredging during 1988 and 1994. With the exception of limited hydraulic dredging in the Tallahatchie River, there was no dredging in the other Yazoo River tributaries, nor were there declines in blue sucker catch rates in these rivers. Throughout the upper Yazoo River basin, blue sucker stocks were dominated by adult fish, and there was little evidence of reproduction or recruitment. Conservation of the blue sucker in the upper Yazoo River basin should include actions that ensure the functional integrity of this floodplain river ecosystem and elimination of channel dredging throughout the basin.     

Sectioned pelvic fin ray ageing of muskellunge Esox masquinongy from a Virginia river: comparisons among readers, with cleithrum estimates, and with tag–recapture growth data

Abstract  The potential utility of pelvic fin rays as ageing structures was evaluated for southern US muskellunge Esox masquinongy Mitchill populations by comparing age estimates among three readers and against cleithrum estimates, and by comparing observed length changes of tagged fish with changes predicted from growth equations based on pelvic fin ray age estimates. Mean coefficient of variation in age estimates among all readers and between the two readers with prior ageing experience was 17.8% and 5.6%, respectively. Exact and within 1-year agreement rates between pelvic fin rays and cleithra were 76% and 100%, respectively. Mean (± 2 SE) estimated absolute error between observed and predicted length changes for 13 tagged muskellunge was 30 ± 14 mm. This evaluation indicated that pelvic fin rays may prove to be a useful, non-lethal method for ageing muskellunge in southern US waters. Validation studies are still needed to ensure that growth rings form consistently throughout fish's life span.     

Evaluation of a stable‐isotope labelling technique for mass marking fin rays of age‐0 lake sturgeon

Abstract The effectiveness of marking age‐0 lake sturgeon, Acipenser fulvescens Rafinesque, pectoral fin rays with a stable strontium isotope was evaluated. Age‐0 lake sturgeon were reared in water spiked with 0 (control), 25, 50 or 100 μg L^{?1 86}SrC0₃ for 10 and 24 days; fish from each treatment group were retained for up to 120 days post‐labelling to assess mark retention. Enriched‐isotope marks imparted to fin rays were distinct from fin ray ⁸⁸Sr/⁸⁶Sr ratios of control fish immediately following marking, with the 100 μg L^{?1 86}SrCO₃ treatments consistently yielding the highest rate of marking success (83–92%). Lower marking success (25–69%) was observed with the 25 and 50 μg L^{?1 86}SrCO₃ treatments. Isotopic marks in fin rays were retained for 120 days post‐labelling. Immersion marking of juvenile fish pectoral fin rays with distinct strontium isotope ratios is possible and does not require sacrificing fish to check for marks.     

Precision and bias in the age determination of blue whiting, Micromesistius poutassou (Risso, 1810), within and between age-readers

Age based assessment forms the basis of management advice for the heavily exploited combined stock of blue whiting (Micromesistius poutassou) in the Northeast Atlantic. However, little historic attention has been given to the reliability of age estimates gathered from several nations involved in this assessment. Using recognised graphical and statistical approaches, bias and precision was investigated for experienced age-readers of blue whiting. Significant linear bias was found to exist between age-readers, with ages differing, on average, by 1 year for important year classes. Indications are that spawning checks and split rings affect the interpretation of annuli for some age-readers. An experience gradient became evident during the analysis; more experienced age-readers had greater levels of precision. Within reader precision was found to be higher than between reader precision; however, within reader bias was also evident with two out of three age-readers systematically revising ages downwards when re-ageing otoliths. Results indicate that differences exist on a limited international level for the age determination of blue whiting. This issue now needs to be addressed by the scientific community.     

滇池鲤4种年龄鉴定材料的比较

为确定鉴定滇池鲤（Cyprinus carpio）年龄的适宜材料,对4种年龄鉴定材料（耳石、鳞片、胸鳍条和鳃盖骨）的形态和年轮标志进行了描述,并对这4种钙化组织鉴定鲤年龄的一致性进行了探讨。2013年5、6、8-11月以及2014年3-7月,使用拖网采集云南滇池鲤584尾,体长范围7.5~50.5 cm,体重范围17.2~3 211.3 g。其中耳石采集于584尾样本,鳃盖骨和鳞片分别采集于276尾样本,胸鳍条采集于274尾样本。微耳石磨片轮纹清晰,在反射光下呈明暗相间的条纹,年龄标志明显。同一鉴定者2次年龄读数的吻合率,微耳石磨片轮最高（88.0%),鳞片次之(84.1%),胸鳍条和鳃盖骨则分别为73.7%和72.1%。2次读龄的平均误差百分比,微耳石磨片和鳞片较小,分别为2.6%和2.9%;胸鳍条和鳃盖骨较高,分别为4.7%和5.9%。以微耳石磨片年龄读数为基准,鳞片年龄读数与其吻合率最高(77.5%),平均变异系数最低(6.14%);鳃盖骨和胸鳍条与其吻合率分别为61.9%和56.2%,平均变异系数均超过12%。综合分析认为,耳石是滇池鲤年龄鉴定的最佳材料,鉴定4龄以下个体年龄时可使用鳞片,鳃盖骨和胸鳍条则不适于滇池鲤的年龄鉴定。     

Elemental analysis of otoliths, fin rays and scales: a comparison of bony structures to provide population and life-history information for the Arctic grayling (Thymallus arcticus)

Abstract –  We used laser ablation inductively coupled plasma mass spectrometry line scans to determine the elemental composition of otoliths, pectoral fin rays and scales of Arctic grayling. Elemental signatures of otoliths and pectoral fin rays effectively provide life-history information on individual fish, important for management of grayling, and potentially all freshwater teleosts. Bulk elemental signatures measured in the otoliths and fin rays were highly correlated to the stream chemistries where the fish were captured. A surprising result of this study was that fin rays showed the strongest relationship with water chemistry for strontium. Scale strontium concentrations were not correlated to water chemistries suggesting that other physiological mechanisms, or remobilisation, may be influencing the deposition of trace elements within scales. Linear discriminant function analyses for otolith and fin ray elemental signatures (and intriguingly also for scales) separated fish from different rivers for all three structures; thus, this technique can be used effectively as a means to discriminate origin of capture.     

南极鱼类年龄与生长研究进展

南极鱼类生长相对缓慢,独特的生物学特性使其年龄鉴定较其他海区鱼类更为困难。但考虑到鱼类年龄鉴定是开展渔业资源评估的基础,因此过去一些年来,硬质部位,如鳞片、鳍条(棘)、脊椎骨以及耳石等仍成为南极鱼类的主要鉴龄材料。本文对南极鱼类年龄鉴定的方法和材料进行了总结回顾,将年龄鉴定的方法和材料进行比较,分析各自优缺点。结果显示:(1)对于具鳞的南极鱼类,因鳞片在鱼类生长过程中存在重吸收现象,因而利用鳞片及鳍条(棘)单独鉴龄所得出的结果通常小于耳石的鉴龄结果,缺乏精确性;(2)南极鱼类生活跨度较大,高龄鱼体长频次分布严重重叠,以致无法准确判断其年龄结构;(3)耳石重量法易受到特殊个体影响而误判年龄;(4)因鳍条易损坏,脊椎骨采集较为困难,且许多南极鱼类无鳞,目前大多数南极鱼类使用耳石鉴定年龄,其也成为目前最为精准的南极鱼类鉴龄方法,但同时利用鳞片和耳石重量等对鉴定结果进行验证;(5)南极鱼类尚存在无统一的鉴龄标准、人为主观性较强以及缺乏早期生活史研究等不足之处;(6)为了研究南极鱼类早期生活史,耳石微化学及微结构等方法将被广泛利用。     

Longer food chains and crowded niche space: effects of multiple invaders on desert stream food web structure

Tributaries of the Colorado River Basin, historically home to a complex of endemic omnivores collectively referred to as the ‘three species’; flannelmouth sucker (Catostomus latipinnis), bluehead sucker (C. discobolus) and roundtail chub (Gila robusta), have experienced the establishment of numerous non‐native fish species. In this study, we examine the impacts of the trophic ecology of non‐native fishes on the ‘three species’ in the San Rafael River, Utah, USA. We employ a suite of abundance comparisons, stable isotope techniques and size‐at‐age back‐calculation analyses to compare food web structure and growth rates of the ‘three species’ in study areas with and without established populations of non‐native species. We found that the ‘three species’ are more abundant in areas with few non‐native fishes present, regardless of habitat complexity. Stable isotope analyses indicate non‐native fishes lengthen the food chain by 0.5 trophic positions. Further, the trophic niche spaces of the native fishes shift and are narrower in the presence of non‐native fishes, as several non‐native species’ trophic niche spaces overlap almost entirely with each of the ‘three species’ (bluehead sucker and flannelmouth sucker 100%, roundtail chub 98.5%) indicating strong potential for competition. However, the ‘three species’ demonstrated no evidence of reduced growth in the presence of these non‐native fishes. Collectively, these results suggest that while non‐native fishes alter the food web structure presenting novel sources of predation and competition, mechanisms other than competition are controlling the size‐structure of ‘three species’ populations in the San Rafael River.     

An evaluation of different structures to age freshwater fish from a northeastern US river

Abstract  Largemouth bass, Micropterus salmoides (Lacepède), smallmouth bass, Micropterus dolomieu Lacepède, and yellow perch, Perca flavescens (Mitchill), were collected from the Hudson River, New York, USA, to compare the precision of age estimates derived from scales and otoliths. Similar procedures were used to compare otolith and spine ages from brown bullhead, Ameiurus nebulosus (Lesueur). Overall percent agreement between readers ranged from 91% to 98% for otoliths compared with 38% to 67% for scales and spines. Disagreement rates associated with scales and spines increased as fish grew older. Average percent error between readers was about an order of magnitude higher for scales and spines than for otoliths. Ages estimated from scales and spines progressively decreased as age increased based on otolith examination. The use of scales and spines to age largemouth bass, smallmouth bass, yellow perch and brown bullheads from the northeastern US was less precise and will likely lead to underestimation of age of larger and older fish.     

Development of wolffish eggs at different temperature regimes

Embryonic development of common wolffish (Anarhichas lupus L.) was studied at constant temperatures 5.0, 7.0, 9.0, 11.0, 13.0 and 15.0°C. Duration of development from egg activation to several morphological stages including 50% hatching was determined. At 5.0–11.0°C, the survival rate of eggs to hatching ranged from 51 to 88% with a tendency to increase at 5.0 and 7.0°C. Morphological anomalies, bacterial contamination and large mortalities were observed in eggs incubated at 13.0 and 15.0°C. The period of hatching lasted from 10 to 50 d in different egg groups. Embryo length and yolk sac volume at identical morphological stages of development showed only slight relation to temperature. At lower temperatures newly hatched larvae were longer and at more advanced stages of ontogeny. Normal numbers of fin rays in larvae (mean values 74 for dorsal fin and 46 for anal fin) were observed at 5.0 and 7.0°C and in most larvae at 9.0°C. At 11.0 and 13.0°C, many rays were absent, with mean values for dorsal fin 60 and 39 respectively and for anal fin 28 and 4 respectively. The approximate upper limit for normal development of fin rays appeared to be 9.0 °C.     

On the analysis of the periodicity in the growth of scales,vertebrae and other hard structures in a teleost

Photometric records of the variation in density of scales, vertebrae opercula, fin rays, Weberian bones and pharyngeal teeth were produced and compared from 39 individuals of Leuciscus idus (Linnaeus, 1758), caught in the IJsselmeer and ranging in age from four to ten years.     

Standardised removal and sectioning locations for shovelnose sturgeon fin rays

Abstract  Fin rays are a common structure used in age and growth analyses, but many inconsistencies exist regarding removal and processing methodology. The purpose of this study was to evaluate precision of age estimates obtained from shovelnose sturgeon, Scaphirhynchus platorynchus (Rafinesque) fin rays sectioned at different locations. Fin rays were examined from 203 shovelnose sturgeon sampled from Pools 9, 13 and 14 of the Mississippi River. Three readers provided age estimates for sections acquired from five locations along fin rays to determine the optimum location for removing and sectioning fin rays. Precision and readability were generally greater for fin ray sections close to the articulating process on the fin ray (i.e. proximal) and decreased as sections approached the tip (i.e. distal). Based on these results, it is recommended that scientists remove shovelnose sturgeon fin rays at the articulating process and section immediately distal to the conspicuous curve in the fin ray close to the articulating process of the ray.     

Identification of stocked muskellunge and potential for distinguishing hatchery‐origin and wild fish using pelvic fin ray microchemistry

The effectiveness of pelvic fin ray microchemistry of muskellunge, Esox masquinongy Mitchill, to identify stocked individuals along with the potential to identify naturally reproduced fish were evaluated. Fish and water samples were obtained from one hatchery and seven lakes with natural differences in water Sr:Ca to determine whether location‐specific environmental signatures were recorded in sectioned muskellunge pelvic fin rays, including fish of known environmental history. Water and fin ray Sr:Ca were strongly correlated. Six lakes in Illinois possessed Sr:Ca signatures that were distinct from the hatchery where muskellunge were raised, resulting in pronounced shifts in Sr:Ca across sectioned fin rays of stocked fish. Hatchery and lake‐specific Sr:Ca signatures were stable across years. Sixteen of 19 individual fish known to have been stocked based on PIT tags implanted at stocking were correctly identified as hatchery‐origin fish using fin ray core Sr:Ca. Results also indicated that the hatchery Sr:Ca signal can be retained for at least 7 years in fin rays of stocked fish. Fin ray microchemistry is a non‐lethal approach for determining environmental history of muskellunge that could be used to assess movement patterns in lake and river systems and the degree to which muskellunge populations are supported by natural reproduction and stocking.     

Recruitment sources and spatial patterns of population demographics of spotted bass in a large river–tributary network

Understanding spatial patterns in population characteristics and the principal natal environments supporting riverine fish populations are important for fisheries management. Fin ray microchemistry was used to identify natal environment, and age estimates from sectioned fin rays were used to estimate growth and mortality rates for spotted bass, Micropterus punctulatus (Rafinesque), in a segment of the Ohio River (Smithland Pool) and three tributaries. Differences in water Sr:Ca and Ba:Ca among the Ohio River and tributaries were reflected in fin ray edge Sr:Ca and Ba:Ca. Fourteen percent of spotted bass ≥ age 2 captured in the Ohio River originated in tributaries, whereas 10% captured in tributaries originated in the Ohio River. Spotted bass in the Ohio River reached larger maximum size (L∞ = 448.7) than conspecifics in tributaries (L∞ = 324.4), although mortality rates were not different. Although 86% of spotted bass were collected in their inferred natal environment, small tributaries may be a supplemental source of recruitment for the spotted bass stock in Smithland Pool.     

大泷六线鱼的外形特征与消化系统结构

观察并描述了大泷六线鱼的外部形态特征,详细测量了30个个体的大泷六线鱼外部形态参数,进行了相关关系分析;并解剖观察了其消化系统结构特征。外部形态参数全长(LT)与体长(LB)相关关系为LB=0.8489LT+1.0309(R2=0.978),体长与体重的关系为W=0.0211LB2.9927,(R2=0.8337),其余形态参数相关性较低;可数性状背鳍、臀鳍、腹鳍、胸鳍、尾鳍鳍条数分别为38～43、18～22、5～7、17～18、13～15;侧线5条;第3侧线鳞数80～128;第1鳃弓鳃耙数16～19;消化系统结构特征:口咽腔较小,颌齿发达;食道短粗;胃发达,具有27～36个幽门盲囊;胃发达且分化明显,肠在腹腔内呈两个盘曲,肠长/体长为0.801±0.01,表明大泷六线鱼为典型的肉食性鱼类。     

中国南海银鲈科鱼类——新记录

2008年11月在广西北海市侨港镇码头采获银鲈科Gerreidae、银鲈属Gerres鱼类标本两尾,经鉴定为大棘银鲈Gerres macracanthus Bleeker,1854,系我国南海鱼类一新记录。其主要特征为：体长卵圆形,侧扁,体长为体高的2.2～2.3倍;体背腹缘均呈弧状隆起,体高以背鳍起点处最高。口小,能活动,伸出时略向下倾斜。体被薄圆鳞,易脱落;侧线鳞41～43枚。背鳍鳍棘部与鳍条部相连;背鳍IX-10,第2鳍棘延长呈丝状,压倒时末端伸达尾柄;臀鳍Ⅲ-7,以第3鳍棘最长;胸鳍长,末端可达臀鳍起点上方;尾鳍叉形。新鲜标本体背部银灰色,腹部银白色,体侧有7～10条青灰色横带;背鳍灰白色,第2鳍棘黑色;臀鳍、胸鳍和腹鳍淡黄色;尾鳍灰黄色,上、下叶内缘暗色,下叶外缘白色。