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1.
Fishes that depend on large‐river habitats have declined in many regions due to human alteration of both mainstems and tributaries. Conserving these species is often complicated by their dependence on long‐distance movements to complete their life cycle, but the location of key habitats is difficult to assess across multiple life history stages. Movement of large‐river fishes between mainstems and major tributaries is commonly observed, but the role of these exchanges at the population level is uncertain. We used shovelnose sturgeon (Scaphirhynchus platorynchus) as a case study for assessing the lifelong spatial ecology of large‐river fishes. Fin ray microchemistry data indicate that shovelnose sturgeon from the Mississippi and Wisconsin rivers represent a unified population that relies on connections among multiple large‐river habitats throughout life history. The tributary serves as an important spawning area, but fin ray chemistry data suggest larvae subsequently drift downstream to nursery habitats in the mainstem; an assertion that is supported by extensive field survey data. Our analyses underscore the lifelong importance of connections within river networks for maintaining viable populations of this, and likely other large‐river species that have been documented to use tributary habitats. These findings support a metapopulation perspective on species that depend on large‐river habitats, many of which are now highly altered and fragmented. For shovelnose sturgeon and species with similar life history, protecting or restoring linkages between mainstem rivers and their tributaries should be a conservation priority.  相似文献   

2.
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3.
The gross, histological and scanning electron microscopic appearance of dorsal fin rot in farmed Atlantic salmon parr, Salmo salar L. is described. The lesions were grouped into seven categories: (1) peripheral erosion and ray splitting; (2) peripheral erosion with some nodularity; (3) severe nodularity with differing degrees of tissue loss; (4) extensive to total loss of the dorsal fin; (5) smooth thickening of the dorsal fin; (6) haemorrhagic dorsal fin lesions; and (7) healed dorsal fin rot lesions. The main sign of injury was clefts extending through the epithelium. These injuries were consistent with bites from other parr. During healing from such wounds, damaged cells sloughed from the surface, and there was swelling and hyperplasia in the remaining cells. The majority of the thickening in the fins was the result of epithelial hyperplasia with a variable cellular inflammatory response. The distal epithelium of fins with severe fin rot (i.e. nodular and eroded) was rough, irregular and swollen with superficial nodular extensions. Wounds in all stages of repair were more numerous in such areas. Fin rays were frequently observed protruding from the abnormal epithelium at the distal edge of the fin. With the exception of the isolation of Aeromonas salmonicida from a small number of cases, no significant bacterial involvement was detected. Under scanning electron microscopy, bacteria were only detected on the exposed fin rays and not in association with the abnormal epithelium. In the majority of cases, the dorsal fin was either the only fin damaged or the most severely damaged. It is suggested that the hyperplastic response to numerous bite wounds is responsible for the accumulation of abnormal epithelium typical of dorsal fin rot in farmed Atlantic salmon parr.  相似文献   

4.
Fin ray biopsies are commonly used to age sturgeon, but the effects of fin ray biopsy on Siberian sturgeon Acipenser baerii swimming performance are unknown. Therefore, the effects of two fin ray biopsy methods on swimming performance of hatchery-reared, juvenile Siberian sturgeon were evaluated in this study. Treatment fish were subjected to one of two biopsy methods: removal of a 2- to 4-cm section from a marginal pectoral fin ray, or full removal of a marginal pectoral fin ray. Control fish were only subjected to a sham operation. A modified 2,936-l Brett-type swim tunnel was used to evaluate 10-min critical station-holding speeds (C SHS) and behavioral swimming characteristics of sturgeon immediately after fin ray biopsies were carried out. Fish sizes (range 65- to 84-cm fork length) were comparable among treatments. Mean 10-min C SHS (mean ± SE) were 113 ± 3.4, 109 ± 2.5, and 111 ± 2.8 cm s?1 for the segment removal treatment, full removal treatment, and control treatment, respectively. ANOVA indicated that the two methods had no significant effect on the 10-min C SHS of Siberian sturgeon compared to the control treatment. Results indicate that fin ray removal has no effect on Siberian sturgeon swimming performance.  相似文献   

5.
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 86SrC03 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 86SrCO3 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 86SrCO3 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.  相似文献   

6.
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.  相似文献   

7.
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.  相似文献   

8.
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.  相似文献   

9.
为了在中华鲟洄游生态学研究上有新突破,实验首次比较研究了中华鲟3种硬组织(耳石、背骨板和胸鳍条)的微结构和微化学特征。结果发现,耳石结构松散,存在多个耳砂(微晶球霰石球晶)颗粒,且每个颗粒均具有独立的核心;背骨板存在分层现象;胸鳍条结构较为致密,且均一。胸鳍条、耳石中生境元素Co/Ca、Sr/Ca和Ba/Ca比特征变化较为一致,而背板由于分层的原因与前二者有所差异。综合考虑非致死性采样、前处理难度、微结构组成以及生境元素生物积累等优势,笔者建议首选胸鳍条作为基于微化学分析来反演中华鲟洄游及生活史履历研究的最佳硬组织材料。  相似文献   

10.
Abstract Evaluating the response of fish populations to environmental influences requires precise age estimation. Pectoral fin rays and scales were compared to determine which is more precise for estimating age of blue sucker, Cycleptus elongatus (Lesueur), from the Missouri River, USA. Mean coefficient of variation was significantly lower for fin rays both among three novice readers (rays 19.9%; scales 23.1%) and among three reads by a single experienced reader (rays 11.8%; scales 18.6%). Additionally, exact per cent agreement (rays 20.0%; scales 14.3%) and within‐1‐year per cent agreement (rays 89.1%; scales 73.9%) were higher for fin rays compared with scales for multiple reads by the same experienced reader. Age–bias plots revealed that scale ages were lower than fin‐ray ages >7. The use of fin rays is recommended for estimating ages of blue sucker until validation procedures are conducted.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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14.
Experiments were conducted with the larvae and early juveniles of three species of sturgeon to determine effects of diet and development on swimming and foraging behaviour as well as depth distribution in 100-L aquaria. About 500 hatchlings were placed in each tank with two or three replicates of three or six diet treatments, including live and dry feeds. Eight types of swimming or foraging activity were recorded with a lap-top event recorder and with fish counts in three depths of water. Analysis of variance showed live diets resulted in greater foraging activity in upper water horizons than most dry diets for Atlantic sturgeon, Acipenser oxyrhynchus Mitchill. Scouring, a foraging activity, differed among diet types in early juvenile lake sturgeon, A . fulvescens Rafinesque. Developmental effects included early peaks in the performance of swim-up for all species and swim near surface for two of three species. Postlarvae (post-yolk-sac larvae) of shovelnose, Scaphirhynchus platorhynchus (Rafinesque), and Atlantic sturgeon swam inverted, an apparent foraging tactic associated with elevated or air-water surfaces. Postlarvae maintained (lake sturgeon) or shifted to (other species) bottom swimming with increased scouring activity. Shovelnose early postlarvae occupied higher average water-column heights than lake or Atlantic sturgeon. Shovelnose (only species tested) postlarvae showed greater activity in upper water horizons at night. These results suggest a fundamental shift to benthic foraging during the postlarval phase, with shovelnose sturgeon continuing to forage in suprabenthic zones to a greater degree than the other two species.  相似文献   

15.
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.  相似文献   

16.
南极鱼类年龄与生长研究进展   总被引：4，自引：2，他引：2  
朱国平  魏联 《水产学报》2017,41(10):1638-1647
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。  相似文献   

17.
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.  相似文献   

18.
To understand quantitative genetic characteristics of hatchery‐produced Japanese flounder in the wild, heritability and genetic correlation of growth‐related and morphometric traits were examined in yearling released individuals at a coastal region in northeast Japan. Quantitative genetic parameters were estimated with restricted maximum likelihood following reconstruction of pedigree by a likelihood method using seven microsatellite loci. Estimates of heritability were 0.65 and 0.51 for growth‐related traits (body length and the proportion of body length to body depth) and 0.45–0.62 for morphometric traits (vertebral count and dorsal and anal fin ray counts). Genetic correlation was significantly positive (0.61) between dorsal and anal fin ray counts, indicating the possibility of pleiotropic genes or gametic phase disequilibrium for these traits. All the estimates of heritability and genetic correlation in the released individuals were close to those of hatchery‐reared juveniles, suggesting that yearling released individuals had similar quantitative genetic characteristics of growth and morphometric traits in the wild to hatchery‐reared juveniles.  相似文献   

19.
Abstract  Transmitter retention and the effects gastrically and surgically implanted telemetry transmitters had on condition and mortality of shovelnose sturgeon, Scaphirhynchus platorhynchus (Rafinesque), >450-mm fork length were examined. Four, 35-day trials were conducted with approximately equal numbers of control fish, fish receiving dummy transmitters gastrically and fish receiving dummy transmitters surgically. Four sturgeon expelled gastrically implanted transmitters during the observation period. Two mortalities occurred among fish receiving gastrically implanted transmitters during the study period and one mortality was recorded for control fish. No mortalities were recorded for fish receiving surgically implanted transmitters. Condition change (Δ K n ) was significantly different between fish receiving surgical implantation (mean Δ K n  ± SE; −5.17 ± 0.94), fish receiving gastric implantation (−2.98 ± 0.72) and control fish (−0.65 ± 1.09). Surgical transmitter implantation is recommended for telemetry studies on shovelnose sturgeon because of increased transmitter expulsion and occurrence of mortality in fish receiving gastric implantation.  相似文献   

20.
Calcein (CAL) from 50 to 250 mg/l and alizarin complexone (ALC) from 100 to 300 mg/l were used for double immersion marking of juvenile qingbo Spinibarbus sinensis. With the exception of the scales, double immersion for 24 h produced detectable double marks in otoliths (sagittas and asterisci), barbs, fin rays (dorsal, pectoral, ventral, anal, and caudal), and fin spines (dorsal, pectoral, ventral, and anal) after 90 days in a laboratory growth experiment. Green fluorescent rings produced by CAL were considerably closer to the inside of the bony structures (including otoliths, barbs, fin rays, and fin spines) than red fluorescent rings produced by ALC. Sagittas, asterisci, and barbs showed acceptable fluorescent marks at higher concentrations (250 mg/l CAL and ≥ 200 mg/l ALC, ≥ 200 mg/l CAL and 300 mg/l ALC, 150–250 mg/l CAL and 250–300 mg/l ALC, respectively). Fin rays and fin spines treated by 200 mg/l CAL and 250 mg/l ALC and 250 mg/l CAL and 300 mg/l ALC simultaneously had both acceptable CAL and ALC marks. There was no statistically significant difference on the survival or growth of marked fish compared to the controls throughout the experiment (p > 0.05). The results suggest that double immersion with CAL and ALC is suitable for double mass-marking of juvenile S. sinensis, and these double marks are useful in the experimental development of biological research or restocking methodologies.  相似文献   

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