新疆赛里木湖3种引进白鲑鱼类的DNA条形码分析

本研究采用DNA条形码技术对新疆赛里木湖引进种贝加尔凹目白鲑(Coregonus migratorius)、高白鲑(Coregonus peled)和宽鼻白鲑(Coregonus nasus)进行了种质鉴定和遗传多样性分析。单倍型检测发现,3种白鲑共检测到15种单倍型,其中贝加尔凹目白鲑独享5种,宽鼻白鲑7种,高白鲑5种,后二者共享2种单倍型为高白鲑特有单倍型,表明二者存在不同程度的基因交流,高白鲑可能将其基因通过杂交渐渗到宽鼻白鲑群体内。系统发育分析显示,15种单倍型分成3组分别聚类在3个不同分支上,每个分支所属白鲑分别与其发表序列聚在一起,表明赛里木湖引进的3种白鲑仍保持着原种良好的种源特性;而贝加尔凹目白鲑的近缘种秋白鲑(Coregonus autumnalis)则单独聚为一支,与贝加尔凹目白鲑的遗传距离最大(0.027),支持将二者划分为两个独立种。遗传多样性分析显示,3种白鲑的遗传多样性适中,但由于宽鼻白鲑存在杂交的可能性,因而其遗传多样性高于贝加尔凹目白鲑和高白鲑。建议赛里木湖渔业生产部门继续在繁殖、捕鱼等生产方式上进行科学规划,引进先进的种质鉴定技术,避免人工杂交造成的种质污染;同时维持和提高白鲑属鱼类的遗传多样性,保证湖区特色渔业的可持续发展。     

Rearing of coregonid fishes (Coregonidae) in illuminated lake cages: I. Growth and survival of Coregonus lavaretus L. and Coregonus peled Gmel.

The paper presents the results of rearing whitefish (Coregonus lavaretus L.) and peled (Coregonus peled Gmel.) in illuminated lake cages during a period of 4 years. In 3 successive years about 97 kg of summer coregonid fry were produced during initial 2-month rearing. Whitefish fry reached a length of 30.0–49.5 mm and an average individual weight of 201 mg–1 g. Peled fry reached 31.0–38.3 mm in length and 300–370 mg in weight. Whitefish survival rates amounted successively to 72.6% in 1977, 51.4% in 1978, and 3.1% in 1979. Survival rates for peled were 57.8%, 63.1% and 6%, respectively. Fishes at the age of 1+ and 2+ years showed high mortalities. Their growth rate was slower than in wild populations, and they did not attain sexual maturity.     

Food composition, habitat use and growth of stocked and native Arctic charr, Salvelinus alpinus, in Lake Muddusjärvi, Finland

Habitat use, growth and food composition of native and stocked Arctic charr, Salvelinus alpinus (L.), were studied in the subarctic Lake Muddusjärvi, northern Finland, to investigate reasons for poor stocking success. Samples were collected with pelagic and epibenthic gill nets. Stocked and native charr occurred in similar epibethic habitats, whereas pelagic habitat was avoided. Native charr grew fast after shifting to piscivory. Growth rate of stocked charr was slow because only a small proportion of stocked fish became piscivorous during the first year after stocking. During the first lake year, stocked charr divided into slow-growing planktivores and fast-growing piscivores. Piscivorous stocked and native charr consumed only whitefish, Coregonus lavaretus (L.), as their prey. Small-sized (<10 cm) whitefish were preferred when shifting to piscivory.     

Does habitat occupancy by lake trout and lake whitefish in large lakes match published thermal habitat envelopes?

Habitat occupancy patterns of lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) in two large Canadian Shield lakes were modelled based on detections of fish from repeated depth‐stratified surveys over several summers. Lake trout and lake whitefish consistently occupied sites outside traditional thermal envelopes and were not detected at some sites within these ranges. This included the metalimnion and shallow epilimnion for lake trout and lake whitefish in Lake Opeongo. Physical habitat covariates were not important in defining lake trout habitat in both lakes. Physical habitat as represented by the hardness/softness gradient based on acoustic substrate surveys was important for lake whitefish in Lake Opeongo but not in Smoke Lake. In addition, thermal envelopes for lake whitefish differed between the lakes possibly because of differences in substrate slope. The wash zone of lakes, where the thermocline contacts the substrate, appears to be a physical habitat feature for lake whitefish in some lakes. Lake whitefish also exhibited diurnal activity behaviour that was reflected through greater detection rates in the morning versus the afternoon. By accounting for imperfect detection, true estimated overall occupancy of lake trout and lake whitefish increased 0.15–0.30 over naïve occupancy. Thermal habitat envelopes for lake trout and lake whitefish are wider than previously thought. Lake trout occupied a consistent thermal habitat envelope while lake whitefish varied between lakes likely because of lake specific differences in basin morphology and wash zone.     

柴窝堡湖高白鲑生长与移殖效应分析

2004年6月-2007年5月,采集柴窝堡湖高白鲑标本79尾,对其年龄与生长状况及高白鲑在柴窝堡湖移殖效应进行了分析。研究表明：柴窝堡湖高白鲑1龄平均逆算体长L1=11.7cm、2龄平均逆算体长L2=26.1cm;体长与体重的回归方程为W=0．013474L^309069;高白鲑在柴窝堡湖生长正常,能够形成捕捞群体,但由于柴窝堡湖现有的渔业捕捞方式,影响了高白鲑在柴窝堡湖渔业移殖效应。     

Islands in the ice stream: were spawning habitats for native salmonids in the Great Lakes created by paleo‐ice streams?

Lake trout Salvelinus namaycush, lake whitefish Coregonus clupeaformis and cisco Coregonus artedi are salmonid fishes native to the Laurentian Great Lakes that spawn on rocky substrates in the fall and early winter. After comparing the locations of spawning habitat for these species in the main basin of Lake Huron with surficial substrates and the hypothesized locations of fast‐flowing Late Wisconsinan paleo‐ice streams, we hypothesize that much of the spawning habitat for these species in Lake Huron is the result of deposition and erosion by paleo‐ice streams. This hypothesis may represent a new framework for the identification and protection of spawning habitat for these native species, some of which are currently rare or extirpated in some of the Great Lakes. We further suggest that paleo‐ice streams may have been responsible for the creation of native salmonid spawning habitat elsewhere in the Great Lakes and in other glaciated landscapes.     

Influences of human activity and climate on the stock-recruitment dynamics of whitefish, Coregonus lavaretus, in Lake Geneva

Abstract  Analysis of long-term catches from the deep peri-alpine Lake Geneva, showed a shift in the stock-recruitment relationship of Coregonus lavaretus (L.), a target species of commercial fishing. This change was mainly related to large-scale meteorological factors. Higher spring water temperatures may have improved larval survival and hence recruitment of whitefish via: (1) a better match between the hatching date of whitefish larvae and development of their zooplankton prey; and (2) the positive temperature effect on larval growth. In Lake Geneva, changes in regulatory mechanisms coupled with stocking and improved water-quality have led to an explosion in the C. lavaretus population in recent years. These results highlight the relevance of long-term changes in the stock-recruitment relationship for management of aquatic ecosystems that are sensitive to climate forcing.     

太湖翘嘴红鮊的生物学及其增殖问题的探讨

本文从研究翘嘴红鲌的生长、各个时期的食性和繁殖生物学出发,对于翘嘴红鲌在太湖渔业资源中的地位及作用作了比较深入的探讨。作者认为,过去把翘嘴红鲌简单地当作有害于太湖鱼类资源的凶猛鱼类而不加节制地加以捕杀,是造成目前太湖鱼类组成小型化和渔获物经济价值下降的原因之一。因此提出了保护和增殖翘嘴红鲌的主张,并且具体地提出了有关翘嘴红鲌的起捕规格、禁渔期和禁渔区、限制有害渔具、实行人工放流和保护水域环境等一系列建议。     

Review of the present knowledge of rearing whitefish (Coregonidae) larvae

Intensive fishing of whitefish (Coregonus lavaretus) and a survival rate of the early stages of the fry that is generally too low lead, at present, to the whitefish stocks not being able to utilize fully the natural food resources now produced many times in excess of the requirements by the eutrophication of lakes.Feeding experiments in aquaria have, for several years, shown very impressively, that there are two main reasons for the high mortality of the larvae in the natural environment: high sensitivity to even a short-term lack of food and specific food requirements — the necessity for the larvae to feed on the juvenile stages of certain zooplanktonic crustaceans.Artificial breeding of whitefish eggs in cold water at 1°C caused a delay in hatching of about 8 weeks compared with natural hatching, thus allowing the release of the larvae at a time when the density of zooplankton is about ten times higher and mainly juvenile stages of crustaceans needed by the whitefish larvae are present. Hence, this is one proven way of improving the survival rate of whitefish larvae in the natural environment.Young fish, after metamorphosis, have less specialized food requirements than the larval stage and can even be fed adequately with dry food. In rearing the larvae, natural zooplankton can be replaced by the nauplii of the brine shrimp, Artemia salina. Larvae have not yet been reared on dry food or even on slowly frozen zooplankton or Artemia, but Artemia nauplii shock-frozen in liquid nitrogen (at ?196°C) were found to be as acceptable as living ones and allowed metamorphosis of the larvae to take place. The substance, assumed to be present in the living Artemia, which was lost on slow-freezing but retained after shock-freezing and was shown to be essential to the whitefish larvae, was insoluble in water. Biochemical investigation and identification of this substance are urgently required in order to synthesize an artificial complete food for whitefish larvae.As long as this artificial food is not available, attention will have to be focussed on rearing the larvae in natural ponds where the specific and essential zooplankton can be encouraged.     

Resource use of native and stocked brown trout Salmo trutta L., in a subarctic lake

Habitat use, food composition and growth of stocked and native brown trout, Salmo trutta L., were studied in the subarctic Lake Muddusjärvi in northern Finland. Stocked brown trout and native brown trout preferred littoral and pelagic areas. Trout were stocked in October. In June stocked trout fed primarily on invertebrates while native fish were piscivorous. From July onwards the composition of the diet of both stocked and native trout was similar and consisted almost entirely of small‐sized whitefish. Brown trout were already piscivorous at a length of about 20 cm. The mean length of prey consumed was about 12 cm. Mean length‐at‐age was similar from the second year in the lake despite of the larger size of stocked fish during the first year in the lake.     

Trophic niche segregation among native whitefish and invasive vendace in a north Norwegian lake system

Introductions and invasions of non-native species alter nutrient cycling and trophic dynamics resulting in significant ecological disturbance. Stable isotope data were used to test for evidence of invader-induced trophic niche differences in a north Norwegian lake system differentially dominated by native European whitefish (Coregonus lavaretus) morphotypes and invasive vendace (Coregonus albula). Aspects of both realised trophic niche position and trophic niche width were affected by the invader, with the effects varying by whitefish morphotype. Densely rakered pelagic whitefish demonstrated a relatively lower reliance on pelagic resources in the presence of the invader and the isotopic niche size was relatively larger in conjunction with the broadening of the prey base. Within the benthic-dwelling sparsely rakered whitefish morphotype, the trophic impacts of invading vendace were size-dependent, with larger individuals experiencing niche compression. Smaller sparsely rakered whitefish increased, contrary to our hypothesis, reliance on pelagic-based energy in the face of invasion. Our findings demonstrate that the trophic ecology of invaded systems can differ in multiple and subtle ways that have consequences for community- and ecosystem-level energy flows, which if persisting over time are likely to have implications for the recruitment, growth and reproductive rate of the native fishes.     

Whole otolith elemental analysis reveals feeding migration patterns causing growth rate differences in anadromous whitefish from the Baltic Sea

Impact of feeding migration pattern on growth rate of whitefish (Coregonus lavaretus L.) from River Kemijoki was investigated. River Kemijoki is located in the northernmost Gulf of Bothnia (Baltic Sea). Whitefish ascending the river to spawn show major growth rate variations. To study whether these variations are related to different feeding areas (migratory connectivity), whole otoliths from fast‐growing (FAST^G) whitefish (n = 9, age 4 years, average weight 790 g) and slowly growing (SLOWLY^G) whitefish (n = 9, age 8 years, average weight 600 g) were analysed for elemental (Ba, Sr, Mg, Zn, Mn, Ca) concentrations by inductively coupled plasma‐optical emission spectrometry. Results showed that the FAST^G whitefish had much lower otolith Ba concentration (~45%, p ≤ .01) than SLOWLY^G whitefish, revealing that FAST^G whitefish have spent more time in water of higher salinity/lower latitude, that is at feeding grounds in the southern Gulf of Bothnia. Otoliths of the FAST^G whitefish had also higher Mg (~25%, p ≤ .001) and Zn (~20%, p ≤ .05) concentrations, but lower Ca (~5%, p ≤ .01) concentrations, than the otoliths from SLOWLY^G whitefish. These results further reveal that FAST^G and SLOWLY^G whitefish have been spatially separated. In conclusion, bulk otolith elemental analysis revealed spatial separation and migration differences in river‐spawning whitefish subpopulations in the Gulf of Bothnia, which apparently lead to differences in fish growth rate. Our results increase the understanding of river‐spawning whitefish biology and its population structure and dynamics and may contribute to a sustainable management of river‐spawning whitefish stocks.     

Hydroacoustic assessment of mono‐ and polymorphic Coregonus density and biomass in subarctic lakes

Density and biomass estimates of pelagic fish are essential to understand food web interactions and ecosystem functioning. We conducted surveys of six subarctic lakes for assessing both mono‐ and polymorphic whitefish Coregonus lavaretus (L.) populations. Monomorphic whitefish lakes were inhabited by a habitat and diet generalist, large sparsely rakered (LSR) morph, whereas polymorphic whitefish lakes had a littoral benthivorous LSR morph, a pelagic planktivorous densely rakered (DR) morph and in two cases a benthivorous small sparsely rakered (SSR) morph inhabiting the profundal zone. In addition, an introduced specialist zooplanktivore, vendace Coregonus albula (L.), inhabited one of the monomorphic lakes. Hydroacoustics was found to be an appropriate method for estimating coregonid densities and biomasses in large and deep polymorphic lakes occupied by the planktivorous DR morph or vendace, but only during dark nights in autumn. The suitability of hydroacoustic assessment for benthivorous LSR and SSR morphs was low, especially in polymorphic whitefish lakes due to their preference for near‐bottom habitat or shallow areas not sampled with hydroacoustics. The pelagic density of DR morph varied from 330 to 1780 fish·ha^?1 and biomass from 1.4 to 13.3 kg·ha^?1 in polymorphic whitefish lakes, whereas corresponding estimates for LSR morph were 10–320 fish·ha^?1 and 0.5–8.4 kg·ha^?1 in monomorphic whitefish lakes. In general, polymorphism tended to increase the density and biomass of whitefish in the pelagic area compared with monomorphic systems.     

Substance essential for metamorphosis of fish larvae extracted from Artemia

Up to now the larval stages of fishes could not be reared successfully past metamorphosis when fed exclusively upon dry food. In rearing whitefish larvae, living Artemia nauplii could be replaced by shock-frozen ones (at ?196°C). This suggested that a substance essential for the whitefish larvae is present in living Artemia and preserved during rapid shock freezing. This substance seemed to be insoluble in water. It could be dissolved and extracted from the nauplii by acetone and could be transferred to a dry food. This enriched dry food offered to the whitefish larvae enabled them to grow up to and past metamorphosis successfully.     

An attempt to determine the survival time for starving fish larvae

Studies were carried out on the respiratory rate of starving and fed whitefish larvae in light and darkness. Using the average respiratory rate and chemical composition of the body, the theoretical survival time for starving whitefish larvae was calculated for a given temperature during the period from hatching to 50% mortality. Applying Q₁₀ coefficients, average survival times were also calculated for starving larvae in different water temperatures.     

Polymorphic mountain whitefish (Prosopium williamsoni) in a coastal riverscape: size class assemblages,distribution, and habitat associations

We compared the assemblage structure, spatial distributions, and habitat associations of mountain whitefish (Prosopium williamsoni) morphotypes and size classes. We hypothesised that morphotypes would have different spatial distributions and would be associated with different habitat features based on feeding behaviour and diet. Spatially continuous sampling was conducted over a broad extent (29 km) in the Calawah River, WA (USA). Whitefish were enumerated via snorkelling in three size classes: small (10–29 cm), medium (30–49 cm), and large (≥50 cm). We identified morphotypes based on head and snout morphology: a pinocchio form that had an elongated snout and a normal form with a blunted snout. Large size classes of both morphotypes were distributed downstream of small and medium size classes, and normal whitefish were distributed downstream of pinocchio whitefish. Ordination of whitefish assemblages with nonmetric multidimensional scaling revealed that normal whitefish size classes were associated with higher gradient and depth, whereas pinocchio whitefish size classes were positively associated with pool area, distance upstream, and depth. Reach‐scale generalised additive models indicated that normal whitefish relative density was associated with larger substrate size in downstream reaches (R² = 0.64), and pinocchio whitefish were associated with greater stream depth in the reaches farther upstream (R² = 0.87). These results suggest broad‐scale spatial segregation (1–10 km), particularly between larger and more phenotypically extreme individuals. These results provide the first perspective on spatial distributions and habitat relationships of polymorphic mountain whitefish.     

Prevalence of stocked whitefish in River Kemijoki,Finland, inferred by micro X‐ray fluorescence analysis of otoliths

Micro X‐ray fluorescence (µ‐XRF) analysis of otoliths was evaluated as a method to estimate the proportion of stocked one‐summer‐old whitefish Coregonus lavaretus L. in catches of adult fish (n = 20) ascending the River Kemijoki to spawn. Laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) analysis was applied as control. Polished otoliths were scanned with µ‐XRF to obtain strontium maps that were used to infer visually the provenance of the whitefish. Thirteen of the fish showed signs of being stocked as one‐summer‐old fingerlings. LA‐ICP‐MS was applied to determine the elemental composition in a spot outside the core of the otolith. The results were largely consistent with the visual inspection of the µ‐XRF mapped otoliths. In conclusion, µ‐XRF mapping successfully identified whitefish stocked as one‐summer‐old fingerlings. The vast majority of whitefish returning to the River Kemijoki to spawn were stocked fish.     

A long-term (1667–1860) perspective on impacts of fishing and environmental variability on fisheries for herring,eel, and whitefish in the Limfjord,Denmark

This investigation reconstructs the development of major fisheries for herring, eel and whitefish in the Limfjord estuary, Denmark ca. 1667–1860, and then evaluates how their long-term dynamics have been influenced by some key fishery and environmental developments. The commercially most important fishery was for herring, Clupea harengus, which spawned in the Limfjord. This fishery underwent large changes in these centuries. High landings occurred in two periods in the early 18th and again in the early 19th centuries, when 4000–8000 metric tonnes were caught annually. In 1830, the fishery collapsed and landings were <1000 tonnes until the 1910s. Even during the 20th century using modern fishing techniques, the herring fishery never exceeded 7000 tonnes. The collapse was most likely due to unsustainable fishing practices (direct impacts on adults, juveniles, larvae and eggs). The second most important fishery of the Limfjord was the eel fishery. Eel, Anguilla anguilla, seems to have fled the fjord after a winter storm in 1825 broke the narrow Agger Tange isthmus which used to separate the Limfjord from the North Sea, and permanently increased the salinity in the western part of the Limfjord from 8 psu to 33 psu. The, so-called pulse seine fishery for eel declined rapidly following the salt water intrusion, and the population needed at least one to two generations to even partly recover. One possible technological reason for the recovery of the fishery was the 1848 invention of a new type of gear in the Limfjord which today is known as the Danish seine. However, the commercial eel fishery in Limfjord ceased by the 1980s coincident with the overall decline in European eel populations. The third fishery analyzed is the fishery for common whitefish, Coregonus lavaretus. A local population formed the basis of a substantial seasonal fishery, but the whitefish did not survive the salinity obstacle presented by the salt water intrusion in 1825. This study documents both the effects of fishing and environmental variability on collapses of different Limfjord fish species.     

Otolith elemental characteristics of whitefish (Coregonus lavaretus) from brackish waters of the Gulf of Bothnia,Baltic Sea

To investigate whether European whitefish (Coregonus lavaretus) groups in the brackish (≤7%) Gulf of Bothnia (Baltic Sea) express specific otolith elemental characteristics, concentrations of elements (Ca, Ba, Sr, Zn, Mn, Fe) in whole otoliths were studied by inductively coupled plasma‐optical emission spectrometry. Whitefish (N = 67) were sampled from six different latitudinal sites; four in the sea and two in rivers along the west coast of Finland, and from a fresh water lake for comparison. The concentration of several elements showed significant differences among sampling sites. Otolith Ba concentrations were higher at the northern sampling sites compared to the southern ones, thereby showing negative association to capture‐habitat salinity. In contrast, otolith Sr and Zn concentrations were lower at the northern sampling sites, thereby associating positively to capture‐habitat salinity. Otolith Mn concentrations did not associate with latitude or salinity but markedly varied between sampling sites. Elevated Fe concentrations occurred in fish otoliths from the two northernmost sites. Ca concentrations were at the same levels in otoliths from all whitefish samples. Otoliths of whitefish from the lake had very high Ba and low Sr concentrations compared to concentrations in otoliths from whitefish in the sea and rivers. Our results show that otolith elemental characteristics of whitefish vary considerably at various geographic scales showing high potential for population identification using elemental fingerprints. Analysis of otolith elemental characteristics may therefore provide an efficient tool for the identification of main areas of residence, spawning locations, and migration routes, thus contributing towards the sustainable management of whitefish stocks.