Length‐weight relationships for nine fish species of Laohegou River,a tributary of upper Yangtze River,China

This paper provides length‐weight relationships for nine fish species from the Laohegou River, a tributary of the upper Yangtze River. Length‐weight relationships for six of these species are recorded for the first time. New maximum lengths for two species are also reported.     

长江上游支流南广河的鱼类多样性及资源现状

南广河是长江上游一级支流, 为全面了解该河流的鱼类多样性, 作者于2017年11月至2018年9月在南广河干流及支流28个采样点进行了6次调查, 共采集鱼类64种, 隶属于5目13科48属, 其中四川省重点保护鱼类有鲈鲤(Percocypris pingi)和岩原鲤(Procypris rabaudi) 2种, 长江上游特有鱼类17种, 列入《中国脊椎动物红色名录》的濒危和易危的鱼类有9种。南广河现有分布鱼类以小型种类为主, 宽鳍鱲(Zacco platypus)和鲤(Cyprinus carpio)为优势种。南广河鱼类多样性总体较高, Margalef丰富度指数、Shannon-Wiener多样性指数、Simpson优势度指数及Pielou均匀度指数分别为6.57、3.10、0.93、0.74; 中游河段的鱼类种类和数量较丰富, 分别占渔获物总种类和总数量的65.63%和28.98%; 支流镇舟河的鱼类种类和数量也较丰富, 分别占37.50%和20.48%。南广河不同河段的鱼类种类组成具有明显差异, 大坝建设和过度捕捞可能影响了鱼类分布并导致其资源量下降。     

Length‐weight relationships of nine fish species from the upper reach of the Gan River,a tributary of the Yangtze River in China

Length‐weight relationships (LWRs) are reported for nine fish species belonging to four families from the upper reach of the Gan River, one of the main tributaries of the Yangtze River, China. A total of 807 specimens were collected from April 2016 to July 2017. Fishes were both sampled using a backpack electrofishing unit and collected from local fish markets that using various fishing gears such as electrofishing boats, gillnets (mesh sizes: 1–12 cm), hooks, and benthic fyke nets (mesh sizes: 0.5 cm and 0.7 cm). The fish species were Siniperca undulata (Fang & Chong, 1932), Pseudogobio vaillanti (Sauvage, 1878), Sarcocheilichthys parvus (Nichols, 1930), Barbodes semifasciolatus (Günther, 1868), Spinibarbus hollandi (Oshima, 1919), Gobiobotia meridionalis (Chen & Cao, 1977), Pseudobagrus albomarginatus (Rendahl, 1928), Pseudogastromyzon changtingensis (Liang, 1942), and Pseudogastromyzon fangi (Nichols, 1931). The a values for the nine species varied between 0.0056 and 0.0366, the b values ranged from 2.333 to 3.318, and r² values from .952 to .994.     

Feeding guild structure of a rocky intertidal fish assemblage in central Chile

The identification and analysis of the guild structure of vertebrate assemblages has played a fundamental role in the understanding of the underlying mechanisms responsible for their community organization and structuring. This approach generally has not been undertaken for temperate water intertidal fish assemblages. In central Chile, fishes are important components of the intertidal community, but no studies attempting to understand their organization and structuring have been done. In the present study, the diets of 13 of the most abundant species which inhabit tidepools in the rocky intertidal zone of central Chile were determined. A total of 660 fishes was collected at 5 sites: Los Molles, Con-Cón, Quintay, El Tabo, and Las Cruces. Dietary overlap between all species pairs was calculated and a phenogram of dietary similarity was constructed and analyzed using a bootstrapping technique to objectively determine guild membership. The results showed that the intertidal fish assemblage of central Chile can be divided into three feeding guilds: two guilds consisting of carnivorous species and one guild of omnivorous and herbivorous species. The possible causes and implications of the resulting guild structure and the potential effects of predation by these fishes on other components of the intertidal community are discussed.     

小型水坝梯级开发对永宁河流域鱼类多样性的影响

永宁河是长江上游右岸的一级支流,其干、支流上共建有20余座小型水坝。为探究梯级水电站对鱼类多样性的影响,在永宁河流域设置共42个采样点,覆盖干支流及各个水坝,分别于2018年7月、10月和2019年1月、4月进行了四次鱼类资源调查。调查期间通过刺网、地笼、电捕等方法共采集到鱼类69种7332尾,隶属于4目13科54属,其中有长江上游特有鱼类13种,列入《中国脊椎动物红色名录》濒危和易危鱼类3种,国家二级重点保护鱼类岩原鲤(Procypris rabaudi)1种。Pinkas相对重要性指数(IRI)值较大主要为宽鳍鱲(Zacco platypus)、鲫(Carassius auratus)乐山小鳔鮈(Microphysogobio kiatingensis)等小型鱼类,29种鱼类的IRI值小于10;平均全长＜10cm的鱼类有24种3620尾,平均体重＜50g的鱼类有47种6493尾,鱼类规格较小,小型化严重。永宁河干流下游种类最多,多样性最高,干流中游鱼类数量最多。受自然环境以及水坝等的影响,永宁河的鱼类分布具有明显的空间差异。水坝类型对鱼类多样性有显著影响;而季节对鱼类多样性影响不显著。无水坝阻隔河段鱼类多样性著高于低头坝和高头坝阻隔河段;夏季的短距离洄游鱼类种数显著高于冬季和春季,但由于数量较少对鱼类多样性的季节性变化影响不明显。各种结果表明水坝阻隔对永宁河鱼类多样性和时空分布存在明显影响,为保护受小型水电站影响河流的鱼类多样性,有必要修复重要鱼类栖息地,适当拆除部分小型水坝,并科学开展增殖放流。     

长江口无脊椎动物群聚特征及其与环境因子的关系

长江口及其邻近海域是连接河流和海洋的重要枢纽,但对该海域生物多样性和相关生态过程,尤其是无脊椎动物群落的了解仍然较少.本研究根据2014年2月、5月、8月和11月4个航次长江口及其邻近海域渔业资源综合调查数据,探讨该海域无脊椎动物群落时空分布特征及其群聚结构变化与环境因子的关系.结果表明: 2014年长江口及其邻近海域4个航次渔业资源调查共采集无脊椎动物35种,隶属于3门10目20科,以甲壳动物(19种)和软体动物(13种)的物种数最为丰富,资源优势种包括葛氏长臂虾、脊腹褐虾、细点圆趾蟹、中国毛虾、三疣梭子蟹和双斑蟳.2014年长江口无脊椎动物丰度和生物量分别为4518.96 kN·km^-2和173.09 kg·km^-2,春季最高,秋季最低.春季和冬季无脊椎动物多样性最高,夏季最低.长江口无脊椎动物各季节群聚结构存在显著差异,冬季、夏季和秋季以南部和北部的差异为主,春季则以近岸和远岸的差异为主.温度和溶解氧驱动无脊椎动物群落季节的时间变异,初级生产水平和营养要素驱动群落季节内的空间变异.     

Length–weight relationships for three freshwater fish species from the Pengxi River (a tributary of the Yangtze River,China)

This study determined the length–weight relationships of three freshwater fish species [Culter oxycephaloides (Kreyenberg & Pappenheim, 1908), Squalidus argentatus (Sauvage & Dabry de Thiersant, 1874), Rhodeus sinensis (Günther, 1868)] from Pengxi River, a tributariy of Yangtze River of China. Fish were collected during 2016 using drift gill nets (mesh size 1, 2 and 3 cm) and cage net (0.5 cm mesh size). For Culter oxycephaloides had no previous length–weight estimates were reported in the science literature. For Squalidus argentatus the present estimate includes a new maximum total length while for Rhodeus sinensis our study confirms the only existing LWR estimate quite well.     

桥边河大型底栖动物生境适宜性

构建精度高,适用性强的水生生物生境适宜性评价模型,为河流生境质量评价和生境修复提供理论依据。以长江一级支流桥边河为例,采用典范对应分析和独立性分析,筛选出影响桥边河大型底栖无脊椎动物优势种河蚬生境质量的关键化学因子和物理因子,利用广义加性模型与多项式拟合模型构建生境因子与生物选择的关系。结果表明:(1)影响桥边河河蚬生境质量的主要因子为COD_Mn、TN、DO、Tur (浊度)和Dep (水深);其中COD_Mn、TN、Tur、Dep与大型底栖无脊椎动物分布成负相关,DO与大型底栖无脊椎动物分布成正相关;(2)桥边河流域河蚬的最适宜COD_Mn含量为1.228 mg/L,最适宜TN含量为0.269 mg/L,最适宜DO含量为11.170 mg/L,最适宜Dep为0.3 m,最适宜Tur为1.130 NTU。(3)线性拟合情况下两种方法均适用;非线性拟合情况下广义加性模型较优于传统多项式拟合模型,且GAM模型在处理离散程度大的数据集时,可以很好的规避多项式拟合过程中出现的过拟合现象。研究显示,运用GAM模型可以更加精确、合理的模...     

Length–weight relationships of three montane fish species from upper Chang River,a tributary of the Poyang Lake,China

Length–weight relationships were estimated for three montane fish species Acrossocheilus fasciatus (Steindachner, 1892), Sarcocheilichthys parvus (Nichols, 1930) and Vanmanenia stenosoma (Boulenger, 1901) from upper Chang River, a main tributary of the Poyang Lake, China. Fish specimens were collected using benthic fyke nets (0.4 × 0.4 × 15 m; mouth opening: 10 × 10 cm; mesh size: 0.5 cm) and electrofishing equipment (12 V) from September 2017 to July 2018 seasonally. New maximum total lengths were recorded for S. parvus and V. stenosoma.     

Distribution of fish in the Virgin River,a tributary of the lower Colorado River

Synopsis The Virgin River, a major tributary of the lower Colorado River, contains a unique, though impoverished, native ichthyofauna (six species) that is largely intact despite the introduction of exotic fishes (13 species) and alterations of the river. The main conclusions of the study are: (1) The longitudinal distribution pattern of the native species does not follow theoretical expectations of a downstream increase in species richness; (2) for the size of the basin (>15,000 km²), the native ichthyofauna is extremely depauperate; and (3) most of the exotic fish are not established in the river, but persist through repeated invasions from downstream reservoirs.     

Length–weight and length–length relationships of seven freshwater fish species from the Daning River,a tributary of the Yangtze River,southwest China

This study determined the length–weight relationships (LWRs) and length–length relationships (LLRs) of seven freshwater fish from the Daning River, a tributary of the Yangtze River, southwest China. Specimens were collected between July 2016 and July 2017 using drift gill nets (mesh size 1, 2 and 3 cm), cage net (0.5 cm mesh size) and electroshock fishing techniques quaterly. Parameter b values of LWRs ranged from 2.647 to 3.276 (r² > .963) and b values of LLRs ranged from 1.091 to 1.213(r² > .985). Six new LLRs and seven new maximum length data are presented. The biometric data and their relationships are relevant to Fishers science to supplement other data sets needed for fisheries management.     

Length–weight relationships for 13 fish species in the Tangwang River,a tributary of Songhua River,China

The present work provides length–weight relationships (LWRs) for 13 fish species belonging to six families. The fishes were collected with gill nets (mesh sizes 10, 20, 40, 60, 90, 120 mm) and set nets (5, 8, 10 mm mesh sizes) from April 2012 to September 2015.     

Diets and trophic‐guild structure of a diverse fish assemblage in Chesapeake Bay,U.S.A.

Dietary habits and trophic‐guild structure were examined in a fish assemblage (47 species) of the Chesapeake Bay estuary, U.S.A., using 10 years of data from >25 000 fish stomachs. The assemblage was comprised of 10 statistically significant trophic guilds that were principally differentiated by the relative amounts of Mysida, Bivalvia, Polychaeta, Teleostei and other Crustacea in the diets. These guilds were broadly aggregated into five trophic categories: piscivores, zooplanktivores, benthivores, crustacivores and miscellaneous consumers. Food web structure was largely dictated by gradients in habitat (benthic to pelagic) and prey size. Size classes within piscivorous species were more likely to be classified into different guilds, reflecting stronger dietary changes through ontogeny relative to benthivores and other guilds. Relative to predator species and predator size, the month of sampling had negligible effects on dietary differences within the assemblage. A majority of sampled fishes derived most of their nutrition from non‐pelagic prey sources, suggesting a strong coupling of fish production to benthic and demersal food resources. Mysida (predominantly the opossum shrimp Neomysis americana) contributed substantially to the diets of over 25% of the sampled predator groups, indicating that this species is a critical, but underappreciated, node in the Chesapeake Bay food web.     

Length–weight relationships for five endemic fish species in the upper Yangtze River basin,China

Length – weight relationships were estimated for five endemic fish species in the upper Yangtze River: Platysmacheilus nudiventris Luo, Le & Chen, 1977, Xenophysogobio nudicorpa (Huang & Zhang, 1986), Homatula potanini (Günther, 1896), Leptobotia rubrilabris (Dabry de Thiersant, 1872), and Euchiloglanis kishinouyei Kimura, 1934. The a values ranged from 0.0079 to 0.0134, and b values from 2.833 to 3.081. These five endemic species are rare, small and difficult to find and capture. Thus the sampling period was lengthy, from May 2010 to May 2014. A total of 718 specimens were available for analysis, and the length – weight relationships are the first reports for these five endemic fish species.     

赤水河鱼类资源的现状与保护

赤水河是长江上游右岸一级支流,为长江上游珍稀特有鱼类国家级自然保护区的重要组成部分。为了了解赤水河鱼类资源现状,于2007年4-10月在赤水河流域进行了鱼类资源调查。在干、支流共51个采样点采集了鱼类标本;对茅台镇、赤水市和合江县三个江段的渔获物进行了统计和分析。共采集到鱼类119种(亚种),隶属于5目16科75属。其中25种为该水域的新记录;34种为长江上游特有鱼类,尤其是宽唇华缨鱼(Sinocrossocheilus labiatus)仅分布于赤水河。在上、中、下游分别采集到鱼类36、61和100种。宽鳍鱲(Zacco platypus)、中华倒刺鲃(Spinibarbus sinensis)、光泽黄颡鱼(Pelteobagrus nitidus)、张氏(Hemiculter tchangi)和蛇鮈(Saurogobio dabryi)为赤水河中主要的经济鱼类,同时,各江段渔获物的组成也存在一定的差别。本研究表明,赤水河流域鱼类种类相对丰富,但过度捕捞和涉水活动导致鱼类资源出现了一定程度的衰减。     

Length‐weight relationships of 77 fish species from the Chishui River,China

Length‐weight relationships are described for 77 fish species belonging to eight families and 56 genera from the Chishui River, a protected tributary of the upper Yangtze River, China. Length–weight relationships for 56 species were unknown to FishBase and new maximum lengths are recorded for 44 species. These results will be useful for fishery research, management and conservation in the upper Yangtze River Basin.     

Seasonal dynamics of guild structure in a bird assemblage of the central Monte desert

Most studies of ecological guilds consider guild membership as a fixed attribute of species, and the guild structure as a fixed attribute of a community. Consequently, almost no study tackled the examination of temporal changes in the guild structure of a particular assemblage. We used data on foraging patterns of central Monte desert birds to assess seasonal differences in resource use by resident species, and to examine seasonal changes in the guild structure of the assemblage. From 1993 until 1999, we quantified the use of foraging substrates, manoeuvres, and height strata, and the utilisation of plants by 18 bird species. Resident species showed different kinds of seasonal dynamics, from no noticeable to drastic changes in their foraging patterns. Seasonal changes in guild structure were remarkable. Only two guilds were present all year round (ground foragers and foliage foragers), although they suffered important species turnover. Three other guilds had a seasonal occurrence: graminivores (during the non-breeding season), arboreal herbivores, and aerial feeders (during the breeding season). Two species changed from one guild to another between seasons. Both presence–absence of migrant species, and changes in the feeding ecology of resident species had an influence on the temporal dynamics of guild structure. These factors appeared to be related with changing resource availability, especially with the birds’ ability for facing lean conditions through migration and with the opportunistic use of seasonally superabundant resources. Our results undermine the trust in studies in which guild structure was assessed irrespective of temporal variations. We show also that guild membership is not a fixed attribute of a species: we should rather evaluate the individuals’ resource use in a given moment to assign them to a guild, instead of obtaining a single measure purporting to represent a species’ fixed attribute.     

Navigation disturbance and its impact on fish assemblage in the East Tiaoxi River, China

We provide the first evidence for navigation impact on resident river fish in China. The survey was conducted in the East Tiaoxi River that discharges into Lake Taihu near Shanghai, on which cargo ship traffic has dramatically increased in the recent economic development period. Water turbidity, ship traffic and other environmental factors were evaluated at 29 sites on the river. In a multiple regression model with the stepwise method, turbidity was significantly correlated with ship traffic (R ² = 0.53). Another survey was conducted at 46 sites in the same area of the river, in which environmental factors were evaluated and fish individuals were electrofished. A generalised linear model with the stepwise method was applied to predict ecological indicators of the fish assemblage (species richness, individual density and Shannon’s diversity index) based on environmental factors. The results showed that the indicators were negatively correlated with turbidity and presence of artificial shore embankment structures. Another analysis further showed that the negative effect of turbid water was especially considerable for fish of smaller size. In conclusion, cargo ship traffic has a negative impact on fish assemblage, especially on smaller individuals, in the East Tiaoxi River. A higher profile for conservation actions and consideration of environmental impacts of such traffic should be given increasing focus for this and other similar East Asian water courses.