Length-Weight Relationships and Condition Factors of 15 Fish Species from the Loémé River Basin (Mayombe, Republic of Congo)

Length-weight relationships and condition factors are among the commonly used parameters to link the length of a fish to its weight. The present study was initiated to find out the growth patterns and overweight status of 15 fish species in the Loémé basin in Mayombe, Republic of Congo. In the period from February 2020 to September 2021, sampling was carried out in eight stations, following a standardised capture method using four gillnets of 10, 12, 15, and 25 mm mesh size and a hawk net of 1.90 m radius with 10 mm mesh size. Length-weight relationships were calculated according to P = aLSb and the condition factor, using K = (P/LSb)* 100. A total of 1153 specimens representing 15 species, 10 genera and 6 families were recorded. The number of specimens ranged from 10 to 214 for Chrysichthys auratus and Enteromius camptacanthus, respectively. The allometry coefficient b minimum of 2.697 for Chromidotilapiamelaniae and maximum of 3.589 for Garraornata, with a mean of 3.03 ± 0.2 is significantly not different from 3 at the 0.05 probability threshold and indicates isometric growth for almost all species, except for E. camptacanthus where b = 2.858 was statistically different from 3 at the same threshold. The positive and high values of the coefficients of determination r2 = 0.787-0.989 of the species, obtained during this study, suggest that weight increases with size in the fish of the Loémé basin. The average condition factor varies from 0.524 ± 0.064 for G. ornata to 4.917 ± 0.440 for C. melaniae.

Fish Species Diversity in Upstream and Downstream of Sittaung River,Bago Region,Myanmar

This research was conducted to generate a primary database on ichthyofauna,distribution and diversities in the upstream and downstream segments of Sittaung River in Bago Region of Myanmar.This study contributes to the information needed on the distribution of river fish in Myanmar.Fish diversities are assessed by calculating the various diversities indices between December,2018 and November,2019.A total of 65 fish species belonging to 9 orders,23 families and 49 genera were recorded.All 65 fish species were found in upstream segment but only 60 species of them were found in downstream segment of the river.In all study sites,Shannon diversity index had value above 3 indicating that the structure of habitat was stable and balanced.Simpson’s index values were close to 1 in all sites indicating that the species richness in the region was satisfactory.The abundance all of above 5%of total catch of Mystus vittatus,M.pulcher,M.cavasius and Erethistes pusillus in their feeding habitat suggested that their upstream and downstream habitats provided suitable feeding conditions.Anguilla bengalensis,Tenualosa ilisha,Mystus gulio,Rita rita and Silonia silondia were least abundant all below 0.1%of total catch showing they could be impacted by unwise anthropogenic activities.Assessing fish species diversity is thus very important to conserve and manage and promote the health of river ecosystem that is necessary for the migration of fish species.

Spatiotemporal distribution of fish eggs and larvae in the Huanghe(Yellow) River estuary, China in 2005–2016

Decreasing fish resources in estuaries is a subject of anthropogenic activities. Studies of the spatiotemporal distribution of fish eggs and larvae can help identify the status and processes underlying recruitment in a fishery. As the fifth largest river estuary in the world, the Huanghe (Yellow) River estuary (HRE) is a typical estuary that has been seriously aff ected by human activities. Annual surveys on ichthyoplankton and environmental factors were conducted in the months of May of 2005 and 2009-2016 in the HRE to investigate the spatiotemporal distribution of fish eggs and larvae and the associated infl uencing factors. A total of 23 and 20 species of eggs and larvae, respectively, were collected. The dominant orders were Perciformes (51.2%) and Clupeiformes (25.6%). The average number of fish species eggs and larvae were 6.0 and 4.1 in average abundance of 0.91 and 0.13 ind./m^3 , respectively. The dominant species were mainly low-commercial-value small-sized fishes, such as Clupanodon punctatus , Harengula zunasi, and Acanthogobius, whereas certain traditional commercial fishes, such as Trichiurus lepturus , and Clupea pallasii, were not seen. Analysis of the fish egg and larval community revealed four temporal assemblages and two spatial assemblages. Salinity was the main factor on the spatial distribution of ichthyoplankton communities, the species number and Shannon-Weiner diversity index (H′) of the fish egg and larval community near the river mouth with lower salinity were signifi cantly lower than the community far away from the river mouth with higher salinity. In addition, increases of water temperature promoted the number and abundance of fish species eggs, and the areas of abundant prey tended to have a more diversified and abundant of ichthyoplankton species. In overall, overfishing, dam construction, and other human activities were the main drivers that led to the substantial decline in fishery resources in the HRE.

MERCURY CONTAMINATION OF FISHES IN THE SECOND SONGHUA RIVER OF CHINA: PRESENT AND HISTORY

The mercury content in 158 fishes and 28 mussels in the Second Songhua river were detected. The range of mercury concentrations in fishes and mussels was 0.02-0.66 mg/kg and 0.002-0.056 mg/kg, respectively. The history change of mercury content in fishes was analyzed in this paper. From upstream to downstream, the average mercury concentrations in fishes increased with the increase of the distance to the headstream, then decreased in the downstream of Wujiazhan town (sampling site). The fact illuminated that the source of mercury contamination was mercury in sediment. In the different species of fishes, the mercury concentration in Parasiburus asvtus was the highest and the order of mercury distribution in fishes was: the mercury value in fishes in the river bottom >that in fishes in the surface and that in predacious fishes>that in herbivorous fishes. In the investigation, there were amount of fishes whose mercury value exceeded the criterion for that in fishes that suggested that the mercury contamination in the Second Songhua River have not completely been eliminated until now.

PRIMARY FISH SURVEY IK THE HUANGHE RIVER ESTUARY

The survey in the, Huanghe River estuary indicated that the 85 fish species found there comprised three faunal elements: warm-water species (29.4%), warm-temperate species (55.3%) and cpld-temperate species. (15.3%). The seasonal changes of fish species, density and bipmass are obvious. The total biomass is highest (7699t) in August and lowest(489 t) in January. Setipinna taty has mean density of 9278 indiv/km2, and is the most important species constituting 25.5% of the total weight of fish caught. Trichiurus haumela was a dominant species in the 1950s, but no one was caught in this survey. There were obvious changes of the dominant fish species during the recent three decades. The demersal fish biomass has dropped greatly to only 1/10 in over 50 years since 1930.

Bioaccumulation of Some Heavy Metals in Fish Samples from River Benue in Vinikilang, Adamawa State, Nigeria

This study was aim to determined the levels of some heavy metals in the gills, liver, stomach, kidney, bones and flesh of four fish species (Tilapia zilli, Clarias anguillaris, Synodentis budgetti and Oreochronmis niloticus) collected at River Benue in Vinikilang, Adamawa State, Nigeria for analysis of Cu, Zn, Co, Mn, Fe, Cr, Cd, Ni and Pb. These metals were chosen because at higher concentrations there might be toxic to the fish and by extension humans that depends on such fish as food. The concentrations of the metals were carried out using Flame Atomic Absorption Spectrophotometer (AAS, Unicam 969). Large differences in trace metal concentrations were observed between different tissues within each fish. The highest concentration of Fe (12.65 μg/g) was recorded in gill of Synodentis budgetti, while the lowest value of 0.68 μg/g was recorded in the flesh of Oreochronmis niloticus. The liver of Synodentis budgetti accumulates significant higher levels of Mn and Cd than other species;Fe and Zn was highest in the stomach of Tilapia zilli, while Clarias angullaris shows more of Cr, Pb, Cd and Co. The stomach of Synodentis budgetti accumulate significant higher levels of Fe than other species;Zn was highest in the stomach of Tilapia zilli, while Clarias angullaris shows more of Mn, Cr, Cu, Cd and Pb. Similarly, the bone of Synodentis budgettiaccumulates significant higher levels of Mn and Cd than other species;Zn and Fe were highest in the bone of Tilapia zilli, while Clarias angullaris shows more of Cr, Pb, Ni, and Co. The highest levels of Fe (12.65 μg/g) observed in this study was recorded in the gill of Synodentis budgetti and it was below the high residue concentrations of Fe (34 - 107 ppm) in fish samples. Based on the above results, it can therefore be concluded that metals bioaccumulation in the entire fish species study did not exceeds the permissible limits set for heavy metals by FAO, FEPA and WHO.

FISH ASSEMBLAGE RESPONSES TO DIFFERENT SECONDARY CHANNEL DESIGNS IN THE LOWER MISSISSIPPI RIVER,U.S.A.:A TEMPLATE FOR RIVER RESTORATION

The lower Mississippi River(LMR) has been heavily modified for multiple human purposes such as navigation, flood control, and bank stabilization. However, the LMR simultaneously supports a diverse fish fauna that includes recreational and commercial fisheries. Due to river training and diversion structures constructed during the past 80 years, the historic characteristics of the LMR have been drastically altered and have likely influenced fishes and fisheries in the system. One common restoration measure used throughout the LMR has been to "notch" wing-dike structures that close secondary(side) river channels. Dike notching allows year-round flows through secondary channels, which enhances habitat diversity and promotes biological productivity at the ecosystem scale. Although notching is presumed good for LMR fishes and other biota, few studies have examined its effects on fish assemblages. In this study, fish assemblages were sampled at seven LMR secondary channels spanning from river kilometer(rkm) 628(Louisiana-Mississippi, U.S.A.) upstream to rkm 1504(Missouri-Kentucky, U.S.A.). Four secondary channels were termed "permanent"(i.e.,with notched dikes) while three secondary channels were termed "temporary"(i.e., without notched dikes).Fishes were sampled by boat-mounted electrofishing conducted during falling and low stages from1995—1997. Fish assemblages differed between permanent and temporary secondary channels, and varied somewhat between falling and low stages. Gizzard shad(Dorosoma cepedianum), threadfin shad(D. petenense), and white bass(Morone chrysops) demonstrated consistent preferences for low-current conditions associated with temporary secondary channels. Conversely, blue catfish(Ictalurus furcatus), flathead catfish(Pylodictis olivaris), and freshwater drum(Aplodinotus grunniens) were more associated with permanent secondary channels. Future restoration strategies in the LMR should consider dike notching and resultant maintenance of permanent secondary channels in selected river reaches. However, temporary secondary channels also contain unique fish species, and also appear to be important sites of riverine primary production. Restoration strategies should consider a balance of both secondary channel types, which should support the greatest biodiversity for the LMR ecosystem.

Constructing the Ontology for Modeling the Fish Production in Pearl River Basin

This paper puts forward a construction method based on ontology for the Pearl River Basin fish production, to facilitate the domain knowledge analysis and information retrieval. By converting the concepts and terms in domain ordinally, the fish production ontology was constructed with the definition of classes, properties, instances, and relationships. The developed ontology model of the fish production knowledge is proposed and applied in the system of fish diseases diagnosis primarily. The research lays the semantic foundation for the further efficient knowledge management and practical application.

A Study about Effects of River Water Quality on Fish Living in Büyük Menderes Basin, Turkey

The measurements for the quality of the water were made at eight stations of Adügüzel Dam, Yenice Regulator, Sarayköy Bridge, Feslek Regulator, Yenipazar Bridge, Aydιn Bridge, Koçarlι Bridge, Söke Regulator located at the Buyuk Menderes River, Turkey. The study was conducted for the period between 2000-2013 for the months of February, April, June, August, October and December. The results received were analyzed for temperature, pH, EC, Cl-, Na, Ca2+, Mg2+, K+, , TDS, TH and SS aquaculture. The results of the analyses revealed that although the water pollution in the river showed variations throughout the year, in fact the samples obtained at various locations displayed high levels of pollutants. The “Regulation on Turkish Water Pollution Control” was made use of in classifying the parameters of the water in this study. These parameters were compared with the WHO Guidelines and TS-266. Among the 8 Dams that were included in the study, the best quality of water was measured in the Adügüzel Dam, which gave the lowest values;and the levels were measured to be higher in the Saraykoy Station than those of the other dams. There was a severe drought in Menderes Basin in 2007, and therefore the highest annual values were measured for the year 2007. In those years, the levels of the irrigation water decreased as low as 4255 m3/ha. The SPSS 21 Statistical Analysis Program was made use of in analyzing the data of the study. The One-Way Anova and Tukey Multiple Comparison tests were also used for the analyses of the data as well. The p < 0.05 level was accepted as being significant in the analyses. The distribution of the data was performed by using the Box-plot Graphs. Furthermore, the effects on fish species and the pollution in Büyük Menderes River were also examined in the study.

Influence of Floodplain Area on Fish Species Richness in Waterbodies of the Chao Phraya River Basin, Thailand

River-floodplain ecosystems are in delicate balance and are impacted by even minor changes in water availability. In this study, we surveyed fish assemblages and investigated environmental and landscape parameters in a total of 135 floodplain waterbodies (rivers, diversion canals, ponds, irrigation ditches, paddy fields, and wetlands) in the Chao Phraya River Basin in rainy (September 2014) and dry (March 2015) seasons. Factors affecting fish species richness in each type of waterbody were analyzed using generalized linear mixed models. Floodplain area around each surveyed waterbody was a major factor determining fish species richness in rivers, diversion canals, and ponds in the region. The contribution of floodplain area was equivalent to that of hydrology (current velocity, water depth) and water quality (dissolved oxygen, turbidity) in the waterbodies. The population of juvenile fishes was increased in temporarily connected floodplain waterbodies to main rivers compared with isolated waterbodies, and fluvial and lacustrine fishes were observed in the temporary inundated floodplain waterbodies during the rainy season. The high dependence of fish species richness on floodplain area in the region appeared to be a result of the use of inundated floodplains by fish species to forage and breed. Our results highlight the impact of flood control measures that reduces floodplain area. These measures must be reviewed to ensure the conservation of fish biodiversity in the Chao Phraya River Basin, one of the world’s most threatened floodplain systems.

The Pulses of the Mekong River Basin: Rivers and the Livelihoods of Farmers and Fishers

The transboundary Mekong River is shared by six SE Asia countries (China, Myanmar, Thailand, Lao PDR, Cambodia, and Vietnam). In this paper the livelihoods of farmers and fishers of Lao PDR, Cambodia and Vietnam are examined to assess impacts of Mekong River development and modernization projects on the rural peoples of the Mekong River and Delta. A high proportion of the 190 million rural people of the Mekong basin are dependent on the diverse and abundant resources of the Mekong River and its tributaries for food security and basic necessities, livelihoods, and cultural identities. Although rice farming and fisheries occupations are primary income sources, many livelihoods involve a diversity of on-farm and off-farm activities. Agricultural specialization and intensification and hydropower dam construction on the Mekong main stem and tributaries are altering traditional rural patterns of household food security, income, and cultural ways of living at an increasingly rapid pace. Rural transformation projects must better assess how these modernization efforts change the ecology of the Mekong River and in turn affect the capacity of rural people to adapt in ways that ensure food security and improve household livelihoods. It will be critical that development efforts recognize, value, and invest in rural people’s roles in producing a stable, affordable food system and managing the integrity of river ecosystems upon which future prosperity depends. Interventions are needed to prevent degradation of the Mekong Basin soil and water resources from large-scale agricultural intensification, water diversion and overbuilding of hydropower dams which are threats to small-scale land holdings and farmers and fishers capacities to provide daily food for their own consumption and to feed SE Asia’s growing urban populations.

Fish Assemblage Responses to a Low-head Dam Removal in the Lancang River

Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam removal on fish communities in Asian mountainous rivers, which are dominated by Cypriniformes fishes, are still not well known. To determine whether dam removal on a mountainous river benefit restoration of fish diversity, we investigated the response of fish assemblage to dam removal using a before-after-control-impact design in two tributaries of the Lancang River(dam removal river: the Jidu River, and control river: the Fengdian River). Fish surveys were conducted one year prior to dam removal(2012) and three years(2013–2015) following dam removal. We observed rapidly and notably spatio-temporal changes in fish biodiversity metrics and assemblage structure, occurring in the Jidu River within the first year after dam removal. Overall, fish species richness, density and Shannon-Wiener diversity all increased immediately in above-and below-dam sites, and maintained a stable level in subsequent years, compared to unchanged situation in the control river. All sites in the Jidu River experienced shifts in fish composition after dam removal, with the greatest temporal changes occurred in sites below-and above-the former dam, resulting in a temporal homogenization tendency in the dam removed river. These findings suggest that dam removal can benefit the recovery of habitat conditions and fish community in Asian mountainous rivers, but the results should be further evaluated when apply to other dammed rivers since the dam age, fluvial geomorphology and situation of source populations could all affect the responses of fish assemblages.

蓄水后向家坝库区鱼类物种、分类和功能多样性变化

为了解向家坝水电工程对金沙江下游鱼类多样性的影响,基于2016-2018年邵女坪(库首)、绥江(库中)和桧溪(库尾)3个江段的鱼类群落调查数据,分析了向家坝库区鱼类物种、分类和功能多样性空间格局,结合蓄水前(2011年)和蓄水初期(2015年)的资料,探讨了蓄水后向家坝库区不同维度鱼类多样性的变化趋势。向家坝库区各江段以广适性的瓦氏黄颡鱼(Pelteobagrus vachelli)和静水性的■(Hemiculter leucisculus)占优势,两者的数量百分比分别为30.15%±14.82%和13.91%±11.16%。非度量多维尺度分析显示,蓄水后向家坝库区库首邵女坪和库中绥江鱼类群落差异最小,库首邵女坪和库尾桧溪鱼类群落差异最大;库中绥江在蓄水前、蓄水初期和2016-2018年3个时期的鱼类群落差异均较大,表明蓄水后绥江江段鱼类群落经历了剧烈变化。库区不同江段鱼类Margalef丰富度指数、Shannon-Wiener多样性指数和Pielou均匀度指数均表现为:桧溪>邵女坪>绥江,鱼类分类多样性指数和分类差异指数均表现为:桧溪>绥江>邵女坪。库区鱼类摄食、运动和繁殖等不同维度的功能多样性(功能丰富度、功能均匀度、功能离散度)空间格局不同,但总体上库中绥江鱼类功能丰富度最高,功能均匀度最低。与蓄水前相比,绥江江段鱼类物种、分类多样性呈下降趋势,鱼类功能丰富度和均匀度也有下降趋势。蓄水后绥江江段鱼类群落主要功能性状发生了明显变化,如蓄水前以下位口、纺锤形体型鱼类占优势,蓄水后以端位口、侧扁形体型鱼类占优势。不同维度多样性指数侧重于鱼类多样性的不同方面,结合多种指数分析有利于更全面地了解鱼类群落对环境变化和外界干扰的响应。研究结果有助于深入了解水电工程建设对金沙江下游鱼类多样性的影响,为鱼类多样性保护提供依据,也可为长江“十年禁渔”效果评估提供本底资料。

An Evaluation of Artificial Fish Nest for Assessment Enhancement Effects of Fishery Resources of in Xiangjiang River

Artificial fish nests are set in Lukou section and Hengyang section of Xiangjiang River from March 20 to May 10, 2019. The structure of artificial fish nest is bamboo frame, with the size of 2.5 m × 5.0 m × 4 and a unit frame area of 60 m2. A total of 58,201 eggs were collected by 24 monitoring times, of which 30,441 were from Lukou and 27,760 from Hengyang. 3831 fish eggs identify 8 fish species using morphological or molecular biological methods. The results showed that the number of eggs peaked from the 8th day to the 24th day after the nest entered the water, and then decreased rapidly. There was significant negative correlation between egg number in per m2 fish nest and days of fish nest (P < 0.01). The economic benefits of artificial fish nests were RMB 11.81 million. The artificial fish nest can not only increase the population of fish, but also has significant economic benefits.

基于耳石微化学的长江禁捕前后鄱阳湖都昌水域刀鲚群体动态变化研究

为了解长江禁捕对鄱阳湖都昌南部水域刀鲚(Coilia nasus)资源的影响,利用电子探针微区分析(EPMA)分别对该水域禁捕前(2014年)和禁捕后(2019年)刀鲚的洄游生态学特征开展了研究。结果显示,所有刀鲚个体耳石自核心至边缘均依次具有锶钙比(Sr/Ca×1000)<3、3~7以及<3的生境履历特征,表现为典型的溯河洄游履历。禁捕后刀鲚数量(17尾)明显多于禁捕前(2尾),体长[(28.1±2.3)cm]也长于禁捕前[(21.3±4.7)cm],且长于禁捕前的已有报道。此外,刀鲚耳石边缘低值区呈现多样化特征[2014年(125.0±63.6)μm、80~170μm,2019年(173.5±73.6)μm、20~290μm],表现出多个上溯群体在该水域混栖的现象。结合该水域多数个体性腺尚未成熟,且都昌南部水域(大矶山至和合乡水域)是刀鲚群体自江湖通道出入鄱阳湖中部和南部湖区及通湖河流(如饶河、信江等)的必经之路,得出都昌水域主要行使刀鲚洄游通道的生态功能,亟须加强保护。

贴沙河环城东路段鱼类群落结构及多样性调查

于2020年11月—2022年6月,对贴沙河环城东路段鱼类群落结构及多样性进行了调查。结果表明,共采集鱼类28种,隶属于5目6科,其中,鲤科鱼类物种数最多,占78.57%。群落Shannon-Wiener多样性指数、Margalef丰富度指数、Pielou均匀度指数分别为1.54~2.32、2.06~3.67、0.70~0.93。单因素方差分析表明,该群落多样性夏秋差异、空间差异均不明显(p>0.05)。贴沙河水域鱼类群落优势种为银鲫、鲢和鳙;5种摄食功能群中,杂食性(50.00%)和肉食性(28.57%)鱼类物种数比例较高;3种生态类群中,淡水定居性鱼类占绝对优势(89.29%)。指出,贴沙河鱼类群落多样性较高,群落相对稳定;外来物种数较多,质量占比高;土著性鱼类个体小型化趋势明显。

Evaluation of Health Risks Related to the Consumption of Fish from the Guéssabo River

Fish is rich in essential nutrients but can remain a potential source of food poisoning. A study was, therefore, carried out with the general objective of highlighting the probable biological and chemical dangers associated with the consumption of fish and freshwater fruits from the Guéssabo river. The present study was conducted on 50 carp fish, 50 mackerel fish, 50 frogs and 50 mollusks caught in the Guéssabo River. Microorganisms were enumerated by conventional tests and heavy metals were investigated by Inductively Coupled Plasma Optical Emission Spectrometry. The enumeration showed high levels of thermotolerant Coliforms (2.5 × 104), Enterobacteriaceae (3.4 × 104), S. aureus (2.3 × 103) and Yeast/Molds (2.1 × 104), in all samples the standards were not in conformity with the required standards. High levels of Al (7230 μg/kg) and Cd (21.57 μg/kg) were observed in carp fish and these values are above the standard. In conclusion, the fish caught in the Guéssabo River could be a health risk factor for the consumer.

祖厉河水生生物群落结构特征及多样性评价

大型底栖动物及鱼类是河流水生态健康评价的主要物种,针对祖厉河水生生物现状底数不清、生物群落结构不明现状,选取干流及最大支流的5个水文断面对大型底栖动物和鱼类进行监测,分析其组成、密度及生物量,采用香农-威纳多样性指数和BMWP指数对其多样性分布格局、时空分布特征进行评价,并探索分析了水生生物多样性与水质环境的相关性,为祖厉河生态保护治理提供技术支撑。调查结果显示,大型底栖无脊椎动物28属种,隶属于3门3纲,其中,节肢动物24属种,占总种数的78.57%,为优势种。鱼类种数较少,共有7种,均隶属于鲤形目,斯氏高原鳅为优势种。从水生生物香农-威纳多样性指数来看,祖厉河大型底栖无脊椎动物的多样性为中等,BMWP指数为较差,而鱼类多样性总体较差。干流和支流的大型底栖无脊椎动物都呈现上游大于下游、夏季大于秋季的趋势。祖厉河支流的鱼类较干流较多。同时,水生生物多样性与水质环境相关分析显示,水温、高锰酸钾指数、氨氮、总氮、总磷、溶解氧是影响底栖动物群落结构及生物多样性的主要驱动因子;鱼类的种类数与氨氮呈显著性负相关(p>0.05),水温与香农-威纳多样性指数呈显著性负相关(p>0.05),由于鱼类种数较少,相关性显著不明显。

鳗苗网兼捕主要经济鱼类潮汐分布调查

为了解长江口北支邻近水域鳗苗网兼捕主要经济鱼类在大小潮期间的分布特征,于2022年2—4月,在该水域设置3个站点,分别在3个大潮和3个小潮期间开展调查。结果表明,主要经济鱼类包括2种洄游性鱼类(刀鲚和凤鲚)、4种海洋性鱼类([鱼免]黄鱼、小黄鱼和半滑舌鳎);共采样72网次,采集到经济种个体数为374尾。刀鲚、凤鲚、[鱼免]、大黄鱼最高单位努力渔获量(CPUE)均出现在大潮期间,小黄鱼CPUE最高值则出现在小潮期间,半滑舌鳎大小潮CPUE值一致。大黄鱼、小黄鱼和半滑舌鳎在大潮期间的体长和体质量中位数均大于小潮期间。刀鲚、凤鲚和[鱼免]最高损伤率均出现在大潮期间的3月1—4日。指出,长江口北支的鳗苗定制网,成为多种经济鱼类洄游通道上的重大阻碍,严重损害其早期资源的可持续发展。

福州城区内河主要野生鱼类体内抗菌药物残留调查与分析

目的:为更好评价福州内河治理后的生态环境,在福州城区内河首次开展主要野生鱼体内6类抗菌药物残留调查。方法:以光明港、晋安河、白马河和凤坂河等4条福州主要内河水系为调查对象,共布设11个调查站位;并分别于2021年12月和2022年6月共采集27份样品,参照GB/T 22955-2008、GB/T 20762-2006等标准方法进行检测。调查结论:福州城区内河生态环境未受大部分常用抗菌药物污染,总体情况良好。