Applicability of the flood‐pulse concept in a temperate floodplain river ecosystem: thermal and temporal components

Annual growth increments were calculated for blue catfish (Ictalurus furcatus) and flathead catfish (Pylodictis olivaris) from the lower Mississippi River (LMR) to assess hypothesized relationships between fish growth and floodplain inundation as predicted by the Flood‐Pulse Concept. Variation in catfish growth increment was high for all age classes of both species, and growth increments were not consistently related to various measures of floodplain inundation. However, relationships became stronger, and usually direct, when water temperature was integrated with area and duration of floodplain inundation. Relationships were significant for four of six age classes for blue catfish, a species known to utilize floodplain habitats. Though similar in direction, relationships were weaker for flathead catfish, which is considered a more riverine species. Our results indicate the Flood‐Pulse Concept applies more strongly to temperate floodplain‐river ecosystems when thermal aspects of flood pulses are considered. We recommend that future management of the LMR should consider ways to ‘recouple’ the annual flood and thermal cycles. An adaptive management approach will allow further determination of important processes affecting fisheries production in the LMR. Copyright © 2006 John Wiley & Sons, Ltd.     

MANAGING THE FLOOD PULSE FOR OPTIMAL FISHERIES PRODUCTION IN THE ATCHAFALAYA RIVER BASIN,LOUISIANA (USA)

The Atchafalaya River Basin in south‐central Louisiana (USA) comprises the largest contiguous river–floodplain swamp in North America and functions as a distributary for the Mississippi River to the Gulf of Mexico. We assessed the impact of the annual flood pulse on fisheries production at a basin‐wide scale. We modelled flood duration (days/year Butte LaRose gauge height >3.6 m) and magnitude (mean daily gauge height) against long term (1987–2009) fishery‐independent and fishery‐dependent data on largemouth bass (Micropterus salmoides), crappie (Pomoxis spp.), blue catfish (Ictalurus furcatus), buffalofish (Ictiobus spp.), gizzard shad (Dorosoma cepedianum) and crayfish (Procambarus spp.). When the Atchafalaya River at Butte LaRose is at flood stage (≥ 3.6 m gauge height) for approximately 121–157 days/year, then annual relative abundances of largemouth bass, crappie, blue catfish and buffalofish are optimized during the fall (October–December). In contrast to the tenets of the flood pulse concept, gizzard shad abundance was optimized during low flow years, when flood duration is ≤10 days/year. Annual proportion of age‐1 largemouth bass was associated positively with flow magnitude during the previous year, whereas proportions of age‐2 largemouth bass and crappie were associated positively with flood magnitude 2 years prior to the fish sample. Results for commercial production metrics were ambiguous. Crayfish catches were associated positively with flood magnitude and duration, whereas gizzard shad landings peaked at a relatively small flood magnitude level and were not related to flood duration. Blue catfish and buffalofish annual landings were not influenced by the annual flood pulse. The annual flood pulse can be managed to optimize the availability of recreational (largemouth bass and crappie) and some commercial fisheries resources (blue catfish and crayfish). We estimate that a minimum discharge of 8807 m³ s^?1 is required at the river's source for approximately 4–5 months during the winter–spring months to optimize fisheries production. Copyright © 2011 John Wiley & Sons, Ltd.     

Recruitment Sources of Channel and Blue Catfishes Inhabiting the Middle Mississippi River

Insight into environments that contribute recruits to adult fish stocks in riverine systems is vital for effective population management and conservation. Catfishes are an important recreational species in the Mississippi River and are commercially harvested. However, contributions of main channel and tributary habitats to catfish recruitment in large rivers are unknown. Stable isotope and trace elemental signatures in otoliths are useful for determining environmental history of fishes in a variety of aquatic systems, including the Mississippi River. The objectives of this study were to identify the principal natal environments of channel catfish Ictalurus punctatus and blue catfish Ictalurus furcatus in the Middle Mississippi River (MMR) using otolith stable oxygen isotopic composition (δ¹⁸O) and strontium : calcium ratios (Sr : Ca). Catfishes were sampled during July–October 2013–2014, and lapilli otoliths were analysed for δ¹⁸O and Sr : Ca. Water samples from the MMR and tributaries were collected seasonally from 2006 to 2014 to characterize site‐specific signatures. Persistent differences in water δ¹⁸O and Sr : Ca among the MMR and tributaries (including the upper Mississippi, Illinois, and Missouri rivers as well as smaller tributaries) were evident, enabling identification of natal environment for individual fish. Blue and channel catfish stocks in the MMR were primarily recruited from the large rivers (Missouri and Mississippi) in our study area, with minimal contributions from smaller tributaries. Recruitment and year class strength investigations and efforts to enhance spawning and nursery habitats should be focused on in large rivers with less emphasis on smaller tributaries. Copyright © 2016 John Wiley & Sons, Ltd.     

The Importance of Shallow‐Low Velocity Habitats to Juvenile Fish in the Middle Mississippi River

Habitat management is a crucial aspect of fisheries management. Without knowledge of habitat associations, fisheries scientists are unable to effectively make habitat conservation or restoration recommendations. This becomes especially prominent when trying to manage commercially harvested populations and protect threatened or endangered species. To determine juvenile fishes habitat associations in the Middle Mississippi River, we analysed mini‐trawl catch data of six common juvenile fish species: blue catfish (Ictalurus furcatus), channel catfish (Ictalurus punctatus), channel shiner (Notropis wickliffi), freshwater drum (Aplodinotus grunniens), paddlefish (Polyodon spathula), and shovelnose sturgeon (Scaphirhynchus platorynchus). Overall, we conducted 2251 mini‐trawl sampling efforts between 2002 and 2013, resulting in the capture of 23,742 target specimens. Catch per unit effort was evaluated by structural habitat (i.e. velocity, depth, and substrate). Overall, these data suggest that juvenile fish species are more prevalent in shallow water and slower velocities. Ultimately the information garnered during this evaluation should be incorporated when considering habitat modifications, especially those modifications that impact the availability of shallow‐low velocity habitats. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of nutrient enrichment on channel catfish growth and consumption in Mount Storm Lake, West Virginia

With the objective of augmenting fish production in Mount Storm Lake, Virginia Electric and Power Company initiated a programme of phosphorus addition to increase primary production, and ultimately, channel catfish ( Ictaturus punctatus ) growth in the 486 ha cooling reservoir. We simulated channel catfish growth dynamics using two bioenergetics modelling scenarios: (i) effects of average reservoir temperature on growth, conversion efficiency and consumption; and (ii) effects of reservoir enrichment on growth, which is simulated by increasing feeding rates. During 1991–1993, fish were sampled monthly, but sampling was increased to every 2 weeks during the peak growing season (June–September). Most of the channel catfish collected were aged 0 year and aged 1 year with rapid annual growth rates ranging from 9.0 to 13.7 J/g. We found many age 1 250–300 mm catfish, but few beyond this size. Conversion efficiency (joules gained/joules consumed) was low at approximately 18–19%. High algae consumption (40%) was evident, but consumption of zooplankton and Asiatic clam ( Corbicula sp.) increased over the study. Simulated increased feeding rates showed that channel catfish were food limited in summer and fall (July–December). Weight gains with 5 and 10% feeding increases were 6–13% and 18–38%, respectively, from the baseline. Catfish of all sizes should benefit from phosphorus additions.     

Distribution,movements and habitat use of channel catfish in a river with multiple low‐head dams

Channel catfish Ictalurus punctatus is a highly mobile species and is known to make extensive seasonal movements in lotic systems. Dams have been suggested to detrimentally affect this species, although abundant channel catfish populations are known to occur in many fragmented rivers. To examine factors that allow channel catfish to persist in impounded rivers, we assessed relative abundance of channel catfish in three impounded and three flowing sites of the Fox River, Illinois, USA. Radiotelemetry was used to determine movement and habitat use patterns of channel catfish among flowing and impounded areas. Relative abundance of channel catfish was consistently higher at flowing sites than at impounded sites during summer. Several radio‐tagged channel catfish moved downstream into impounded areas in fall, and all tagged individuals were found in impounded areas during winter. The majority of tagged channel catfish moved upstream into flowing areas during spring. Channel catfish used a wide range of depths (0.28–2.60 m), and were always found in current velocities less than 0.50 m s^?1. They selected most strongly for coarse substrates, but were infrequently found near cover. Although low‐head dams restrict the movements of channel catfish, impounded areas appear to provide overwintering habitats that may eliminate the need for seasonal long‐distance movements. Small run‐of‐river impoundments, however, may contain unsuitable conditions for channel catfish during other seasons. Copyright © 2010 John Wiley & Sons, Ltd.     

Longitudinal patterns in flathead catfish relative abundance and length at age within a large river: effects of an urban gradient

We investigated the spatial variation of flathead catfish (Pylodictis olivaris) relative abundance and growth in the 274 km long Kansas River to determine if population dynamics of catfish are related to urbanization. Electrofishing was conducted at 462 random sites throughout the river in summer, 2005–2006 to collect fish. Relative abundance of age 1 fish (≤200 mm), subadult (>200–400 mm) and adult fish (>400 mm) ranged from 0.34 to 14.67 fish h^?1, mean length at age 1 was 165 (range: 128–195) mm total length (TL) and mean length at age 3 was 376 mm TL (range: 293–419 mm TL). The proportion of land use within 200 m of the river edge was between 0 and 0.54 urban. River reaches with high relative abundance of age 1 flathead catfish had high relative abundance of subadult and adult catfish. River reaches with fast flathead catfish growth to age 1 had fast growth to age 3. High urban land use and riprap in the riparian area were evident in river reaches near the heavily populated Kansas City and Topeka, Kansas, USA. Reaches with increased number of log jams and islands had decreased riparian agriculture. Areas of low urbanization had faster flathead catfish growth (r = 0.67, p = 0.005). Relative abundance of flathead catfish was higher in more agricultural areas (r = ?0.57, p = 0.02). Changes in land use in riverine environments may alter population dynamics of a fish species within a river. Spatial differences in population dynamics need to be considered when evaluating riverine fish populations. Published in 2008 by John Wiley & Sons, Ltd.     

Fish catch and fishing practices in the Nam Theun 2 Reservoir and watershed (Lao PDR)

A fish catch and fishing practice monitoring survey were conducted from 2008 to 2014 in villages adjacent to the Nam Theun 2 Reservoir and its upstream tributaries. The reservoir fisheries exhibited – the three expected phases following impoundment (i.e. trophic upsurge, trophic depletion and stabilization, respectively). This study focused on assessing fish catches and fishing practices from communities living next to the reservoir, and those living upstream of the reservoir, over these phases, and to identify factors that could influence total fish catch. The fish catch appeared to be higher among communities located next to the reservoir, compared to communities living in upstream areas. Fish catches in the upstream tributaries remained relatively stable after impoundment, with a slight increase in the average catch. The reservoir exhibited a low fish yield, compared to similar reservoirs, which could be linked to its oligotrophic status. The majority of the total catch biomass of the reservoir was comprised primarily of two species (i.e. Oreochromis niloticus; Hampala macrolepidota) since a stabilization of the catches was observed. Reservoir fisheries appeared to be mainly driven by hydrological factors, specifically the influence of the rainy season peak. The results of this study indicated no over‐exploitation of fisheries occurred overall, although the fishery resource is still fragile. Fishing activities are known to occur in protected zones (productive areas with large inundated habitat areas), with higher annual total catch being observed during periods of poor enforcement of these zones. As fisheries have become an important income source for villagers living along the NT2 Reservoir, regulation and adequate management of the reservoir are recommended to maintain the reservoir fisheries as a sustainable activity.     

棘洪滩水库浮游藻类变化及富营养化防治

详细分析了2004~2006年度棘洪滩水库浮游藻类的细胞密度及种群结构变化。2004年进水口与放水口藻类细胞密度年均值分别为3.892×106/L和2.269×106/L,冬季以硅藻为主,春季以隐藻、金藻为主,夏、秋季以蓝藻为主。2005年进水口与放水口藻类细胞密度年均值分别为6.654×106/L和5.903×106/L,冬、春季以硅藻、隐藻为主,夏季以绿藻为主,秋季则以蓝藻为主。2006年进水口与放水口藻类细胞密度年均值分别为3.001×106/L和3.687×106/L,夏末至秋季绿藻占优势,代替了先前在此阶段占优势的蓝藻,其他季节多以硅藻为主,隐藻和金藻分别在冬季和春季占有一定比例,说明2006年的水质状况较2004年、2005年有所改善。棘洪滩水库藻类峰值出现在夏末和秋季,此阶段水库的水质呈中富营养状态,其他月份为中营养或贫营养状态。Shannon-weaver多样性指数显示,目前水库的水质总体呈中度污染。入库的源水质量对水库水质影响很大,控制引入的源水质量并采取相应的生物防治措施可有效避免水库发生富营养化。     

Investigating reservoir sedimentation and its implications to watershed sediment yield: The case of two small dams in data‐scarce upper Blue Nile Basin,Ethiopia

Bathymetric and sedimentation surveys were conducted with a sonar‐based depth gauge system in two small reservoirs (Selamko and Shina) in the data‐scarce upper Blue Nile Basin, Ethiopia. Bathymetric survey data were merged within geographic information system (GIS ) software to provide detailed visualization and analyses of current depths. Preimpoundment topographic information was obtained from dam owners and designers. Bathymetric differencing was used to investigate and quantify the distribution and estimate volumes of deposited sediment, long‐term average annual sediment fluxes and remaining water storage capacity. Calculated long‐term average sediment accumulation rates were used to estimate remaining lifetimes of each reservoir. Results from the depth sonar surveys and GIS analyses suggest a projected lifetime of ~7 years for Shina Reservoir, compared to a projected lifetime of ~22 years for Selamko Reservoir. It also indicated the annual average sedimentation rate for both reservoirs was greater than the global average of one per cent (1.67% for Shina Reservoir; 2.295% for Selamko Reservoir). The specific sediment yield (SSY ) is relatively larger for both watersheds (2,499 and 4,333.6 t km^?2 year^?1 for Shina and Selamko, respectively) indicating the watersheds are degraded by any global standard. The Revised Universal Soil Loss Equation (RUSLE ) model‐generated erosion magnitude was only slightly larger from the watersheds of both reservoirs, compared to the bathymetric estimates. These data and analyses also provide a baseline relevant to understanding sedimentation processes and are necessary for developing long‐term management plans for these reservoirs and their watersheds.     

汾河水库蒸发渗漏水量损失分析计算

采用简易公式计算及实测资料水量平衡计算两种方法,计算出汾河水库库区年均各种水量损失占年来水量的8.76%.     

基于SWAT的北江流域蓝绿水评估及其干旱响应

为探究北江流域的水资源状况及其在不同程度干旱下的变化特征,利用SWAT模型模拟北江流域径流过程,并在此基础上评估北江流域的蓝绿水资源时空变化及其对干旱的响应特征.研究表明:北江流域水资源以蓝水为主,多年平均蓝水量为1149.08 mm,绿水量为981.08 mm,绿水系数为0.48;1966-2010年间,北江流域蓝绿...     

三峡水库蓄水后上下游河段水沙特性变化及影响因素分析

泥沙淤积问题是三峡工程的关键技术问题之一,关系着长江水资源的开发利用、生态环境保护、经济发展。基于2002-2016年期间,三峡水库上、下游设置的11所重要控制性水文站水文泥沙监测资料,深入系统地探讨水文泥沙参量的变化特征,进一步分析水文泥沙参量的相关性和三峡水库的冲淤特性,探究了泥沙特性变化的原因。研究结果表明:三峡水库自施工期蓄水、初期蓄水、试验性蓄水的整个过程,对三峡水库上下游河道的水沙特性影响较大。越靠近三峡大坝的河段,受三峡水库的影响越大;三峡水库抬高水位,导致上游大部分河道流速变小,河道过水断面和水动力条件发生改变,导致入库泥沙越来越少,越来越细;三峡水库上游长江干流和支流上修建的梯级电站拦蓄了大量的泥沙,年输沙量、年均含沙量、中值粒径、年输沙模数都显著降低。年径流量和输沙量、年均含沙量、年输沙模数在2004-2013年间具有较好的相关性,曲线变化规律类似,2013年后受三峡水库蓄水的影响,出现弱相关;年径流量能表征泥沙参量的变化特性;年输沙量和年均含沙量在2002-2016年间皆具有较好的相关性。2007年前三峡水库淤积量呈增长趋势,其后三峡水库泥沙淤积量逐渐降低。在水库冲淤和泥沙特性方面,汛期三峡水库水位对其影响较大;枯水期的高水位对其影响并不大。研究成果将为长江流域梯级电站和航道的规划设计、三峡水库的运行管理提供理论支撑。     

Development and application of a simulation model for reservoir management

The success of irrigation system operation and planning depends on accurate quantification of supply and demand, and an equitable distribution of available water. The ultimate aim of this study was to determine how to meet the irrigation water demands if possible or to minimize the gap between the water supply and the demand. Most of the irrigation literature focuses only on the demand and the distribution aspects of this issue Irrigation projects that receive water from reservoirs, however, can be challenging to manage because the annual fluctuations in available water release from a reservoir can have a considerable impact on the irrigation management strategy. In real‐world situations, the reservoir operating rules guide reservoir operators in making actual water release decisions. This study develops a water balance simulation model for reservoir management, as well as testing it for Kangsabati Reservoir, West Bengal, India. Two rule curves for deciding irrigation water available from the reservoir were generated by taking the average and minimum stage values on a daily basis for a 16‐year period (1988–2003). Maintaining a minimum stage of 120.4 m throughout the year served as another rule to decide the release water available for irrigation. The minimum allowable stage of reservoir corresponding to a particular date of the year can be determined from those reservoir specific rule curves generated for irrigation purposes. The maximum permissible water release/outflow for irrigation from the test reservoir was taken as the volume of water available above the minimum allowable stage corresponding to the selected rule curve. The saturated hydraulic conductivity value (K_S) was calibrated to be 4.31 mm day^?1 for Kangsabati Reservoir.     

Mercury Distribution in the Biota of a Great Lakes Estuary: Old Woman Creek,Ohio

A study of mercury contamination in a wetland ecosystem was undertaken to assess degree of contamination in various compartments of the food web, and determine the most important routes for mercury to enter fish species. Old Woman Creek is a freshwater estuary on the southern shore of Lake Erie and has been recognized as an important nursery area for fish. Although there is no point source of mercury to the wetland, there is evidence of biomagnification of mercury in the food web. Mercury concentrations in water were not detectable (< 20 ng/L) by methods used in this study. The sediments had a mean concentration of 0.04 /μg total Hg/g wet weight. Zooplankton, benthos, and macro-phytes had less than 0.05 μg total Hg/g wet weight, but mean concentrations in fish tissue ranged from 0.001 to 0.636 μg total Hg/g wet weight. There was a positive correlation between mercury concentration and both length and weight in channel catfish Ictalurus punctatus and common carp Cyprinus carpio. In general, channel catfish accumulated higher levels of mercury than common carp, suggesting that the pelagic food web may be more efficient in delivery of mercury (to channel catfish) than the benthic pathway (to common carp). The highest value for fish occurred in a bowfin Amia calva. Tissue from one great blue heron Ardea herodias had the highest concentration at 1.62 μg total Hg/g wet weight. In this system, as in others, top predators tended to accumulate the highest mercury levels and were therefore most susceptible to mercury poisoning, even at sublethal levels.     

The first five months of the supa reservoir,river Kali,India

The Supa Reservoir began to fill in 1984, as part of a hydroelectric power scheme on the Kali River in south-central India. There were significant increases in electrical conductivity and concentrations of chloride, phosphate, iron and manganese in the impounded water during the filling phase. There were also decreases in pH, turbidity, and dissolved oxygen, accompanied by the evolution of hydrogen sulphide. Nutrients leached from the flooded soil and from decomposition of submerged vegetation contributed to blooms of the cyanobacterium Microcystis aeruginosa. The new reservoir has potential for fisheries based on two major carp species, the mrigal (Cirrhinus mrigala) and the rohu (Labeo rohita).     

水库泥沙淤积滞后响应的理论模型

河床演变中普遍存在着滞后响应现象,而以往的水库泥沙研究对滞后响应现象很少考虑.本文在作者近期关于水库泥沙淤积滞后现象研究的基础上,从河床演变学的自动调整原理出发,建立了水库泥沙淤积滞后响应的理论模型.并以三门峡水库泥沙淤积为例,利用提出的理论模型分析了库区累计淤积量对流量加权平均坝前水位的响应、潼关高程对年入库水量的响应及水库末端比降对年平均坝前水位的响应,结果表明所建理论模型能够描述泥沙淤积的特征,为水库泥沙淤积的研究提供了一种新的方法.     

Multi‐dimensional effects on Cladoceran (Crustacea,Anomopoda) assemblages in two cascade reservoirs in Southeast Brazil

The Cladocera assemblages in two cascade reservoirs located in the Paranapanema River in Brazil were studied during two consecutive years. Upstream Chavantes Reservoir is an accumulation system, with a long water retention time, high depth and oligo‐mesotrophic status. The downstream Salto Grande Reservoir is a small, run‐of‐river reservoir, with a short water retention time, shallow depth and meso‐eutrophic status. The goal of this study was to determine the inter‐ and intra‐reservoir limnological differences with emphasis on the Cladocerans assemblages. The following questions were posed: (i) what are the seasonal dynamics of the reservoir spatial structures; (ii) how dynamics, seasonally, is the reservoirs spatial structure; and (iii) are the reservoir independent systems? A total of 43 Cladoceran species were identified in this study. Ceriodaphnia silvestrii was the most abundant and frequent species found in Chavantes Reservoir, while C. cornuta was most abundant and frequent in Salto Grande Reservoir. The Cladoceran species richness differed significantly among sampling sites for both reservoirs. In terms of abundance, there was a significant variation among sampling sites and periods for both reservoirs. A cluster analysis indicated a higher similarity among the deeper compartments, and the intermediate river‐reservoir zones was grouped with the riverine sampling sites. For the smaller Salto Grande Reservoir, the entrance of a middle size tributary causes major changes in the system. A distinct environment was observed in the river mouth zone of another small tributary, representing a shallow environment with aquatic macrophyte stands. A canonical correlation analysis between environmental variables and Cladoceran abundance explained 75% of the data variability, and a complementary factorial analysis explained 65% of the variability. The spatial compartmentalization of the reservoirs, as well as the particular characteristics of the two study reservoirs, directly influenced the structure of the Cladoceran assemblages. The conditions of the lacustrine (dam) zone of the larger Chavantes Reservoir were reflected in the upstream zone of the smaller downstream Salto Grande Reservoir, highlighting the importance of plankton exportation in reservoir cascade systems. The comparative spatial–temporal analysis indicated conspicuous differences between the two reservoirs, reinforcing the necessity of considering tropical/subtropical reservoirs as complex, multi‐compartmental water systems.     

Phytoplankton community and algal growth potential in Taipinghu Reservoir, Anhui Province, China

An integrated investigation of the community structure and growth potential of algae in Taipinghu Reservoir, Anhui Province, China, was conducted from July 1993 to October 1994. A total of 112 algal species belonging to eight phyla were observed. Green algae were the dominant population, representing 55% of the total recorded taxa. Diatoms and blue‐green algae formed the second and the third largest algal groups, respectively. The total species and population of algae were relatively steady in spring, summer and autumn, but exhibited some variety in winter. Compared to earlier data, the species richness decreased by 36% and the number of genera decreased by 23% over an eight‐year period. The maximum values of the annual mean cell count, biomass and chlorophyll a concentration appeared in summer and the minimum in winter. The algal growth potential of the original water without supplemental nutrients was much lower than that of the control culture, but equal to or a little higher than the control culture which was supplemented with complete nutrients. The study results imply that phosphorus is the limiting nutrient for algal growth and that the trophic status of the reservoir is changing from mesotrophic to eutrophic. Based on these data, some advice on how to manage the reservoir is offered.     

Assessment of the impacts of a new artificial lake mouth on the hydrobiology and fisheries of Chilika Lake, India

The degraded state of the fragile ecosystem of Chilika Lake, located on the east coast of India, was undergoing restoration through an effective hydrological intervention during the year 2000. Studies on the lake’s hydrobiology and fisheries for the period of 7 years before and 7 years after the hydrological intervention indicated a rapid recovery of the lake fishery immediately after opening of the new lake mouth, with a sixfold increase in the average annual fish landings. During 2000–2001 to 2006–2007, the average fisheries output (11 051.3 t), catch per unit effort (6.2 kg boat^?1 day^?1), the economic valuation of the average annual catch (637 million rupees) and productivity (11.97 t km^?2) exhibited dramatic increases of 498%, 464%, 1177% and 498.5%, respectively, compared with the 7‐year pre‐intervention data. Multivariate statistical analysis inferred that most of the lake’s environmental variables are strongly associated with salinity factor, which seems to have governed the lake ecology. The salinity dynamics of the lake are governed by both freshwater inflows and seawater ingress through the new artificial lake mouth. Correlation analysis indicated that salinity was positively correlated with prawn catch (R² = 0.542; d.f. = 25; P < 0.01), crab catch (R² = 0.628; d.f. = 25; P < 0.001) and fish catch (R² = 0.476; d.f. = 25, P < 0.05). The average increase in the salinity regime (43.8%) for the lake during the post‐hydrological intervention period, compared with the pre‐hydrological intervention period, appears to have positively impacted the fish, prawn and mud crab catches. A gradual decrease in total fisheries output since 2005–2006, however, was attributed mainly to a continuing increase in destructive fishing practices in the absence of any conservation and regulatory measures for fishing, and large‐scale collection of shrimp juveniles from the outer channel for shrimp aquaculture. Thus, carefully planned conservation and regulation measures must be ensured, with active participation of local communities during this early phase of lake restoration. In the absence of such measures, the present scenario of fisheries enhancement might not be sustained over the long term.