Species- and tissue-specific mercury bioaccumulation in five fish species from Laizhou Bay in the Bohai Sea of China

Mercury (Hg) concentrations in the tissues (muscle, stomach, liver, gills, skin, and gonads) of five fish species (mullet Liza haematocheilus, flathead fish Platycephalus indicus, sea bass Lateolabrax japonicus, mackerel Scomberomorus niphonius and silver pomfret Pampus argenteus) collected from Laizhou Bay in the Bohai Sea of China were investigated. The results indicate that Hg bioaccumulation in the five fish was tissue- specific, with the highest levels in the muscle and liver, followed by the stomach and gonads. The lowest levels were found in the gills and skin. Fish at higher trophic levels (flathead fish and sea bass) exhibited higher Hg concentrations than consumers at lower trophic levels. Mercury bioaccumulation tended to be positively correlated with fish length in mullet, silver pomfret, mackerel, and flathead fish, but was negatively correlated with fish length in sea bass. The Hg concentrations in the muscles of all fish species in Laizhou Bay were within the permissible limits of food safety set by national and international criteria. However, the suggesting maximum consumption of sea bass is 263g per week for human health.

Fish species diversity in the Huanghe Estuary

This paper lists 50 fish specs in the Huanghe Estuary, which belong to 9 orders, 22 families and 37 genera. The paper describes the seasonal distributions of these fish species and the succession of the important fish species during the past 50 a. The authors discuss the main factors that have resulted in the changes in fish species diversity and the fishery resources. These include the overexploitation of the fishery and the sharp reduction in the fresh water discharges from the Huanghe River.

Influence of sampling frequency on detectability of fish community and fish species in a fishery-independent survey

Understanding the dynamics and regulation of a particular ecological process requires monitoring of the process at appropriate spatial and temporal scales.Information collected at an inappropriate spatiotemporal scale may be insufficient for capturing spatio-temporal dynamics of fish populations and community.In this study,a Monte Carlo method was developed to evaluate the detectability performances of different sampling frequencies,sampling timings and sampling intensities on fish community indices and fish species.Species richness indices tended to decrease with an increased sampling frequency,while species diversity indices had small changes in response to changes in sampling frequency.The diversity index was more likely to be influenced by the choice of sampling timing compared to the richness index.The total number of species,especially seasonal and rare species present in the simulated sampling,increased with sampling frequency.Although sampling frequency is more important than sampling intensity,sampling intensity is also important for the detectability of fish species.This study showed that sampling frequency and intensity could greatly influence the estimation of fish community.Choices of sampling timing,sampling frequency and intensity may result in different estimates of fish species compositions and community structure.It is very necessary to consider the importance of sufficient sampling frequency and intensity in a survey program.

Assessing potential protection effects on commercial fish species in a Cuban MPA

Cuba has been leading marine protected area(MPA)designation in the Caribbean region to ensure conservation of its valuable marine ecosystems.Yet,an efficient monitoring program for MPAs is still to be implemented and will benefit from pre-existing information.The highly regulated MPA of Punta Francés National Park is one of the first Cuban MPAs and was established mainly to protect species and ecosystems for tourism purposes.Monitoring of protection effects on commercial fish species was lacking in this MPA.This study aimed at increasing local scientific knowledge by providing a baseline study about the most commercially fished families(Haemulidae,Lutjanidae and Serranidae)around Punta Francés MPA.Data collected represent only a limited period but can be used as a base point to support future monitoring.Fish abundance in number and biomass,and size were collected to test for differences between inside and adjacent areas outside the Punta Francés MPA,in different coral reef types.The main result of this study was the significantly larger size and biomass of snappers and groupers outside the MPA where intense fisheries occur.An observation consistent with a large spawning aggregation was also recorded outside the MPA.Even with a limited set of data,these results suggest that,at least temporarily,the most targeted species[and sizes]are still highly vulnerable to fisheries.Relevant habitats in the adjacent area,that are apparently missing within the MPA,may support some of the results found.Extending the limits of the Punta Francés MPA to include those habitats outside may be critical to ensure the effectiveness of this MPA in contributing to protect the most commercial species of the region.This should be done together with efficient fisheries management measures in the region,such as the significantly increase of minimum legal sizes and temporal closures during spawning migrations.

Abundance and biomass of assorted small indigenous fish species:Observations from rural fish markets of West Bengal,India

The small indigenous fish species(SIS)are harvested as ensemble of different fish species of varying size and shape.An appraisal of the abundance and biomass of fish species constituting such ensemble was carried out with samples collected from fish markets ofWest Bengal,India.The data revealed that at least 22 different fish species were present varying in numbers and species combinations.The abundance and biomass of the individual fish species was negatively correlated,indicating numerical dominance of small sized species.Logarithmic regression showed a good fit of the relative abundance(y)with the species richness(x)in the samples of SIS(y=55.72ln(x)e 77.27;r^(2)=0.940),while power regression was best fit for the relative biomass of individual fish(y)with the species richness(x)in the samples of SIS(y=24.58x^(-1.54);R^(2)=0.831).In overall both species specific and individual based biomass and abundance relationships were negatively correlated.In order to ascertain the harvest and marketability of the SIS in a judicious manner,monitoring of the fish assemblages in natural habitats is recommended.

“Releasing Nemo”May Harm Local Fish Species

有人将家中养观赏鱼投入大海放生。可是,你是否知道,这将给海洋的生态系统带来灾难性的后果。

Community Structure of Fish in Nanji Islands National Nature Reserve and Its Relationship with Environmental Variation

Community structure of fish in relation to environmental variation was investigated in Nanji Islands National Nature Reserve (NINNR). In order to test this relationship, we delineated 25 survey stations with bottom trawling and measured environmental variables. Samples were taken from November 2013 (autumn), February 2014 (winter), May 2014 (spring) and September 2014 (summer). We found a very strong correlation in space and time between temperature and salinity;abundance and biomass in winter;depth and DO in summer then a strong correlation was found respectively between temperature and biomass;salinity and biomass in winter too and finally a moderate correlation between depth and biomass in spring, (P-value < 0.01) with positive correlation (that the other variable or factor has a tendency to increase). We also found out a negative correlation (P-value < 0.05), respectively between salinity and DO;DO and chlorophyll in summer;temperature and salinity;salinity and DO in spring period (mean that the other variable or factor has a tendency to decrease). A negative correlation observed between temperature, salinity and chlorophyll in winter, spring and autumn period were due by a temperature and salinity window open for species blooms through the movement of the TWC and Jiangzhe coastal current close to shore. By comparing diversity of fish species with environmental factors, the community structure of fish varied significantly as physicochemical parameters changed between different stations for each season. As results and according to the species referencing of environmental factors;species diversity, abundance and evenness vary among different stations, corresponding to significant differences of environmental factors (e.g. physicochemical parameters and chlorophyll-a concentration in different sites). Species richness of microfauna was negatively correlated with salinity levels. Furthermore, they were related to the fish community according to the results. This may be due to the fish community’s adaptability in these different variations of environmental factors, but only tolerant members remaining.

Status and historical changes in the fish community in Erhai Lake

Erhai Lake is the second largest freshwater lake on the Yunnan Plateau, Southwest China. In recent decades, a number of exotic fish species have been introduced into the lake and the fish community has changed considerably. We evaluated the status of the fish community based on surveys with multimesh gillnet, trap net, and benthic fyke-net between May 2009 and April 2012. In addition, we evaluated the change in the community using historical data （1952-2010） describing the fish community and fishery harvest. The current fish community is dominated by small-sized fishes, including Pseudorasbora parva, Rhinogobius giurinus, Micropercops swinhonis, Hemiculter leucisculus, and Rhinogobius cliffordpopei. These accounted for 87.7% of the 22 546 total specimens collected. Omnivorous and carnivorous species dominated the community. A canonical correspondence analysis （CCA） plot revealed that the distribution of fishes in the lake is influenced by aquatic plants, water temperature, pH, and season. The abundance of indigenous species has declined sharply, and a majority of endemic species have been extirpated from the lake （a decrease from seven to two species）. In contrast, the number of exotic species has increased since the 1960s to a total of 22 at present. The fishery harvest decreased initially following the 1960s, but has since increased due to the introduction of non-native fish and stocking of native fish. The fishery harvest was significantly correlated with total nitrogen, not total phosphorus, during the past 20 years. Based on our results, we discuss recommendations for the restoration and conservation of the fish resources in Erhai Lake.

Current Situation of Fish Resources in the Lower Reaches of the Songhua River

The Songhua River is one of the seven major rivers in China and an important river in Northeast China, with rich fish species and resources. Based on historical data, on-site visits and field investigation, this paper analyzed the changes of fish resources in the lower reaches of the main stream of the Songhua River, so as to understand the current situation of three grounds and one channel and resources of fishes. This study provides reference for fish conservation in the lower reaches.

Changes in fish diversity and community structure in the central and southern Yellow Sea from 2003 to 2015

The central and southern Yellow Sea is an important overwintering ground for many fish species in the Bohai Sea and Yellow Sea. For better understanding the status of the fish community after years of heavy exploitation, variations in fish community structure and diversity were analyzed using data from bottom trawls during 2003–2015. Five fish assemblage indices all showed fluctuations without clear trends from 2003 to 2015, yet there were strong positive and significant correlations(P < 0.05) among them. The top-five dominant species accounted for a high weight percentage(49.7%–82.1%) in the annual fish catch. Multivariate analysis showed that two year groups could be pooled for the fish community: Group Ⅰ consisted of the years 2006, 2007, 2008 and 2015, while Group Ⅱ consisted of the years 2003, 2004, 2005, 2009, 2010 and 2014; the groups aggregated with 63.71% similarity, indicating a high level of similarity among all years. The multivariate dispersion values were 1.455 and 0.818 for Groups Ⅰ and Ⅱ, respectively, indicating greater variances in fish assemblage structure in Group Ⅰ than that in Group Ⅱ. Similarity of percentage analysis demonstrated that the average similarities for Group Ⅰ and Group Ⅱ were 71.58% and 67.51%, respectively. Size-spectra analysis revealed no consistent trend in the intercept and slope( P > 0.05); there were also no significant differences between the slope of the size-spectra and fishing ef fort. The catch per unit ef fort and mean individual weight analyses of the whole fish assemblage both showed a significantly decreasing trend over time. Overall, the results showed that the fish community structure in the central and southern Yellow Sea was relatively stable from 2003 to 2015 and the study could be used as a reference for supporting ecosystem-based fishery management.

Aquatic resources and feed diversification:Reviewing three case studies from South East Asia with a viewpoint of trophic intensification in rice fish culture

Management of fed-fish culture practices,at present,stands on two broad feed categories,(i)formulated proteinaceous aquafeeds and(ii)the natural resources.Judicious use of the later is gaining popularity since it offers sustainability to fish culture.Polyculture often targets phyto-and zooplanktonic resources,but mostly ignores periphyton.This review discusses the works on feed diversification performed independently at different times.Fishes,viz.Cyprinus carpio,Labeo rohita and Amblypharyngodon mola were projected as potential candidates for resource-nutrient management with feed diversification in rice fish culture.With C.carpio the rice fish culture called Aji Gnui Assonii in terrace water-logged rice field of Apatani Plateau,Arunachal Pradesh(India)is referred as self-substrating aquaculture practice.This monoculture practice experiences high carp productivity since there remains surplus of resources below the threshold level in these rice fields.Similarly,L.rohita,explores periphytic resources in ponds when substrates are installed.As a result,filter feeders get more foraging aquatic phase intensifying the resources for exploration in pond.This concept is suggested for rice fields with water depth above 50 cm where rice stems act as substrate.With trenches or refuge canals,resource intensification may be managed for more cultivable fishes in rice fields with<50 cm water depth.This model of resource intensification further allows inclusion of Small Indigenous Fish Species(SIFs)-which are rich source of many micronutrients.Thus,integration of SIFs confers huge potentiality for intensification of nutrients,especially protein and micronutrients in rice fields.

Assessment of post-harvest fish losses Croaker Pseudotolithus elongatus,(Bowdich,1825),Catfish Arius heudeloti,(Valenciennes,1840)and Shrimp Nematopalaemon hastatus(Aurivillius,1898)in Ondo State,Nigeria

The study assess post-harvest fish losses among three(3)dominant marine fish species along coastal areas of Ondo State,Nigeria.Simple random sampling was used to select 100 fishermen from 5 viable fishing communities along coastal areas of Ondo State while questionnaire was used for data collection.Descriptive statistics shows that small-scale fishing is dominated by males with mean age of 39 years.The fishermen incurred average post-harvest fish losses of 8.15%for croaker,7.76%for catfish and 7.57%for shrimp respectively.Causes of post-harvest fish losses in the study area includes lengthy duration of fishing cycle,poor handling practices,lack of covering facilities,failure to use ice,lack of storage facilities and lack of good means of transportation.Regression model revealed a statistical significant relationship(P<0.05)with age,educational level,fishing experience,duration of fishing cycle,storage and transportation facilities against percentage fish losses(Croaker:Pseudotolithus elongatus,Catfish:Arius heudeloti and Shrimp:Nematopalaemon hastatus).In order to ensure food security,post-harvest fish losses needs to be reduced to the barest minimum.Government should provide adequate infrastructural facilities to the small-scale fisheries sector in order to improve their standard of living and increase their income level.

Spatiotemporal variation of shallow water fish assemblages along the coastline of Çanakkale,Turkey

Objective:To determine the shallow water fish species richness ofÇanakkale and to analyse the spatiotemporal variations of these fish assemblages.Methods:Samplings were carried out monthly with a beach seine between January and December 2007.Samples were collected from 6 stations(No.1,2,3,4,5,6).Stations 1 and 4 located in theÇanakkale Strait,2 and 5 in North Aegean Sea,3 and 6 in Sea of Marmara.Results:A total of 112 fish species were sampled and the two most common species were Atherina boyeri and Pomatoschistus marmoratus.A total of 93 species were sampled in theÇanakkale Strait,85 in the Aegean Sea,and 77 in the Sea of Marmara.Shannon diversity index was the highest in the Aegean Sea.Dominant species were caused significant differences of both regional and seasonal fish assemblage fluctuations.Species richness and abundances decreased significantly in winter.Although more species were caught at night and a greater abundance of fishes was obtained during the day,no significant differences were found between day and night in terms of species richness and abundance.Conclusions:The results supported the biogeographical differences between the Aegean Sea,theÇanakkale Strait and the Sea of Marmara in terms of the shallow water fish community.The inventory in the current study can serve as baseline data prior to management strategies to ensure sustainable conservation of the area.