Evaluation of approaches to estimate fish catches on Lake Victoria: a case study using CAS and frame data from Uganda

Since 2005, harmonized catch assessment surveys (CASs) have been implemented on Lake Victoria in the three riparian countries Uganda, Kenya, and Tanzania to monitor the commercial fish stocks and provide their management advice. The regionally harmonized standard operating procedures for CASs have not been wholly followed due to logistical difficulties. Yet the new approaches adopted have not been documented. This study investigated the alternative approaches used to estimate fish catches on the lake with the aim of determining the most reliable one for providing management advice and also the effect of current sampling routine on the precision of catch estimates provided. The study found the currently used lake-wide approach less reliable and more biased in providing catch estimates compared to the district based approach. Noticeable differences were detected in catch estimates between different months of the year. The study recommends future analyses of CAS data collected on the lake to follow the district based approach. Future CASs should also consider seasonal variations in the sampling design by providing for replication of sampling. The SOPs need updating to document the procedures that deviate from the original sampling design.

Castalia Trout Club

One of the many hunting and fishing clubs along Lake Erie shoreline was the Castalia Trout Club founded around 1890. It provided access to Cold Creek, the only area watercourse with trout habitat.

A survey on prevalence rate of aflatoxigenic species of Aspergillus and residues of aflatoxins by ELISA method in cold-water cultural fish (rainbow trout) feeds in Tehran and West Azarbayjan provinces-Iran

Aflatoxins are one kind of fungal toxins produced by species of toxigenic Aspergillus (A. flavus and A. parasiticus) and in other words they are secondary metabolites which are considered as one of the threatening factors of food consumer's health. In this research 96 samples of cold-water cultural fish feed, rainbow trout, during the seasons of spring and summer of 2007 (every fifteenth of the month) were randomized (by simple and stratified random) to determine: 1. The prevalence rate of aflatoxigenic species of Aspergillus in stored feed of cold-water cultural fish in West Azarbayjan cultural fish farms in both seasons (spring and summer); 2. The residues of total aflatoxin in stored feed of fish in cultural fish farms of West Azarbayjan in both seasons by ELISA method; and 3. The residues of that toxin in feed produced in aquatic feed factories in Tehran and West Azarbyjan provinces with the same method. In order to study prevalence rate of toxigenic species of Aspergillus, pour-plate culture method by general medium such as Malt Extract Agar (M.E.A.) and Sabouraud-Dextrose Agar (S.D.A.) and by standard No.997 of Iranian Standard Institute were used. The produced colonies were examined microscopically. To determine the aflatoxins residues, ELISA method using Agra-Quant kit of Romer Lab company, were applied. The results of this survey indicated that only 8.3% of the samples were infected by A. flavus. A. parasiticus was not observed. There were no significant differences between the prevalence rate of AFT and seasons/months, either (P<0.05). Evaluating mean of aflatoxin rate showed that the rates of this variable are lower than the tolerance levels designated by the joint FAO/WHO expert committee (The mean of AFT in all data was lower than 11 ppb). Furthermore, mean of total AFT residues rates of stored feed of various cultural center of West Azarbayjan and Tehran factories were comparable in spring and summer, and no significant differences were observed (P<0.05). But there were significant differences between the total aflatoxin rates in the feed of West Azarbayjan factory and spring and summer (P<0.05), and AFT residues in spring (8.6 ppb) were higher than summer (6.1 ppb). Prevalence rates of AFT in Tehran feed factories (9.2 ppb) are higher than W. Azarbayjan (7.4 ppb). In other words, location was considered as a decisive factor in total AFT rates of samples. Moreover, the results indicated that there was significant difference between total aflatoxin rates of feed and cultural centers (P<0.05). The mean of AFT rates in embankment dam cultural fish farms (6.75 ppb) and multi-functions cultural fish farms (6.25 ppb) was higher than individual cultural pond (4.67 ppb). In conclusion, the finally results of this survey indicated that the lower rates of Aspergillus is not effective on the presence of total aflatoxin rates in trout feed. Due to low levels of aflatoxin rates (lower than 20 ppb), the produced feed of cold-cultural fishes, Rainbow Trout, in Tehran and West Azarbayjan provinces, in spring and summer of 2007, were safe and healthy both for fish and their consumers.

The study of histopathological damage in heart and bulbus arteriosus in rainbow trout

This study investigated the pathological changes of heart and bulbus artrius of rainbow trout breeders in several group of ages and density. The aim of study was to consider the process and the intensity of the heart and bulbus arteriosus damages in accordance to gender, age and stocking density of trout in three fish culture center (Zarghezel, Niyak in Haraz Region,Mazandaran and Espiran in Tabriz city environs). In field research, the all records the feed and feeding type, rate of mortality, stocking density of spawners and per spawners fishes, water chemical and physical specification was screened. Stocking density was considered as the most important stressor. 10 fish specimens from 7 weight groups (less than 90g, 90 to 300g, 300 to 500 g, 500 to 1000g, 1 to 3 kg, 3 to 5 kg, over 5 kg), totally 210 specimens were sampled and heart and bulbus arteriosus were taken. Samples were fixed in 10 % formalin and transferred to pathology laboratory of veterinary faculty of Tabriz Azad University. Histopathological slides and H&E staining were prepared from these samples. In total, 47 male and 73 female samples showed cardiovascular injury (29 cases in extensive system, 41 cases in semi intensive system, 50 cases in intensive system). The most important was damages, edema and hyperemia in spongy layer of atrium and ventricle muscles, but degeneration the muscle fibers, moderate edema , minor vascular damage. Hemorrhage as the effect of severs vascular damage, thrombus, sever inflammation, sever degeneration in muscle fiber, necrosis and fibrose were further pathological changed. The results of this study showed that the severity of damage increased by increasing the age (weight) of fishes. This situation was seen in all three culturing system (extensive system, semi intensive system, recirculation system). Histopathological changes is obviously seen in samples over 500g, therefore the damages were found to be important (P<0.05). Pathological effects and its severity in recirculation system was significantly high (P<0.05). Comparison with two other culturing system, histopathological changed in heart and bulbus arterius between male and female was significantly different.

Mushroom growing as a livelihood option to fishing among Lake Edward fisher communities

Fisheries activities are the main source of livelihood for the communities that live at Lake Edward fish landing sites. The landing sites include: Kazinga, Katwe, Kayanja, Kishenyi Rwenshama and Katunguru and are located within Queen Elizabeth Conservation Area (QECA). In spite of being the main source of livelihood, 74% of the respondents in a 2013 survey reported that catches for the main targeted fish species namely: Bagrus docmak (Semutundu), Oreochromis niloticus (Tilapia) and Protopterus aethiopicus (Mamba) were declining due to overfishing and catching of immature fish by the rapidly increasing population. Lake Edward Frame surveys had shown that the number of fishing crafts increased from 302 in 2008 to 330 in 2011, while the number of fishers increased from 355 to 600 during the same period. Between 2008 and 2010, catch per boat, for Bagrus docmak (Semutundu) declined from 5.25 kg to 4.04 kg and for Protopterus aethiopicus (Mamba) from 2.63 kg to 1.03kg. It has been suggested that reducing pressure on the lake should be handled using different approaches, one of which is introduction of programs for enhancing livelihood options which do not conflict with conservation of Queen Elizabeth Conservation Area (QECA). The main goal of this study was therefore to identify, prioritize and pilot livelihood options at selected landing sites of Lakes Edward and George.

Study on the inhibitory effects of native medicinal plants on growth and aflatoxin production by toxigenic Aspergilli isolated from rainbow trout feed

In the present study, natural occurrence of fungi and aflatoxin B1 (AFB1) in pellet feed and feed ingredients used for rainbow trout was investigated with emphasis to Aspergillus section Flavi members and medicinal plants inhibitory to Aspergillus growth and/or AF production. The feed samples were cultured on the standard isolation media including dichloran rosebengal chloramphenicol agar (DRCA) and Aspergillus flavus/parasiticus agar (AFPA) for 2 weeks at 28 °C. Identification of fungal isolates was implemented based on the macro- and microscopic morphological criteria. AFs were detected using high performance liquid chromatography (HPLC). Based on the results obtained, a total of 109 fungal isolates were identified of which Aspergillus was the prominent genus (57.0%), followed by Penicillium (12.84%), Absidia (11.01%) and Pseudallscheria (10.10%). The most frequent Aspergillus species was A. flavus (60.66%) isolated from all the feed ingredients as well as pellet feed. Among 37 A. flavus isolates, 19 (51.35%) were able to produce AFB1 on yeast extract-sucrose (YES) broth in the range of 10.2 to 612.8 [tg/g fungal dry weight. HPLC analyses of trout feed showed that pellet feed and all feed ingredients tested except gluten were contaminated with different levels of AFB1 in the range of 1.83 to 67.35 lig/kg. In order to finding natural inhibitors of fungal growth and/or AF production, essential oils (EOs) and extracts of 49 medicinal plants were studied against an aflatoxin-producing A. parasiticus using a microbioassay technique. The EOs was analyzed by gas chromatography/mass spectrometry (GC/MS). Based on the results obtained, Achillea millefolium sub sp. elborsensis, Ferula gummosa, Mentha spicata, Azadirachta indica, Conium maculatum and Artemisia dracunculus remarkably inhibited A. parasiticus growth without affecting AF production by the fungus. Besides of Thymus vulgaris and Citrus aurantifolia, the EO of Foeniculum vulgare significantly inhibited both fungal growth (-70.0%) and AFs B1 and G1 (-99.0%) production. The EO of Carum carvi and ethyl acetate extract of Platycladus orientalis suppressed AFs B1 and G1 by more than 90.0%, without any obvious effect on fungal growth. The IC50 values of bioactive plants for AFs B1 and G1 were determined in the ranges of 90.6 to 576.2 and 2.8 to 61.9 µg/ml, respectively. Overall, results of the present study indicate the importance of AF contamination of trout feed as a risk factor for fish farming and thus, an urgent necessity for constant monitoring of trout feed for any unacceptable levels of AF contamination. Likewise, antifungal activities of bioactive plants introduced here would be an important contribution to explain the use of these plants as effective antimicrobial candidates to protect feeds from toxigenic fungus growth and subsequent AF contamination.

Study of rainbow trout neoplasia in the region of Haraz

This study was carried out in order to determine neoplasia presence in rainbow trout in Haraz area. Neoplasia in various species of fishes including freshwater, brackish water and marine fishes was reported in other countries. But up to now there is no documented report of rainbow trout neoplasia in Iran. The study was performed in 20 farms of Haraz area during 2004-2005. All fishes of each farm firstly were observed in order to any abnormal mass which is suspicious to neoplasia. Besides in order to observation of external and internal organs, 20 fishes was sampled randomly from each farm and were examined clinically and necroptically. Any suspicious lesions were sent to pathology laboratory in 10% formalin followed by taking pictures of the lesions. Then histopathological evaluations were performed. From 400 fishes, 3 neoplastic cases including hepatocellular carcinoma along with bile duct papilloma, hepatocellular carcinoma and bile duct adenocarcinoma and intestine adenocarcinoma were found which all were in brooder fish.

Effect of temperature on genomic and some biological indices during embryonic and larval development of Caspian trout Salmo trutta caspius Kessler, 1877

Since 1966 especially recent decade, Caspian trout (Salmo trutta caspius Kessler, 1877) considered as a strategic endemic species for Caspian Sea fisheries resources also coldwater aquaculture in Iran. Nowadays habitat condition effects on this subspecies during life stages, artificial breeding and incubation period noticed by research and execution sessions of fisheries in Iran. Incubation duration of Caspian trout from artificial fertilization followed by green egg and eyed egg, hatching and yolk sac absorption identified as most sensitive stages for fish and any pollution, stress and deviation by natural life conditions of embryo up to larvae could provide possible mortalities and observable or hidden alterations. Among all vital factors for Caspian trout welfare even in conservation plans and stocks rehabilitation programs or recent attempts for domestication of this fish for introduction to cold water aquaculture industry, water temperature as the most important physical factor which might conserve or induce stress to rearing environment condition is not considered yet. In hatcheries activities, the temperature for incubation and rearing Caspian trout eggs is determining by available water temperature and wide range of temperatures in governmental or private farms is using depend on the water resources availability. Also global climate change consideration and increase temperature trend accompany with group of physical and chemical factors provided by fish farm discharges and other source points entered to the migration pathway of Caspian trout in spawning season were not investigated before. Natural spawning migration pathway is upstream of Caspian tout south and south west rivers especially in Cheshmehkileh upstream in Tonekabon, Iran directed this research focus on the mentioned location. For simulation of natural spawning bed for Caspian trout, water supplied from the upstream of Daryasar branch as headwater of Cheshmehkileh River which provided REDD water condition for in vitro incubation. Green eggs treatments of wild and F1 cultured brooders both 3+ were incubated. Incubation implemented in dark, constant temperature (4, 8, 12 degree centigrade) and DO–pH–temperature digital monitoring in 3 recycling incubators ended to yolk sac absorption and entering larval stage. Hatching success, possible genome alterations by HSP70 gene expression and comet assay implemented as diagnostic tools in 3 life stages of eyed egg– Alevin and Larvae. Numbers and diameters of larvae white fiber muscles measured by histology experiment and Hematoxylin–eosine staining. Results stated significant effect of incubation temperature on hatching success, genome and white fiber muscles of wild and F1 samples. Hatching success measured as 31% and 38% for cultured and wild cold treatments, 79% and 91% for normal and 64% and 73% for warm cultured and wild treatments respectively. Considerable mortality occurred for cold treatment and 8 degree centigrade stated the best thermal condition in normal incubator according to hatching success in wild Caspian trout samples.

PHYTOPLANKTON AND NUTRIENT DYNAMICS WITH A FOCUS ON NITROGEN FORM IN THE ANACOSTIA RIVER, IN WASHINGTON, D.C. AND WEST LAKE, IN HANGZHOU, CHINA

Nutrient loading has been linked with severe water quality impairment, ranging from hypoxia to increased frequency of harmful algal blooms (HABs), loss of fisheries, and changes in biodiversity. Waters around the globe are experiencing deleterious effects of eutrophication; however, the relative amount of nitrogen (N) and phosphorus (P) reaching these waters is not changing proportionately, with high N loads increasingly enriched in chemically-reduced N forms. Research involving two urban freshwater and nutrient enriched systems, the Anacostia River, USA, a tributary of the Potomac River feeding into the Chesapeake Bay, and West Lake, Hangzhou, Zhejiang Province, China, was conducted to assess the response of phytoplankton communities to changing N-form and N/P-ratios. Field observations involving the characterization of ambient phytoplankton communities and N-forms, as well as experimental (nutrient enrichment) manipulations were used to understand shifts in phytoplankton community composition with increasing NH4+ loads. In both locations, a >2-fold increase in ambient NH4+:NO3- ratios was followed by a shift in the phytoplankton community, with diatoms giving way to chlorophytes and cyanobacteria. Enrichment experiments mirrored this, in that samples enriched with NH4+ lead to increased abundance of chlorophytes and cyanobacteria. This work shows that in both of these systems experiencing nutrient enrichment that NH4+ supports communities dominated by more chlorophytes and cyanobacteria than other phytoplankton groups.

Biological Impacts and Uses of Black Bass Competitive Fishing Tournaments on Large Lake Systems

Thesis (Master, Biology) -- Queen's University, 2016-09-28 15:06:46.124

¬FISH DISTRIBUTIONS IN LAKE ONTARIO’S EASTERN BASIN AND THE UPPER ST. LAWRENCE RIVER: AN ANALYSIS USING GIS AND OCCUPANCY MODELLING TECHNIQUES

Predictive models of species distributions are important tools for fisheries management. Unfortunately, these predictive models can be difficult to perform on large waterbodies where fish are difficult to detect and exhaustive sampling is not possible. In recent years the development of Geographic Information Systems (GIS) and new occupancy modelling techniques has improved our ability to predict distributions across landscapes as well as account for imperfect detection. I surveyed the nearshore fish community at 105 sites between Kingston, Ontario and Rockport, Ontario with the objective of modelling geographic and environmental characteristics associated with littoral fish distributions. Occupancy modelling was performed on Round Goby, Yellow perch, and Lepomis spp. Modelling with geographic and environmental covariates revealed the effect of shoreline exposure on nearshore habitat characteristics and the occupancy of Round Goby. Yellow Perch, and Lepomis spp. occupancy was most strongly associated negatively with distance to a wetland. These results are consistent with past research on large lake systems indicate the importance of wetlands and shoreline exposure in determining the fish community of the littoral zone. By examining 3 species with varying rates of occupancy and detection, this study was also able to demonstrate the variable utility of occupancy modelling.

Unexpectedly high catch-and-release rates in European marine recreational fisheries: implications for science and management

While catch-and-release (C&R) is a well-known practice in several European freshwater recreational fisheries, studies on the magnitude and impact of this practice in Europeanmarine recreational fisheries are limited. To provide an overview of the practice andmagnitude of C&R among marine recreational anglers in Europe, the existing knowledge of C&R and its potential associated release mortality was collected andsummarized. The present study revealed that in several European countries over half of the total recreational catch is released by marine anglers. High release proportions of > 60% were found for Atlantic cod (Gadus morhua), European sea bass (Dicentrarchus labrax), pollack (Pollachius pollachius), and sea trout (Salmo trutta) in at least one of the studied European countries. In the case of the German recreational Baltic Sea cod fishery, release proportions varied considerably between years, presumably tracking a strong year class ofundersized fish. Reasons for release varied between countries and species, and included legal restrictions (e.g. minimumlanding sizes and daily bag limits) and voluntary C&R. Considering the magnitude of C&R practice among European marine recreational anglers, post-release mortalities of released fish may need to be accounted for in estimated fishingmortalities.However, as the survival rates of Europeanmarine species aremostly unknown, there is a need to conduct post-release survival studies and to identify factors affecting post-release survival. Such studies could also assist in developing species-specific, best-practice guidelines to minimize the impacts of C&R on released marine fish in Europe.

Evaluation of community participation for the development of culture-based fisheries in village reservoirs of Sri Lanka

In this paper an attempt is made to identify the socioeconomic characteristics of a community that influences the development and management of culture-based fisheries in village reservoirs of Sri Lanka. Socioeconomic data were collected from 46 agricultural farming communities associated with 47 village reservoirs in Sri Lanka. Principal component analysis indicated that scores of the first principal component were positively influenced by socioeconomic characteristics that are favorable for making collective decisions. These included leadership of the officers, age of the group, percentage of active members of the group, percentage of kinship of the group, percentage of common interest of the group, and percentage of participation of the group. The size of the group had negative effect on the first principal component. The principal component scores of communication were positively related to willingness to pay (P< 0.001). The communities with socioeconomic characteristics favouring collective decision making were in favor of culture-based fisheries. Homogeneity of group characteristics facilitated successful development of culture-based fisheries.

Implicit discount rates and fisheries management : is there a relationship?

Fishers are faced with multiple risks, including unpredictability of future catch rates, prices and costs. While the latter are largely beyond the control of fisheries managers, effective fisheries management should reduce uncertainty about future catches. Different management instruments are likely to have different impacts on the risk perception of fishers, and this should manifest itself in their implicit discount rate. Assuming licence and quota values represent the net present value of the flow of expected future profits, then a proxy for the implicit discount rate of vessels in a fishery can be derived by the ratio of the average level of profits to the average licence/quota value. From this, an indication of the risk perception can be derived, assuming higher discount rates reflect higher levels of systematic risk. In this paper, we apply the capital asset pricing model (CAPM) to determine the risk premium implicit in the discount rates for a range of Australian fisheries, and compare this with the set of management instruments in place. We test the assumption that rights based management instruments lower perceptions of risk in fisheries. We find little evidence to support this assumption. although the analysis was based on only limited data.

Impacts of vessel capacity reduction programs on the efficiency in fisheries. The case of Australia's multispecies in northern prawn fishery

Capacity reduction programs in the form of buybacks or decommissioning programs have had relatively widespread application in fisheries in the US, Europe and Australia. A common criticism of such programs is that they remove the least efficient vessels first, resulting in an increase in average efficiency of the remaining fleet. The effective fishing power of the fleet, therefore, does not decrease in proportion to the number of vessels removed. Further, reduced crowding may increase efficiency of the remaining vessels. In this paper, the effects of a buyback program on average technical efficiency in Australia’s Northern Prawn Fishery are examined using a multi-output distance function approach with an explicit inefficiency model. The results indicate that average efficiency of the remaining vessels was greater than that of the removed vessels, and that average efficiency of remaining vessels also increased as a result of reduced crowding.