Mixture Toxicity of the Heavy Metals, Mercury and Cadmium to the Indian Major Carp, Labeo rohita

Being a UNESCO-World Heritage Site, the Galápagos harbors the largest global shark biomass in the world’s oceans and a unique marine biodiversity.

In this research, the toxic effects of Cadmium chloride (CdCl2 ), which can seriously pollute aquatic environment and threaten human health, are evaluated based on the behavior responses and the brain Acetylcholinesterase (AChE) activity of zebrafish (Danio rerio). The results showed that Behavior Strength (BS) of test groups (changed from 0.15 to 0.65), which was recorded using an online behavior monitoring system, was lower than the control groups (changed from 0.65 to 0.85). The behavior responses of zebrafish suggested that both dose and time effect relationships existed between Cd2+ stress and zebrafish BS. Meanwhile, the brain Acetylcholinesterase (AChE) activity of zebrafish were strongly inhibited by Cd2+: the AChE activities were lower than 60% after 0.5h Cd2+ exposure in both 1 TU (Toxic Unit) and 2 TU. The AChE activities in 0.1 TU Cd2+ treatment were about 60% in the first 2h and then increased to about 100% in 4h with a decrease tendency in the following exposure time (8h to 48h), which changed from 100% to 70%-80%. Totally, the brain AChE activities of zebrafish showed similar rules with BS after correlation analysis, which might provide an understanding of the ecotoxicological assessment of heavy metal Cd based on zebrafish.

Composition and abundance of larval fishes in Campeche Bay were studied during two seasons, winter, 2013 (24 stations) and summer, 2014 (31 stations). Sampling was carried out with open-close nets, mouth 75 cm and 505 µm mesh. The data of salinity and temperature allowed distinguishing three oceanic sub-regions: North, East, and West. There were 236 taxa, belonging to 74 families, 168 species, 154 taxa occurred in winter and 171 in summer; the composition in both cruises was similar with around 70 % of oceanic and 30 % of neritic larvae. The larval density was almost three times larger in summer than winter. The Campeche Bay hydrodynamics fits well with the results; the West sub-region is located where a cyclonic gyre takes place, the North and East sub regions are located in the area of influence of warm currents over the Yucatan shelf. The hydrodynamics also allows understanding the differences in the proportion of neritic larvae among the three oceanic sub-regions, the West and East with the lower and higher number of neritic larvae, respectively. The large difference among regions is related to some neritic taxa occurring exclusively in some of them. Of the total taxa, 55 neritic occurred only once and it means that more than a half of neritic taxa were represented by one organism, 31 from 85 neritic taxa occurred in the layers of 600 to 1000 m depth. Of the neritic larvae, only Syacium papillosum and Apogon sp. appear among the 20 more abundant.

This study was conducted to determine the effects of photoperiod on egg hatchability, growth and survivability of hybrid catfish (Heterobranchus bidorsalis X Clarias gariepinus) larvae, using hormone-induced spawning method. Eggs were stripped from two sexually matured and healthy female Clarias gariepinus of average weight of 1kg/each and fertilized with milt from two sexually matured male Heterobranchus bidorsalis of average weight of 2kg/each. An average of five hundred (500) eggs were introduced into each ten aquaria tanks of size 70cm x 45cm x 40cm/tank, using a pre- determined spoonful estimation at five photoperiod regimes: (T1) 24L:00D (Light:Darkness); (T2) 18L:6D; (T3) 12L:12D; (T4) 6L:18D and (T5) 00L:24D in two replicates. Aquaria tanks were arranged in a flow- through system at a flow rate of 1.5L/min with aerators to maintain good water condition. Provision of light during the night for illumination of the aquaria tanks was kept constant at 1200 1x, using solar panel (Mono)/inverter (Microtex) light energy. Growth and survivability of the fish larvae were monitored for six weeks. They were fed with laboratory-cultured live feed (Daphnia) to achieve maximum feed utilization. Percentage hatchability of eggs and best growth performance of fish larvae were significantly (p<0.05) highest (92.5%, 91.2 ± 0.21mg) respectively in T5 (00L:24D), while percentage survivability of hatchlings was significantly (p<0.05) highest (94.4%) in T3 (12L:12D). It was observed in this study that the highest hatchability of eggs and optimum growth performance of hatchlings were under complete darkness, with reduced survivability of fish, as a result of observed cannibalism. The fish were photophobic. To achieve a balance result in terms of hatchability of eggs, growth and survivability of fish fry, it is suggested that incubation and hatching of eggs should be done under complete darkness, while rearing of fry should be under equal light and darkness exposure.

About 60-70% of world’s biological resourcesis contributed by India, of which fish represents 80% of the global fishes. Uttar Pradesh blessed with vivid aquatic bioresources in innumerable forms contributes about 14.68% of Indian fish biodiversity with substantial scope of inland fisheries development and aquaculture. Ganga, the mighty river of this state reportsabout 265 freshwater species from its river system [1]. Besides, other rivers viz. Ramganga, Gomti, Ghaghara, Yamuna, Gandak, Kosi and Damodaract as reservoir of different f ish stocks. In past, no study highlights the assessment of the fish biodiversity of this state in holistic way except by Khan (2000) who justreported a compilation of 129 fishes under 27 families [2]. To substantiate and revise the assessment, the fish diversity of this state was assessed by investigating these rivers, analyzing and documenting the information on different fisheries measurements including biology, distribution and conservation status. About 10,000 individuals were collected and the analysis of individuals revealed 126 fish species under 28 families and 74 genera nearly mitigating the earlier reports. The highest species diversity was recorded in the river Ganga (90) followed by Gerua (87) and then Gomati (68). 37 species were found common in Gomati, Ghaghara, Ganges, Son, Tons and Yamuna. Out of 90 species, 6 species were recorded from the river Ganga. In addition, the new distribution of a threatened torrent catfish Amblyceps mango is was recorded from the rivers Gomati, Ganga and Ramganga. The economical assessment unravels nearly 33% as ornamental, 87% as food and 10% as sport fishes.

Among anthropogenic threats to marine mammals, bycatch is one of the major and increasing concerns. This report describes three species of small cetaceans, including a short-beaked common dolphin (Delphinus delphis), a bottlenose dolphin (Tursiops truncatus), and two dwarf sperm whales (Kogia sima), which were found stranded with pectoral fins, dorsal fins and caudal fin removed. The dolphins were found at the beaches of San José de Las Nuñez and San Pablo, respectively (Santa Elena Peninsula Province on 14 August 2017), while the dwarf sperm whales were found in Puerto Lopéz and Crucita (Manabí Province) in July 2014 and August 2015, respectively. Possible explanation for the dolphins and dwarf sperm whales missing fins support the event as a possible case of fishery interaction or bycatch with systematic removal of their fins. Although remnants of artisanal gillnets were not found near the two dolphin species, one of the dwarf sperm whales showed marks of artisanal gillnets on the body as evidence of bycatch. Trade of dolphin carcasses and their parts for bait by fishers cannot be ruled out as there is some evidence of this practice in the past. Both dolphins species are vulnerable species at the national level and commonly involved in incidental captures with gillnets of artisanal fisheries in Coastal Ecuador. Cetacean bycatch is a grave conservation problem affecting several cetacean species in Ecuador’s waters. Fisheries and environmental authorities must be vigilant and enforce actions to proactively mitigate possible anthropogenic impacts and promote environmental education activities in fishing communities to conserve vulnerable dolphin species in Ecuador’s waters. Further, to comply with new rules and regulations of the US Marine Mammal Protection Act (MMPA) intended to reduce the bycatch of marine mammals in foreign commercial fishing operations that export fish and fish products to the United States, a regulatory program is urgently needed to mitigate and reduce fisheries interactions with marine mammals in Ecuador.

Toxic metals have contaminated the aquatic ecosystems to a large scale, and they eventually enter human systems by contaminated air, food, water and soil. Recently, arsenic toxicity has become an alarming concern around the globe. Major areas of North-Eastern states of India have been demarcated with an arsenic content of 50-1000 µg/l in drinking water sources and aquatic ecosystems. Arsenic range in Barak Valley is many folds higher than the permissible limit of WHO and BIS as 10µg/l and 50µg/l respectively, which is present in the form of Sodium Arsenite in water. Fishes are the major dwellers of aquatic ecosystem and serves as good bio-indicators for determination of health status of an aquatic ecosystem. They also form the staple diet of North Eastern people. Labeo rohita is one of the most commonly available and consumed in large scale. The present study was carried out in Labeo rohita in vivo. Labeo rohita (n=10) of similar size and weight were exposed to sodium aresnite at concentrations 100 µg/l and 250 µg/l along with controlled set up for 10 days. The morphological, behavioral, hematological and histopathological changes were evaluated. Fishes exposed to Sodium arsenite showed irregular ocular movement, fin movement, swimming pattern and loss in scales with higher prominence in 250 µg/l of arsenic group than those at 100 µg/l. The hematological indices revealed decrease in RBC count and increase in WBC count in both sodium arsenite exposed groups. The histopathological study of liver revealed parenchymal disorganization and atypical residual body in both sodium arsenite treated groups. Results obtained showed major damages to fishes due to contamination with sodium arsenite. These fishes, when consumed by humans, leads to increase in several thousand folds of sodium arsenite by means of biomagnification. High exposure of arsenic in human through fishes leads to several disorders. The possible way of eradicating sodium arsenite entry into humans is banning fishing activities in highly contaminated aquatic ecosystems. Community education and local participation are also essential to get a fruitful outcome.

This work attempts to reconstruct historical fisheries profile by filling in the missed underestimated catch information for some reasons of industrial fishing, artisanal fishing, inland fishing, illegal fishing, discards and aquaculture production of Cameroon from 1950 to 2016.This reconstruction was carried out based on data published by various authors, the Ministry of Fisheries and Livestock (MINEPIA), the Limbe Research Center on Fisheries and Oceans and FAO reports. The dataset allowed us to reconstruct the fishing profile of Cameroon by completing the missing data by interpolation. Then we compare the data obtained with those of FAO. Reconstructed catches were estimated at 13,834 tons and aquaculture production was estimated at 19 tons in 1950 compared to 12,000 tons and 14 tons published by FAO, With the agricultural reforms and development of projects focused on the primary industry, catches increased around 94,122 tons in 1977(compared to 70,167 tons reported by the FAO) to 102,975 tons in 1981(compared to 79,761 tons reported by the FAO), declined to 78,790 tons in 1986 because of the reduction of the Exclusive Economic Zone of Cameroon (EEZ) by the geographical presence of the insular part of Equatorial Guinea (Malabo Island), then increased to 186,204 tons in 2005(compared to 142,345 tons reported by the FAO), declined to 154,800 tons in 2008(compared to 129,000 tons reported by the FAO). Since 2011 it became stable and reached around 240,000 tons against 220,000 tons published by FAO. Overall, there are discrepancies between the reconstructed data and the data provided to FAO: the reconstructed data is 30% higher than the FAO data. This information about fisheries production in Cameroonian waters shows that many locals, fisheries managers and stakeholders depends on fish products for either incomes or food safety; therefore, the recent decline of fish production in Cameroon is of no good sign to the abovementioned persons. These observed fish production decline indirectly threatens the food security of the people of Cameroon and low financial income to the state coffers.

A study on the effect of the substitution of fishmeal by Lima bean flour was conducted between March and May 2018 within the AIO ICG of the Batié District, with the global objective of contributing to the development of alternative sources of animal protein. Specifically, the aim of the study was to evaluate the effect of the substitution of fishmeal by Lima bean flour on the growth performance, survival and feed cost of Clarias gariepinus. For this purpose, 300 fry of Clarias gariepinus with an average weight of 3 ± 1.41g were divided into five batches and fed three times a day with rations corresponding to 5% of their ichthyo biomass. The rations R0, R25 R50, R75 and R100 respectively corresponded to the substitution rates of 0, 25, 50, 75 and 100% of fish meal by that of Lima bean. The physic-chemical characteristics of the water (pH, temperature, dissolved oxygen, nitrites and nitrates) were measured daily. The following results were obtained: The highest weight gains were obtained with the rations R25 (20.56 ± 0.40 g), R50 (20.64 ± 0.32 g), R75 (20.98 ± 0.46 g) and the lowest with the ration R100 (16.21 ± 0.28 g). For this average daily gain, the highest values were 0.36 ± 0.02 g; 0.37 ± 0.01 g, 0.38 ± 0.01 g respectively for the R0, R50 and R75 rations and the lowest with R100 (0.29 ± 0.01 g). The highest value of the specific growth rate (2.47 ± 0.07%) was obtained with the ration R0 and the lowest (1.61%) with the ration R100. The consumption index reached its highest and lowest values with the rations R100 (4.74 ± 0.42) and R50 (3.57 ± 0.43) respectively, compared to the value of the ration R0 (3.31 ± 0.37) for this parameter. Concerning the condition factor K, the highest value was recorded with the R50 diet (1.11 ± 0.49) while the lowest value was obtained with the R75 diet (0.95 ± 0.45). The cost of producing one kilogram of food was higher with the R25 ration (504.59 FCFA) and lower with the R100 ration (443.20 FCFA). This study found that incorporating 75% Lima bean flour into the feed increases the growth performance of Clarias gariepinus fry and reduces the cost of food production.

In order to improve the production of Clariidae, a study on the type of cultivation of Heterobranchus longifilis and Clarias gariepinus in post fingerlings growth phase was carried out in tanks. It took place from March to May 2018 at the IRAD fish station in Koupa-Matapi (LN: 5º 21 ‘to 5º 58’ and LE: 10º 17 ‘to 11º 02’) west region Cameroon. For this fact 180 fry therefore 90 Heterobranchus longifilis and 90 Clarias gariepinus with an average weight 3.55 ± 0.68 g; 8.46 ± 0.41cm of total length and 7.37 ± 0.30 cm of standard length were used. The 180 fry were divided into three treatments of 60 individuals (T1 treatment: Clarias gariepinus, T2 treatment Heterobranchus longifilis and T3 treatment: Clarias gariepinus + Heterobranchus longifilis). Each treatment was repeated twice. The fish were fed twice per day at a rate of 10% of the ichthyobiomass readjusted each month after control fishing with a feed at 42% crude protein. From the results of this trial, it appears that unlike the higher mortality rates (11.66 ± 2.36%) recorded in monoculture Clarias gariepinus, the highest cannibalism rates were obtained in monoculture of Heterobranchus longifilis (13.33 ± 4.71%). The survival rate was not influenced by the type of culture. Nevertheless, the highest rate (94.44 ± 0.00%) was observed in Heterobranchus longifilis in polyculture. The highest growth values were recorded for C. gariepinus in polyculture and the weakest for H. longifilis in polyculture. For linear growth, the highest values were recorded in C. gariepinus in monoculture. In order to reduce the rate of cannibalism and mortalities in Clarias gariepinus and Heterobranchus longifilis in post f ingerlings growth phase, it is preferable to combine these two species.