African Journal of Fisheries Science

African Journal of Fisheries Science ISSN 2375-0715 Vol. 5 (1), pp. 210-214, January, 2017. © International Scholars Journals

Full Length Research Paper 

A study of the levels and seasonal variation of heavy metal contamination of E. radiata from creeks in Burutu area of Delta state, Nigeria 

James Azuka, Adaku Ijeoma and Ijeagha Ifeatu

Department of Fishery and Aquaculture, Faculty of Agriculture & Natural Resource Management, Ebonyi State University, Abakaliki, Ebonyi State, Nigeria.

*Corresponding Email: [email protected]

Accepted 12 November, 2016

Abstract

Levels of heavy metal concentrations in tissues of Egeria radiata from Obotebe and Gbekobor Creeks in Burutu Local Government Area were investigated. E. radiata samples were collected fortnightly for 12 months in 2008. The soft tissues of E. radiata were extracted, weighed and dried in oven for three days at 60⁰C. Ten grams of the dried samples were homogenized and digested before analysis using the atomic absorption spectrophotometer (AAS) to determine levels of heavy metals such as (copper, lead, manganese, cadmium, mercury, chromium and nickel). The results obtained showed that tissues of E. radiata from the creeks were contaminated with heavy metals. The mean concentrations of heavy metals in tissues of E. radiata followed an increasing sequence of Hg < Cd < Cr < Mn < Pb < Cu < Ni. Heavy metal concentrations in tissues of E. radiata were higher but were not significant in the dry season than in the rainy season. Levels of heavy metals in tissues of E. radiata were found to be below the FAO/WHO acceptable limits of heavy metal pollution in fishes and shell fish. Mean levels of lead (Pb), manganese (Mn) and Cadmium (Cd) were found to be higher than world standard but not significant. Nickel were significantly lower than world standard. There is a need for constant monitoring of levels of heavy metals in the area of study in order to forestall any significant rise in their levels.

Key words: Heavy metals, E. radiata, creeks, Burutu, Nigeria.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 5 (2), pp. 215-221, February, 2017. © International Scholars Journals 

Review 

A review of the marine fisheries policy and management   in Nigeria

*Ita Bassey, James Ibas and  Edet Akpan

Nigerian Institute for Oceanography and Marine Research, Victoria Island, Lagos, Nigeria. 

Accepted 24 October,  2016

Abstract

We reviewed the marine fisheries laws as contained in the Sea Fisheries Decrees of Nigeria promulgated in 1971, 1972 and revised in 1992. We found out that these decrees were lacking in scientific data needed to effectively enforce the laws, both for industrial and artisanal fisheries. The major habitats of the different species, their breeding and nursery grounds; the migratory movements and seasons for different species; size selection of the fishing gears for different species caught simultaneously by relevant gears; sizes at first maturity of the different species; feeding/trophic relationships of the various species; maximum and optimum sustainable yields of the resource, and the corresponding effort, are some of the missing scientific information. This paper stresses the importance of these scientific data requirements for effective policy options and sustainable fisheries management.

Keywords: Fisheries management; Marine fisheries; Sea fisheries; Fisheries policy; Nigeria

African Journal of Fisheries Science ISSN 2375-0715 Vol. 4 (1), pp. 204-205, January, 2016. © International Scholars Journals

Full Length Research Paper

Outbreak of epizootic ulcerative Syndrome (EUS) in Seranochromis robustus Fish species in Darwendale dam, Zimbabwe

¹Calvin Gomo, ²T. Hanyire, ³P.V. Makaya and ³S Sibanda

¹C. Gomo, School of Agricultural science and Technology, Department of Animal Production and Technology, Chinhoyi University

²Wildlife Unit, Department of Livestock and Veterinary Services, Harare.

³Department of Livestock and Veterinary Services, Harare.

*Corresponding author.E-mail: [email protected]

Received 30 June, 2015; Accepted 28 July, 2015

Abstract

The aim of the study was to investigate the causes of mortality of fish in Darwendale Dam in Zimbabwe. Findings of laboratory gross examination of lesions were consistent EUS. Histopathology examination showed that the fish had mycotic granulomas. Fish of all ages were affected. High mortalities and severity of ulceration suggests a relatively recent invasion by A. invadans at Darwendale dam. EUS spread from Darwendale to other areas due to improper surveillance and poor control strategy due to lack of EUS knowledge by fishermen and authorities. More studies needed to be done in Zimbabwe to determine species of fish affected, strain A invadans circulating and control measures to prevent spread of diseases.  EUS was confirmed in Seranochromis robustus in Zimbabwe in 2013. The study is the first published account of infection with Alphanomyces. invadans in the wild fish populations (Seranochromis robustus) of the Darwendale Dam in Zimbabwe.

Key words: EUS, Darwendale, Zimbabwe, Alphanomyces, Invadans, wildfish.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 3 (3), pp. 197-203, March, 2015. © International Scholars Journals

Full length Research paper

Hatcheries management troubles, economic losses and environmental impacts by shrimp hatcheries on coastal Ecosystem, Mexico

Miguel Rodrigo Coffman

Department of Fisheries, Faculty of Agriculture, Universidad Veracruzana, Xalapa, Mexico.

Email: [email protected]

Accepted 24 February, 2015

Abstract 

In Mexico, shrimp hatcheries have been developed as intensive monocultures, resulting in hatcheries management troubles, economic losses and environmental impact. Therefore, the aim of this work was compare to a traditional culture vs. a mixed culture. Shrimp juveniles were distributed in aquariums and ponds at the same density (51 shrimps/m²) but ponds, also had oysters and macroalgae. Shrimps in aquaria and ponds were feed with same food amount. Water was change each two days, but in ponds only 20%. To compare traditional vs. mixed culture, shrimp’s growth, feed efficiency conversion and nutrients concentration, in aquariums and ponds were recorded. At experiment’s end, shrimps grew 35% more in ponds than aquariums; feed efficiency conversion was 0.68 units lower in ponds than aquariums, and NH₄ concentrations were close to 3 and 1 mg/L in aquariums and ponds respectively. The mean increase weight in oyster and macroalgae, was 4.04 and 19.3 g respectively. Therefore, mixed culture has many ecological and economic advantages over traditional culture. Therefore it is suggested that scaling this technology to commercial level, in addition to shrimps, oysters and macroalgae are produced, which could be used for human consumption and animal fodder respectively. Also, this model improves water quality and reduces the environmental impact.

Key words: Shrimp-monoculture, mixed-culture, oysters, macroalgae, higher productivity, water quality, environmental impact.