African Journal of Fisheries Science

African Journal of Fisheries Science ISSN 2375-0715 Vol. 7 (3), pp. 001-007, March, 2019. © International Scholars Journals

Full Length Research Paper

Evaluation of some heavy metals in Pangasius hypothalmus and Tilapia nilotica and the role of acetic acid in lowering their levels

Tarek Elnimr

Medical Physics Research Laboratory, Faculty of Science, Tanta University, Tanta, Egypt. E-mail: [email protected].

Accepted 11 January, 2019

Abstract

Concentrations of cadmium, mercury, manganese, phosphorus, lead and zinc in samples of Basa fish (Pangasius hypothalmus) and some fresh water fish (Tilapia nilotica, named Bolti and Karmout) collected from Kafer-El-Zayat were determined. Karmout fish contained the highest level of metals where phosphorus level was 3.45 µg/g, lead (1.51 µg/g), zinc (1.03 µg/g), cadmium (0.17 µg/g), manganese (0.08 µg/g) and mercury (0.007 µg/g). In Bolti fish, phosphorus level was 4.03 µg/g, lead (0.83 µg/g), zinc (0.62 µg/g), cadmium (0.12 µg/g), manganese (0.08 µg/g) and mercury (0.004 µg/g). In Basa fish, phosphorus level was 4.06 µg/g, lead (0.79 µg/g), zinc (0.62 µg/g), cadmium (0.12 µg/g), manganese (0.07 µg/g) and mercury (0.004 µg/g). Cadmium and lead levels in all examined fish were higher than permissible safety level of human use (0.1 ppm). Pre-treatment of fish muscles by acetic acid (5%) for a period of 15 min resulted in marked reduction of metals in these fish. When the Basa fish was immersed in 5% acetic acid, the cadmium level in the flesh was reduced from 0.12 to 0.07 µg/g (41.6%) and lead level was reduced from 0.83 to 0.41 µg/g (51.9%). In Bolti fish, pre-treatment of the fleshy parts by acetic acid reduced cadmium level from 0.12 to 0.07 µg/g (58.3%) and lead was reduced from 0.83 to 0.02 µg/g (24%). The same result was observed in Karmout fish, where pre-treatment with acetic acid lowered the cadmium level from 0.17 to 0.05 µg/g (29.4%) and lead was lowered from 1.51 to 0.82 µg/g (54.3%).

Key words: Basa fish, Tilapia nilotica, Karmout, acetic acid, heavy metals.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 7 (3), pp. 001-008, March, 2019. © International Scholars Journals

Full Length Research Paper

Aquaculture in Europe: Media representations as a proxy for public opinion

Anne Katrin Schlag

King's College London, Strand, London WC2R 2LS, UK. E-mail: [email protected]. Tel: +44 (0)20 7848 1598.

Accepted 07 January, 2019

Abstract

Fish is traditionally considered a healthy and pure food. However, with the development of modern aquaculture, a range of potentially controversial issues are emerging. These could significantly impact the future success of the industry. In the absence of in-depth data on lay perceptions on farmed fish and fish farming, this paper utilises media representations as a proxy for public opinion. Media representations of aquaculture were investigated in Germany, Norway and the UK over a five-year timeframe (May 2002 to May 2007). A total of 1049 articles from both broadsheet and tabloid newspapers were analyzed with the qualitative software Atlas/ti. We compare the article framings cross-nationally, focusing in-depth on four major analytical themes which emerged: the environment, the economy, human health and trust/regulation. Despite general similarities, these themes are represented with different salience and foci across the countries of analysis. These divergent media representations of aquaculture are discussed in terms of their likely impacts on lay perceptions of farmed fish and fish farming. In turn, the understanding of consumer perceptions is a vital component for policy making about aquaculture.

Key words: Aquaculture, farmed fish, risk, media analysis, cross-national research.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 7 (2), pp. 001-005, February, 2019. © International Scholars Journals

Full Length Research Paper

Reproductive biology, length–weight relationship and condition factor of the African snake head, Parachanna obscura, from River Oshun, South-west Nigeria

Olurin K. B.* and Savage O. D.

Department of Plant Science and Applied Zoology, Olabisi Onabanjo University, P. M. B. 2002, Ago – Iwoye, Ogun State, Nigeria.

Accepted 12 February, 2019

Abstract

Aspects of the biology of the African snake head, Parachanna obscura, obtained from River Oshun, South-west Nigeria, from August 2006 to February 2007, were studied. Fish were captured with gill nets. The species attained a maximum total length of 36.4 cm and body weight of 389.36 g. The length/weight relationship indicated allometric growth for males and isometric growth for females. Gonado-somatic index ranged between 1.1 and 2.8% in the females. Values of condition factor were high for males. There were more females than males, and immature fish dominated the catch. Eggs ranged in size between 0.88 and 1.11 mm, while fecundity estimates ranged between 1711 and 4000 and were not related to length and body weight. P. obscura in this study did not show any distinct seasonal pattern of breeding.

Key words: Parachanna obscura, River Oshun, Nigeria, reproductive biology.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 7 (2), pp. 001-004, February, 2019. © International Scholars Journals

Full Length Research Paper

Socio-economic evaluation of rural women and the estimation of profitability of fish marketing in four markets in Nigeria

Yisa T. A.*, Tsadu S. M. and Mohammed I.

Department of Water Resources, Aquaculture and Fisheries Technology, Federal University of Technology, Minna, Niger State.

Accepted 09 October, 2018

Abstract

The level of unemployment, poverty, hunger and disease is growing at an alarming rate in developing countries despite global technological and entrepreneurship development. Fish is known to be the most important food commodity handled by rural women in Katcha Local Government area of Niger State because of abundant water from River Niger and streams. This study examined the socio-economic characteristics of rural women involved in marketing; the problems and constraints associated with fish marketing, as well as its socio-economic benefits and profitability. Four markets randomly selected were used for data collection. Structured questionnaire was designed to elicit information from twenty (20) respondents in each selected market. Analytical tools used were simple descriptive statistics such as percentages and benefit cost ratio. The results showed that 32.5% of the respondents were within the age range of 36 to 45 years. The percentage profits margin were 10.33, 9.77, 8.48 and 7.26% for Katcha, Chapo, Dibbo and Ndalada markets while percentage of total profit were 32.23, 26.74, 22.34 and 18.68% respectively. Similarly, benefits/cost ratio for Katcha, Chapo, Dibbo and Ndalada markets were 1.10, 1.09, 1.08 and 1.07 respectively; indicating that fish marketing is a profitable venture. This index can be used as a tool for economic empowerment and poverty reduction among rural women.

Key words: Rural women, fish marketing, poverty reduction, economic empowerment.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 7 (2), pp. 001-004, February, 2019. © International Scholars Journals

Full Length Research Paper

Reverse transcriptase polymerase chain reaction is a sensitive diagnostic tool for detection of nodavirus infection in Macrobrachium rosenbergii

D. P. Behera*, K. Devdas and L. Nayak

Department of Marine Sciences, Berahmpur University, Bhanja Bihar, Berhampur, Orissa-760007,India.

Accepted 13 November, 2018

Abstract

Macrobrachium rosenbergii is the most important cultured Palaemonid in the world. It is farmed on a large scale in many countries including India, once upon a time this species was considered as disease free animal but towards later part of 2001, the hatchery and nursery pond of these animals suffered a massive loss due to a new viral disease named white tail disease. Till date different diagnosis has been established for detection of this disease but reverse transcriptase polymerase chain reaction (RT-PCR) techniques is the most sensitive diagnostic tool among those present available for detection of MrNv (Macrobrachium rosenbergii nodavirus). The designed primer fair (1F/1R) in 1st step PCR was carried out using 1 µl e DNA like wise in 2nd step RT-PCR product the nested primer 2nd 1 µl of 1st RT-PCR product were utilized. At the end of 8 µl of each step PCR product was analyzed by electrophoresis on 1% agarose gel along with sample. The confirm positive and negative sample were run in the gel, the gel electrophoresis of RT-PCR product positive control (Lane-3) is expected amplified product of about 489 bp size of noda virus presence in sample.

Key words: Reverse transcriptase, diagnostic tool, nodavirus, Macrobrachium.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 7 (1), pp. 001-008, January, 2019. © International Scholars Journals

Full Length Research Paper

Toxicity of pawpaw (Carica papaya) seed powder to sharptooth catfish Clarias gariepinus fingerlings and effects on haematological parameters

Ezekiel Olatunji Ayotunde, Benedict Obeten Offem*, Irom Bassey Okey, Gabriel Ujong Ikpi, Stephen Ncha Ochang, Nnanke Effiom Agbam and Dodeye Eno Omini

Department of Fisheries, Faculty of Agriculture and Forestry, Cross River University of Technology, P. M. B. 102, Obubra Campus, Calabar, Cross River State, Nigeria.

Accepted 22 November, 2018

Abstract

The mesocarp of pawpaw fruits (Carica papaya) is a delicacy in the Tropics but the seeds are known to contain toxic substances (Carpine, Papain). However, there have been very few studies on the toxicity of these substances to organisms. First part of the present study determines the toxicity of an aqueous extract of pawpaw (Carica papaya) seed powder to catfish (Clarias gariepinus) fingerlings using static bioassay. The second part investigates the haematological effects. 400 healthy catfish (Clarias gariepinus) fingerlings 10.5 ± 3.2 cm (total length), 15.5 ± 6.4 g (body weight) were exposed to triplicate concentrations of 10, 11, 12, 13, 14 and 15 mg/l in eighteen 30 L glass tanks, each with 22 fish in 20 L aerated rain water. 24, 48, 72 and 96 h LC₅₀ values were 19.0 ± 3.3, 13.0 ± 2.8, 12.8 ± 1.6 and 12.9 ± 2.1 mg/L, respectively. There was significant reduction (p < 0.05) in the value of blood parameters [Blood cell count (erythrocytes and leucocytes) and basic erythrocyte indices (mean cell haemoglobin concentration (MCHC), mean corpuscular volume (MCV), and mean corpuscular haemoglobin (MCH)] of C. gariepinus fingerlings after exposure to 96 h in aqueous extract of C. papaya seed powder. Toxic reactions include; erratic movement, air gulping, loss of reflex, molting and discoloration. Maximum admissible toxicant concentrations ranged from 0.1 to 1.29 mg/L (confidence level: 22 - 78.8%). The results showed that concentrations of pawpaw seed powder in excess of 1.29 mg/L can be potentially harmful to C. gariepinus fingerlings.

Key words: Toxicity, pawpaw seed, catfish, fingerlings, haematology, water quality.