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Fishery and Aquaculture Division

  

Dr. Ruby Asmah
(Senior Research Scientist)

 

 Dr. Francis Amevenku
(Senior Research Scientist/Head of Division)

3Mr. Theodore Quarcoopome
(Senior Research Scientist)

 

Dr. Seth K. Agyakwah
(Research Scientist/ OIC ARDEC)

6Mr. Etornyo Agbeko
(Research Scientist)

 

 

8

Dr. Francis A. Anani
(Research Scientist)

9

Mr. Solomon A. Owiredu
(Research Scientist)

 

10Mr. Emmanuel
Tetteh-Doku Mensah

(Research Scientist)

 

 

 

 

 

 

 

3.3       FISHERY DIVISION

 

The mandate of the Fishery Division is to generate scientific information, the application of which would enhance sustainable management and development of Ghana’s fish, fisheries and aquaculture resources. The Division’s goal is to increase local fish production to support livelihoods through increasing yield from existing fisheries and development of sustainable aquaculture and culture-based fisheries practices. 

Currently, the Division’s major research and development programmes are aquaculture development, environmental impact assessment and monitoring of fish populations in relation to socio-economic development activities, fisheries enhancement and culture-based fisheries.

The research activities undertaken during the year under review are presented below.

 

3.3.1    Comparison of Different Generations of Oreochromis niloticus Cultured at the Aquaculture Research and Development Centre Using Molecular Diagnostic Techniques

(Project Staff: Mrs. Rhoda Lims Sakyi – Research Scientist, Dr. Felix Attipoe – Research Scientist, Dr. Seth Agyakwah – Research Scientist, Dr. Mike Osei-Atweneboana – Senior Research Scientist, Nana Aso Amonoo – Technical Assistant)

Fish is the most important source of animal protein in Ghana. However, the fisheries sector has over the past two decades registered a slow growth of 3% per annum. Ghana is thus presently not self-sufficient in fish production.  However, the demand for fish would continue to increase with increasing population growth. Aquaculture production is therefore expected to play a key role in ensuring food security. Efforts are now geared toward maximizing fish production, particularly Tilipia (Oreochromis niloticus). The Aquaculture Research and Development Center (ARDEC) of the CSIR Water Research Institute at Akosombo, has over the years been involved in breeding O. niloticus. Based on best performances, the center has been able to produce improved stocks of O. niloticus up to the 10th Generation, which is currently being supplied to over 200 commercial producers and over 30 hatcheries. There is however other important research focuses to enhance the efficiency of the selective breeding programme. These include; protecting the integrity or quality standard of the Akosombo Strain, maximizing fisheries (aquaculture) production and promoting the health of the fish, thus contributing to meeting the MDG with regards to food security. Towards achieving these goals, there was the need to study and understand the genetic diversity of the Ghanaian populations of Oreochromis niloticus, particularly those under culture to determine how they have evolved over the years, from one generation to the other to help maximize fish production in Ghana. It was against this background that the study was started in 2012 to identify genetic variation among different generations of Oreochromis niloticus at WRI-ARDEC to enhance production and management of disease conditions in the aquaculture systems. The specific objectives were to:

  • •identify genetic changes in some loci of the O. niloticus genome that could discriminate different population of O. niloticus at WRI-ARDEC; and
  • •identify genetic variations associated with ‘strains’ of O. niloticus with desirable traits (growth, survival rate, etc.) that would maximize production in selective breeding. It is expected to end in 2015.

During the reporting year, Oreochromis niloticus were sampled from generation 5 to generation 9 (G5 to G9) at WRI-ARDEC. The non-destructive sampling approach was employed. Fish sampled from each generation were assessed for their phenotypic characteristics. A total of 40 fish fins were obtained from each generation. A piece of the caudal fins, approximately 1-2 cm were cut from each fish, preserved in 95 % ethanol and kept frozen at the laboratory. At the laboratory, samples were taken through the processes of DNA Extraction, using qiagen kit extraction method; Microsatellite amplification, through the running of Polymerase Chain Reaction (PCR) in a peQlab thermal cycler using the Microsatellite primer set UNH 222 (PCR conditions: 94°C  for 2mins, denaturing at 94°C for 30sec, annealing temperature, 48°C  for 30s, extension 72°C for 1min and final extension at 72°C for 5min at 33cycles); and Gel electrophoresis, where all amplified DNA products were visualized by 1.5% agarose gel under a UV transilluminator after ethidium bromide staining.

After Microsatellite analysis of the various Generations, it was observed that Generation 5 amplified at the expected amplicon, which is 200bp (Figure 20). However, after the fifth Generation, the amplicon size varied for the subsequent Generations (G6 to G9), and were significantly lower than Generation 5, around 180bp and 190bp (Figure 20). These differences in amplicon sizes could be attributed to the fact that there may be deletions in the sequences of the other generations.

Preliminary results of the study indicated that with regards to band patterns from gel electrophoresis, there were some differences among the various generations of O. niloticus cultured at WRI-ARDEC. Further analysis associating these differences with phenotypic traits would be established after sequencing. The sequence from a particular generation that would consistently show strong association with phenotypic or good performance traits like fast growth, high survival, fecundity rates and disease resistance, etc., would be used to develop a panel of markers as a diagnostic tool for selective breeding and disease management on aquaculture farms.

 

                                                             11    

                      Figure 20: A representative 1.5% agarose gel showing the band patterns of Generation five to nine (G5, G6, G7, G8, G9, M: 100bp Marker, NC: Negative Control) of Oreochromis niloticus from WRI ARDEC

 

3.3.2    Enhancing Food Security through Cage Fish Culture and Water Conservation by Reafforestation of Reservoirs in Northern Ghana

(Project Staff: Mr. Etornyo Agbeko – Research Scientist, Dr. Felix Akpabey – Senior Research Scientist, Mr. Michael Kumi – Research Scientist, Mr. Gerard Quarcoo – Research Scientist, Mr. Daniel Nsoh Akongyuure – Research scientist)

Aquaculture is one of the fastest growing agricultural sectors in the world. Aquaculture particularly with tilapia cage fish culture is fairly new in Northern Ghana, despite having numerous water bodies and reservoirs. The Institute, in collaboration with the Ministry of Local Government and Rural Development (MLGRD), Ministry of Fisheries and Aquaculture Development, Forest Services Division of Forestry Commission and CSIR-Forest Research Institute of Ghana initiated the study in 2013 to implement a Community-Based Cage Fish Culture (CBFC) in the Vea and Bontanga reservoirs in the Upper East and Northern regions of Ghana. This Community Based Fish Culture is a sub-project under the Food Security and Environment Facility (FSEF) Project funded by the Canadian Government Foreign Affairs, Trade and Development Canada (DFATD). This report covers the first phase involving stocking, management, growth and harvesting of the Nile Tilapia in cages mounted in Bontanga and Vea reservoirs in Northern Ghana.

The objectives were to:

  • increase fish production through cage fish culture with fast-growing ‘Akosombo strain’ of Oreochromis niloticus to ensure food security and alleviate poverty;
  • create green belts through the planting of Cassia sp. for water conservation in the reservoirs for sustainable fish production;
  • monitor reservoir water quality and identify any spatial or temporal variations in       water quality over time in relation to cage fish culture to ensure reservoir ecosystem health; and
  • make recommendations in respect of water quality for sustainable cage fish culture and fish production in reservoirs in Northern Ghana.

Activities undertaken during the reporting period included:

  • fabrication, installation of nets, mounting and mooring of sixteen cages in the reservoirs;
  • stocked cages with fingerlings of mean weight of 1g of Nile tilapia (Akosombo strain of Oreochromis niloticus);
  • Nile Tilapia growth assessment, collation of mortality data and adjustment of feeding rate based on percentage body weight of fish;
  • hands-on training of project participants on feeding and management of Nile tilapia;
  • re-stocked of cages for the second Phase of fish production;
  • Quarterly water quality monitoring samples were taken from the up, mid and downstreams of two reservoirs (Vea and Bontanga) and microbial analysis were carried out in the laboratory;
  • Bacteriological parameters such as total coliform, faecal coliform, E. coli, Salmonella spp and total heterotrophic bacteria were determined.

A total of 16 cages with a 5x5x2 m dimension were fabricated locally and mounted with production nets and inner/hapa net for culturing of Nile tilapia fingerlings into adult fish. A cover netting was installed to prevent predation of fish by birds such as the king fisher. Each cage was stocked with 5000 to 6900 fingerlings (i.e. 100 - 138 fish per m3). A total of 93,020 fingerlings were stocked (Table 7). Total survival rate of 52.9 % was recorded during the first phase of cage culture of Nile tilapia in the reservoirs. It was observed that factors such as poor fish conditioning, stress due to transportation and poor feeding exacerbated fish mortality. The Specific Growth Rate (SGR) was slightly better in the Vea Reservoir (2.2 %/day) compared to that of the Bontanga Reservoir (2.1 %/day). The calculated FCR indicated that 2.3 kg and 2.1 kg of feeds were required to gain 1 kg of fish weight in the Bontanga and Vea reservoirs, respectively. The growth pattern based on Length-Weight relationship for O. niloticus under cage culture in the reservoirs was allometric (i.e. K: 3.4 and 3.5). Thus, increases in length and weight for Akosombo strain of O. niloticus were not equal during the culture period. Most Tilapiine species commonly known as bream or mango fishes (family: cichlidae) exhibited similar condition factors (K).

Table 7: Stocking, survival rate and growth parameters of Nile Tilapia (O. niloticus, Akosombo strain) under cage culture in selected reservoirs in Northern Ghana (First phase of production)

Parameters

Bontanga Reservoir

Vea Reservoir

Total no. Stocked

43,420

49,600

Survival rate (SR %)

62

45

Weight of fish at Harvest

(Wt.) Mean ± S.D

(Wt. min – Wt. max) g

 

189.6 ± 29.5

(137.0 - 249.3)

 

284.3 ± 16.1

(263.4 - 303.9)

Length (L) Mean ± S.D

(L min – L max) cm

21.7 ± 1.6

(19.2 - 24.3)

24.3 ± 1.7

(23.9 - 25.0)

Specific Growth Rate (SGR), %/day

2.1

2.2

Average Daily Weight Gain (g)

0.8

1.1

Food conversion ratio (FCR)

2.3

2.1

Total no. of fish harvested

26,910

22,320

Condition factor (K)

3.4

3.5

Marketing of Tilapia was based on the size categories of the fishes during harvest period. Interaction with most fish-mongers at the landing sites along the reservoirs indicated a preference for Regular (251-350 g) and Economy (150-250 g) sizes of Tilapia fish. Project participants were trained on sorting, grading and marketing of tilapia by size categories using weighing scale (kilograms) instead of bowls (Figure 21). 

 

 

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Figure 21: Percentage composition of harvested Nile Tilapia (Akosombo strain) based on marketing size categorization

The mean results of bacteriological parameters (Total coliform (TC), Faecal coliform (FC), E.coli, Total heterotrophic bacteria (THB) and Salmonella spp. (SS) analysed for the water quality of the Bontanga and Vea reservoirs in the Northern and Upper East regions of Ghana, respectively, are shown in Figures 22 and 23. The higher bacterial loads could be attributed to run-offs carrying faecal matter of animals such as goats, sheep and cattle into the reservoirs as these animals were observed to be grazing along the bank of the reservoirs during the sampling period. Though the bacterial loads varied during the one year period for the reservoirs compared to their baseline values, all bacterial loads (TC and FC) of the reservoirs were below the USEPA and WHO permissible levels of 10000 CFU/100ml and 1000 FC/100ml, respectively, for fresh and wastewater for aquaculture.

 

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Figure 22: Variations of bacteria parameters studied in the Bontanga reservoir

 

 

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Figure 23: Variations of bacteria parameters studied in the Vea reservoir

 

3.3.3    Evaluation of Farm-Made and Commonly Used Commercial Fish Diets by Small-Scale Pond Fish Farmers in Five Selected Regions of Ghana for Nile Tilapia (Oreochromis niloticus L.)

(Project Staff: Francis A. Anani – Research Scientist, Dr Francis K. E. Nunoo – Principal Supervisor, Prof. M. Steiner-Asiedu – Co-Supervisor, Dr T. Nortey – Co-Supervisor and Dr Nelson W. Agbo – Co-Supervisor)

The Institute, in collaboration with the University of Ghana, Legon and Kwame Nkrumah University of Science and Technology, Kumasi, started the study in 2012 to evaluate two most commonly used commercial diets and two farm-made diets formulated and prepared using six selected commonly used feed ingredients on growth and feed utilization of O. niloticus. It was also to evaluate the digestibility of the commercial fish diets and the compounded ones in O. niloticus; assess the state of health and physiological well-being (condition factor) of O. niloticus when fed separately with the farm-made diets and that of commercial ones; assess the effect of the farm-made diets and that of the commercial ones on water quality; and evaluate the cost effectiveness of the farm-made and commercial diets.

In the reporting period, proximate composition analyses of 6 selected feed ingredients (cassava flour, fishmeal, maize, palm oil, soybean meal and wheat bran) and 5 fish diets namely A, B, C, D and E were carried out. Diets A and B were farm-made diets formulated and prepared using the selected ingredients. A was supplemented with vitamins, minerals and amino acids whilst B was not. Diets C and D were the 2 commonly used commercial fish diets by small-scale pond fish farmers in Ghana, namely Coppens and Raanan respectively. Diet E was a 1:1 mixture of diets B and Raanan. Feeding trials were conducted for Nile tilapia for 20 weeks (5 months) with the various diets at ARDEC, Akosombo.

The highest final mean weight (187.6 g) of O. niloticus was observed in diet D (Raanan) whilst the least (131.0 g) was in farm-made diet B (diet without supplements) (Figure 24). Fish fed on Raanan had the highest weight gain (165.0 g) followed by those fed on Coppens (125.8 g) and the least (108.2 g) were those fed on diet B(Figure 25).

 

 

15Figure 24 Growth performance of O. niloticus fed commercial and farm-made fish diets for twenty weeks

 

 

16Figure 25: Weight gain by O. niloticus fed commercial and farm-made fish diets for 20 weeks [Bars with different letters are significantlydifferent ( p < 0.05)]

 

Apparent nutrient digestibility coefficients were high (> 60 %) in all the dietary treatments. The supplemented Farm-made diet and Raanan were the most efficiently assimilated. There were no internal and external abnormalities in O. niloticus fed with the various diets. Both the farm-made and commercial diets were found to have no effect on water quality for O. niloticus. In terms of cost-effectiveness, the farm-made diets were between 130.19 and 135.85 % more profitable than the commercial ones.

The results indicated that nutritionally balanced farm-made fish diet is cost-effective and will boost growth of aquaculture in rural areas where semi-intensive pond aquaculture is mainly practised in Ghana. The current fish production (2,500 kg ha-1 yr-1) by Ghanaian small-scale pond fish farmers could increase up to a fourfold by using appropriately formulated and prepared farm-made fish diets with locally available ingredients. This is likely to increase their profit margin to over four hundred percent of what they are making currently using commercial fish diets. The costs associated with the use of commercial fish diets by small-scale pond fish farmers are high, and in terms of fish growth and economic returns, the use of appropriately formulated and prepared farm-made diets will be a better alternative.

3.3.4    Planning for Improved and Sustainable Cage Aquaculture in Lake Volta (Project Staff: Dr. Ruby Asmah – Senior Research Scientist, Mr. Anthony Karikari – Research Scientist, Mr. Daniel Amoah – Technical Officer, Mr. Serapis Appiah – Technical Officer and Mr. Godwin Amegbe – Technical Officer)

Lake Volta is one of the World’s largest man-made lakes. It was created in 1964 by the damming of the Volta River primarily for the generation of hydroelectric power. The uses of the Lake have over the years been enhanced with cage aquaculture becoming an important activity; over 80 percent of aquaculture fish production in Ghana is from the Lake. With dwindling fish stocks from capture fisheries in Ghana, the reliance on fish production from aquaculture is expected to increase as aquaculture is considered a possible solution to the collapse of fish stocks worldwide (Naylor et al 2000). The benefits from aquaculture is, however, considered mixed; increasing fish supplies and food security, contributing to poverty alleviation, employment and community development in tropical and subtropical regions (Allison 2011) on one hand but also having the potential to negatively impact the environment (Pillay 1992). Fish cages discharge their wastes directly into the aquatic environment. A large part of the wastes are solids, made up of uneaten food particle and faecal pellets which are subject to sedimentation (Islam 2005) causing organic enrichment of the seabed and negatively affecting the biogeochemistry of benthic communities. Enrichment of the water column with nutrients and the potential of algal blooms is also possible if the operations are not managed. It was against this background that the Institute, in collaboration with the Institute of Aquaculture, University of Sterling, United Kingdom, initiated the study in 2012 to build capacity in environmental monitoring and assessment and to formulate a plan for improved and sustainable cage aquaculture on Lake Volta. The specific objectives were:

  • Estimation of waste discharges from fish cages to Lake Volta
  • Discovery of fate of aquaculture wastes and estimation of likely areas of deposition in Lake Volta
  • Assessment of interactions between aquaculture and the environment and potential impacts on biota in Lake Volta
  • Increased capacity building in environmental impact assessment in Ghana
  • Evaluation and recommendations for environmental monitoring, assessment and locations for sustainable aquaculture in Lake Volta
  • Optimization of site selection on Lake Volta

It is expected to end in 2015.

In the reporting year, the bimonthly monitoring of water and sediments at Kpeve Tornu in stratum II of the Volta Lake was continued. Samples were collected in the months of February, April, June, August, October and December. Besides the physico-chemical parameters, the macro-invertebrate communities in the sediments were also monitored. Current velocities and direction of flow of the Lake water were measured using drogues. Stakeholder meetings were also held to analyse and discuss preliminary findings obtained so far.

Sediments in the sampling sites were largely sandy soils with traces of clay. They comprised 47.7 % to 64.1 % sand, 15.9 % to 22.7 % silt and 18.9 % to 22.9 % clay (Figure 26). The differences between these components for the various sites were generally insignificant (p > 0.05), except for sites 4 and 5 in relation to silt (p 0.05). The sediments were acidic with pH values ranging from 4.49 to 5.02 (Table 8). The concentrations of total organic carbon (TOC), organic matter (OM) and total nitrogen (TN) showed minimal variation between the sites (p > 0.05). Macro-invertebrate were found at all the ten sampling sites. The composition and densities are presented in Figures 27 and 28, respectively. Three (3) to 7 taxonomic groups were found at the sites. Chaoboridae and Chironomidae were the dominant species at all the sites. The Shanon diversity index (H’) ranged from 0.32 to 0.63. The highest index was recorded at site beneath the cage (Site 8).

 

17Figure 26: Grain size distribution of sediments at Kpeve Tornu

 

Table 8: Physicochemical characteristic of sediments and water depth at Kpeve Tornu

Parameter

1

2

3

4

5

6

7

8

9

10

p-value

pH

4.50

4.49

4.67

4.86

4.69

4.96

4.70

5.02

4.67

4.58

p > 0.05

TOC [%]

6.83

4.68

6.08

4.97

5.04

5.38

5.10

5.68

5.53

5.35

p > 0.05

OM [%]

11.7

8.04

10.5

8.55

8.67

9.25

8.77

9.51

9.51

9.20

p > 0.05

TN [%]

0.59

0.40

0.52

0.43

0.43

0.46

0.44

0.48

0.48

0.46

p > 0.05

H’

0.53

0.62

0.64

0.32

0.53

0.48

0.60

0.63

0.50

0.39

 

Water Depth[m]

23.9

21.9

17.0

15.2

13.4

20.9

13.8

18.1

30

17

 

 

18 19

 

Figure 28: Macroinvertebrate densities in the sediments at Kpeve Tornu

Figure 27: Macroinvertebrate composition in the sediments at Kpeve Tornu

 

3.3.5    Fish Fauna Assessment of the Water Storage Facility at Newmont Akyem Mine (Wet Season)(Project Staff: Mr. Theodore Quarcoopome – Research Scientist and Mr. Edem K. Amerdome – Technologist)

The overall objective of the multidisciplinary study was to assess the ecological status of the Water Storage Facility (WSF) at Newmont Akyem Mine. The specific objective was to identify the types of fish species present, determine their relative importance, well-being and diversity as well as the ecological balance of the fish community.

During the reporting year, the WSF was divided into three (3) sections and fish sampled overnight during the wet season using sets of both monofilament and multifilament gill nets of different mesh sizes. The samples were identified and sorted into species and sexes and counted while each individual was weighed and measured for standard and total length. Species composition, Relative abundance, Length-weight relationships, Size distribution, Condition factor, Forage/carnivore ratio, and Biodiversity of fish species namely Shannon-Weaver diversity index (H’), Species richness (D), and Species evenness (J) were estimated.

A total of 257 fishes weighing 125,753g comprising eight species, seven genera and five families were recorded. C. anguillaris was the most abundant species in terms of both number (63.81%) and weight (72.48%) of total sample. In terms of number, the next most important species were O. niloticus (16.73%), C. gariepinus (10.12%) and H. bidorsalis (5.45%) in that order. In terms of weight, the next most important species were C. gariepinus (10.40%), H. bidorsalis (10.10%) and O. niloticus (4.35%) in that order. With the exception of H. bidorsalis, the 'b' values for the main fish species were within the expected range of 2.5 - 3.5 indicating that the growth pattern of fishes showed both positive and negative allometric characteristics meaning that increases in fish length and weight were not equal during growth. The correlation coefficient indicated medium to strong relationship between length and weight among the species. Fish condition factors were within the range expected for tropical fishes indicating that the WSF is suitable for fish growth. The WSF was fairly species-diverse but low in species richness with individuals fairly evenly distributed among the species. The fish community of the WSF was ecologically imbalanced with very low carnivore representation.

 

3.3.6 Effects of Upwelling on Biological Production in the Gulf of Guinea -Applications in Fisheries Management (Project Staff: Mr. Solomon Amoah Owiredu – Research Scientist, Dr. H. R. Dankwa – Principal Research Scientist, Nagarajah M. Kumar - ESSO-INCOIS - India, Mr. Kwame Adu Agyekum - ECOWAS Coastal and Marine Resources Management Center, UG-Legon)

The waters of the Gulf of Guinea provide an important fishing ground for both small to large scale fishing activities. These resources form a major source of protein, provide employment and contribute to the economy through fish trade. However, the excessive harvesting of resources from the oceans has led to near or actual collapse of fish populations. Satellite remote sensing of the marine environment has therefore become instrumental in ecology for the purpose of environmental monitoring, impact assessment, conservation issues and fisheries management in an ecosystem approach. It was against this background that the study was conducted in collaboration with Institute of Meteorological Training and Research/World Meteorological Organisation-Regional Training Center, Nairobi, Kenya; ECOWAS Coastal and Marine Resources Management Center, University of Ghana; and Marine and Fisheries Research Division, Ministry of Fisheries, Ghana, to apply Earth Observation (EO) data to understand seasonal dynamics of ocean processes and their influence on fish distribution in the Gulf of Guinea. The specific objectives were to determine:

  • upwelling intensity and extent in the Gulf of Guinea;
  • the trends in fish catch over a ten-year period; and
  • the effect of variations in chlorophyll ‘a’ (Chl-a) and sea surface temperature (SST) on fish distribution and abundance.

In the reporting year, monthly Level -3 SST and Chl-a data was obtained from MODIS-Aqua for the period 2002 to 2009 at a spatial resolution of 4 km. This was acquired from http://oceandata.sci.gsfc.nasa.gov/MODISA/Mapped/Monthly/4km/. The data were in netcdf format and processed using netcdf libraries in Matlab. Chl-a and SST in raw digital numbers were converted into parameter values i.e. in mg/m3 and degree Celcius (°C) using a linearly scaled equation with intercept and slope values which were provided in the netcdf attributes. Data for the Gulf of Guinea region were extracted between Latitudes 5°S to 12°N and Longitudes 20°W to 12°E. Descriptive statistical images (mean SST) were calculated across time from the monthly SST and Chl-a composite images to show the mean spatial pattern for the whole time series and areas of greatest variance, as well as the seasonal and interannual spatial variability. These images were examined to identify important oceanographic features, as well as large scale patterns of seasonal and interannual variability.

The study indicated that coastal waters with SST at 27oC in January gradually warmed to about 29oC in May (Figure 29) until in June when both coastal and oceanic waters reached temperatures between 25-27oC. From June till September, SST dropped as low as 21oC when the upwelling was intense. The coldest waters were on the continental shelf off Ghana. There was a weak front during this period as SST in the entire Central West African Upwelling (CWAU) was reduced from the coast to the equator. By October, SSTs had slightly increased, as coastal waters off the coast of Togo and Benin were between 27-28oC, and during November coastal waters were as high as 29oC. In December, there was a slight drop in SST relative to the surrounding oceanic waters at the western coast of Cape Palmas and Cape Three Points. At this period coastal SST were not below 26oC with oceanic regions reaching as high as 29oC which marked the beginning of the minor upwelling that last till January.

 

 

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Figure 29: Mean monthly SST from January to December

 

 

Low levels were observed in January and coastal and oceanic regions had chlorophyll-a ranging from 0.1–1.0 mg/m3, dropping further by March (Figure 30 (1-3)). Chlorophyll-a concentration peaked from July to September and then receded drastically between January and May. The coastal regions recorded high chlorophyll-a concentration from June to September. Chlorophyll-a concentration began to increase in June and between July and September, coastal regions of Cote d’Ivoire and Ghana had high chlorophyll-a, approximately between 3 mg/m3 and 100 mg/m(Figure 30 (6-8)). However, during July, chlorophyll-a concentrations on the coastal shelf of Cote d’Ivoire were slightly higher than at the coast of Ghana though SST was lower for the coast off Ghana than in Cote d'Ivoire.

 

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Figure 30: Mean monthly chlorophyll-a for January to December showing areas of primary productivity 

 

 

Maps generated from the study would be converted into a form of fishery advisory map that demarcates the probable fishing zones as lines or areas with aggregations of fish in the region. These fishery advisory maps could be generated on daily basis and would be disseminated to fishing communities. A typical advisory map that is proposed to generate using the satellite data is shown in Figure 31. Additional information such as bathymetry, sea currents, etc. may be included in the advisory maps. To ensure understanding of the local fishing communities, these advisories may further be converted in the form of a text in local languages. The text advisories would provide the fish advisory with reference to each fish landing site, fishing village, harbor, etc

It was observed in the year that the major upwelling occurred between July and September whilst the minor upwelling occurred in January. Generally, chlorophyll a abundance peaked between July and September. A Fishery Advisory Template for Ghana and Ivory Coast was proposed to help fishing communities carry out cost effective fishing operations and the government to adopt the most productive and non-productive areas to ensure appropriate management measures to develop the ecosystem.

 

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Figure 31: Proposed Fishery Advisory Template for Ghana and Ivory Coasts

 
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