FSN-FM 0005
EFFECT OF RAINFALL PATTERN ON FISH PRODUCTION IN OGUN STATE, NIGERIA
1OLAOYE, O. J., 2AKINTAYO, I. A., 3UDOLISA, R. E. K. AND 3A. O. COLE
Agricultural Media Resources and Extension Centre University of Agriculture, Abeokuta, Ogun State, Nigeria1 Nigeria Institute for Oceanography and Marine Research Victoria Inland, Lagos State, Nigeria 2 Department of Aquaculture and Fisheries Management University of Agriculture, Abeokuta, Ogun State, Nigeria3 Copyright 2010, Fisheries Society of Nigeria.
This paper was prepared for presentation at the 25th
Annual International Conference and Exhibition in Administrative Staff College of Nigeria (ASCON), Topo-Badagry, Lagos, Nigeria, 25th – 29th
October, 2010.
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ABSTRACT
The role of water in fish production could not be overemphasized. This is because water is required for the total functioning of fishes. This study therefore examined the relationship/effect of rainfall pattern on fish production. Secondary data were collected on mean annual rainfall and total annual fish output for the period of 10 years (2000-2009). The study showed that high rainfall was recorded in the year 2001 which marked the lowest fish production year due to floods effect on fish enclosures. These therefore implies that fish farmers should be encouraged to construct ponds with protective measures such as screens, dykes, freeboards, etc. which prevents total loss of stocks during heavy rainfall.
Keywords: Rainfall, water, fish production
INTRODUCTION
Rainfall is a climatic element affecting fish production in the tropics. The rain being generally seasonal, having district wet and dry seasons, regulate the agricultural calendar. Therefore, rainfall variability either within the year or from year to year is responsible for fluctuations in fish, the
time of the onset of the rainy season, total amount, distribution, number of rainy days, duration of rainfall as well as the time of its cessation (Akintola, 1995). Apart from the importance of rain to agriculture, rainfall affects the humidity conditions of the atmosphere (Akintola, 1995).
There are three different types of rainfall which are; Convectional, Cyclonic/frontal and Orographic or relief rainfalls (Figure 1, 2, 3, show the three types of rainfall respectively). Convectional rain occurs from convective clouds, e.g. cumulonimbus or cumulus congestus; it falls as showers with rapidly changing intensity. Cyclonic rainfall occurs as a consequence of slow ascent of air in synoptic systems such as in the vicinity of cold fronts and near poleward of warm surface fronts. Orographic rainfall occurs on the windward side of mountains and is caused by the raising air motion of a large-scale flow of moist air across the mountain ridge, resulting in adiabatic cooling and condensation (Pidwirny, 2008; Encarta, 2009).
Fish generally plays a vital role in the economy of Nigerians. Apart from being a source of protein, containing all the essential amino acids, its high lysine content makes it a good supplement to cereals; in addition, it contains Vit. A, D, and E. Above all, fish remains the cheapest source of animal protein for an average Nigerian (Alexander, 1974; FDF, 2008 and Olaoye, 2010). Fish is less tough and more digestible than beef, mutton, chevron, and chicken due to more muscle protein than connective tissue protein (Eyo, 2001;
Olaoye et al., 2007). These advantages coupled with increase in economic and population growth make the demand of fish to always supersede the supply (Ita et al., 1997). Therefore, it is the focus of this study to investigate the relationship between rainfall and fish production in Ogun State of Nigeria.
MATERIALS AND METHOD
The data used are secondary data. The annual rainfall data were collected from the department of Agrometrology and Water Resources Management, University of Agriculture, Abeokuta, and Annual fish production data from Ogun state Agricultural Development Programme, (OGADEP), Abeokuta. Both data ranges for a period of 10 years (2000-2009). The data where plotted against each other to determine the relationship that exist
between fish production and amount of rainfall yearly.
RESULTS AND DISCUSSION
Rainfall Situation in Nigeria: The decade experienced light to heavy rains with thunder activities especially the southern, and some parts of the northern parts of the country with concomitant flooding in some parts of the southern states. The highest rainfall amounts were recorded in the eastern flank of the country. In the south, Ikom recorded the highest decadal rainfall of 300.5mm in 6 rain days followed by Umuahia with 195.6mm also in 6 rain days. In the north, the highest rainfall amounts were recorded in Markurdi with 177.2mm in 6 rain days followed by Lafia with 166.8mm in 5 rain days. The Table 1 below shows different stations over the country and their rainfall (mm) and the rain days.
Table 1: The relationship between annual rainfall and rain days in Nigeria
STATION RAINFALL RAIN DAYS
ABEOKUTA 192.7 6 ABUJA 22.4 3 ASABA 104.0 6 AWKA 129 6 BENIN 169.4 5 BIDA 29.3 4 CALABAR 143.7 6 EKET 136.6 6 ENUGU 239.1 7 GOMBE 125.1 2 IBADAN 76.4 5 IKEJA 56.3 6 IKOM 300.5 6 ILORIN 54 5 ISEYIN 52.5 4 KADUNA 10.6 3 KANO 21.7 2 LAFIA 166.8 5 LOKOJA 58.8 5
MAIDUGURI 30.7 4 MAKURDI 177.2 6 MINNA 60 4 NGURU 11.3 2 OSHOGBO 72.7 4 OGOJA 47.5 7 ONDO 91.8 5 OSHODI 93.3 8 OWERRI 95.7 5 POTISKUM 51.3 3 SHAKI 69.8 3 UMUAHIA 195.6 6 UYO 103.1 7 WARRI 75.6 7 YELWA 73 4 YOLA 55.4 4 ZARIA 32.6 6
Source: The Nigerian Meteorological Agency, May 2009 Agrometerological bulletin
Effects of Rainfall on Fish Production in Ogun state: Rainfall could be harvested to serve as water supply for fish production (Figure 4). But, the limiting factor is that for how long would a farmer harvest rain for fish production? This brings about the issues of damming. They are seasonal ponds which depend on the seasonal changes, such as rainfall, run-offs, etc. before fish production could be carried out. The dammed rain water is able to serve the farmer to a specific period of time which is extended into the dry season. Two of the principal hydro-meteorological events that often have deleterious effects on agriculture are flooding and heavy rainfall. Although it is recognized that in some cases these events can have positive effects, examples include heavy rainfall from a tropical storm ending a long agricultural drought, or recurring, annual flooding that would be dammed for fish production and replenishes topsoil and soil nutrients. Table 2 shows mean rainfall (mm) and fish production (tonnes) for the
period of 10 years (2000-2009) in Ogun state.
CONCLUSION AND RECOMMENDATION
Fish production is an important sub-sector of the Nigerian economy. The various participants in this sub-sector are important contributors to the economic development of this country. Rainfall plays an important role on fish production growth, but could serve as a factor of low fish production during low/no rainfall periods and high or over flooding rains. It is recommended that
Standard methods of impact assessment should be developed and disseminated for use by meteorological services.
Efforts should be made to strengthen the links between the information generators and the users of agro-meteorological
information and provide training to information users.
In addition to long term strategies, short-term remedial programmes should be put in place for dealing with immediate problems such as low rainfall, soil erosion, salinization, designed to alleviate their more immediate manifestation.
Since too much rainfall reduces fish production output due to over flooding, farmers should include sluice gates, spill ways, etc. to help stop over flooding there fish farms. REFERENCES
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The Nigerian Meteorological Agency, May 2009 Agrometerological bulletin
Fig 1: CONVECTIONAL RAINFALL Fig 2: CYCLONIC/FRONTAL RAINFALL
Fig 3: OROGRAPHIC/RELIEF RAINFALL
Table 2: Showing Rainfall and Fish Production in Ogun State YEAR MEAN RAINFALL (mm) FISH PRODUCTION (tonnes) 2000 77.2 8,435.00 2001 84.9 2,966.50 2002 64.2 3,485.00 2003 70.8 3,886.50 2004 59.5 4,856.40 2005 82.6 4,560.00 2006 96.1 6,333.00 2007 4.45 7,963.50 2008 9.33 6,735.50 2009 3.67 7,856.00 Source:
Ogun State Agricultural Development Programme (OGADEP) Department of Agrometrology and Water Resource, UNAAB
Fig 5: A graphical representation of fish production and rainfall in Ogun state
0 100 200 300 400 500 600 700 800 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Rainfall Fish production
