CLIMATE CHANGE AND GLOBAL FISH PERFORMANCE IN NIGERIA (A CASE STUDY OF RIVERS STATE)
BACKGROUND OF THE STUDY
Global marine fisheries not only face overfishing, pollution and other anthropogenic impacts, but also climate change (Halpern et al., 2008; Pauly et al., 2002).
Climate change is the most widespread anthropogenic threat for ocean ecosystems (Halpern et al., 2008), causing sea-level rise, sea temperature change, ocean acidification, changes in precipitation and changes in ocean circulation (Brander, 2007). These climate elects on ocean conditions will impact ocean
organisms, the composition of marine communities and ecosystem function (Brown et al., 2010), increasing the complexity of the challenges facing current fisheries (Sumaila et al., 2011). Climate change impacts fish stocks either directly or indirectly. Direct impacts act the physiology and behaviour and alter
growth, reproductive capacity, mortality and distribution. Indirect effect change the productivity, structure and composition of the marine ecosystems on which fish depend (Brander, 2010; Hare et al., 2010; Perry et al., 2005). Changes in the geographic distribution of fish species in marine ecosystems have already been documented throughout the world (Barange and Perry, 2009; Brander et al., 2003; Perry et al., 2005), and several studies have predicted that changes in water temperature, driven by climate change, may lead to local extinctions and also to colonization by species previously absent in those areas (Cheung et al., 2009; Vinagre et al., 2011). These shis in geographic range will most likely aect the abundance, distribution and composition of fisheries catches, and consequently fishing operations, catch shares and the eectiveness
of fisheries management measures (Gamito et al., 2013; Kim, 2010; Sumaila et al., 2011). However, these eects might not necessarily be negative, as new fishing opportunities may also arise in some areas of the world. The eects of climate change on fisheries may then be regarded to act on resource availability, fishing operations, fisheries management and conservation measures and profits from fisheries (Cheung et al., 2012). Both the observation of recent climate change and predictions of climate change in future scenarios show that the eects of climate change will not be homogeneous throughout the world (IPCC, 2007). Belkin (2009) has studied changes in sea surface temperature (SST) in large marine ecosystems (LMEs). LMEs are large coastal areas with broad ecosystem similarities, such as bathymetry, hydrography, productivity and
trophically dependent populations (Sherman and Duda, 1999; Watson et al., 2004). Belkin (2009) has found a coherent global pattern of rapid warming in LMEs, from 1982 to 2006. This rapid warming (net SST change higher than 0.6 ºC) was observed for three groups of LMEs: (1) Scotian Shelf, NewfoundlandLabrador Shelf, Canadian Eastern Arctic-West Greenland, Iceland Shelf and Sea, Faroe Plateau and Norwegian Sea; (2) North Sea, Baltic Sea, Black Sea, Mediterranean Sea, Iberian Coastal and Celtic-Biscay Shelf; (3) Yellow Sea, East China Sea, Japan/East Sea and Kuroshio Current. A slow warming was observed in the Indian Ocean LMEs and most LMEs around Australia and between Australia and Indochina. The only cooling LMEs were the California Current and the Humboldt Current, both located in the Eastern Pacific upwelling areas. As the LME spatial system groups together large coastal areas with similar ecosystem characteristics, this methodology has recently been used for several large-scale marine studies (Merino et al., 2012; Pauly et al., 2008; Pikitch et al., 2014; Sherman and Duda, 1999; Watson et al., 2004). From a global perspective, analyses on the LME scale are extremely valuable for marine ecosystembased management. And, as climate change increases the complexity of fisheries management, it is of the utmost importance that these analyses include the eects of climate change on fisheries. Therefore, the present paper aimed to analyse climate change and global fish performance.
1.2 STATEMENT OF PROBLEM
There is an increasing concern over the consequences of climate change and fish performance and the state of marine ecosystems. Climate change is an additional pressure on top of the many (fishing mortality, loss of habitat, pollution, disturbance, introduced species) which fish stocks already experience.
This means that the impact of climate change must be evaluated in the context of other anthropogenic pressures, which one have greater and more immediate effect . It will be proper to assemble and analyse evidence of eects of climate on fish performance in order to (i) show that climate affect the distribution, productivity and resilience of fish stocks, (ii) develop our understanding of the processes, and (iii) draw lessons from past experience. The scientific study of the impacts of climate change on fish performance has developed very rapidly, but is unevenly spread geographically and methodologically. Until the past decade or so the principal subject for investigation was the effect of climate variability (i.e. decadal and shorter variability) on recruitment, with related work on regime shis and on distribution changes.
1.3 AIMS OF THE STUDY
The major purpose of this study is to examine the effect of climate change and global fish performance. Other general objectives of the study are:
1. To examine the nature of climate change.
2. To examine fishery performance and its adaptation on climate change.
3. To examine climate change and its effect on fish production.
4. To examine the problems fish farmers face due to effect of climate change.
5. To examine the relationship between climate change and global fish performance.
6. To suggest the strategies for alleviating the impacts of climate change on agricultural practices in Nigeria.