This document discusses the impacts of climate change on fisheries through various physical and biological changes. Physically, climate change can cause increased ocean acidification, warming of ocean layers, sea level rise, and increased water salinity. Biologically, it can alter fish stock distributions and migrations, change timing of spawning and peak abundance, and allow for more invasive species and diseases. All of these changes threaten fisheries through reduced productivity of target species and loss of coastal fish habitats. The document focuses on these climate change impacts in Sub-Saharan Africa, where key fisheries rely on lakes, reservoirs, and river and coastal systems.

1. Topic
Models on climate change and capture fisheries
Presented by
Abhishek gautam
Gaurav kumar
Acharya Narendra Deva University Of Agriculture And Technology, Kumarganj, Ayodhya

7. CLIMATE CHANGE IMPACTS ON FISHERIES
 climate change can be expected to impact fisheries through a diverse range of pathways and
drivers.
Type of changes Physical changes Processes Potential impacts on fisheries
Physical environment (indirect
ecological)
Increased CO2 and ocean
acidification
Effects on calciferous animals e.g.
molluscs, crustaceans, corals,
echinoderms and some phytoplankton
Potentially reduced production for
calciferous marine resources and
ecologically related species and
declines in yields
Warming upper layers of the ocean Warm-water species replacing cold-
water species
Shifts in distribution of plankton,
invertebrates, fishes and birds towards
the North or South poles, reduced
species diversity in tropical waters
Sea level rise Loss of coastal fish breeding and nursery
habitats e.g. mangroves, coral reefs
Reduced production and yield of
coastal and related fisheries

8. Fish stocks (indirect
ecological)
Higher water
temperatures
Changes in sex ratios
Altered time of
spawning Altered time
of migrations Altered
time of peak
abundance
Altered timing and
reduced productivity
across marine and
fresh water systems
Changes in ocean
currents
Increased invasive
species, diseases and
algal blooms
Reduced productivity of
target species in marine
and fresh water systems

10. Overview of the Impact of Climate Change on Fisheries
 Natural climatic fluctuations, particularly those at medium (decadal) scale, have
always affected fisheries as well as their management performance (Garcia and
Rosenberg, 2010).
 The major aquatic habitats in SSA include
 The Great Rift Lakes such as Lakes Malawi and Victoria; man-made
reservoirs
 Such as Lake Kariba; large river and floodplain systems

11. Physical Changes
Water Surface Temperature Rise-
 Rising water temperature also threatens biodiversity.
 Generally, fish have a thermalpreference that optimizes physiological
processes (Abowei, 2010).
 If water temperature risesabove the maximum tolerable threshold of a species,
then its existence is threatened.

12. Sea Level Rise
 Globally, sea level has already risen by 10 to 20 cm during the 20th
century.
 largely due to thermal expansion, and by 2100 a global rise in sea level of
between 9 cm and 88 cm has been predicted.
 Based on the Intergovernmental Panel on Climate Change’s full range of
35climate projection scenarios (Church et al., 2001 in OECD, 2010).
 In coastal areas, sea levelrise may alter the salinity of estuarine habitats,
inundate wetlands, and reduce or eliminate thea bundance of submerged
vegetation,
 Adversely affecting those species which rely on these coastal habitats for
reproduction and recruitment (Hlohowskyjl et al., 1996)

13. Increasing Water Salinity
 Climate change can cause an increase or decrease in water salinity in multiple
ways.
 While tropical oceans are increasingly becoming saltier, oceans closer to the poles
have become fresher.
 This highlights that tropical oceans are very likely to suffer more from the
potential impacts of increasing water salinity relative to waters in higher latitudes.

14. Biological Changes
 Climate change is already affecting the trends of some important
biological processes.
 Resulting in changes in primary production (Taucher and Oschlies,
2011) and changes in fish distribution (Sumeila et al., 2011).
 Climate induced changes in primary production and fishstock
 Distribution have negative implication on food security in many
tropical coastal states in general and SSA in particular

15. Changes in Fish Distribution
 Change in fish distribution is among the most commonly reported
ecological responses of marine species .
 Fish species are believed to respond to environmental changes such as
warming water temperatures by shifting their latitudinal and depth ranges.
 Changes in ocean dynamics could lead to changes in migration patterns of
fish.
 possibly reduce fish landings, especially in coastal fisheries of many
African countries .
 Marine fisheries are an important food source, and therefore, changes in
the total amount or geographic distribution of fish.