Fisheries and aquaculture in Africa - Royal Museum for · PDF file ·...

Royal Museum for Central Africa (RMCA, Tervuren)

“FishBase and Fish Taxonomy” training session 2015 Edition

Fisheries

© R

MC

A

and

aquaculture

in Africa

©R

MC

A



Capture fisheries vs. aquaculture

(Capture) fisheries Aquaculture

• Aquatic organisms harvested by an individual or corporate body which has owned them throughout

their rearing period contribute to aquaculture

• Aquatic organisms which are exploitable by the public as a common property resource, with or

without appropriate licenses, are the harvest of fisheries

- organized effort to catch fish or other aquatic

organisms

- exists for the purpose of providing human food (other

aims possible, such as sport or recreational fishing), or

obtaining ornamental fish or fish products (e.g. fish oil)

- categorized by the capture species, the location, the

purpose, the fishing gear used and the level at which a

fishery is managed nationally and/or regionally.

- farming of aquatic organisms under (semi)controlled

conditions

- implies some form of intervention in rearing process

to enhance production (increase growth & reproduction,

reduce natural mortality)

- implies individual or corporate ownership of the

stock being cultivated

Fishery = activity leading to harvesting of fish; may involve capture of wild fish or raising of fish

through aquaculture



1.1. Volume of the catches – inland & marine

1. The state of capture fisheries in Africa

• One-third of total capture fisheries production in Africa comes from inland waters; mainly African Great Lakes,

Nile (Egypt), Niger (Nigeria) and Congo River (DRC) basins

(FAO State of World Fisheries and Aquaculture 2012)

o spectacular increase in production

since 1960s

o underestimation (non-commercial circuit,

local trade)

o « Value of African Fisheries »: a study

highlighting the importance of inland

fisheries in terms of economic value and

employment in Africa

http://www.fao.org/3/a-i3917e.pdf



1.2. Volume of the catches – inland & marine

• East Africa: almost 80% of the total production

comes from continental fisheries; lacustrine

fisheries have strongly increased (mainly due to

introduction of Lates in Lake Victoria)

• West Africa: marine fisheries most important,

with less developed aquatic continental

ecosystems

Marine fisheries

Continental fisheries

Year

Fis

her

ies

pro

du

ctio

n (

ton

nes

)

• total landings have

increased dramatically in

West African marine zone,

from 600,000 tons in 1960

to 4.5 million by 2000

• it is one of the most diverse

and economically important

fishing zones in the world

- Differences in origin of catches:

Fidi (1996) in Lévêque (2006)

www.thefishsite.com

http://www.google.be/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=http%3A%2F%2Fwww.thefishsite.com%2Farticles%2F1520%2Fmmo-overview-of-the-world-fishing-industry&ei=uhFoVcDBHcz-UoS9gMgE&bvm=bv.94455598,d.d24&psig=AFQjCNH0i8cSRj_A2dgen0OdPt0bSnrkRg&ust=1432970039936135



1.3. Main species -- inland

- Riverine:

• large number of species caught; often

spatio-temporal changes of catch

composition

- Lacustrine:

• large part of capture consists of small

number of species (mainly Cichlidae,

Centropomidae and, except for West Africa,

pelagic Clupeidae)

• Lakes Kivu, Kariba and Victoria: large

portion of capture consists of introduced

species

Lévêque (2006)



Oreochromis niloticus, Tanzania

(introduced in Lake Victoria)

© ML.J. Stiassny

Oreochromis macrochir, Burundi (introduced in Lakes Kivu and Kariba)

© L. De Vos

Lates niloticus, Uganda

(introduced in Lake Victoria)

© Pierro

Limnothrissa miodon, Zambia (introduced in Lakes Kivu, Kariba, … )

© Mohammed A.D.

http://research.amnh.org/ichthyology/staff/mljs/mljspubs/mljspubs.html



1.4. Threats and challenges for inland fisheries in Africa

• inland fisheries are valuable and an integral component of the lives of many people throughout Africa

important contribution to sustainable development, including economic growth and poverty reduction

• BUT: fish stocks in many African waterbodies are declining through a combination of overfishing (e.g. Lake

Tana), invasive/introduced species (e.g. Lake Victoria) and habitat degradation

Lake Tana

• traditional (subsistence) fishery with reed boats and variation of

techniques until 1980s

• 1986: introduction of motorised boats and nylon gill nets (mainly around

Bahir Dar)

• increase in total annual catches from 39 tonnes (1987) to 360 tonnes

(1997)

• landed fish in Bahir Dar: declines of 75% (biomass) and 80% (number)

of Labeobarbus species

• explanation: recruitment overfishing (seasonal, targeting spawning

aggregations) and poisoning of spawning stocks in rivers

• By 2022 population growth in Africa will outpace fish production, and fish consumption per capita will decline

increasing fish availability is urgent! (rebuild depleted stocks, conservation measures, aquaculture, … )

Labeobarbus brevicephalus

© L. Nagelkerke

© A. Davey

http://upload.wikimedia.org/wikipedia/commons/8/8d/Fishermen%2C_Lake_Tana_%282260748777%29.jpg

http://www.wewur.wur.nl/popups/vcard.aspx?id=NAGEL001&lang=uk



2. Freshwater fisheries: centres of production

2.1. River and floodplain fisheries

- floodplains contribute to production of rivers (food, spawning, refuges, …)

- production largely depends on the extent and

duration of seasonal floods (e.g. Niger, Kafue,

Cross)

- large dams have placed severe constraints on

these systems: deleterious effects on

downstream floodplain environments

• e.g. Lake Kainji: loss of downstream

fisheries only just balanced by increased

fishing from reservoir

- other examples: Niger (Nigeria, Mali and

Niger), Kafue (Zambia) and Shire (Malawi)

Wagenia Falls near Kisangani, DRC

© Wikipedia

© RMCA



2.2. Wetlands

2.3. Natural lakes

- various water bodies with water less than 3 m deep

- includes many rivers and floodplains, shallow lakes (Chad,

Chilwa, Mweru Wa’Ntipa), marshes and swamps (Bangweulu

Swamps, Niger Inland Delta, Okavango)

- variable environments related to rhythmic changes in

water levels

- many are major centres of production; most are now near

the optimal level of exploitation

- e.g. Lake Victoria, Lake Malawi, Lake Tanganyika and

Lake Turkana, but also Lake Mweru

© www.iucnredlist.org Okavango, Botswana

© Wikipedia Lake Victoria



2.4. Man-made lakes (reservoirs)

2.5. Estuaries and brackish waters

- first large impoundement: Lake Kariba (1955-

1959); thereafter man-made lakes have

proliferated in Africa, especially in southern

Africa

- mostly build for hydro-electric power: fisheries

are usually an unplanned benefit, but can

nevertheless readily be established

- extensive coastal lagoons exist in West Africa

(e.g. Sine Saloum), Mozambique, South Africa

and Madagascar

- these are important nursery areas for

commercially valuable fish (e.g. eels and mullets)

Lake Kariba dam (Zambia/Zimbabwe)

Mugil cephalus

© Randall J.E. (1997)

© Wikipedia

http://www.fishbase.org/photos/HI_Reef_Shore_Fishes.pdf



3.1. Stock assessment – direct methods

• induced mortality • poisoning: plant extracts (Tephrosia vogelii), synthetic pesticides (illegal),

rotenone (p. ex. Aquatox); only good results in closed/dammed areas that are

not too large or too deep, and with precise estimation of water volume treated

L’utilisation de roténone

3. Stock (biomass) assessment and management

© Iowa Department of Natural Resources

• exhaustive fishing: always an underestimation because certain species/individuals escape and

because effort is ceased when captures are decreasing; time-consuming (absolute estimate)

• reclamation of small, dammed areas: specific density in biomass (kg) and number of individuals

is obtained; precise and reliable results, but only applicable to small areas (absolute estimate)

© RMCA

• explosives: dangerous and illegal; effects very local and destructive; induced mortality



• acoustic techniques: mainly used in large lakes (e.g.

Lake Tanganyika); only general estimations possible,

without indication of species responsible for echo;

difficult to apply in shallow areas; seasonal variations

(e.g. Stolothrissa in Lake Tanganyika); remote method

3.2. Stock assessment – direct methods

© RMCA

• electric fishing: repeated passages necessary; fish learn

very quickly to avoid the electrodes; sensitivity of fishes

very variable (size and species dependent); conductivity,

temperature, etc.; useful in fast-flowing waters, undeep

environments and rocky bottom habitats

© BioSonics

Stolothrissa sp.

• Mark-recapture, telemetry, catch

depletion, …

Total removal methods = costly, time consuming

Welcomme (2001)

© Jouko Sarvala



- reliable data and statistics on continental fisheries in Africa are lacking (many different techniques,

spatio-temporal variation, no sensibilisation of local fishermen, … ) biomass difficult to assess

- amount of fish captured for particular fishing effort allows to estimate stock; excellent results

But: establishing the total tonnage fished and estimating total effort constitute major problems; data

for multiple years is necessary !

- empirical methods developed to estimate yield:

- Morpho-edaphic indices (MEI; Ryder 1985) – based on conductivity/depth relationship; fish-yield

estimator

- Gulland (1971) formula – based on estimation of biomass and mortality of stock (valuable in

temperate areas, but problematic in tropical freshwaters)

Whatever method is used, one should be aware that biomass and density are related to intrinsic

productivity of the environment, its alimentary resources, the presence/absence of shelter, and

seasonal and annual changes:

Biomass is variable!

3.3. Stock assessment – indirect methods



3.4 Stock exploitation – monospecific communities

- ‘logistic growth curve’:

• B = biomass

• BM= carrying capacity of

environment (biomass)

• t = time

• ΔB = increase in biomass

during time Δt

- maximal increase in biomass occurs when B = BM/2 (inflexion point)

- P = production = the amount of biological material produced by a biomass during a certain time

frame

- when B = BM, an equilibrium is reached, the production P then compensates losses due to natural

mortality (M) P = B * M

- B = biomass = weight of all

fish on certain oment;

expressed as weight per

unit area or volume



- fishing a certain stock will result in a yield Y = B * F, with F = mortality due to fishing

• if Y < P: biomass will still increase, at slower pace than without fishing, and biomass will

stabilize at value B lower than BM, with production P compensating fishing

• if Y > P: biomass will decrease

Ye = sustainable yield; no variation in biomass occurs (equilibrium)

MSY = « maximum sustainable yield » =

biomass of stock is maintained at BM/2

BUT: MSY = simplification of reality, misused,

Y

- ideally, it should always be possible to increase or

decrease the fishing efforts (Y) in relation to

unexpected changes in biomass; this is however

rarely possible without socio-economic effects

Stock change = Recruitment + Individual growth -

Natural mortality - Harvest



- optimal exploitation will keep

biomass at much lower lever

compared to unexploited

situation

- mean age of exploited stock

<<<< mean age in unexploited

stock

Both effects are normal consequences for ration exploited

stocks, so none of them can be used as an index of

overexploitation

© WWF South Africa © AP/Schalk van Zuydam



3.4. Stocks exploitation – multispecific communities

- freshwater fisheries in general affect all (or almost all) species in the exploited environment; the

effect of fishing effort on different species may nevertheless be different:

• the optimal effort for one species may be disastrous for other more fragile and vulnerable

species!

- Species with a low production and low P/B value (= low regeneration time, e.g. long-living species) will

be most affected by fishing multispecies communities (e.g. Lates and clupeid fishery in Lake

Tanganyika)

© McEachranand Notarbartolo di Sciara (1995)

Hoplostethus atlanticus

© www.aquamaps.org



- aquaculture in Africa is of relatively recent

origin

- aquaculture started with breeding of sport

angling fish (bass and trout)

- breeding of fish for food is more recent and is

correlated with increase in human population

after WW II; probably started with carp in South

Africa; first tilapia farming recorded in Kenya in

1924

- aquaculture = maximize yield by manipulating

growth, reproduction and recruitment, and

natural mortality rates ( capture fishery =

maximize yield by increasing fish mortality rate)

4. Aquaculture in Africa

© www.fao.org

Stock change = Recruitment + Individual growth - Natural mortality - Harvest



(FAO State of World Fisheries and Aquaculture 2012)

Aquaculture production in Africa

in 2010

(Modified from FAO State of World Fisheries and Aquaculture 2014)

Aquaculture by region: quantity and percentage of world total production



© FAO State of World Fisheries and Aquaculture 2014

Share of aquaculture in

total fish production • Relatively new, no tradition

• Limited expertise and

know-how (growth,

reproduction, recruitment,

natural mortality rates)

• Low cost-effectiveness on

large scale

• No ‘investment

environment’ for

aquaculture



- aquaculture in Africa distinct in the use of indigenous species (tilapia’s, clariids, Heterotis), which

significantly contributed to fish farming both locally and elsewhere (e.g. Asia)

- there is also culture of:

• ornamental species for aquarium trade

(mainly cichlids)

• pest-control species: o molluscivorous species for schisto/bilharzia control

o mosquitofish (Gambusia affinis) and guppy

(Poecilia sp.) as predator on mosquito larvae

© Robert McDowall

Gambusia affinis

Heterotis niloticus

© Albert Schenk

Oreochromis niloticus

© M.L.J. Stiassny

5. Aquaculture fish species in Africa




5.1. Indigenous species

© M.L.J. Stiassny

Tilapia zillii

© L. de Vos

Tilapias (‘aquatic chickens’)

• endemic to Africa, but established in culture in most warmer parts of the world

• mainly from the mouth-brooding, arena-breeding, mainly vegetal detritus-phytoplankton feeding

genus Oreochromis (e.g. O. mossambicus and O. niloticus), and the pair-forming, substrate

spawning, mainly higher plant-eating genus Tilapia (e.g. T. zillii, T. rendalli and T. sparrmanii)

• first culture probably in Kenya (1924) of O. mossambicus




• main problems: high temperatures required for breeding

and rapid growth, propensity in culture towards

dwarfing, males have more rapid growth. Possible

solutions: « young-of-the-year culture », selective

breeding of cold-resistant strains, growing of all-male

monosex cultures, hybridization resulting in (fertile) all-

male offspring, production of « red tilapia » and sex-

reversal of females by steroid hormones

• advantages: palatability, general popularity, rapid

growth, hardiness, euryhalinity, ease of breeding and

culture in extensive or semi-intensive systems, diversity

of opportunities for intensive culture and relative

cheapness of feeding in all situations have led to pre-

eminence in modern fish farming

• ultimate limiting factor in tilapia culture is the very large

number of broodstock needed due to limited egg

production

Oreochromis mossambicus

© Johnny Jensen

Tilapia rendalli

© Lothar Seegers

© Lothar Seegers

Tilapia sparrmanii

http://www.jjphoto.dk/



Serranochromis macrocephalus

© Brian Gratwicke

Hemichromis bimaculatus

© www.geocities.com/pruts54/

Other cichlids

• molluscophagous species cultured for control of schistosomiasis: Serranochromis

macrocephalus, Serranochromis mellandi, Astatoreochromis alluaudi, Hemichromis

bimaculatus and Paratilapia sp.

• culture of ornamental cichlids for home aquarium trade: especially small brightly-coloured

endemic species of Lakes Malawi and Tanganyika, but also various other genera (e.g.

Pelmatochromis, Pseudocrenilabrus); culture mainly in Far East, Europe and USA



Clariid catfishes

• mainly Clarias gariepinus

• Advantages:

+ relatively inexpensive maintenance

due to catholic range of diet (with high

protein content)

+ rapid growth

+ wide temperature range tolerance

+ ability to breathe atmospheric oxygen (no need to aerate ponds at night in intensive culture)

+ excellent boneless fillets which preserve well

• Disadvantages:

- high mortalities caused by dietary problems and disease in newly hatched larvae

- aggressive behaviour (mainly of males) often resulting in wounds prone to fungi and

bacterial infection

• an important development has been the hybridization of male Heterobranchus longifilis with

female C. gariepinus, the former known to reach 60 kg

© Lothar Seegers

Clarias gariepinus



Mugilidae

• best species for brackish or freshwater

culture appears to be the cosmopolitan

Mugil cephalus

• extensive culture mainly in countries with

coastal littoral; wild-spawned fry are

collected as soon as they enter inland

waters after hatching from the sea

• Advantages:

+ wide salinity tolerance

+ feeding on diatoms and other organisms low in the food web

+ palatability

+ high market values

• Disadvantage:

- seawater necessary for reproduction and the subsequent rearing of the larvae

Mugil cephalus

© Randall J.E. (1997)

http://www.fishbase.org/photos/HI_Reef_Shore_Fishes.pdf



Heterotis niloticus

• Advantages:

+ microphagous feeder (low on

the food chain)

+ tolerant of low limits of dissolved oxygen (respiration via air bladder)

+ capable of extremely rapid growth (10 g per day)

+ maturing slowly (does not spawn until 19-20 months old) but producing thousands of larvae

• Disadvantages:

- survival of juveniles (feed exclusively on zooplankton)

- fish need to be kept in intensive culture (small ponds not suited, and growth is adversely affected by

crowding)

• culture of this species is confined to West Africa (except for Madagascar where it was introduced),

mainly in Cameroon, Gabon, DR Congo and Nigeria

Heterotis niloticus

© Solomon David



Chrysichthys nigrodigitatus

© Sven Klimpel

Other African species

• mainly Chrysichthys nigrodigitatus, C. walkeri, Auchenoglanis occidentalis, Bagrus docmak and

recently Schilbe mystus

• grow well in ponds once fingerling size is reached, but serious constraints remain in the

spawning and rearing of larval and fry stages

• predators (Hepsetus odoe, Gymnarchus niloticus) might be

important in controlling overpopulation in extensive culture

and because of their high market value

• Lates niloticus is used in polyculture in Nigeria

Bagrus docmak Auchenoglanis occidentalis

© L. De Vos © L. De Vos

Hepsetus odoe

© www.hippocampus-bildarchiv.de

http://www.hippocampus-bildarchiv.de/



Bass

• useful sporting fish in cool and clear

freshwaters that are too warm for trout

• widely introduced, originally mainly to South African hatcheries: largemouth bass (Micropterus

salmoides) in 1928, smallmouth bass (M. dolomieu) and spotted bass (M. punctulatus) in 1937

• less cultured in hatcheries nowadays, fry required taken from established wild stocks, few

marketed for consumption

• also introduced in Kenya (1928), Zimbabwe (1932), Madagascar (1951) and Algeria (1970)

© Garold W. Sneegas

5.2 Exotic species

Micropterus punctulatus



Trout

• brown trout (Salmo trutta) ova from Scotland

first hatched in Natal in 1890; 3 still functioning

hatcheries established by 1895

• rainbow trout strains were found to be better in requiring less cold temperatures; now commonly

bred, but often mixed steelhead (S. gairdneri irideus) and shasta (S. g. shasta) strains due to

unselective mingling (both subspecies now synonimized with Oncorhynchus mykiss)

• at present hatcheries in South Africa, Zimbabwe, Kenya, Lesotho and Swaziland

• trout first introduced in Kenya (1910), which today is one of the major trout-producing countries

in Africa (over 300 ton/year)

• both rainbow trout and brown trout introduced in Kilimanjaro and Mbeya streams in Tanzania

Salmo trutta

© John F. Scarola



Common carp

• earliest exotic species introduced; introduced

from Germany to South Africa in 1859: apparently

of mixed genetic stock; firmly established in rivers

and farm ponds by the turn of the century

• also introduced elsewhere, e.g. in Zimbabwe (1925), Morocco (1925) and Nigeria (1954)

• much less random and increasingly more intensive culture of domesticated varieties since late

1950s (e.g. Aischgrund carp)

• carp is not as adaptable as first imagined: establishment only from breeding populations in

temperate areas which suit them, not in too cold or too hot water; this excludes them from the

great bulk of the African continent, except for temperate southern Africa and cooler upland

areas in tropical Africa; when established there is no evidence of adverse effects upon local

populations

Cyprinus carpio

© Germano Schüür

http://www.photographia.com.br/usa.htm



Chinese carp

• first introduction to Egypt: silver carp

(Hypophthalmichthys molotrix) and grass carp

(Ctenopharyngodon idella) from Japan (1962) and

Hong Kong (1968)

• grass carp introduced to control and make use of aquatic

vegetation, silver carp because of its value as

phytoplanton feeder in polyculture

• bighead carp (Aristichthys nobilis) later introduced as

filter feeder on zooplankton and larger phytoplankton

items in polyculture

• reproduction of these carps requires cold-temperate

water temperature and large water volumes for egg

incubation; both attributes do not occur together in any

African river, which explains the lack of spawning

populations in the wild

Hypophthalmichthys molotrix

© http://zzzy.cafs.ac.cn

Ctenopharyngodon idella

© Leonard Lovshin

Aristichthys nobilis

© http://zzzy.cafs.ac.cn

http://www.fishinfo.cn/

http://www.fishinfo.cn/



6.1. Cage culture

- defined as the rearing of fish stocks

(generally from juvenile to marketable size) in a

totally enclosed water volume through

which a free water circulation is

maintained

- in Africa, main species used in cage

culture are tilapias and trout

6. Some special aquaculture methods

© www.sarnissa.org



6.2. Brackish water aquaculture

- offers many opportunities in Africa:

• many euryhaline species in Africa (particularly tilapias)

• supply of freshwater is limited in many areas (limited rainfall or priority given to irrigation of agricultural crops)

- coastal brackish water culture is a natural extension of fisheries for wild coast species, and is

broadly defined as any increase in fish production from an area by human intervention beyond that

of merely harvesting the fish (e.g. introduction of exotic species, provision of shelter from predation,

improvement of primary production, ...)

- e.g. Tilapia rendalli, Mugil cephalus, Chrysichthys spp., Ethmalosa fimbriata, Hemichromis

fasciatus, Lutjanus sp., Cyprinus carpio, Sparus auratus, …

© J.D. Durand

Ethmalosa fimbriata Hemichromis fasciatus

© K. Mody

© www.fao.org

http://www.dis3muge.univ-montp2.fr/



6.3. Rice-fish culture

- usually fish is by-crop to rice, with little extra effort

- Advantages:

+ insects and molluscs, some possibly harmfull or

disease-carrying, are predated by fish

+ fish excretory products help to fertilize paddy

- Disadvantages:

- necessity of pits or trenches for the fish (reducing

land available for rice culture)

- higher water levels needed (rice variation, dams, …)

- increasing practice of spraying rice with insecticides

harmfull to fish

- use of heavy machinery

© http://kaleidoscope.cultural-china.com

© FAO Fisheries Department



Oreochromis niloticus culture in Bujumbura (Burundi)

© RMCA

6.3. Aquaculture in ponds



Lévêque (1997) Welcomme (2001)

Pillay & Kutty (2005) FAO (2014)

Lévêque (2006)



Fisheries and aquaculture in FishBase



- FAO is a FishBase Consortium member and an important collaborator

since the very beginning of FishBase

- FAO manages datasets on global production, capture production and

aquaculture production

- « Yearbook of Fishery Statistics – Catches and Landings (1963)/

Fishery Commodities (1964)/Aquaculture production (1985)

- since 2006 replaced by « Yearbook of Fishery and Aquaculture

Statistics » : a compilation of data on capture production, aquaculture

production and commodities

- since 1995: « State of world fisheries and aquaculture (SOFIA) »

- data used to prepare advice on fisheries policy to member countries



- data summarized by FAO represent live weight (tonnes)

equivalent of landed quantities caught during the annual period

covered (except for marine mammals, which are reported in numbers)

- FAO data on capture production and aquaculture production

available via FishBase

- also available via FishBase are ICES (International Council for

the Exploration of the Sea). Data presented in the same way, but

data restricted marine species in the Northeast Atlantic.



• FAO data on capture production (inland/marine) available in FishBase from:

« Human uses » on the Species Summary Page

Species Summary Page

B. FAO data on capture production



Search Page



Information by Country/Island on Search Page



Search Page



Information by Country/Island on Search Page

Tools section on Search Page



B. FAO species profile (fisheries)




C. Catch analysis

This tools allows to visualize the

catch composition for a certain

FAO area with respect to trophic

level

Search Page



“Fishing down marine food webs”:

decrease in mean trophic level of fisheries catches

Pauly, D., V. Christensen, J. Dalsgaard, R. Froese and F. Torres, Jr. 1998. Fishing down marine food webs. Science 279(5352):860-863.

1950 1997



• FAO data on aquaculture production (since 1984) accessible from: :


D. FAO data on aquaculture production



Search Page



Information by Country/Island on the Search Page





Information by Country/Island on the Search Page

Tools on the Search Page

Search Page



E. FAO Species profile (aquaculture)



- knowledge on the culture performance of fish in various aquaculture systems is useful to assess the

suitability of species for aquaculture and to help identify appropriate aquaculture methods and

culture systems for these species

- Aquaculture systems is accessible from:

Search Page > Information by Topic (18 species)

Species Summary Page > More information

F. Aquaculture systems

Search Page




- objective of this table: to summarize data on aquaculture experiments for a certain species

- table contains information on experimental systems and includes physico-chemical parameters,

quality and quantity of nutrient inputs and production of species thus providing a model for a form

which scientists might follow when reporting aquaculture experiments

Tilapia zillii

© L. De Vos



Culture experiments often involve more than one

species (polyculture). Production per species is

reported in sub-table with one record per species.



• ‘mini-essays’ of up to 1,000 words for each species, using free text but with a standardized

structure

• the aquaculture profile are accessible from:

Search Page > Information by Topic (7 species)

Species Summary Page > More information

G. Aquaculture profiles

Search Page


Fisheries and aquaculture in Africa - Royal Museum for · PDF file ·...

Documents

Transcript of Fisheries and aquaculture in Africa - Royal Museum for · PDF file ·...