Carp domestication is thought to
date back as early as the Neolithic but culturing for food is predominantly
thought to have started with the Romans. This domestication was then expanded
upon by monks who kept them in ponds at monasteries followed by the prolific
culture of nishikigoi (Koi) in Japan where ‘fancy coloured carp’ are kept for
pleasure. Wild carp lived up to 15 years old, weighed up to 5kg and were over
half a meter long however a wild form may no longer exist (are very rare) due to the rampant
introduction of domesticated species as well as the elimination of their
natural habitat - floodplains (Balon, 1995).
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| Original wild carp from Danube (Left). Domesticated Koi with size and colour variation (Right). |
A study done on two species of common carp by Klefoth (2013) found that
domesticated fish are more vulnerable to angling. Some theories suggest that domesticated
fish (especially for human consumption) have reduced cognitive abilities due to
selection for rapid growth, which corresponds with reduced energy allocation
into the construction of the neural network. Or that artificial conditions in
which fish are held are responsible for the inability to learn complex tasks,
which lead to a constantly higher catchability of domestic fish compared to
wild species.
However, vulnerability
was tested across two environments (pond and fish tanks) where both species’
indicated learning a hook avoidance by exhibiting decreased catchability over
time. Fish
are regulated by hereditary anti-predator behaviour as a result of established predator-prey
relationships. Although anti-predator behaviour is genetic in carp, learning
from experience over time can influence the development of the behaviour. In
ornamental tank fish where there are no predators, this genetic behaviour
becomes lost or diminished throughout generations, but can be ‘re-learned’.
Under farming conditions,
domesticated fish have become adapted to carbohydrate rich artificial food
which alters their food preference and digestive ability from that of wild
counterparts. Along with food preferences, consumption rate and food-intake
speed also differ. It is believed boldness of behaviour (especially when
foraging) is a developed trait in domesticated species that plays an important
role in rendering these species vulnerable to angling. Overall, domesticated carp
are found to be vulnerable to angling mostly due to genetics and bold behaviour
that have been selected for in the process of domestication (Klefoth et al., 2013).
Koi image: http://amazepicsvids.blogspot.com.au/2010/05/koi-fish-or-japanese-carp-colourful.html
Websites accessed: 03/04/2014
This is very interesting. I’m curious about one thing – you say that domesticated species have different food preferences and digestive ability to wild fish. How then do they do better than natural species? (you indicate that the wild form of carp is very rare due to introduction of domestic species). Are they competitors, even with different food needs?
ReplyDeleteHey Tasmin, the wild ancestor (Cyprinus carpio) is found in only the Black, Caspian and Aral Sea basins in small populations. Their decline is mainly the cause of channelization and dams as they require special conditions to spawn (specific flooding of areas at certain times). But also due the introduction of cultivated ‘stock’ species in large quantities for human food and sport fishing (from European/Asian species). It’s not food competition or domestic species ‘invading’ their natural habitat as such but rather the large amount of hybridisation between the wild ancestor and its various domesticated descendants that are causing low numbers of ‘pure wild bloodlines’. I suppose similar to the interbreeding between Dingoes and escaped (feral) dogs that cause loss of the ‘pure’ dingo form.
ReplyDeletehttp://www.iucnredlist.org/details/6181/0 (accessed 7/04/14)