Do smelly fish make better friends?

12 April 2000

Researchers have shown that Scottish salmon are much more likely to fight each other when their smells are concentrated.

How do you win friends and influence people? Pay for dinner at a restaurant? Adopt a considerate approach to colleagues? Try an expensive new perfume? It seems that in the fish world making friends depends on how smelly you are! In a report to be published in May in Animal Behaviour, researchers at Glasgow University and the FRS Freshwater Laboratory at Pitlochry have shown that Scottish salmon are much more likely to fight each other when their smells are concentrated, for example in pools rather than fast-flowing rivers.

The responses of fish to one another's smells can depend on whether the fish are related. Brothers and sisters are able to recognize the odour of friendly family members and therefore choose not to fight one another. However, the strong smell of some fish betrays them as being unrelated and unfriendly, and battle commences. It's all about protection of genes for future generations; brothers and sisters don't waste their time and energy fighting, which means they are able to concentrate on the important things in life - like growing and maturing sufficiently to produce offspring.

"It's amazing! Fish are obviously much cleverer than we've given them credit for in the past," says Dr Siân Griffiths, a member of the research team that made the discovery.

"Traditionally fish have been thought of as simple and unsophisticated, but these salmon can actually recognize each other, and actively decide to be nicer to their siblings." Her colleague Dr John Armstrong agrees that the old wives tale of goldfish with no brainpower will have to be updated.

But why should we be interested in the brainpower of salmon? Many species of fish, such as salmon guard territories for much of their lives. However, energy spent chasing away intruders means that less energy is available for growth. So it is in the interest of fish (and fishmongers) that brothers and sisters are kept together because fish that are less aggressive grow bigger and live longer.

The research has fisheries management implications. Fish farmers can help their fish conserve energy - and promote growth - by keeping brothers and sisters together. However, for managers restoring fisheries, the decision of whether to stock family members into a river together will depend on the type of habitat, and the likelihood of smells becoming concentrated.

Further information

Dr Siân W. Griffiths
Fish Biology Group, Division of Environmental & Evolutionary Biology, Institute of Biomedical and Life Science, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ.
Tel: 0141 330 6621/0141 339 8855 ext.5506 (messages)

NERC Press Office
Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU
Tel: 01793 411561
Mob: 07917 557215

Notes

1. Siân Griffiths is a NERC funded Postdoctoral Research Fellow at Glasgow University and the FRS Freshwater Laboratory at Pitlochry. FRS provides advice to the Scottish Executive on marine and freshwater fisheries management and collaborates widely with university researchers throughout Europe.

2. The Natural Environment Research Council (NERC) is the leading body in the UK for research, survey, monitoring and training in the environmental sciences. NERC funds research in universities and in its own Centres and Surveys. NERC trains scientists for the future -more than 3,000 postgraduate students have been funded by NERC over the last five years.

Press release: 06/00

Do smelly fish make better friends?

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