Soc for experimental Biol Annual Meeting - Salzburg 2012

John F. Steffensen (University of Copenhagen, Denmark)
When a fish school swims through the water, every individual consumes a
certain amount of oxygen, which means that less will be available for the
trailing fish in the school. In 1967 McFarland and Moss reported that the
oxygen saturation decreased approximately 30% from the front to the rear
of an approximately 150-m long school of mullets swimming in normoxic
water. They also observed that the decline in oxygen saturation at the rear
resulted in the school disintegrating into smaller separate schools.
Oxygen consumption of swimming fish increases exponentially or as a
power function with respect to swimming speed, and hence the decrease
in oxygen saturation through the school is related to the swimming speed
of the school. A model describing the oxygen saturation in a fish school
from front to rear at different swimming speeds will be presented. The
model reveals that the school has a maximum length at the optimal
swimming speed, and that a very large school cannot swim at slow speeds.
Oxygen saturation through a fish school is also influenced by several
parameters other than swimming speed, i.e. nearest neighbour distance,
water temperature, gill oxygen extraction, gill ventilation capacity, etc. Fish
swimming in a school have been shown to have energetic advantages
when trailing behind neighbours, resulting in up to 20% energy saving.
The effect of this energy saving is that the fish schools can be longer.
A model of oxygen saturation through a fish school will be presented.
Email addressforcorrespondence: JFSteffensen@bio.ku .dk