Behavior - the sum of all the motor responses of an organism to all the external and internal stimuli acting upon it.

Social behavior of animals is the sum of inter-individual relationships among the members of that population.

Behaviors involved in interactions among species are agonistic behaviors, predator-prey behaviors and reproductive behaviors.

These behaviors result in individual distance the "kick-kiss" distance.

Spacing patterns and social groupings

Fish/groups may be randomly distrubuted or clumped as in home ranges, territories, and schools.

Home range; the area through which an animal or group regularly travels during daily activities, but there may be a core area. The shift from random distributions to home ranges of solitary fishes may relate to differences in resource richness.

Territory; an area occupied almost exclusively by one or more animals, by active repulsion of potential intruders through defense or advertisement.

Advantages of a territory;

• knowledge of territory, including refuges, good breeding sites etc.
• access to mates.
• access to food - within an economically defensible area.

The concept that territories are economically defensible units is one of the easier of postulated advantages to test. Defining optimal territory size (radius) as that maximizing net energy per unit time, optimal size may be expolred using:

Schools: groups of fishes range from aggregations to polarized schools. A polarized school has been defined as relatively long-term association of three or more fish moving in concert at fixed distances. Long-term associations, lacking rigid organization may be called non-polarized schools or shoals.

In schooling associations, there is no apparent behavioral differentiation among members, there are no leaders, no persistent ties among near-neighbors and no dominance relationships. There is no overt aggression, but inter-neighbor distances (individual distance) are conservative in polarized schools.

Schooling behavior is very common among fish; Cyprinidae, Salmonidae, Clupeidae, Atherinidae, Scombridae, Engraulidae. Most fish school as young but only about 20-25% as adults. Numbers in school vary from a few individuals to millions in herring, menhaden. Atlantic herring schools sometimes encountered in winter occupying 279 to 4580 m3 with 0.5 to 1 fish.m-3.

Behavioral patterns.

• Short radius behavior.
• Loose cruising association.
• Predator encircling.
• Flash expansion.
• Mills.

Advantages of Schooling.

• reduced risk of predation.
• increased efficiency of finding food.
• increased reproductive success.
• increased swimming efficiency.

Factors Affecting School Structure

• Threat.
• time.
• environment; presence of food, current etc.
• life history stage.
• Reproduction.