[4] Females in estrus are typically more dispersed than land-breeding pinnipeds and the distinction between foraging and reproductive behavior is less apparent.

[6] Female harbour seals start making foraging trips shortly before weaning their pup and consequently are widely dispersed when in estrus.

Harbour seal males use underwater vocalizations and display dives within their aquatic territories, for both female attraction and male-male competition.

[11][7][6] Male harbour seal vocalizations consist of low-frequency broadband growls that peak in occurrence during the mating season.

[11] Territory holders use the acoustic displays of intruders to locate and challenge invaders and will respond aggressively to a male call.

[6] Aquatic hierarchies in harbour seals develop before the breeding season and dominance is determined by direct male contests.

These contests involve repeated confrontations between two males using surface splashing, fighting, paired somersaulting, and chasing techniques.