| Home: Special status species: Harbor porpoise: Natural history |
SPECIAL STATUS SPECIES: Harbor porpoise (Phocoena phocoena)
NATURAL HISTORY |
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| General |
| Taxonomy: |
Suborder Odontoceti (toothed whales); Family Phocoenidae (porpoises). Rice13 described 3 subspecies; the subspecies in the eastern North Pacific is Phocoena phocoena vomerina. |
| Appearance: |
Like all porpoises, the harbor porpoise is small in size; adult females average 157 cm and 62 kg.2 Females are slightly larger than males. The robust body of this species is dark gray on top with lighter sides and belly. One or more dark gray stripes run from mouth-to-flipper. The mouth is lacking a beak and contains laterally compressed, triangular teeth in both jaws. The dorsal fin is medium-sized and triangular in shape. |
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| Feeding Behavior |
| Overview: |
Usually feed individually; cooperative feeding has not been observed. May be seen alone, in small groups (2-8 individuals), or rarely in large aggregations, presumably in areas of high food availability. |
| Prey Items: |
Feed on cephalopods (primarily market squid) and nearshore schooling and demersal fish (e.g., Northern anchovy, spotted cusk eek, rockfish, Pacific hake, Pacific sardine, Pacific herring, plainfin midshipmen, Pacific sanddab, Pacific tomcod).14,15,16 Post-wean calves often ingest small crustaceans (e.g., krill). |
| Method of
Capture: |
Forage in the water column or along the sea floor. Dives can exceed 200 meters and last at least 5 minutes, but typically range between 14-41 m and 44-103 seconds.2 Harbor porpoise are active predators that find prey using echolocation and eyesight. |
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| Reproduction |
| Overview: |
The harbor porpoise is a short-lived species with limited lifetime reproductive capacity. |
| Time to Maturity: |
Females mature at an average length of 150 cm (3-4 years) and males mature at an average length of 140 cm (3-4 years).17 |
| Longevity: |
Approximately 10-14 years.18 |
| Breeding
Season: |
In central California, females give birth in summer with a peak in July.16 Conception also occurs in the summer. |
| Frequency
of Breeding: |
Mature females in many populations give birth every year; off California females probably give birth only every other year.2 |
| Gestation
Period: |
10-11 months.2 |
| Number of
Offspring per Pregnancy: |
One |
| Parental
Care: |
Female nurses calf for 8 to 12 months.2 |
| Mating
System: |
It appears that both females and males mate with multiple members of the opposite sex. Males may compete for fertilizations through sperm competition.16 |
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