Harbour Seals (Phoca Vitulina) are the most widely spread of all the seals. However, competition for the same fish that are commercially harvested has seen these animals being persecuted, blamed for eating too much and destroying fishing nets. In several countries (such as Norway, Canada and the United Kingdom) it is legal to shoot these seals in order to protect fisheries and fish farms. Despite conclusive evidence to the contrary, calls to cull the species are frequently called for by the uneducated few who believe them to be responsible for a drop in fish stocks.
HARBOUR SEALS BREEDING BEHAVIOUR
Also known as common seals, this species is generally gregarious in nature. They haul out in groups to breed, nurse and moult. Haul out locations tend to vary considerably and include sandy beaches, reefs, rocky shores, piers and inter-tidal mud bars, though the species is reluctant to haul out where there is human interference.
Mating takes place in the water and birthing peaks usually from between April-June. Gestation period is one year with a portion of that as delayed implantation. Pups weigh in at around 12-16kg at birth and are very active within just a few short hours, taking to water almost immediately. Weaning takes on average 6-7 weeks during which stage the pup can double its weight.
Females reach sexual maturity at between 4 and 5 years while males take a little longer, generally between 5-7 years. Females have a high pregnancy rate of almost 92% per annum though this figure does drop off slightly after the age of 25. The average life span of Harbour Seals is just over 30 years. There is no significant difference in size between males and females.
Hundreds of these seals also die by entanglement in gill-nets each year and commercial hunting of the species has seen the population disappear from several traditional sites in Greenland where they are prized for their meat and fur that forms part of traditional costume.
Harbour Seals have prominent eyes which are adapted for shades of black and white. Compared to humans, they have superior vision underwater but not so on land. Vision does not appear to impair the species though and blind, yet otherwise healthy specimens have been noted.
They are the least vocal of pinnipeds, making vocalizations as a defence mechanism and only when threatened.
They dive to an average depth of only 90m but can hold their breath for up to 28 minutes. By slowing their heart rate from 120 beats per minute to as few as 4 beats per minute they are able to conserve their oxygen.
Diet for these seals tends to change according to the season. They typically feed on herring, perch, flounder, octopus, squid and shrimp. They get most of their water from their food and dehydration is usually only the result of illness.
The pre-historic ancestors of harbour seals were very similar to dogs. Despite having mans best friend as an ancestor, Harbour seals have been hunted and persecuted by man for thousands of years.
They are preyed upon by Orca’s, sharks, coyotes, wolves, Polar Bears, Steller Sea Lions, Walruses and even eagles will snatch small pups.