And the role of mother’s in the types of marine mammals in the Salish Sea.
Mother’s day is celebrated around the world by various countries to celebrate and honour motherhood. General information of mother’s day from Wikipedia (the online encyclopaedia) indicates that it is celebrated on various days world wide; however two primary dates exist for “mother’s day”:
• The
second Sunday of May, which is the larger of the two primary dates but is the more modern celebration of mother’s day. It started in the 20th century in the United States by Anna Jarvis, with many countries following suite including Canada.
• The smaller date is the
fourth Sunday in Lent, which comes from the United Kingdom’s “Mothering Sunday” celebration. This tradition dates back to the 16th century.
The observance of Mother’s Day around the world is relative recent occurrence as it has evolved from North America and Europe. However, some festivals and celebrations of honouring mothers have existed prior to pre-colonization (i.e. Africa). Mother’s day gives us an opportunity to provide our mother with a little extra love and attention. The hectic-ness of life usually reduces our opportunities to spend quality time as a family and to appreciate all the things our mom (and dad) does to make our life easier. Therefore, getting together on mother’s day as a family to celebrate all that our mom has done for us i.e. driving us to practices, shopping, etc. is special and helps to improve our family relationship.
We all know the role that our mother’s have played in our lives, but what are the roles of mother’s in the types of marine mammals in the Salish Sea?
The Pinnipeds (Seals and Sea lions)
The Salish Sea is utilized by primarily four species of pinnipeds or the
wing-footed mammals. Two species from the family Otaridae (eared or fur seals and sea lions) and two from the family Phocidae (true seals). The
male California (
Zalophus californianus) and
Steller (
Eumetopias jubatus) sea lions utilize the Salish Sea as winter haul out and foraging grounds. In May, the majority of the male Steller sea lions have staked out and defend key breeding territories on remote rookies in Northern British Columbia and Alaska. The females arrive later giving birth to their pups that they carried for 11 ½ months, and then proceed to lactate for up to 3 years. The majority of the pups are weaned after a year, which allows the female to start nursing the next pup which was conceived 11 to 14 days after the birth of the other pup. The male California sea lions proceeds south in the spring to breeding colonies off of California and Mexico. The females give birth to their pups from late May through July, which they’ve carried for 9 months, and remain ashore with their pups for up to ten days. The females then return to sea on foraging forays that may last up to 3 days; however the females will return to the shore for a day to nurse their pup. The pups sometimes join their mothers on foraging events, but majority remain on shore in large social groups. After six months, pups are abruptly weaned and abandoned (goodbye mom and thanks for life). The female California sea lion will be ready to mate twenty to thirty days after the birth of their pup, but has the ability to delay the implantation of the fertilized egg by three months. As a result, the female sea lion is not pregnant for only one month out of the year.
Could you imagine being pregnant for the majority of your life span?
The phocids or true seals in the Salish Sea utilize the area either year round or for the majority of the year.
Harbour seals (
Phoca vitulina) are found in the Salish Sea year round. The Harbour seals are quite territorial of haul out sites from sandy and pebbly beaches to intertidal rocks and ledges, which they tend to, forage and feed off of. The female Harbour seals haul out to give birth to their pups in the summer months June through August. The pups are able to swim and dive immediately, but usually hitch a ride on mom’s back using their fore flippers. The pups are nursed for three to four weeks, then abruptly weaned and abandoned by their mother. The females then mate shortly after the weaning process.
Mommy! The three week nursing period is similar for the
Northern elephant seal (
Mirounga angustirostris)
, except the female remains ashore on the sandy beach, fasting and defending her pup from other females and pups. After the three weeks is up, the pup is weaned by desertion. However, the female mates with the dominant bull elephant seal whose territory she’s given birth in just prior to the weaning of her current pup. Although, the majority of the northern elephant seals are breeding off the coast of California and Mexico, utilizing the Salish Sea for the majority of the year as foraging sites and molting sites. The first witnessed birth of a Northern elephant seal occurred at
Race Rocks Marine Protected Area. Although, three weeks seems incredibly short, the phocids
lactation period ranges from
4 to 50 days within the various species. The pups may not receive long periods of motherly love but thankfully the milk is richer than any other marine mammals from 45 – 60% fat.
The Mysticetes (Baleen Whales)
Although the Minke whale (
Balaenoptera acutorostrata) is the most common and widely distributed of baleen whales, very little is known about the Minke whales reproduction and breeding. Hein bank in the Salish Sea is an incredibly productive summer feeding ground for the Minke whales, however, no mother-calf pair sightings have occurred at this feeding site. This indicates that weaning might occur prior to arrival at summer feeding grounds. The locations of Minke whale calving grounds for the Minke whales that forage in the Salish Sea are still a
mystery for the whale referred to as the commoner. Unlike the Minke whale, the other baleen whales that utilize the Salish Sea as summer feeding grounds arrive with their offspring.
The Gray whale (
Eschrichtius robustus) calves are independent of their mothers just prior to the fall migration back to the warm, breeding lagoons off the coast of Baja California. However, the migration to the northern feeding grounds of the Salish Sea is filled with perils for the Gray whale cow-calf pairings, with attacks from Southeast Alaskan transient killer whales. Gray whales defend their calves from these attacks, indicating a strong cow-calf connection, although not every mother is successful (
BBC Blue Planet Disc 1 – Ocean World footage).
In recent years (late-1990s), cow-calf pairings of Humpback whales (
Megaptera novaeangliae) are being seen in the Salish Sea, which means the Humpbacks are recognizing and teaching their calves that this is part of their summer feeding grounds. Humpback whales were hunted and removed from British Columbian waters, with the last whaling station in
Coal Harbor closing their doors in 1968. Therefore, new humpback calves are learning to utilize this area prior to the return to the warm tropical breeding waters off of Mexico, Hawaii and even as far away as Japan. The return to these breeding grounds is the end of the cow-calf pairing, for the mothers have now taught them the official migration route from the breeding grounds to feeding grounds and back again. The majority of baleen whales experience a birthing interval of two to three years, with a twelve month pregnancy. However, the Minke whale might be an exception giving birth annually.
The Odontocetes (Toothed Whales, Dolphins and Porpoises)
The Salish Sea is incredibly unique that it is part of the home range of the largest oceanic dolphin, the killer whale (
Orcinus orca) . It’s utilized by two different ecotypes of killer whales, transients (mammal-hunting) and residents (fish-hunting). The Northeast Pacific killer whales are some of the longest studied marine mammals since the early 1970s, with the
Centre for Whale Research being set up to study the Southern resident community of killer whales. The research of Northeast Pacific killer whales has revealed a complex social structure in these animals. The social structures of killer whales are incredibly unique because it has reviled that killer whales are cultural based mammals. These culture traditions such as hunting techniques and language are taught by the
females, for killer whales are a matriarchal society. The base social level of
killer whales is the matriline, which is made up of a
female and her offspring (both juvenile and adult male and females). A killer whale pod consists of several related matrilines that contain a common maternal ancestor. The clan is the next level in the social structure of killer whales, which indicates the relatedness of pods through the vocal dialects that they speak. Similar dialects of clan members reflect the common matrilineal heritage of the pods. The community is the last level of the social structure, and is made up of pods that associate with one another quite regularly. Therefore, killer whales demonstrate one of the most significant maternal connections in marine mammals.
What’s an empty nest? Killer whales also experience the longest gestation of any marine mammal ranging between 15 to 18 months, and calves may not be weaned until two years of age.
Two of the six porpoise species, forage and reproduce in the Salish Sea. The Harbour porpoise (
Phocoena phocoena) is highly elusive around vessels but huge foraging associations are witnessed in highly productive areas in the Salish Sea. The breeding season for the harbour porpoise appears to be late summer in the Salish Sea. The male harbour porpoise breeds with multiple females due to their weighty advantage of largest testes-to-body size ratio. Sexually mature females are able to give birth annually; therefore the females are under nutritional stress for most of their adult lives, due to overlapping periods of lactation and pregnancy. Due to the elusive nature of the harbour porpoise, mother-calf pairings are a rare sight. Unfortunately, my first sighting of a mother-calf pairing of a harbour porpoise ended with the calf being utilized/consumed as a teaching tool for T100D a young transient killer whale by his or her mother T100.
It was AWESOME! During the productive summer months in the Salish Sea, the male Dall’s porpoise (
Phocoenoides dalli) escort and breed with a single female since they aren’t as “
ballsy” as the harbour porpoises. The following summer months, after nearly a year gestation period, a new calf is born. However, the new calf surprisingly might not be only a Dall’s porpoise but a hybrid between a Dall’s and a Harbour porpoise. Those harbour porpoises are definitely “
ballsy” mating with one of the fastest cetacean species. Similar to the Harbours the Dall’s females in their prime probably give birth annually, but might not be a stressed due to a shorter lactation period of two months to eight months.
National Audubon Society: "Guide to Marine Mammals of the World" 2002 Chanticleer Press, Inc.
