Two Sides of Marine Life

This entry starts with seaweed, one of the most basic forms of life in the sea, and ends with two important species of marine mammals for the Pacific Northwest. 

Eelgrass: green, grass-like blades about 1/2 inch wide and 3 feet long. Eelgrass is found submerged or floating primarily in colonies. These colonies are referred to as eelgrass "beds". 

Eelgrass grows in the muddy or sandy substrate of the shallow sub-tidal zone, down to a depth of approximately 22 feet in the Northwest.  Eelgrass fills an important function in the marine foodweb at two levels: it is directly consumed by organisms such as waterfowl, urchins, worms, snails, and microorganisms. In addition, many other species (such as salmon, crabs, and heron) consume the organisms that live in the eelgrass colonies.

Eelgrass can also protect animals from overheating caused by exposure to solar rays in shallow water during low tides and in shallow areas. On tidelands, animals bury themselves underneath mats of eelgrass to avoid dehydration.  Eelgrass has historically been used for a variety of human needs such as food, basket weaving, compost, bedding, insulation and high-grade paper. Most industries stopped processing eelgrass in 1930-31 when the Wasting Disease nearly wiped out eelgrass populations along the Atlantic Coast of North America and Europe.

Bull kelp: Bull kelp is best known for the long, smooth, brown bull whips that wash up on beaches in fall and winter. This long stipe, or stalk, leads on one end to a bulbous gas float, attached to long, flat, leaf-like blades. At the other end of the stipe is a holdfast - a disc-shaped, root-like structure that adheres to rocky substrates at depths to 60 feet. Bull kelp is found in the turbid subtidal waters of ocean coasts and straits. The fastest growing seaweed in the world, bull kelp can grow from a tiny spore to a 120 foot mature plant in a single season. On the blades of mature kelp, spore-forming patches, called sori, develop and sluff off, leaving holes or notches in aging blades. These heavy patches often fall near the parent's base, but some may drift a distance to release their spores in new territories. Kelp typically break from their holdfast during fall storms, die and wash up onto beaches, ending their life after just one season. The calmed waters of the kelp beds serve as refuges for seabirds such as ducks, grebes and gulls which also take advantage of the food reserves within. Kelp does not recover well from harvest so kelp is protected from collection. An important economic value of kelp forests has been the habitat provided for salmon, herring and other forage fish, which have been commercially harvested.

Sargassum: A disc-shaped holdfast glues the bushy alga to the substrate. From this base grow several stalks, or fronds, often over three feet long with alternating leafy branches. Among the golden-brown, leaf-like blades are pea-size floats, or vesicles, and similarly shaped reproductive organs. Sargassum's vigorous spread upon arrival in the Pacific Northwest may be due to simple but effective methods of reproduction and dispersal. Each individual plant contains both male and female reproductive parts. Once fertilized, the heavy offspring fall off, usually settling within a few feet of the parent. 

Sargassum can be found colonizing rocky substrates in lower intertidal and shallow subtidal habitats. The rapid growth of this algae, along with its ability to reproduce in a single season allows it to establish itself quickly, particularly in disturbed areas of sheltered bays that provide open substrate for offspring to settle and mature. Once established, Sargassum reduces abundance of native algae by shading.

The ecological impact of Sargassum is not fully known. On one hand, the complex branching of the fronds provides habitat for large numbers of grazing small creatures that are in turn fed upon by other species. As with eelgrass and kelp, Sargassum provides spawning surfaces for Pacific herring, which lay eggs on the blades. However, where habitats overlap, aggressive colonization by Sargassum shades out eelgrass, kelp and other native algae - vital habitat for juvenile salmon, forage fish, and other marine species. The harvest of sea-weeds is not allowed because of marine vegetation's vital role in providing habitat to important species.

Habor Seals: Harbor seals use specific shoreline areas on a regular basis to haul-out of the water and rest. These resting areas are called seal haul-outs and include beaches, rocky areas, log booms and floats. Time spent on the haul-out is essential for their survival as they rest, dry out, interact and regulate their body temperature. In addition to resting, Harbor seals give birth to and nurse their pups on the haul-out, and undergo an annual molt of their pelage or fur. 

As we approach the months of March through June, harbor seal presence and activities will intensify leading up to the late-June to mid-August popping season. The early weeks are challenging for many baby animals, and seals are no exception. During this time period, mortality rates for harbor seals can reach as high as 50 percent. The NMFS marine mammal viewing guidelines mandate a minimum approach distance of 100 yards. The approach distance will reduce the potential for disturbing or stressing a resting or injured animal.

Orca Whales: Dorsal fins are curved in females and immature males, and become straight and triangular, reaching a height of up to 6 feet in mature males. Males grow to a length of 30 feet and can weigh over 8 tons.  Females grow to 24 feet long and usually weigh over 4 tons.

Orcas begin reproducing in their mid-teens. Females have a gestation period of 17 months. They give birth to a single calf that is usually about 7 feet long and weighs 400 pounds. Orcas will give birth at 4-6 year intervals having a total of 4-6 calves throughout their lifetime. Resident calves stay with their mothers in the same pod for the rest of their life. There are three pods (J, K, and L) with a total of 90 members in the Southern Resident Pacific Northwest community.

Pods are extended families that range in size from a few to 50 members. Whales always stay within their pod; they move, hunt and play as a group.  Each pod can communicate over several miles with its own “dialect” of calls, shrieks, and whistles.  A few times during the summer and early fall, all the pods in the Southern Resident community come together to form a “superpod”.  In addition to socializing, one main function of the superpod is reproduction.  Adults mate with adults from other pods.  This ensures genetic diversity and protects against inbreeding.

Scientists have described three population categories of orcas —residents, transients and offshores. Residents hunt in large groups, eat fish, and have a total range of about 500 miles. Transients eat marine mammals (such as seals, sea lions, dolphins, and whales), travel in smaller groups, and have a range of about 900 miles.  The offshore orcas are usually found 10 to 30 miles off the coast from California to Alaska and tend to travel in groups of 30 or more.  Very little is known about offshores, except that they possibly eat schooling fish.  

Orcas engage in a variety of behaviors, such as breaching and spyhopping. A whale is considered breaching if 2/3 of its body is out of the water.  This activity is often seen during times of socializing and foraging.  When spyhopping, an orca raises its head vertically out of the water. Orca whales have excellent eyesight and it is believed that spyhopping is a way for them to look at their surroundings.

On average, females live 50 years and have been known to live up to 80 or 90 years.  Males have a much higher mortality rate and usually live 30 years with a maximum lifespan of 50 to 60 years.

The population of orcas was hurt in 1960s and 1970s, when many juveniles were captured for use in live displays in oceanariums. The population slowly recovered in the late 1990's, however, the population quickly declined in 2001 and was due to a variety of factors, including decline of salmon stocks (a main food source), bioaccumulation of toxins in their blubber, and pressures of the whale-watching industry.   In April 2004, Washington’s Fish and Wildlife Commission listed the Southern Resident orcas, along with transients and offshores, as endangered species. The Southern Resident community has recently been listed as “endangered” under the Endangered Species Act.  As of late summer, 2005, there are 90 orcas in the Southern Resident Area.