Shellfish, Pacific Northwest
We are so lucky here on the West Coast to have such a variety of amazing shellfish. Although, many of the commercial species we have here were introduced from other parts of the world. But I think that they have had little impact on the native shellfish population and have indeed found a nitch here.
Mussels have bluish-black shells that look like a flattened teardrop. The inside of the shell is pearly violet to white in color. Projecting from between the shells on the flat side is a bundle of tough, brownish threads, which are used to anchor itself to hard surfaces. Inshore waters support the native Blue Mussel, which can reach 9 cm in length.
Wave-swept rocky west coast shores have beds of the larger Giant Pacific Mussel, which can grow to 25 cm in length. The mussels in the bottom photo are giant mussels. The Blue mussel has a smooth outer shell surface with growth rings, while the Giant Pacific Mussel has raised radial ribs.
A mussel is a type of bivalve mollusk that can be found where the ocean meets the shore. Like many other shellfish, they are cultivated and caught in the wild to serve as food for humans, and they also have a number of predators in the natural environment.
These mollusks reproduce sexually, with the young hatching loose in the water. The larvae float until they reach a suitable living space, which distributes them more widely and gives them a better chance at survival. The primary diet of a mussel is plankton, along with other shellfish, They are filter feeders, sucking in water and filtering out nutrients to eat.
The ocean waters flowing down the coast from northern climates are rich with nutrients and very cold. This makes the prime areas for shellfish production around the central area of Vancouver Island. The cold waters we have here are necessary for fine flavors of our shellfish. The nutrients that are in this water provide plenty of food for rapid growth.
Pacific Oysters change sex at some point during their life, usually spawning first as a male and subsequently as a female. Environmental conditions may affect sex. When food supplies are plentiful, males tend to change into females, and vice versa when food supplies are in poor supply.
Pacific oysters usually produce between 50 to 100 million eggs which they release over several spawning bursts. The female discharges her eggs up to 30 cm from its body in the form of white clouds. The male oyster adds its sperm.
The Pacific Oyster can live and grow in water temperatures between 2 to 20°c but has higher growth rates in water temperatures of 12 to 15°c. Spawning is temperature dependent and occurs in the summer months when water temperatures are typically warmer.
The overall growth varies by tidal height, season and the area in which they grow. The Pacific Oyster prefers to attach itself to a hard surface and can be found on firm mud, sand, gravel or a rock substrate in the lower intertidal zone, down to a depth of roughly 4.2 meters.
The moonsnail glides on a very large, mucus-covered foot which, when fully extended, can be up to 30 cm long. When this fleshy mantle is extended, it will nearly cover the snail’s shell. The animal can discharge water which allows it to shrink, slide into its shell and seal the opening by closing its operculum. The snail cannot stay in the shell for long periods because it needs to breath.
Moonsnails feed on clams, mussels, and other various mollusks and sometimes they will even prey on their own species. They use their foot to clamp onto the clamshell and then using their tongue, they can drill a hole in the clam’s shell. The foot can form a siphon which they push through the hole and suck up the flesh of the clam.
This animal is quite unique in its reproduction. In late spring and early summer, the egg case of the Lewis Moonsnail can be found. It is a mixture composed of sand and mucus that forms a single gelatinous ribbon sand collar. In between the layers of this sand collar are thousands of eggs. As the sand disintegrates over a period of weeks, the larvae are released into the water column. The larvae move into deeper water and feed as herbivores on diatoms and sea lettuce for a while, then switch to shellfish as they grow. When wet, the collar remains quite rubbery and pliable but becomes brittle when it dries out. Fascinating snail to observe in the wild.
There are many freshwater shellfish in the Pacific Northwest, although most are not edible, they are still very fascinating to study. Made a freshwater mussel chowder and found it to be quite tasty. There is something quite awesome about seeing the variety and abundance of shellfish on Vancouver Island.
We have the protected Abalone here, very beautiful creature. Then there are the variety of Barnacles that can be found growing alongside the many types of mussels, love seeing the giant species of both. Many different types of clams can be harvested along the entire coast as well as all the outer islands.
Scallops occur all along the pacific northwest coast, Spiny scallops are found subtidally from 5 to 150 meters in depth, while Pink can be found to a depth of 200 meters. Spiny scallops prefer gravel or rocky bottom. Pink prefer a sand or mud substrate. Both prefer areas with some current. Rock Scallops prefer a very rocky bottom.
Both spiny and pink have distinctive fan-shaped shells that are ivory and pink in color, the rock scallop is round and almost invisible with its shell covered in various bits and pieces. they can reach up to 9 cm in size. Minimum size for harvest is 5.5 cm
Harvesting is by dive and trawl, although they are commercially farmed in on the coast as well. The meat color ranges from ivory to pinkish white and can have a tender yet sometimes chewy texture. It is sweet and moist.
Pink and spiny types have separate sexes and are mature at 2 years of age. Spiny scallops spawn from mid-August to late October while pink scallops spawn from January to March. The fertilized eggs develop into planktonic larvae that drift for 3 to 4 weeks and are dispersed by water currents before they settle.
They are suspension feeders, feeding mainly on plankton and zooplankton. Predators of these bivalves include sea stars, octopus, snails, fishes, and boring worms.