2.3.1: Shellfish
- Page ID
- 114246
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Figure \(\PageIndex{1}\): Purple sea urchins (Strongylocentrotus purpuratus) ready to be harvested from Santa Cruz Island, CA. Gregory "Slobirdr" Smith, CC BY-SA 2.0, via Flickr
Shellfish is the common way of referring to species of marine organisms with a shell that are harvested for consumption, and thus, are managed fisheries species. Shellfish include mollusks, arthropods, and some echinoderms.
Mollusks
Mollusks include bivalves (2 shells), gastropods (1 shell or no shells), and cephalopods (octopus and squid). Bivalves such as oysters, clams, and scallops are commercially important (seafood industry) and thus, their populations have to be managed. Some molluscs have seasons in which they – there are seasons to harvest them, etc. Some mollusks, such as oysters, stay in one place. Others, such as scallops, swim and even have eyes. Conchs (Caribbean) and abalone (here in CA) are managed gastropods that have been severely overfished. Fishing and collecting rules vary by locality, state, and nation.
Arthropods
Arthropods are another group of harvested shellfish. Arthropods means “many legs”. This is the animal phylum with the most species, because it contains insects AND ocean dwelling shellfish. Crabs, lobster, and shrimp are the most important species commercially. The fisheries for these tend to be on the ocean bottom, and they are either caught by trap or by trawl. Trawling can result in many other species being caught as bycatch, so modifying the equipment so that it only captures the target species is one of the more important considerations in these fisheries.
Other shelled organisms
Other marine organisms such as sea urchins are also eaten as a delicacy, and there are sometimes localized fisheries for them. In northern California, red and purple sea urchins are collected for roe during certain seasons of the year. Collection is encouraged because populations of sea urchins are out of control and are destroying kelp forests.