Galvanising: Process by which iron is coated with zinc.

Gas bladder: A gas-filled sac found in many fishes. Gas bladders help provide buoyancy; they're also called swim bladders.

Gastropod: A group of molluscs that travel on a single, muscular foot and often secrete a one-piece shell for protection. Snails, slugs, limpets and abalones are all gastropods.

Gear limits: Management term used to limit the type of fishing gear used by fishers.

Gender limits: Fish protected by sex, e.g. female mudcrabs are protected by law from being taken by fishers.

Genera: A collective term used to incorporate like-species into one group. The first part of the Latin name of any creature refers to the genus.

Genus: In biology, a category that's part of the scientific system for grouping together related plants, animals and other organisms (kingdom, phylum, class, order, family, genus, species). Genus is the category that ranks below a family and above a species.

Geology: The scientific study of rocks, the earth's crust and the earth's interior.

Gill: An organ that an animal uses to breathe under water. Gills absorb oxygen from the water.

Gill covers: The tough flaps of tissue that cover a fish's gills.

Gill net: A type of fishing net that catches fish by their gills or gill covers.

Global positioning system (GPS): An electronic system that uses signals from satellites to locate things far below on the surface of the earth or ocean. GPS technology is being used to make very accurate new maps of the earth and ocean. GPS devices let scientists and fishers find their way very precisely.

Godwit: A long-legged shorebird with a very long, straight bill.

Golden-eye mysid: A shrimp like animal that lives on the seafloor. The golden-eye mysid was named for the way its eyes reflected the lights of remotely operated vehicles (ROVs) exploring the deep sea.

Gondwanaland: A hypothetical protocontinent of the Southern Hemisphere, named for the Gondwana region of India, which included the present continental masses Africa, Antarctica, Australia, India and South America.

Goofy foot (surfing): Refers to stand up surfers who put their right foot forward when surfing.

Gorges: Fish hooks without curves, made from bone.

Gorgonian: A member of a group of corals that grow in tree like shapes; some live in cold, deep water and grow very slowly.

Gravitational attraction: Force of attraction between two objects.

Gravity: A force of attraction towards the centre of objects.

Greases: Thick oily substances used to lubricate marine parts.

Greenhouse effect: A build-up of carbon dioxide, methane and other gases in the atmosphere preventing heat from escaping from Earth.

Grow-out farms: Places where adult aquaculture animals are raised until they are harvested.

Groynes: Boulders placed by humans that jut out to sea to capture sand and form a beach. Found to be ineffective because they only cause erosion on the opposite side of the rock wall.

Guano: The droppings of birds or bats. In some places, like penguin colonies, huge deposits of guano build up over many years. People sometimes harvest this guano to use as fertilizer for farms and gardens.

Guitarfish: A flattened fish in the shark family, not quite as flat as a skate or ray.

Gulfs: Portion of sea partly enclosed by land.

Gullet: The throat.

Gunwale: The upper edge of the side of a boat.

Gutting: Removing intestines and other internal organs of a fish.

Gyres: Currents moving in large circles in the Northern and Southern Hemispheres.