An instrument that uses radio-echo sounding to determine ice thickness. It is attached to the bottom of an airborne vehicle and measures ice-thickness below the instrument. This is a costly method with 3-D spacial limitations.

Fish that spent the majority of their life in the ocean but migrate via rivers into freshwater to spawn. Young develop in freshwater before returning to the marine environment as adults. Examples include salmon, shad, river herring, and striped bass.

Aquaculture is the cultivation of aquatic organisms under controlled conditions. The purpose is to increase fish harvest to satisfy demand. Aquaculture started 4,000 years ago in China. In 1987 and 2000 the global aquaculture product of fish (including shellfish) was 4 million and 14 million, respectively. In 2005, 2% of the fish consumed in the Un [..]

An instrument used to count and measure the size of particles suspended in an electrolyte fluid, such as water, by detecting changes in electrical resistance. This counter is often used to measure cells (bacteria, phytoplankton, etc.) and suspended sediment. https://www.beckmancoulter.com

(a.k.a demersal): Pertaining to the bottom of the ocean, or the seafloor. Fish species may be categorized as “demersal” -even those that swim through the water column- if their diet consists primarily of benthic organisms. Examples of demersal fish species include flounder and most hake species.

The process that leads to accumulation of pollutants over time in the fatty tissue, or lipids, of living things. The primary chemicals that tend to bioaccumulate are persistent organic pollutants because they dissolved easily in fatty tissues and are not easily metabolized in the body.

How diverse an ecosystem is with regards to how many different organisms are present in a given environment at a given time.

The attachment of an organism or multiple organisms to a surface that is in contact with water for a period of time (think of barnacles and algae, or “scum” if you will…, attaching to the bottom of a boat in the water).  More here.

When the concentration of a compound is higher in a predator than in its prey, the compound is said to biomagnify. This process is important for many bioaccumulative pollutants, and causes them to concentrate at high levels in top predators.