Commercial fisheries

Warm up 3/4

1. What is the cause of nutrient pollution?

2. What is eutrophication? Explain the steps.

3. What are 3 examples of chemical pollution?

4. What is biomagnification?

Commercial fisheries

EQ

How do we effectively manage our fisheries so that we have fish for future generations?

What is a fishery?

A commercial fishery is the industry of catching a particular fish species for profit

Ex: Tuna, cod, salmon

What are some fishing methods?

Bottom trawls – heavy nets dragged across the seafloor to catch shrimp, cod, rockfish

Longlines – can range from 1 – 30 miles long, evenly spaced hooks

Gillnets – walls of stationary netting that trap midwater fish

Fishing methods

Problems with commercial fishing

Two major problems:

Bycatch – catching species not targeted

Habitat destruction – destruction of the home/environment of animals

How are humans so good at fishing?

Technology has greatly altered the way humans exploit fisheries

This leads to…

Overfishing- fishing faster than fish can replenish (greatest threat to marine biodiversity)

What kind of technology?

Advances such as the ability to catch lots of fish at once (nets, longlining, trawls), SONAR, better engines and boats

Case study – Atlantic cod

Historically, cod was so abundant off New England that early explorers named it Cape Cod for this fish

High fishing pressures as a result of technological progress (radar, sonar, navigation systems) caused a collapse

Case study – Atlantic cod

Adversely affected in two ways: increasing depth and areas of where cod was fished, also caught enormous amounts of non-commercial fish (bycatch)

Cod populations could not keep up, resulting in the collapse

Atlantic cod today

Populations will take decades to recover from the impact of fishing – due to ignoring scientific data and the effect of the “tragedy of the commons”

Tragic fishing

We will now do a fishing activity using goldfish, straws and a bowl (ocean)

We will have five fishing seasons, each season lasting 30 seconds. You can catch as much fish as you want in that time.

After every season, each fish that you have left will create another of themselves. Max 20 fish (carrying capacity of the ocean).

If you don’t catch a fish in a season, your family will starve and can’t fish the next seasons.

Case study – Bluefin tuna

Max length about 10 feet and can reach about 2000 lbs undisturbed

Three stocks, one in eastern Atlantic/Mediterranean Sea, one in the Pacific ocean and one in the southern ocean

Case study – Bluefin tuna

Populations have fallen to just 2.6% of what they were

Market is driven by Japanese markets, where they are willing to pay tens of thousands of dollars for otoro- extremely fatty cut of sashimi

Record price as of today - $3 million, $5,000/pound

Bluefin tuna today

Bluefin tuna stocks are highly depleted, and still being fished heavily.

IUCN Redlist (determines what status a species is) says the following about the stocks of the Bluefin:

Atlantic Bluefin populations are endangered and decreasing.

The Pacific Bluefin populations are vulnerable and decreasing.

The Southern Bluefin populations are critically endangered and decreasing.

Why have fisheries been depleted?

Ecological ignorance – people don’t believe that they are affecting the environment, ignoring scientific data

Tragedy of the commons – a shared resource is depleted when everyone acts in their self-interest (human greed)

Solutions

More sustainable fishing methods – choose methods that have less bycatch and don’t take as much (Hook & line, trapping, trolling)

Better management- catch limits, better technology to reduce bycatch

More awareness – educate people on the importance of choosing where their fish comes from

Do you want to make more sustainable choices?

Seafood watch program

Brochure