L22 - Humans and the Ocean

Question 1

Our changing relationship with the ocean?

Answer 1

Technology, growing population and increased understanding of the system is increasing the number of ways we use the ocean. Tourism - Fishing - Aquaculture - Mining - Energy - Culture

Question 2

How far back does evidence go of Homo sapiens using the marine enviro for food?

Answer 2

> 150,000 years ago to Africa. Fishing practices have possibly shaped human evolution through nutrition.

Question 3

What did Huxley say?

Answer 3

T. H. Huxley 1883: I believe, then , that the cod fishery and all probably all the great sea fisheries, are inexhaustible: that is to say that nothing we do seriously affects the number of fish. And any attempt to regulate these fisheries seems to be useless

Question 4

Change in cod catch in Eastern canada?

Answer 4

Peaked at 1970 - 800,000 t. Lowest 2000-2019 0-10,000.

Question 5

Fish catch in United Kingdom?

Answer 5

Higher in UK than England and Wales

Question 6

Wild fish catch by gear type? Largest to smallest?

Answer 6

Bottom trawl, purse seine, small scale, pelagic trawl, other gear, unknown gear, gillnet, longline. IN order largest to smallest.

Question 7

What is aquaculture and aquaculture production?

Answer 7

Aquaculture is the farming of aquatic organisms including fish, molluscs, crustaceans and aquatic plants. Aquaculture production refers to output from aquaculture activities, which are designated for final harvest for consumption.

Question 8

What is crucial in regard to fisheries?

Answer 8

Effective and efficient management. There is a whole (multidisciplinary) scientific field with its own methods and terms behind it.

Question 9

Define fishing effort?

Answer 9

The magnitude and/or distribution of fishing activity in a given area and over a given amount of time.

Question 10

What is CPUE?

Answer 10

Catch per unit effort, the quantity of caught fish (weight or numbers) per unit of fishing effort. C/f = qN, C = no of fish caught, f = unit of expended effort, q = probability of catch per effort unit, N = no of fish in the overall stock.

Question 11

Define stocks?

Answer 11

Discrete pops of a species, breeding separately from other stocks and therefore (mostly) self-sustaining. The primary management unit in fisheries science.

Question 12

Define MSY?

Answer 12

Maximum sustainable yield. Maximum annual catch that can be taken from a stock indefinitely, without causing population decline.

Question 13

What does the UN food and agricultural organisation (FAO) release?

Answer 13

A report on fisheries and aquaculture every 2 years.

Question 14

What is the current state of global fisheries?

Answer 14

2022: Global fish production: 185 million tonnes (worth 452 billion), 79.7 million tonnes captured from marine areas, 35.3 million tonnes from marine aquaculture.

Question 15

What is happening to most marine fisheries?

Answer 15

They are overfished or maximally fished - though this varies by region.

Question 16

Where are fisheries located?

Answer 16

95% of major marine fisheries are located in coastal waters. >50% of catches come from <7% of the ocean. Upwellings are highly productive parts of the ocean.

Question 17

What is human consumption?

Answer 17

20.5kg per capita, 88% is for direct human consumption, 9% for fish feed and fish oil, proportionally, more is eaten today than ever before.

Question 18

What are the largest catches for fisheries?

Answer 18

Clupeiod fishes: herrings (sardines), anchovies, sardines (pilchards), menhadens and shads. 2018: 71.9 millions tonnes of fish, 6.0 million tonnes crustaceans, 5.9 million tonnes molluscs.

Question 19

What species?

Answer 19

Peruvian anchoveta (Engraulis ringens) - 7 million tonnes. Alaskan pollock (Gadus chalcogrammus) - 3.4 million tonnes. Skipjack tuna (Katsuwonus pelamis) - 3.2 million tonnes. Humboldt squid (Dosidicus gigas) - 0.9 million tonnes. Natantian decapods (prawns) - 0.85 million tonnes.

Question 20

What are the two main distinctions of fishing practice?

Answer 20

Artisanal & commerical

Question 21

What is Artisanal?

Answer 21

Small scale, low-technology, low-capital, fishing practices undertaken by individuals fishing households. Local, maybe for subsistence or for income.

Question 22

What is Commercial?

Answer 22

For profit. Often mechanised, and often food collected for transport far from origin.

Question 23

Common industrial fishing gear - Trawls?

Answer 23

Dragging of a large, cone-shaped net. Might be pelagic (pulled through midwaters) or bottom trawl (on or just above the seabed).

Question 24

Common industrial fishing gear - Purse seine?

Answer 24

Net drawn around a school of fish, the drawn/tightened inward. Tends to be low bycatch. Species targeted include tuna, anchovies, mackerel (form dense single-species groupings).

Question 25

Common industrial fishing gear - Long line?

Answer 25

Long lines of baited hooks, sometimes kilometres long, either on surface or along the bottom. Target species include sharks, swordfish, squid, tuna and others. Can have significant accidental bycatch, including birds.

Question 26

Common industrial fishing gear - Pots and traps?

Answer 26

Deployed on the seabed. Cone-shaped entrance to prevent escape Primarily for crustaceans. Used in some coral reef fisheries

Question 27

Common industrial fishing gear - Gill nets?

Answer 27

A curtain of net hanging in the water. Salmon, reef fish, ground fish (cod, hake) - size of the mesh determines size of the fish. Bycatch can be high - hard to target certain species.

Question 28

Fishing down the food web?

Answer 28

The process of first catching top predators and then, as they are overfished, the fishery becomes dominated by lower trophic levels.

Question 29

What is one of the indicators of overfishing?

Answer 29

Mean trophic level (MTL), Decline in MTL in a catch over time. Each species is assigned a trophic level based on its diet e.g. 2 = herbivore, 5 = apex predator. MTL is then calculated based on the weight of each species in a catch. Changing MTL evidences changing food web structure.

Question 30

Habitat destruction -> Bottom trawling?

Answer 30

Up to 41% of biota can be removed by one pass. Penetrates seabed >15cm. Can take 2-6.5 yrs to recover (but unlikely to be given that long).

Question 31

Habitat destruction - Bycatch?

Answer 31

Unselective fishing catches non-target species - injured or killed. Some fisheries can have large ratios of non-target species (e.g. gulf of mexico). Some solutions do exist - including controlling net mesh sizes - but ultimately, pole and line method with the lowest unintentional bycatch associated.

Question 32

What categories are in global aquaculture?

Answer 32

Finfish - inland aquaculture, finfish - marine and coastal aquaculture, crustaceans - coastal aquaculture, crustaceans - coastal aquaculture. Molluscs, other aquatic animals, algae.

Question 33

What is shifting baseline syndrome?

Answer 33

A gradual change in what we deem to be the acceptable norm for the condition of the natural environment. Might be due to a lack of knowledge of what things used to be like, a lack of experience of the ideal conditions, or the reality that we can't revert to the original conditions.

Question 34

The future - Health of fish stocks by fish groups?

Answer 34

Health is measured by their biomass: the no of individuals multiplied by their mass. Decline in all species.

Question 35

The future - Management and protection?

Answer 35

United nations convention on the law of the sea (UNCLOS) established exclusive economic zones (200 miles/ 370km offshore). Marine protected areas (MPAs) vary by country by country, fishing might be banned or restricted in some way (e.g. seasonally, every x years, size limits, etc). Both biodiversity and biomass in MPAs are generally higher in MPAs than in non-protected areas.

Question 36

What % of fishing is illegal?

Answer 36

15

Question 37

What are the most affective MPAs?

Answer 37

1. No-take 2. Well enforced 3. Old (>10 yrs) 4. Large (>100km2) 5. Isolated by deep water or sand

Question 38

What are the problems with fisheries?

Answer 38

Unselective fishing and bycatch, habitat destruction, changes to species abundance, shifting baseline syndrome, illegal, unreported and unregulated fishing (IUU)

Question 39

What are the solutions with fisheries?

Answer 39

Selective fishing via regulations, gear improvements, eco-labels. Regulations, gear improvements, MPAs. Fish conservatively (MSY), avoid largest individuals and spawning sites, MPAs. MPAs, fishing below MSY for population rebuilding. International treaties and enforcement.

Question 40

What are the problems to aquaculture?

Answer 40

Feed ratios and sources, drug use (e.g. antibiotics), farm locations, eutrophication.

Question 41

What are the solutions to aquaculture?

Answer 41

Effective feed research and sustainably sources ingredients, organic methods and mutualisms, away from migration routes (salmon), or high value ecosystems (mangrove forests). Mutualisms