Fisheries

Question 1

Features of industrial fisheries?

Answer 1

Diverse target species.
Single species operations (eg: Peruvian anchovy fishery) vs multispecies/nation fisheries (eg: North Sea fishery).
Continental shelf = most productive area.
High mechanisation = capital intensive.

Question 2

Environmental concerns w/ industrial fishing?

Answer 2

Overexploitation of target species.
Bycatch of non-target species.
Damage host ecosystems.

Question 3

Fishery production statistics?

Answer 3

Capture fishery increased until 1980s, then levelled off.
Aquaculture fishing increased since 1980s.
Global fisheries produce 20kg fish per capita. 50% produced by wild fisheries.
4.6 million ships, 1/3 decked, 2/3 undecked.
80% motorised fishing vessels in Asia. Europe = 3%. Africa = lowest.

Question 4

Overfishing statistics?

Answer 4

1970s: 40% stocks underfished, 10% overfished.
Now, more stocks overfished + fewer stocks underfished.
Max sustainably fished stocks increased slightly, but not in proportion = too much overfishing.
Mediterranean + Black Sea = least sustainably fished. Pacific = most sustainably fished.
Atlantic: Alarming that it’s so unsustainably fished, because surrounded by nations w/ knowledge.

Question 5

Fishing trade flows?

Answer 5

Europe imports 39%, keeps 61% for internal trade.

Oceania imports 88% (69% from Asia) + keeps 12% for internal trade.

Question 6

Fishing classifications?

Answer 6

Demersal vs pelagic.
Active vs passive.
Target species: roundfish - cod, flatfish - sole, whitefish - hake.
Depth: Inshore (200m deep, 6 nautical miles out), pelagic (tuna + mackerel), + deep-water (orange roughy).

Question 7

Trawling?

Answer 7

Demersal + pelagic fishing.
Variations: Side, stern, beam, otter, mid-water.
Bottom trawl: Prawns, flat fish, round fish.
Catch high-value fish (eg: monkfish, rays, flatfish).

Question 8

Impacts of trawling?

Answer 8

Destroy seabed (levels). 
Low selectivity = high bycatch. 
Energy-demanding (esp bottom trawling).

Question 9

Netting?

Answer 9

Floats on top, lead rope on bottom. Can adjust height.
Selectivity: Opening size + strength.
Variations: Set (static), encircling, seine, purse seining (sardines, herring), + trammel-gill.
Fish aggregation devices (but issues w/ bycatch).
Large spring tides collapse nets. Neap tides = max time w/ net extended.

Question 10

Trolling?

Answer 10

Outrigger arms w/ baited lines.
Selective = low bycatch.
Used for mackerel + tuna.

Question 11

Longlining?

Answer 11

Many km long, set w/ baited hooks, soaked for hours.

Monofilament mainline attached to drum/reel.

Question 12

Potting/creels?

Answer 12

Crabs/lobsters.
Selective (pot neck width, mesh width, escape doors, min body size).
V-notch young/female crabs = can’t be sold until moulted.
Baited pots soak for 2-3 days (avoid cannibalism).

Question 13

Stock assessments?

Answer 13

Estimate current + future fish stocks.
- Inform management plans.
- Fishing pressure scenarios.
- Inform annual quotas.
- Long-term fleet management prevents fleet decommissions (expensive + job losses).
Issues: Can’t count all fish, fish move, + recruitment variability.

Question 14

Max sustainable yield?

Answer 14

Catch made in a yr w/o endangering future capacity.

EU goal = MSY, but most stocks still overfished.

Question 15

Fishery management values?

Answer 15

Fishing mortality (F): Proportion of fish stock taken each yr by fishing.
Spawning stock biomass (SSB): Minimum adult pop needed for sustainable pop. MSY achieved when fishing mortality doesn’t exceed SSB.
Recruitment: No. of young fish produced that survive to adulthood.
Fish landings: Fish tonnage landed in markets.

Question 16

EU fish stocks?

Answer 16

58% commercial stocks not in Good Environmental Status.
Only 12% in GES for both fishing mortality + reproductive capacity.
Regional differences (Mediterranean + Black Sea poorly assessed).
Remains largely unsustainable, but improving in NE Atlantic + Baltic.

Question 17

Estimating fish abundance?

Answer 17

Fish landed at port.
Fishing activities at sea.
Landing data; Total catch, body length, age, + breeding health.
Research vessel surveys.
EU member states coordinated by International Council for Exploration of Seas.
England + Wales = Cefas. Scotland = Marine Scotland.

Question 18

Calculating fish age?

Answer 18

Otoliths.
Lack of young fish = poor spawning.
Lack of older fish = overfishing.

Question 19

Data from fishermen?

Answer 19

Discards at sea.
Catch per unit effort.
Perception data.
Tagging.

Question 20

Research vessel surveys?

Answer 20

Cross-check + validate fish landings.
Hydroacoustic biomass surveys (non-invasive) + plankton surveys.
Fish tag + release (fish movement, preferred habitat, lifespan, catchability).
Tag manufacturers (eg: Cefas, Vemco, Wildlife Computers).

Question 21

Fish egg + larvae surveys?

Answer 21

Relationship between no. of eggs + no. of adults. 
CPR Survey (1936, Alistair Hardy) = fish stock estimation.

Question 22

Acoustic surveys?

Answer 22

Used for pelagic fish stocks (eg: herring, sardines).

Eg: Towed Fisheries Acoustic Systems.

Question 23

Worm et al (2006).

Answer 23

Declining diversity = Resource collapse, + decreased recovery potential, productivity, stability, + water quality.
Biodiversity loss impaired critical ecosystem services:
- 33% viable fishery decline.
- 69% nursery habitat decline.
- 63% filtering/detoxification service decline.
Rate of fishery collapse increasing - 29% currently-fished species considered collapsed in 2003.
Global collapse of currently-fished species predicted by mid-21st century.

Question 24

Sumaila et al (2012).

Answer 24

Rebuilding fisheries = increase profits $600 billion to $1400 billion in 50yrs.
Rebuilding would cost $203 billion.
Benefits would exceed costs 12yrs after rebuilding.
Negative impacts of fish stock collapse seen in northern cod collapse off Newfoundland.

Question 25

Worm et al (2009).

Answer 25

63% assessed fish stocks need rebuilding.
Rebuilding fisheries in poorer regions more difficult.
Progress hindered by unwillingness/inability to bear short term costs.
Rebuilding needs to begin before overexploitation becomes drastic, but only New Zealand + Alaska taking action.
Unreported + illegal fishing hinders progress (2000-03: average 18% total catch illegal).
Under 1% ocean area currently MPA.
MSY should be upper limit, not management target.