An introduction to fisheries

Question 1

Protein

Answer 1

150g fish = 50-60% adult’s daily protein requirement

globally, aquatic foods provide about 17% of animal protein

fish protein is vital nutritional component in some densely pop countries, where total protein intake levels = low; can contribute 50% of animal protein in some countries in Asia + Africa

Question 2

where is fish esp important?

Answer 2

developing countries

Question 3

Target fish

Answer 3

demersal fish (flatfish, gadoids…)

pelagic fish:
- small (herring, mackerel, anchoveta)
- large (tuna, swordfish)

Question 4

Fishmeal

Answer 4

significant, but declining, proportion of world fisheries production = processed into fishmeal, mainly for high-protein feed, and fish oil (aquaculture feed additive but also as a health product in humans)

produced from whole fish, fish remains or fish by-products

Question 5

3 types of fisheries

Answer 5

artisanal
recreational
commercial/industrial

Question 5

Fisheries are associated with productivity

Answer 5

largest fisheries occur over the continental shelf (<200 m depth; nutrient turnover in winter) or areas of upwelling of deep water

2 things needed for good primary production in ocean: sunlight + nutrients

largest fisheries = in shallow water

yield for open ocean = relatively low

Question 6

Capture data

Answer 6

fishery landings used to estimates of stock or pop size

inaccurate reports of landings will give imprecise stock estimates + management quotas, which can lead to overfishing

Question 7

UK fisheries

Answer 7

most valuable fisheries - shellfish (Nephrops, scallops, crabs, lobster)
demersal fish (haddock, cod, monkfish, lake)
pelagic fish (although, by spp, mackerel is the most valuable fish)

Question 8

Exclusive Economic Zones (EEZ)

Answer 8

Sea zone prescribed by the United Nations Convention on the Law of the Sea over which a state has special rights regarding the exploration + use of marine resources

200 nautical miles from coast

fisheries management = based on these zones

But how do the fish know to stay in the zones?
Transboundary stocks + Straddling stocks

Question 9

Transboundary stocks

Answer 9

stocks that range in the EEZs of at least 2 countries

Question 10

Straddling stocks

Answer 10

within an EEZ as well as the high seas

Question 11

What about highly migratory fish?

Answer 11

tuna + tuna-like spp, billfishes, oceanic sharks

present management challenges as migrate through different countries’ EEZs

Question 12

Maximum yield?

Answer 12

all fish
BUT need make it sustainable = Maximum sustainable yield

Question 13

Maximum sustainable yield

Answer 13

largest yield that can be harvested from a stock indefinitely
based on carrying capacity + rate of recruitment to population

Question 14

Deep sea fisheries

Answer 14

as shallow water fisheries become fully (or over) exploited, fishing fleets have ranged farther offshore into deeper waters

deep sea (continental slope) spp = long-lived + slow growing, reproducing at much greater ages

deep water fisheries = v. low l-t sustainability - e.g. the sustainable biomass of orange roughy been estimated as 1.5 - 2% of pre-exploitation biomass

deep water fisheries = essentially non-renewable resources

Question 15

Capacity for recovery?

Answer 15

substantial concern implementation of the moratorium did not produce the anticipated recovery

is the collapsed state a new equilibrium?

evidence that this altered ecosystem = transient + recovering to state of domination by benthic predatory fish

driven by enhanced recruitment + post-recruitment survival in these fish