FISHERIES PT.1 Flashcards

1
Q

5 reasons fish are taken from the ocean

A
  • Food – people get 20% protein from fishes – 27% of protein = from fish
  • Natural products – oil, swim bladders, medicinals
  • Curios / aquaria
  • Sport – catch + release
  • Fish meal
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2
Q

what is fish meal

A

nutrient rich feed ingredient made from fish – used in the diets of domestic animals + as a fertilizer

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3
Q

How much have we taken from the ocean

A
  • number of fishing vessels has doubled since the 1970s - but catch rates have only increased by 30% before declining
  • The ocean yields 100–120 mmt of seafood per year
  • We have reached / exceeded the sustainable limit of fisheries biomass extraction
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4
Q

5 places fisheries efforts concentrated

A

Nontropical shelves = most
Tropical shelves
Upwelling zones
Coastal and coral
Open oceans

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5
Q

5 countries that fish outside their EEZ’s

A

China
Spain
Taiwan
Japan
South korea

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6
Q

what percent of the oceans are fished

A

> 55%

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7
Q

8 ways the fish are collected

A
  • Purse sein nets – net connected to ship - pelagic fish – get some bycatch
  • Drift nets – let go and collected at a later point
  • Gill nets
  • Long lines
  • Trawls – benthic + demersal fish
  • Hook and line
  • Pots
  • Traps
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8
Q

what kind of fish are fished

A
  • 35,800 fish species contribute to fisheries
  • 58% = marine
  • 1% = diadromous
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9
Q

3 main taxonomic groups of fisheries

A
  1. Jawless – agnatha e.g. hagfish, lampreys
  2. Class chondrichtyes, elasmobranch – cartilagenous fishes e.g. sharks, skates, rays
  3. Bony fishes, perciformes – 725,000 – e.g. salmon, tuna, sturgeons (caviar)
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10
Q

characteristics of the most fished species

A
  • small-bodied - big ones have been already fished out
  • low in food chain
  • schooling species
  • 8 are pelagic
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11
Q

what are the Most fished species used as

A

fish meal

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12
Q

4 popular Non-fish fisheries

A
  • Whales – most are protected but some countries still fish
  • Sea otters
  • Stellar sea cow extinct – manatees and dugongs now protected
  • Sea turtles

Invertebrates
- Corals - jewelery
- Bivalves e.g. oysters, clams
- Crustaceans e.g. crab, shrimp
- Urchins

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13
Q

how much of the overall take does recreational fishing account for

A

4% – but a very big portion of the take for individual species

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14
Q

lethal and sublethal effects of recreational fishing (catch and release)

A
  • increased mortality
  • Sublethal effects: alter social behaviour, impaired reproduction, physiological stress, reduced activity, increased vulnerability to predation
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15
Q

why are Nociceptors

A

Sneddon et al
pain-like receptor organ in fish – 6x more sensitive to stimuli than ones in human skin

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16
Q

what percent of global fish are overexploited

17
Q

what is overfishing

A

fishing mortality above threshold

18
Q

what is overfished

A

biomass below threshold

19
Q

what is rebuilt

A

has stock rebuilding plan, in year x of x year plan

20
Q

where does the US fall in the world for global takes

21
Q

9 main Characteristics of species vulnerable to depletion

A

Slow pop turnover
Low reproductive potential
Low capacity for recovery
Restricted range – geo or with depth
Small pop sizes
High trophic positions
Reduced larval dispersal
Large body size
Long life span

22
Q

explain the slow pop turnover characteristic for species vulnerable to depletion

A

Long life span
Slow growth rates
Long natural mortality
*take long time to grow, mature and reproduce

23
Q

explain the Low reproductive potential characteristic for species vulnerable to depletion

A

Low fecundity
Single lifetime reproductive event
Long time between successful repro
Late sexual maturity
Gender change (male -> female)
Density dependent repro

24
Q

explain the Low capacity for recovery characteristic for species vulnerable to depletion

A

All number 1 and 2
Limited dispersal
Density dependent effects on settlement or recruitment

25
Q

explain the Restricted range characteristic for species vulnerable to depletion

A

Dependent on estuaries
Near shore occurance
Predictable spawning location

26
Q

common characteristics of a long life span species

A

Low natural adult mortality
Large body
Low annual recruitment to adult stocks
Late maturation
Breed in aggregations
Variable annual repro success

27
Q

Adaptations that were good for long life span species before humans

A
  • Large adult standing stock biomass -> Seemed limitless
  • Reduced predation risk
  • Reproductive success - Low fecundity risk – high fecundity does NOT protect
  • Repro success increases with age
  • Indeterminate growth -> Increase fecundity with size / age
28
Q

Responses of species to exploitation

A

Loss of egg production
Changes in offspring quality
Changes in adult behaviours
Poor recruitment years are exacerbated
Changes in gender ratios

29
Q

name Most vulnerable fish groups to exploitation

A

scorpeanids, serranids, elasmos, sturgeons

30
Q

what is CPUE

A

catch per unit effort (catch / effort)
- declines when increasing effort results in fewer fish caught -> indicating overexploitation

31
Q

Fishery activities that lead to decline

A
  • increases in technology
  • Overcapitalization + overcapacity – spend more on fishing than we catch
  • Declining ocean productivity - long term declines in fish
32
Q

Technological advancements enabling overfishing

A

Radar
Electronic nav
Satellites
Planes / helicopters
Improvments in equipment

33
Q

how do we spend more on fishing than we catch

A

Declining stocks / returns
Displaced effort - move to other locations once pops decline in one area
Great irony of fisheries
Global commercial fishing is not economically justifiable

34
Q

Fish taxonomy families

A

Family Acipenseridae – sturgeon (caviar)
Family Branchionichtyidae – spotted handfish
Family Sygnathidae - Long-Snouted Seahorse
Family Serranidae – groupers
Family Serranidae – sea bass - 30% of listed endangered species
Family Sciaenidae – croakers and drums
Family Scorpaenidae – lion + scorpion fish
Family Gadidae – Cod, Pollocks, Whitings
Family Scombridae – tuna
Family Scombridae – Mackerel
Family Engraulidae – anchovy
Family Trichiuridae – Cutlassfishes and HairTails
Family Osmeridae – Capelins
Family Clupeidae – Herring