Fisheries 1 - General + Cod Case Study Flashcards
Overview
- Fishing importance and situation/ action?
- Risk assessment
3 Main threats + challenges - Cod case study
-Background
-history
-Patterns
-Political Response
- Lessons learnt
- consequences - Synergistic pressures from CC
1 . Fishing importance / situation a) Situation now? past? Mass extinction? (2 pertubations)
global catches have levelled off since 1990s
Pelagic fish/ groundfish / Peruvian ancoveta
key stressor is overfishing - more fishing yet less fish
most planet yellow/red - high to medium impact everywhere apart from polar regions
late devonian fish - shows in past severe pertubations led to catastrophic declines BUT
difference is RATE
ie living fossil “coelacanth” persisted hundreds of milions of years
YES rate several orders of mangnitude higher than bacground
Temporal - pulse perubations (ie oild spills) and press (climate change
Spatial - “point source” effects ie industtrial outfalls and diffuse effects ie Eutrophication
- note large scale effects v difficult to control ie boundary porblems
- Intro
b) importance? (3)
But what is happening?
1) integral part of aquatic ecosystems (diversity ie for reef maintenance - coral/algae persists?)
2)importanyt source of protein for humans (provisioning service)
3)major source of income via ecotourism
PUERTA rica
global stocks are collapsing (not just rare)
Nature 2006 –> decline in deep sea fishes and multiple spp in as little as 20 yrs (alarming wrt gen time)
2004 Nature study findings details?
global declines) (dob
decline of deep sea fish in as little as over 20 yyrs
decline in downward trend seen in 5 deep sea spp in canadian waters (1975-1995)
- Intro
c) what can be done?
Trenkel et al
2013
paper testing CPUE derived spatial occupancy as indicator of stock abundance (logbook data)
result?
policy levers through which market operates
can see where policy play comes in and example of policy in effect
c) what can be done? wider
tie in with Modelling
EvE
Ecosim
Ecopath
Ecospace
FOr policy and modellingh
- Fish risk assessment
a) what traits do vulnerable spp posses (1 or more) (6)
1) Large
2) Rare
3) high up in food web
4) limited / range / dispersal ability
5) low fecundity
6) slow growth to maturity
- Fish risk assessment
b) why is important to look at life history?
3
example of K selected and r selected
1) k selected spp ie sharks less resilient to r selected spp
2) covariance in traits ( have synergistic effects on vulnerability)
3)this means large spp higher in food web ALSO tend to be rare/ slow growing / slow to reporduce and so populations are
LESS RESILIENT
shark/rays vs teleosts (large # offsrping and rapid growth)
- Main threats /challenges
a)major 4 threats
synergy?
cc
pollutants (toxin/acidifcation/pollutants)
habitat destruction
biotic (fishing pressure spp intro/invasions)
note this act synergistically
- mainb threats / cjhallenged
b) detail for each 4 threats
CC - shhift in range of coral growing zones (acificication + bleaching)
Biotic - habitat destruction by C taxifola in meditteranean - reduced structural diversity ans causes homogenous habitat (less # niches)
habitat destruction- Trawling and fishing - loss of seab bed after trawling
Note overfishing is just as bad as terrestrial habitat destruction in fact the trawled area far exceeds that of land lost to deforestation
example of biotic threat to fishes
C taxifola
reduced structural diversity - less niches
- Threats and challenges
c) challenged
rapid depletion of predatory fish communities
collapses so need to aid RECOVERY (lots of news papers) but need Data- models and back again
- Cod Case Study
overview (5)
- Background
- History
- Patterns
- Political Response
- Lessons learnt
3.threats and challenges overview
1) major threats (4)
2) detail
3) challenges
4. cod case study Backgorund -myers -"cod" -trophic position?
Myers 1995
Atlantic cod Off Newfoundland Canada - loss of key ecosystem service
“Cod” Mark Kurlanksy -0 biogeography of fish that changes the world
Atlantic cod was keystone spp thus is
1) highly connected to many spp
2) accounts for large proportion of fish bioass + hence fish productivity
- Code Case study
b) History
Early
18th cent
19th cent
20th cent
Vikings discovered america before columbus - ate dried cod
Trade allowed N England (N america ) to become financially and politically independed of british empire –> now USA
George Banks and Grand Banks offf NE seaboard most productive fisheries in world
NEVER ENDING SUPPLY
leewenhoek - “9.4 million eggs in codfish”
Off Newfoundland used to account for 70-80% of biomass of total fish stock - now 99.9% of cod stock has since been lost
collapse of fishery in late 20th century
Cod became increasingly 1)rarer 2)smaller
who counted 9,.4 million eggs in a cod fish
Leewenhoek
NY 1858
cyclopedia of commerce
- difficult to exterminate
- COd
how bad?
- suspected?
- baseline shifts?
cod patterns
how bad?
suspected?
v bad
Labrador and NE newfoundland 98.9% collaspe
Not just america
Yes - was predicted back in 1990s
TM cook et al 1997
4.cod
patterns
shifting baselines?
yields collapsed as fishing mortality rose in N sea
patterns seen in many fish spp (shift to smaller)
shifting baseline- basically political problem 5 yr in office
4.Cod Case study
Political response?
approach looking at short time scales MASSIVE FUCK UP
ie
2004 Ben Bradshaw
Labour Fisheries minister
BBC - said social pain meantnot year to close areas
2007 invetible crash front pafe news
what does the political response of Ben Bradsshaw show?
science vs political pressure
political will must be aligned
inevtibale crisis ! we DID NOT LEARN FROM NEFOUNDLAND
4. Cod Case study Lessons learnt (history) 15th - 19th end of 18th century Mechanisation
passive fishing - iniefficient but actualy stooped overfishing
by this time Newfoujndland and New england ecporting 22k tons cod per year
Mechanismation - steamship wth otter trawl could catch 6X more than fish sail ship
regulation was imposed in 1920s in Canada - fleet expansion banned but this was because too many fish (skewed marked economy) - to regulate market
4. Cod case study Lessons learnt lessons from history continued 1928 1950s 1977
End of cod ?
diesal powered trawlers also Cpatain birdseye - freezing
industrialisation of cod fishery 1)dragging nets 2)high powered ships 3)onboard freezing FACTOR ships - only limit was net size
1977 there was an intervention and CANAda created 200 mile exclusion zone around Nova Scotia coast (cod and groundish were disappearing)
- some people didnt listen as fishing often patchy
1992 - Northern cod fisheries in canada closed
1994 all cod fisheries closed
End of cod consequences
when?
detail on closure
3000 fisherman lost their jobs
1992
commerically x=extinct (herring and cod) large are losers
no longer economicaly viable
What followed closure?
conflict and scapegoating followed
Conflict examples (4)
- British icelandinc cold wars in 1970s
- British - spanish over CFP and collapse of british stock
- Canadian - spanish (canadians accuse spanish of overfishing Grand banks 80s-90s)
- Scots - russians –> scots accuse russians o stealing “their “ cod
Examples of scapegoating?
Sealhunting
1995 canada and norway lifted ban on seal hunting
culling of harp seals
BUT there are 100s of links in the food web
less valuable spp may be benefitting from its demise and hindering its recovery
consequences (oerview) (5)
closure conflict scapegoating food web shifts recovery?
food web shifts?
losers - herring and cof
winner - capelin and whiting
artcic cod (only 8 inches) rays /skates / dogfish are taking up slack sshrimp and crabs have also expanded southwards
Will the cod stocks recover?
models
still no models to reliably say
how much biomass for stocks to regenerate
or how long it wil take
will the cod stocks recover?
Barents sea
Barenst sea off norway
yes some recovery but were suspended BEFORE they collapsed
N sea is encouraging with rebounding fisheries
5.Synergistic pressures from CC
freezing stock example
April 2003
> 7000 tonnes of Nefoundland cod stock frozen
unusually cold currents
- Synergistic pressures from CC
Paper by>
Greene and Pershing
2007
Science
Greene and Pershing Paper
resilience is being tested
vlimate- forcing from bottom up
predator explitation - from top down
Take home point
UN FAO highlighted the global fishing as long ago as 1946
we must not start fishing too early as this threatends long term viability of the fishery
