Transcript Lecture 15 -Fisheries 11906KB Apr 06 2009 05:49:05 AM

•Biology 450: Fish Week
Lecture 15: Fisheries
Scott Heppell
Department of Fisheries and Wildlife
Oregon State University
042 Nash Hall 737-1086, [email protected]
Fisheries –Direct and indirect effects
•Fishermen go fishing because
we buy the fish they catch.
•When fishing is good and the
fishers make good money,
more fishers join the fishery.
•They don’t stop joining until
they stop making good money.
What is a sustainable fishery?
“one in which fish populations are allowed to replace
themselves”–CA Marine Life Management Act
“one that prevents overfishing while achieving
optimal yield”–Sustainable Fisheries Act
“one that is environmentally non-degrading and
ensures the attainment and continued satisfaction
of human needs for present and future
generations”–FAO Sustainable Fisheries
Development
•Trawling
•Trolling
•Other Methods
•Traps &
Pots
•Long-Line
•Oregon’s Commercial
Fisheries
1992-2001
•Average Pounds
•Av. Landed Value
•245.3 million / yr
•$69.6 million / yr
• Other
•Salmon
•Albacore
•Shellfish
•Groundfish
•Groundfish
•Shellfish
•Oregon’s Commercial
Fisheries
Groundfish
Pounds
rockfish deepwater
misc gf & whiting
flatfish
Millions of Pounds
200
150
•Shoreside Fishery
•for Whiting
100
50
0
'80
'82
'84
'86
'88
'90
'92
'94
'96
'98
'00
•Commercial Fishery Issues
• Over-capacity in the fishing fleets.
• Sport versus commercial fishing allocations.
• Individual fishing quotas.
• Can we do the stock assessments?
• Bycatch and discards.
• Mixed stocks - protecting the weak stocks.
• Wild versus hatchery salmon.
• Habitat damage by fishing gear.
• Marine reserves - how big and where?
• Ecosystem management.
•Pacific Fishery Management Council
•The Pacific Fishery Management Council is one of eight regional
fishery management councils established by the Magnuson Fishery
Conservation and Management Act of 1976 for the purpose of
managing fisheries 3-200 miles offshore of the United States of
America coastline. The Pacific Council is responsible for fisheries off
the coasts of California, Oregon, and Washington.
•www.pcouncil.org
Magnuson-Stevens Fishery Conservation and
Management Act (1976, amended 1996)
•
Any fishery management plan which is prepared by any
Council, or by the Secretary, with respect to any fishery, shall:
1.
2.
3.
4.
5.
contain conservation and management measures
contain a description of the fishery
assess and specify the present and future condition of the fishery
specify the pertinent data needed for management and conservation
consider and provide for temporary adjustments regarding access to the
fishery
6. describe and identify essential fish habitat
7. assess and specify the nature and extent of scientific data needed
8. include a fishery impact statement
9. specify objective and measurable criteria for identifying when the
fishery is overfished
10. establish a standardized reporting methodology for bycatch and to
minimize bycatch
Direct effects of fishing in marine
ecosystems
Direct effects of fishing
• Reduced biomass
• Changes in age structure
• Increased per capita productivity
• Unreported catch
Reference points used in stock
assessment (PFMC)
• B0 is the estimated biomass of the stock before fishing
(assumed to be at carrying capacity)
• “overfished” = biomass estimated to be at 25% of unfished
stock (B25% )
• “Recovery Goal” is B40%
• Target fishing mortality rate (F50% ) is one that should result in
a fished stock biomass of 50% of B0
• “Allowable Biological Catch” (ABC) =
F50% * exploitable biomass
• Optimum Yield (OY) <= ABC
Two kinds of overfishing
• Growth overfishing
– Harvesting fish before they have a chance to reach their
full growth potential
• Yield per recruit analysis – fishing levels to the right of the
“hump”
• Reduces average mass of individuals in the catch
• Recruitment overfishing
– Harvesting fish at a rate that reduces, rather than
augments, the average reproductive potential of
individuals
• This is what leads to population decline!
•Decline of West Coast Rockfishes
•rebuilding target year
•
•2038
•2030
•2074
•2023
•2090
•yelloweye
•2027
•2058
•NOAA Fisheries
Unreported catches for some species may be 90%!!!
Indirect effects of fishing in
marine ecosystems
Indirect effects of fishing
•
•
•
•
Food web impacts of directed harvest
Bycatch and Discards
Habitat impacts
Pollution
Fishery Bycatch
Catching More than You Bargained
For
Hal Weeks, OR Dept of
Fish and Wildlife
What is Bycatch?
• Common sense
definition - the
unintended capture of
unwanted organisms
• - wrong species
• - wrong size
• - wrong sex
• - tastes bad, can’t
sell it, regulations, etc
• Legal definition - The term
bycatch means fish which are
harvested in a fishery, but
which are not sold or kept for
personal use, and includes
economic discards and
regulatory discards. Such term
does not include fish released
alive under a recreational catch
and release fishery management
program.
• MSFCMA Sec 3, Para 2.
Why Do We Care?
• M-SFCMA National Standard 9: Conservation and management
measures shall, to the extent practicable, (A) minimize bycatch and (B)
to the extent bycatch cannot be avoided, minimize the mortality of
such bycatch
• M-SFCMA Section 303 (required provisions of fishery management
plans)
• (11) establish a standardized reporting methodology to assess the
amount and type of bycatch occurring in the fishery, and include
conservation and management measures that, to the extent practicable
and in the following priority • (A) minimize bycatch; and
• (B) minimize the mortality of bycatch which cannot be avoided
Potential problems from bycatch
(Why do we care - REALLY?)
• conservation - levels of mortality on
incidentally caught species
• allocation - deprive other groups of harvest
opportunities
• philosophical - how we interact with
natural resources
No Fishing Gear is Perfectly
Selective
Mixed Catches are Inevitable
Issues to Consider
• How do we define the
problem?
• How do we measure the
problem?
• Why bycatch and discard
occur?
• What tradeoffs are
acceptable?
• Is it context specific?
Charistmatic dolphins vs.
Insignificant
invertebrates?
• Role of management
actions in both creating
and solving the problem?
Bycatch is a multi-faced problem
• No bycatch only
when
INDIVIDUAL
prey items are
taken
• Harpoon fisheries
• Dipnet fisheries
Fishing Nets as Filter Feeding
• People and fishing
vessels are essentially
predators and require
substantial energy
• Nets are filtering
mechanisms to
capture many prey
• Target concentrations
of desired prey
• Not terribly selective
unless species schools
can be targeted (e.g.,
mid-water trawls)
Why Does Bycatch and Discard
Occur?
• Ecological associations - fishing gear is
non-selective to some degree
– Nets are filters
– Baited hooks and traps attract a mix of species
• Regulations - sometimes you’re not
allowed to keep what you catch
Pacific halibut bycatch in
groundfish fisheries
• Halibut are large flatfish;
ecologically they are part
of the groundfish
community
• Traditional hook and line
fishery; managed by
International Pacific
Halibut Commission
• Harvest by nets and traps
(pots) not permitted
• Bycatch is largely an
allocation issue
Halibut Bycatch Issues
• Bycatch in NPFMC
groundfish fisheries
– LL for sablefish, cod
– pot fisheries for cod, crab
– Groundfish trawl fisheries
• Constraining bycatch
mortality limits catch of
target species
Measures to Reduce Halibut
Bycatch Mortality
NPFMC Halibut Bycatch Caps in Fixed and Mobile Gear
Fisheries
- Close Groundfish Fisheries before Target Catch Attained
Trawl Fisheries - NPFMC Vessel Incentive Program
(largely ineffective)
More Effective Measures Include:
•
increased awareness and communication
– Publish bycatch numbers!
•
•
fishery structuring (areas, seasons)
more careful handling on deck
Fishery interactions with marine
mammals, birds, and sea turtles
• Competition
• Predation
(usually us on them)
• Benefits from discards
• Bycatch
• Indirect food web
effects?
Bycatch of turtles, birds and
mammals
•
•
•
•
Trawls
Gillnets
Long lines
Fixed gear
Problem is generally not that encounters are high on an individual basis, but that
there are so many boats, nets, and lines out there.
Example: in southeast U.S., most shrimpers say they only caught 1-2 sea turtles per
year, sometimes none at all. There were over 30,000 boats licensed.
Seabird Bycatch in AK Longline
Fisheries
• Seabirds attracted to
vessels and baits
• If baits are
accessible, seabirds
can become hooked
• Seabirds taken in AK
long-line fisheries
include Northern
fulmars, albatrosses,
gulls, and
shearwaters
Efforts to reduce seabird bycatch
•
•
•
•
•
Industry
Outreach
Regulatory
Observer Data
Set techniques – line
droppers
• Blue bait
• Tori poles and
streamer lines
Eastern Tropical Pacific Tuna Purse
Seine Fishery
• Purse seining
developed in
1950s
• Previous methods
were pole and
line, and long-line
• West Coast
albacore are NOT
caught with purse
seines
Purse Seine Operations
• Tuna schools near
the surface
• Circular net set
around tuna
school, then
“pursed” closed
Dolphin often Indicate Tuna in the
ETP
Why encircle dolphins?
• Indicators of larger,
more valuable tuna
• Tuna and other fishes
follow floating objects
(logs, debris, dixie
cups, etc)
• Larger tuna are able to
follow and keep up
with dolphins
• Why? Not known!
Dolphin Release
• Dolphins will not
jump out of the net
• Small mesh panels
reduce entanglement
• Backdown procedure
pulls net out from
under dolphins
• Small boats hold net
open and herd
dolphins to submerged
portion
Dolphin mortality a philosophical
and conservation problem
• Affection for marine
mammals in the U.S.
• Steep declines in some
dolphin stocks
Dolphin mortality reduction
• Regulations on
U.S. - flag fleet
• Marine
Mammal
Protection Act
Dolphin mortality reduction
• Gear modifications Medina panels
• Behavior changes backdown and release
procedures
• IATTC observer
program
• Limit seining to
daylight hours
• Political and market
pressures
• Mortality limits
• Captain-captain
education and
persuasion
Bycatch TradeOffs in Tuna Purse Seine Fisheries
Numb er of Discarded Ani mals Per
10 00 tons of yel lowfin tun a pro duced
Dolphins
LOGS
0.1
TUNA SCHOOLS
0.2
DOLPHIN
27 .4
What About Other Species?
Numb er of Discarded Ani mals Per
10 00 tons of yel lowfin tun a pro duced
Dolphins
Marlins
Sailfish
Bla cktip Sharks
Silky Sharks
Whitetip Sharks
Other Sharks & Ra ys
Mahi-m ahis
Wahoo
Triggerfishes
Ye llow tail
Rainbow Runner
Other Fishes
Sea Turtle s
Ye llow fin tuna (tons)
LOGS
0.1
TUNA SCHOOLS
0.2
DOLPHIN
27 .4
1.4
2.7
26 .2
4.0
2.8
22 .7
3.3
1.0
5.2
14 .5
0.0
20 0.9
0.4
9.3
No Free Lunch!
Numb er of Discarded Ani mals Per
10 00 tons of yel lowfin tun a pro duced
Dolphins
Marlins
Sailfish
Bla cktip Sharks
Silky Sharks
Whitetip Sharks
Other Sharks & Ra ys
Mahi-m ahis
Wahoo
Triggerfishes
Ye llow tail
Rainbow Runner
Other Fishes
Sea Turtle s
Ye llow fin tuna (tons)
LOGS
0.1
68 .5
2.2
94 3.9
33 0.5
19 8.4
32 1.7
30 ,144 .8
14 ,971 .0
37 ,761 .2
75 6.0
60 5.3
63 ,031 .5
4.2
16 1.0
TUNA SCHOOLS
0.2
6.2
10 .6
15 3.2
24 .6
7.2
11 6.9
61 7.1
46 6.0
78 9.4
16 9.9
2.0
1,839.9
1.1
16 .3
Sou rce: Pacifi c Fishi ng m agazin e ba sed on IATTC d ata (1993 - 19 95)
DOLPHIN
27 .4
1.4
2.7
26 .2
4.0
2.8
22 .7
3.3
1.0
5.2
14 .5
0.0
20 0.9
0.4
9.3
Sea Turtles
• Gulf of Mexico and
South Atlantic
shrimp fisheries
• Kemp’s ridley turtle
critically
endangered
• Mortality in shrimp
trawls due to
drowning
• Turtle mortality
reduced through
use of excluder
devices
• Significant
opposition from
fishermen due
to reduced catch
rates
How to estimate bycatch?
• Logbooks
• Observers
• Dead animals
• All require extrapolation...
Recent West Coast Actions to Reduce
Bycatch of Overfished Rockfishes
Bycatch Reduction Devices (BRDs) in Shrimp Trawls
-Small Footrope Rule in Groundfish Trawls
-“Pineapple trawl” – headrope starts way back from footrope
Where do we go from here?
Thinking “big picture” in fisheries
management
Ecosystem-based management of
marine resources
• NOT managing ecosystems
• Managing resource extraction with ecology in mind
– Interactions among organisms
– Responses to physical variance
– Responses to direct and indirect effects of fishing
• Managing human activities in a holistic framework
– Multiple uses, multiple stakeholders
Scientific Consensus Statement
on Marine Ecosystem-Based Management , COMPASS 2005
Some issues with EBM:
• Ecosystem definition and boundaries
• Multiple use = multiple agencies, nations
– Enforcement?
• Data quality
• Stochasticity
• Lack of assessment tools that integrate
physical and biological information
Key elements of EBM:
• Protection and restoration of marine ecosystems,
rather than single species
• Maintain native biodiversity and resiliency
• Consider cumulative impacts
• Facilitate connectivity
• Develop multiple indicators of ecosystem health
• Acknowledge uncertainty
• Coordinate policy
• Encourage participatory governance
Ocean Zoning
• Concept: designate areas for particular uses, including
networks of reserves or protected areas
• Examples in Alaska, tropics
• Areas may be permanent or rotating (time-area
closures)
• Example activities:
–
–
–
–
–
Trawling
Other fishing
Aquaculture
Tourism
Energy acquisition
Group 1
Group 2
Stewart-Smith, Kathryn E.
Rogers, Micah M.
Dinger, James T.
Moore, Christine M.
Farris, Michael R.
Taylor, Linda Louise F.
Murphy, Gayle D.
Alvord, Charlotte A.
Cannoy, Noah
Patton, B. Wren
Group 3
Group 4
Henderson, Jeremy S.
Miller, Skylar E.
Lycett, Kristen A.
Silbernagel, Justin J.
Eder, Esther H.
Lamb, Robert W.
Correa, Jansen
Preston, Daniel L.
West, Darcie E.
Baxter, Trista A.