Transcript Lecture_09_Fisheries_Oce

Fisheries Oceanography
Lecture 9: 6/12/2014
Some terms...
• Oceanography: physical, chemical, geological, biological, …fisheries
• Fishery: a particular stock of fish (single or multi-species) and the fishing
activities associated with their harvest (fisherman, gear, vessels, facilities)
• Fisheries Management: “To ensure the sustainable production over time from
fish stocks, …” (Hilborn and Walters 1992).
• Fisheries Science: study of fisheries, including fisheries biology, marine
ecology, social science, modeling, stock assessment, etc.
• Fisheries Oceanography: ?
– Understanding the factors affecting the spatial and temporal dynamics of marine fish
populations
– Some key variables? Temperature, Dissolved oxygen
Historically...
• 1497: "the sea there is full of fish that can be
taken not only with nets but with fishingbaskets"
• 1600: “so thick by the shore that we hardly have
been able to row a boat through them”
Shifts in Environmental Ethos
• Preservation vs. Conservation
1. Prior to 1960s—Boundless Sea
2. 1970s to 1990s—Environmental Capacity
3. 1990s to 2000s—Precautionary Principle
4. 2000s to present—Ecosystem Based
Management
Law of the Sea Treaty (1982 UN)
• Arose from the rapidly developing
marine drilling technology
• Territorial: Out to 12 nm
• Contiguous Zone: 12-24 nm
• Exclusive Economic Zone (EEZ):
State has sole exploitation rights over all natural resources
Significant Federal Conservation Legislation
• Endangered Species Act (1973)
• Magnuson Stevens Fishery Conservation Act (1976)
• Clean Water Act (1972)
• Oil Pollution (1990)
• Sustainable Fisheries Act (1996)
• American Recovery/Reinvestment Act (2009)
Magnuson Stevens Act (1976)
•
Established comprehensive federal management
1. Established EEZ to 200 nm (1983)
2. Created federal fishery management councils
3. Established loan programs to increase US fishing
•
Main goals:
1. Prevent overfishing while achieving optimum yield from
each fishery for US fishing industry
1. Conservation and management based on the best
scientific info available
Sustainable Fisheries Act (1996)
• First attempt to institute a precautionary
approach to management
1. Fishery management plans (FMPs) must specify
stock status determination criteria
2. Rebuilding plans required for overfished stocks
3. Bycatch limits
Management
EEZ: United States
www.whitehouse.gov
Linking Oceanographic Data  Fish
Case Study: The Bering Sea
• Alaska - 40% of fisheries yield in US
– Mainly Walleye Pollock (Pictured), cod, salmon
• Landings (last decade)
– Walleye Pollock 0.48-1.40 x 106 tons (Ianelli et al.
2011) SE Bering
– Cod 0.12-0.18 x 106 tons (Thompson and Lauth,
2011) eastern Bering Sea
• $1.7 billion economic value
• What controls the Pollock?
The Oscillating Control Hypothesis (OCH)
(Hunt et al. 2002, 2011)
• Relates the timing of ice, stratification,
phytoplankton to the abundance of age0 pollock’s
food source … large crustacean zooplankton
• Ice is dynamic (Stabeno et al. 2012, Ave days of ice
cover in March and April … period important for
phytoplankton bloom and zooplankton)
Oceanography of the OCH
Fisheries of the OCH
Combined
OCH
Model
(Fig by Krause &
Lomas, 2013)
A Revised
OCH
Model
(Fig by Krause &
Lomas, 2013)
Includes:
- Microzoo
- Diatom quality
vs. quantity
- More complex
foodweb
Acoustic fingerprints of fish
(Benoit-Bird et al. 2003)
Oceanographic/Ecological Variables
explain distribution of pollack
Benoit-Bird et al. 2013
Oceanographic/Ecological Variables
explain distribution of pollack
Benoit-Bird et al. 2013
Fisheries 101
All terms vary in response to changing
oceanographic and ecological variables
Natural Mortality, M
Recruitment, R
Growth, G
Fishable stock
P
(for population)
Fishery Mortality, F
Also called the Yield
• Recruitment: fish are ‘recruited’ to the stock when they are
large enough to be harvested by the fishery (nets, crab pots,
etc). Recruitment is highly variable, and depends on the number
of eggs produced and survival of the young to recruitment size.
Recruitment rate, R
Maximum recruitment rate
At intermediate stock size
High stock: the large
number of old big
fish compete with
young fish for food,
or even eat them,
resulting in an upper
limit of stock size
Low stock:
few adults,
few eggs
Stock size, P
• Growth: amount of biomass added per unit time varies with the
age of the fish, typically with maximum growth rates at
intermediate ages
Size of fish
Age group with
maximum growth rate
Age at first recruitment
Age of fish
MSY: Maximum Sustained yield
• The largest yield that
can be taken from a
stock
• Maintain pop. Size
for max growth and
optimized mortality
• Allow pop to be
productive
indefinitely
• Natural Mortality, M
This is very difficult to determine
It is often approached by mark and recapture: tagging and
releasing a certain number of individuals in the fish stock, and
then keeping track of the proportion of tagged individuals are
recaptured (by the fishery or by the taggers)
Problems:
• tagged individuals may be ‘catch-prone’, not representative of
the population;
• statistics are lousy since only a small fraction of tagged
individuals are likely to be recaptured
• The process of tagging can cause mortality in the tagged and
released fish
3 Modes of Fishing
1. Recreational:
– No sell
www. knowledge.allianz.com
2. Commercial:
– Catch and sell
www. nmfs.noaa.gov
3. Artisanal:
– Low tech
– Developing countries
– Small scale
The units involved:
• 1 metric ton = 1000 kg = 2200 lbs
= 1 large fish box
• 1 million metric tons = 109 kg
= average football stadium full of fish
• Approx. annual world catch
= 90 million metric tons
= 90 football stadiums
Ecosystem Based Management
1.
Diverse ecosystem service provision
2.
Importance of natural boundaries
3.
Integrated management
4.
Accounting for cumulative impacts and tradeoffs among services
5.
Making decisions under uncertainty
Goal: Sustain long-term capacity of systems to deliver
ecosystem services.
– Shortfall of management: All assessments are based on
individual stock instead of incorporation into system
Ecosystem Services
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Gas regulation
Water regulation/supply
Soil formation
Nutrient supply
Waste treatment
Refugia
Biological control
Genetic resources
Recreation
Cultural
The Case of Marine Mammals and Whaling
• History of Whaling: 8,000 yrs
BP
• Early modern whaling 16th C.
– Oil and meat
• 50k+ whales killed by 1930s
• Marine mammal populations
• Moratorium on blue whale in
1966: all great whales 1986
www.school.discoveryeducation.com
www.christchurchcitylibraries.com
Aquaculture: What is cultured?
1. Ornamentals and Aquaria
www. windmill.co.uk
www. do-while.com
2. Research
3. Stock Enhancement
4. Food
www. fau.edu
www. en.wikipedia.org
Aquaculture: The Blue Revolution
• The rapid increase in aquaculture
production in the past 25 years
and the technology that made it
possible
• CHINA – BY FAR the global leader
• The 2 great promises of
aquaculture:
– To supply protein to a global
human population that is in
desperate need of additional
sources of protein
– Aquaculture is touted by some as
a panacea for overfished natural
populations because it
theoretically would
as reported by http://faostat.fao.org/site/629/default.aspx
• Make up for shortfalls in natural
production
• Recover natural stocks by
alleviating fishing pressure
Main aquaculture countries in 2010
http://en.wikipedia.org/wiki/Aquaculture#mediaviewer/File:Global_aquaculture_production_by_country_2010.png
Aquaculture: Negative Issues
• Environmental effects great in
some forms of aquaculture
– Destruction of natural habitats
– Eutrophication and
sedimentation
– Excessive usage of resources
– Negative effects on native fishes
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Disease transfer
Parasite transfer—sea lice
Invasive species
Genetic impacts
Antibiotics
Predator conflicts
www.seagrant.uaf.edu
Sea Lice
www.earthaction.org
Aquaculture: The Future
www. foodfreedom.wordpress.com
www. fis.com
The Argument of Fishing down the web vs.
Fishing through the web
• Fishing down the
web: start
with the top predators then
move down the smaller and
smaller species
Pauly (1998)
What do you think? Which is worse?
• Fishing through the web:
start with meso-predators
then started on the extreme
ends with sharks.
Fishing down marine food webs:
Presently the catch of ‘small
pelagics’ (10-30 cm in length)
is about 1/3 of the total global
marine fish catch. Small
pelagics are vitally important
as food for larger fish, such as
cod. Depleting prey fish stocks
keeps larger fish stocks from
recovering, and disrupts
marine ecosystems.
…a strong lobby exists which …challenges the obvious to
maintain the unacceptable. (Daniel Pauly 2003)
Atlantic cod: a text-book example of over-harvesting a fish stock
Cod abundance has declined sharply since the late 80s in most areas
of its distributional range. For some cod management units,
spawning stock biomasses are sufficiently low that fisheries have
been closed since 1993.
1900
1975
1950
1999
As traditional fish stocks have declined, alternate fish populations are
being exploited, including deep water species (which grow and
reproduce slowly so are highly vulnerable to overfishing).
Status of World Fisheries
• Capture fisheries are unlikely to increase production in the future
• Likely increasing importance of aquaculture
Tilapia - aquaculture success story
A solution? Personal choices
AVAILABLE FOR DIFFERENT SECTIONS OF THE COUNTRY:
http://www.mbayaq.org/cr/cr_seafoodwatch/download.asp
A solution? Local choices
A solution? Government regulation
Locations of current US marine sanctuaries
Marine Reserves/Sanctuaries
• Marine reserves : ocean
areas fully protected from
activities that remove
animals and plants or alter
habitats, except as needed
for scientific monitoring
• Protected Areas: multiple
types
A solution? International efforts
From Greenpeace, Roadmap to Recovery: A Global Network of Marine Reserves