Fisheries Oceanography

Lecture 9: 6/12/2014

• 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

Some terms...

• 1497: "the sea there is full of fish that can be taken not only with nets but with fishing-baskets"

• 1600: “so thick by the shore that we hardly have been able to row a boat through them”

Historically...

• Preservation vs. Conservation1. Prior to 1960s—Boundless Sea2. 1970s to 1990s—Environmental Capacity3. 1990s to 2000s—Precautionary Principle4. 2000s to present—Ecosystem Based

Management

Shifts in Environmental Ethos

• 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

Law of the Sea Treaty (1982 UN)

• 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)

Significant Federal Conservation Legislation

• Established comprehensive federal management1. Established EEZ to 200 nm (1983)2. Created federal fishery management councils3. Established loan programs to increase US fishing

• Main goals:1. Prevent overfishing while achieving optimum yield from

each fishery for US fishing industry

2. Conservation and management based on the best scientific info available

Magnuson Stevens Act (1976)

• 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

Sustainable Fisheries Act (1996)

Management

EEZ: United States

www.whitehouse.gov

Linking Oceanographic Data FishCase 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

CombinedOCHModel

(Fig by Krause & Lomas, 2013)

Any issues

in food web

model?

A RevisedOCHModel

(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

Fishable stockP

(for population)

Recruitment, R

Growth, G

Natural Mortality, M

Fishery Mortality, F

Fisheries 101All terms vary in response to changing oceanographic and ecological variables

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.

Rec

ruitm

ent r

ate,

R

Stock size, P

Low stock: few adults, few eggs

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

Maximum recruitment rateAt intermediate stock size

• 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 f

ish

Age of fish

Age group with maximum growth rate

Age at first recruitment

• 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

MSY: Maximum Sustained yield

• Natural Mortality, MThis 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

1. Recreational: – No sell

2. Commercial: – Catch and sell

3. Artisanal: – Low tech– Developing countries– Small scale

3 Modes of Fishing

www. knowledge.allianz.com

www. nmfs.noaa.gov

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

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 Based Management

• Gas regulation• Water regulation/supply• Soil formation• Nutrient supply• Waste treatment• Refugia• Biological control• Genetic resources• Recreation• Cultural

Ecosystem Services

• 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

The Case of Marine Mammals and Whaling

www.christchurchcitylibraries.com

www.school.discoveryeducation.com

1. Ornamentals and Aquaria

2. Research

3. Stock Enhancement

4. Food

Aquaculture: What is cultured?

www. do-while.comwww. windmill.co.uk

www. fau.edu

www. en.wikipedia.org

• 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• Make up for shortfalls in natural

production• Recover natural stocks by alleviating

fishing pressure

Aquaculture: The Blue Revolution

as reported by http://faostat.fao.org/site/629/default.aspx

Main aquaculture countries in 2010http://en.wikipedia.org/wiki/Aquaculture#mediaviewer/File:Global_aquaculture_production_by_country_2010.png

• Environmental effects great in some forms of aquaculture

– Destruction of natural habitats– Eutrophication and sedimentation– Excessive usage of resources– Negative effects on native fishes

• Disease transfer• Parasite transfer—sea lice• Invasive species• Genetic impacts• Antibiotics• Predator conflicts

Aquaculture: Negative Issues

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

Pauly (1998)

• Fishing down the web: start with the top predators then move down the smaller and smaller species

• Fishing through the web: start with meso-predators then started on the extreme ends with sharks.

What do you think? Which is worse?

…a strong lobby exists which …challenges the obvious to maintain the unacceptable. (Daniel Pauly 2003)

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.

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.

Atlantic cod: a text-book example of over-harvesting a fish stock

1900

19991975

1950

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