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SMS-100

Class 27

Tuesday December 9, 2014

Fish and Fisheries… Some definitions and Clarifications:

1. Fisheries (plural of Fishery) catch fish; and sometimes they catch too many fish;

2. The word ‘Fishery’ refers to the business of catching fish: which can be ‘commercial’ or ‘recreational’;

3 ‘Fishery’ can also refer to the species or group of3. Fishery can also refer to the species, or group of species, being fished; e.g., the “tuna” fishery, or the “ground fish fishery”;

4. The key point here:Fisheries involve the extraction of living marine resources, and the replacement of those resources by natural oceanographic, ecological and biological processes.

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New Bedford, Massachusetts; August 3, 2011

How Commercial Fisheries Work:  1. Fisheries Production…stuff grows in the ocean; we take it out, and eat it…

= 1.5

Number ofTrophicSteps

How Commercial Fisheries Work: The Amount depends on the number of trophic linkages:

= 3

= 5

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• Low Nutrients Æ Lower Overall Pprod AND Smaller Cells Æ More Grazer Intermediates Æ Longer Food Chain Æ Low Fish Production;

This all means that:

• High Nutrients Æ Higher Overall Pprod & Larger Cells Æ Fewer Grazer Intermediates Æ Shorter Food Chain Æ High Fish Production;

All of this also means that:

The oceans can produce only so many tons of fish – a fi i i b i d i i “fi d” b

Short food chains (in nutrient-rich waters) can have greater fish production...and vice versa

finite quantity – because primary production is “fixed” by solar energy & nutrient availability, etc.

Therefore, based on what we know about oceanography in different regions of the world ocean, we can estimate the theoretical amount of fish production possible…

He showed:

9 Theoretical Max. Fish Production in world ocean ~240 MMT per year.

And he warned:

These ideas formed the basis of a classic study published in 1969 – by John Ryther:

9 Cannot catch all those fish…

9 We have to leave enough fish to produce the next generation or else the Fishery will Collapse.

9 And that: Maximum we can catch, he calculated, is ~100 MMT per year

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Statistics onWorld Fisheries Landings are kept by the United Nations:

(Food and Agriculture Organization FAO)Organization, FAO)

100100 MMT = Maximum predicted by Ryther in 1969

Tons 1969

Most recent data from FAO:World Marine Fisheries Landings, 1950-2012:

Maximum was ~ 86 MMT in mid 1990s

Year

Milli

ons

of M

etric

Freshwater Landings ~ 11MMT in 2012

The Fertile Crescent:

ca. 11,000 years ago:The birth of agriculture, and the beginnings of  world population growth…

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World Population Growth:  From 11,000 years ago to today

Agriculture

Fisheries and Fishing Pressure:The California Sardine Fishery:

Fisheries and Fishing Pressure:Landings of Anchovy and Sardines: Boom and Bust

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John Steinbeck’s Novel:Cannery Row (1945)

First Edition cover

Nobel Prize Literature (1962)

Steinbeck’s friend, marine biologist Ed Rickets (“Doc” in Cannery Row) and his 1939 book.

Fisheries and Fishing Pressure:The Gulf of Maine Redfish Fishery:

Fisheries and Fishing Pressure:Landings of Redfish off New England: Boom and Bust

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History: Commercial Fisheries:

Baiting  hooks on long lines, or 

tub trawls

The Atlantic Cod Fishery: A Rich History

Basics of Fishing Methods:  Fish netsGill Nets:

Purse Seines:

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Basics of Fishing Methods:  Fish nets

The Otter Trawl:

Mid‐20th Century:New Trawlers and Trawls

Before

Trawlers and The Benthos:

After

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“Rock Hoppers”

The Fishing Banks of North America:  The Grand Banks of Newfoundland, 

New England, and Georges Bank

New England & Georges Bank:  Landings Crash

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The Foreign Fleet:  Trawlers and “Factory” Ships

The Foreign Fleet:  Trawlers and “Factory” Shipson Georges Bank in the 1960s

Trawlers and their capacity to catch fish: 

(modern examples)

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Fisheries LandingsNew England & Georges Bank

onne

s

400x103

450x103

500x103

The Magnusen Fisheries Conservation and Management Act of 1976:

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Met

ric T

o

200x103

250x103

300x103

350x103 1976

Fisheries LandingsNew England & Georges Bank450x103

500x103

Passage of MFCMA (1976)

Look what happened after 1976:

New England & Georges Bank

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Met

ric T

onne

s

200x103

250x103

300x103

350x103

400x103

450x10

Fisheries LandingsNew England & Georges Bank450x103

500x103

Passage of MFCMA (1976)

Look what happened after 1976:

New England & Georges Bank

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Met

ric T

onne

s

200x103

250x103

300x103

350x103

400x103

450x10

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HaddockCod Yellowtail Fromdesirablespecies

Species composition flipped:

From 67% Cod, Haddock and Flounders in 1963

To14% in 1986 Dogfish

SkateTo

less-desirablespecies

Solutions?1. Reduce Fishing Pressure…  it worked during two wars…

…but not in Newfoundland…not yet, anyway

The North Sea

2. Ecosystem‐based Management?e.g., the current approach isn’t working…

Magnuson‐Stevens Fishery Conservation and Management 

Reauthorization Act of 2006

Passed by Congress Dec. 9, 2006

– 240 pages in length

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And then, even they were targeted:

Georges Bank: Cod & Haddock Landings Last Century:

Haddock: 1904 ‐ 2004

Haddock

Northeast Fisheries Science Center Reference Document 05-13, August 2005

Cod: 1893 ‐ 2004

Cod

New Bedford Fishing Fleet:  (still waiting)

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Principles of Fishery Science:

1. Young fish grow; but many die young, before we can catch them;

2. Fish mortality includes: starvation and predation;

3. Fish that don’t die early may grow large enough to be caught, to enter the fishery, to be ‘recruited’;to be caught, to enter the fishery, to be recruited ;

5. Fisheries catch fish, sometimes too many fish; the goal of Fishery Scientists and Managers:

To be able to predict how many fish can be safely caught, without depleting the stocks.

4. Recruitment is highly variable among years and difficult to predict;

1.  Young fish grow ─ but many die young, before we can catch them; 

Cod:  Growth in Length Cod:  Growth in Weight

1.  Young fish grow ─ but many die young, before we can catch them; 

Weight

Numberof Fish

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So:  For each age group of fish (1 yr‐olds, 2 yr‐olds, etc.):We multiply number of fish times their weight…  giving aStock Biomass. 

For example:  European Plaice

impo

rtant)

This line is Mortality. One hopes that it is offset , or matched, by Recruitment…

Age Group

Log Biom

ass (

units un

Stock Biomass(for each age group)

Biomassof

RecruitsThis point, at some positive value ofStock biomass, is also obvious…

A hypothetical Stock‐Recruitment Curve:

Stock Biomass (all ages)

Recruits

This point, at the origin, is obvious:At zero stock biomass, there can be no recruits

Stock biomass, is also obvious…

A hypothetical Stock‐Recruitment Curve:

Biomassof

Recruits ?

Stock Biomass (all ages)

Recruits ?

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The Principle of Maximum Sustainable Yield:

The problem with this approach?It doesn’t always work …

─ that is, more often than not, it doesn’t work.

This is because of Recruitment Variability…─ recruitment is highly variable

from year to year…

CriticalPeriod?

Johan Hjort and theCritical Period Concept

D.H. Cushing and the Match‐Mismatch Hypothesis

Recruitment Variability: Evolving Ideas

Johan Hjort1869 ‐ 1948

David H. Cushing1920 ‐ 2008

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One conclusion of all this:These two graphs tell it all: 

Our population growth rate far exceeds the oceans’ capacity to supply commercially‐harvested food fish… 

Marine Fish LandingsWorld Population

World Aquaculture Production, as of 2008:It continues to rise fast:

Two basic types of aquaculture:Extractive Additive

e.g., Shellfish Aquaculture e.g., Salmon Pens

Oysters & Mussels

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Mussel & Oyster Farming:

Maine Salmon Aquaculture Landings

Salmon Farm in Eastern Maine

Courtesy C. Bartlett, Univ. Maine Sea Grant

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The Future of Aquaculture…

A call for action:…to get serious about Aquaculture