Week 4

1
Week 4
Fishery Biology and Management
Week 5 Eric B. May 2101 Carver Hall
Ecological Harvesting and Human Intervention
2
Trophic Levels The Battery View Robust
Community Structure
The Old Sun of a Gun
100 Calories
Battery 4
200 Calories
Battery 3
Battery 2
450 Calories
700 Calories
Battery 1
Solar Cells
1000 Calories
3
Response to Loss
The Old Sun of a Gun
92 Calories
Battery 4
184 Calories
Battery 3
415 Calories
Battery 2
646 Calories
Battery 1
1000 Calories
Solar Cells
4
Food Webs and Energy Matrices
5
The Web II
6
An Issue of Technological Advancement
Air Planes
Internal Combustion (Trucks)
Steam Engines (Trains, Boats)
Wheel (Horse Drawn Carts)
Radial Distance From Home
Walking (Hunting Gathering)
Boats
Rowing Devices
Sail
Steam Engines
Internal Combustion
7
Development of Markets
National
Regional
Local
8
Market Expansion
Shift to Population Increase as Driver
Demand
Time (Lots of Years)
Wheel
Trucks
Air Planes
Trains
Refrigeration
By Increasing Availability Through Shipping,
Demand Increases
9
Impact on Fish Stocks
Local Fishing
Open Seas Fishing
Local Fishing
By our technology we have opened up large areas
to fishing.
10
Reiteration - Technology
Sail
Engine
Airplane
Refrigeration
Refrigeration
Rail
11
Gear Innovations
Boat Seine
Net
Beach Seine
Otter Trawl
12
Trawls
Simple Scrape
Scrape Dredge
Beam Trawl
13
Trawls In General
Otter
Flat Bottom
Beam
14
The 35 Yankee
15
The Big One
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Gill Nets
17
Trammel Nets
18
The Ultimate The Purse Seine
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Not to Leave Out Recreational Anglers
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AND ON IT GOES
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Boats
22
The Ultimate in Finders
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The Combined Effect
Collapse
Recovery
Overexploited
Growth Phase
Fully Exploited
Development Phase
Predevelopment Phase
24
Harvest Control
Fishery Biology and Management
Harvest Control And Data Sources
25
Development of Models

• Grahams Theory of Sustainable Fishing (1935)
• If removals can be replaced by stock production
  each year, the fishery is sustainable.
• If stock size is maintained at half its carrying
  capacity, the population growth rate is fastest,
  and sustainable yield is greatest (Maximum
  Sustainable Yield).

26
A View of a Fishery
Population Biomass
Population Strength
Or

• Total Available
• Spawning Stock Biomass
• Measure is CPUE

• Total Available
• Cohort Strength
• Converts to Biomass
• Fishery Independent

From Fogarty 2005 Modified by May - 2006
27
Growth
From Fogarty - 2005
28
Length Weight Relationships
Weight is a cubic function of length wtaL3
A 40 cm YT weighs .511 kg
We can convert length to weight easily

• A 40 cm fish weighs .511 kg

From Fogarty - 2005
29
Haddock Age Structure
Low Contribution to Biomass
Significant Loss With Age
From Fogarty - 2005
30
Cohorts, Growth and Numbers
Age 1
Age 2
Age 3
Age 4
Age 5
31
Week 4
Fishery Biology and Management
Recruitment
32
Recruitment

• Age to Sexual Maturity A Definition of Risk
• Long Lived
• High Fecundity Long juvenile and sub-adult
  period, high egg production
• Example Sturgeon
• Low Fecundity Long juvenile and sub-adult
  period, low egg production
• Example Sharks
• Short Lived
• High Fecundity Short juvenile and sub-adult
  period, high egg production
• Example Pacific salmon such as Chinook
• Low Fecundity Short juvenile and sub-adult
  period, low egg production
• Example Bay anchovy

33
Age to Maturity
90 Mature
70 Mature
Length
0
4
0
100
17
2
Age in Years
Age in Years
34
Age to Maturity
Reproductive Life
Maturation varies by species and region
Reproductive Life
Maturation is also sensitive to density,
temperature, food resources.
From Fogarty - 2005
35
Stock Recruitment
Use the data or Fit a curve and use the curve and
its properties.
It is important to note Spawning stock biomass
is not always connected to numbers of juveniles
entering the fishery, such as menhaden
From Fogarty - 2005
36
Fluke Recruitment-age 1

• New fish entering the population from a previous
  years spawning
• Different each year, related to spawning stock
  size and environmental factors

From Fogarty - 2005
37
Menhaden
38
Management
39
Harvest Control Models
M
F
Overview of Harvest Control Model
S T - (F M) Where R or
Recruitment S S Instantaneous Survival T
Total Biomass F Fishing Mortality M Natural
Mortality

• A 1-e-Z

And Then

• SNt1/Nt
• Z-lnS

40
Fishing Mortality
S T - (F M) Where R or Recruitment
S S Survival
F C R Where C Commercial
Harvest
R Recreational Harvest
C CK CB
R RK RB Where C Total Harvest
R Total Harvest CK
Total Kept RK Total
Kept CB By-Catch RB
By-Catch
41
The Issue of By-Catch

• Difficult to Determine Current methods are to
  utilize on-board observer programs where the
  number of fish caught and sold is compared to
  those returned
• Survival following return to the water is a
  function of species, length of time in capture
  device, type of capture device, water
  temperature, handling etc. Guess what not all
  fish survive release.
• Not all fishing gear has been evaluated, nor all
  fishing trips monitored.

42
Relational Aspects of By-Catch
C1 CK1 CB1
Fisheries 1
C2 CK2 CB2
Fisheries 2
C3 CK3 CB3
Fisheries 3
C1 B1 B21 B31
C2 B2 B12 B32
C3 B3 B13 B23
43
By-Catch Issue is to Relate Landings With By-Catch

• On Board Observers
• Generate Data for each Fisheries
• Determine Relation Between Kept and Discarded
• Develop Model to Apply to By-Catch For that
  Fisheries
• Continue Observer Program Until Relation is
  Within 95 Confidence

• Apply to Landing
• Use Model to Compute Yearly By-Catch as a
  Function of Landings
• Incorporate By-Catch into Total Biomass Loss
• Use That Figure to Determine the Sustainability
  of the Fisheries
• Incorporate the Impact of Other Fisheries on the
  Primary Fisheries Using Similar Relational Models

The Catch is in the Reporting
44
On to the Recreational Harvest
R RK RB
R The total of all fish taken by a
recreational Fishery RK The total of legal
fish kept RB The total of fish released
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But What About RB

• Driven by the desire to minimize impact on a
  fisheries Large Mouth Bass
• Driven by methods used to control harvest All
  Fisheries
• Driven by the physiology of each recreationally
  important species Striped bass, Bluefish
• Driven by the anatomy of each recreationally
  important species - Flatfish

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An Alternative to Keeping?
Total Released
Total Catch
Years 1980 to 2004
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Striped Bass - Field
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Striped Bass Experimental
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Striped Bass Field and Experimental I
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Striped Bass Field and Experimental II
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An Issue of Anatomy I
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An Issue of Anatomy II
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An Issue of Anatomy III
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Natural Mortality
Population Biomass
Population Strength
Or

• Total Available
• Spawning Stock Biomass
• Measure is CPUE

• Total Available
• Cohort Strength
• Converts to Biomass
• Fishery Independent

From Fogarty 2005 Modified by May - 2006
55
What About Natural Mortality
Disease
Predation
Trauma
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A Holistic View of Natural Mortalities

• Environment
• Biotic
• Abiotic

• Nutrition
• Macronutrients
• Micronutrients

• Genetic
• Phenotypic
• Genotypic

57
Current Regulatory Process Promotes Catch and
Release (Seasons)

• Season Restrictions
• Spawning Protect Spawning Stock
• High Risk Periods Reduce By-Catch Mortality
• Abundance Periods of Schooling (Concentration
  Effect
• Trophy Seasons Not sure about this one
• This does not preclude fishing, it precludes
  keeping

58
Effect of Seasons
Protected Spawning
Reduced ByCatch
Length
0
4
0
100
17
2
Age in Years
Age in Years
Trophy Seasons?
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Regulatory (Area)

• Area Closures
• Spawning Grounds Protect Spawners
• Marine Protected Areas Protect habitat and all
  species
• Areas of Congregation Protect concentrated fish
  groups
• This does not preclude fishing, it precludes
  keeping

60
Effect of Area Closures
Protected Spawning Areas
Protected Concentrations
Length
0
4
0
100
17
2
Age in Years
Age in Years
Marine Protected Areas
61
Regulatory Size

• Upper Limits Protects optimal spawners
• Lower Limits Decrease time at risk from young
  to age at maturity
• Slot Limits Do both
• This does not preclude fishing, it precludes
  keeping

62
Effect of Limits
Lower Limits
Length
0
4
0
100
17
2
Age in Years
Age in Years
Upper Limits
63
Limited Entry and Regional Entry

• Limited Entry
• Limit Licenses
• Limit Number of Boats
• Regional Entry
• Limit Number of Boats for a Region
• Decision Prior to Season
• Combinations of Both

64
Commercial Gear Restrictions

• Gill Net Mesh Size
• Specific Nets Banned i.e. Pound Nets
• Excluder Devices
• Size of Devices Used

65
Terminal Gear Restrictions

• Hook Size
• Small Reduce Impact on Larger Fish
• Large Reduce Impact on Smaller Fish
• Hook Style
• Barbed vs. Barbless
• Single vs. Double vs. Treble
• Metal Composition
• Lures and Bait
• Live Bait vs. Lures
• Chumming

66
The Science in Fishery Management
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Informational Needs
Risk Effort Relation to Population Size
68
Effort

• Number of Individuals Involved
• Number of Licenses
• Creel or Bag Surveys
• Arial Survey
• Boat Surveys
• Catch per Unit Effort (CPUE)
• Intercepts
• Tagging or Mark Recapture
• Landing Statistics Compared to Fleet Size

69
Population Size
Population Biomass
Population Strength
Or

• Total Available
• Spawning Stock Biomass
• Measure is CPUE

• Total Available
• Cohort Strength
• Converts to Biomass
• Fishery Independent

From Fogarty 2005 Modified by May - 2006
70
Rule of Diminishing Returns
Effort
Size, CPUE and Effort
CPUE
Size
Time
71
Stocks, Recruitment and Fishing Effort
10
5
10
10
S
F
R
Overfishing
Habitat Limited
Population
Population
Habitat and Fishing
Time
Time
15
10
Overfished
Habitat
Population
Fishing
Time
72
Pacific Salmon A Case History
Commercial Fishing
Dam
Spawning
Sport and Commercial Fishing
Nursery
Unrestricted Logging
Nuclear Power Plant
Spawning
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Assignment
Decades ago the supply of striped bass (Morone
saxatilis) seemed plentiful. However, advances in
fishermen's ability to catch, preserve, and sell
fish quickly exceeded the ability of fish stocks
to reproduce. In 1973 commercial striped bass
harvest was at 5 million pounds, but within a
decade the commercial harvest slumped to less
than two million pounds. An Emergency Striped
Bass Research Study suggested that excessive
fishing pressure likely decimated the striped
bass stock and precipitated the decline. A
moratorium on commercial and recreational fishing
for striped bass was imposed in 1984 and reopened
in 1990 with small seasons and quota limits. When
the striped bass stocks began to recover in 1994,
Maryland State law capped the number of
commercial licensees able to participate in the
commercial striped bass fishery at the current
number of participants, 1231. As a migratory
species, striped bass are monitored by the
Atlantic States Marine Fisheries Commission
(ASMFC), a regulatory agency designed to
coordinate the conservation and management of
nearshore fishery resources through a joint
program with Atlantic coastal states. State and
district quotas are set by ASMFC based on
sampling data and models. Maryland then further
divides their portion of the quota among
different gear types assigned to different
seasons. Maryland regulatory regimes attempt to
reduce overfishing through various types of
restrictions limits on the amount of time during
which fishing can occur, lengths of the season,
number of fisherman, equipment, the size of the
allowable catch, and limits on the amount of fish
caught. The adoption of these regulations proved
to be a huge step in the restoration of striped
bass population. In 1995 when the striped bass
stock was formally declared recovered, ASMFC
Amendment V was adopted and replaced the original
ASMFC fishery management plan and subsequent
amendments. The biological target for determining
the stock restored has been defined as "the
average spawning stock biomass (SSB) or total
weight of sexually mature striped bass females
observed between 1960 and 1972. The goal of
Amendment V is "to perpetuate the stock of
striped bass so as to allow a commercial and
recreational harvest consistent with the long
term maintenance of a self-sustaining spawning
stock and provide for the restoration and
maintenance of essential habitat."
74
Based on the Previous

• As a Group Exercise
• Evaluate the approach taken to restore striped
  bass, were the key questions answered prior to
  the moratorium
• This evaluation should involve circumstances
  prior to the crash, at the crash and today
• You must consider the scientific, political and
  policy frameworks in place then and now
• Was the moratorium necessary, there are natural
  biological cycles that need consideration
• Pay Attention to
• Key dates 1975 through 1984, 1984, 1990, 1995 and
  2006 (today)
• The ecological role of striped bass
• Environmental, nutritional and genetic factors
  involved prior to, at the crash and now
• Was it the Right Action?
• Final Product
• I will serve as the Governor of Maryland. I am a
  republican, fiscal conservative and strongly
  believe that the need for economic growth
  outweighs environmental issues
• You have 10 minutes of my time, you must convince
  me that it was the right action then and now
• Select a team leader and break down the problem
  into its legal, policy, biological, social and
  economic components.
• You all sink or swim together