Lecture 9:Overview of Fisheries Assessment - PowerPoint PPT Presentation

1 / 14
About This Presentation
Title:

Lecture 9:Overview of Fisheries Assessment

Description:

Best Management Practices for Agriculture and Forestry ... The use of statistical and mathematical calculations to make quantitative ... – PowerPoint PPT presentation

Number of Views:56
Avg rating:3.0/5.0
Slides: 15
Provided by: forestr1
Category:

less

Transcript and Presenter's Notes

Title: Lecture 9:Overview of Fisheries Assessment


1
Lecture 9Overview of Fisheries Assessment
  • WMAN 445
  • Fish Management
  • Lecture Notes

2
Fisheries Management Approaches
  • Manage Fish Populations Directly
  • Stocking
  • Harvest Regulations
  • Size limits
  • Creel limits
  • Technology limits
  • Limited Entry
  • Seasonal Limits
  • Special Reg Areas

3
Fisheries Management Approaches
  • Manage the Associated Community
  • Food / Prey supplementation
  • Control Predators / Parasites
  • Improve Conditions for Prey

4
Fisheries Management Approaches
  • Manage Habitats and Water Quality
  • Habitat Improvement Structures
  • Treat pollution / acid precipitation
  • Bank Stabilization
  • Artificial Reefs
  • Limit Activities that Destroy Habitat (bottom
    trawls, Dredging)

5
Fisheries Management Approaches
  • Manage Activities in the Watershed
  • Best Management Practices for Agriculture and
    Forestry
  • Development Planning to minimize impacts to
    aquatic systems
  • Erosion Control
  • Stormflow Control

6
Fisheries Management Approaches
1
3
4
Targeted Fish Species
Aquatic Habitat and Water Quality
Watershed Processes
Aquatic Communities
2
More Sustainable
Less Sustainable
7
Need for Fisheries Stock Assessments
  • All fish management approaches require
    quantitative information on the status of the
    fishery and factors that influence, have
    influenced, or are likely to influence that
    status.

8
Need for Fisheries Stock Assessments
  • Managers must know the answer to questions such
    as
  • What is the size of the targeted fish population?
  • What is the populations age structure?
  • What is the reproductive capacity of the
    population?
  • How many fish can be harvested each year? Which
    sizes should be left alone?
  • Which habitat or water quality conditions
    influence the population?
  • Do interactions with other species affect the
    population?
  • Which human activities other than fishing affect
    the fishery?

9
Some Important Definitions
  • SPECIES a group of similar organisms that can
    freely interbreed (example Coho Salmon)
  • POPULATION a group of individuals of the same
    species that have a high probability of
    interacting with each other and interbreeding
    (example Upper Snake River Coho Salmon)
  • STOCK a harvested or managed unit of fish (may
    include more than one population or species)
    (example Pacific Northwest Salmon off Oregon and
    Washington Coast)

10
And a Couple More
  • SUBSPECIES taxonomically distinct individuals
    that occupy non-overlapping geographical ranges,
    but share the essential characteristics of the
    species such as interbreeding (example
    Yellowstone Cutthroat Trout, Southern Appalachian
    Brook Trout)
  • EVOLUTIONARILY SIGNIFICANT UNIT (ESU) a
    geographically isolated portion of the species
    population has high level of genetic difference
    from other subpopulations of the species, but not
    recognized taxonomically as a separate subspecies
    or species (California Coho Salmon)

11
What is a Stock Assessment?
  • The use of statistical and mathematical
    calculations to make quantitative predictions
    about the response of fish populations to
    alternative management choices.

12
Components of a Stock Assessment
  • Population Assessment
  • Predictive Models

13
Stock Assessment vsFisheries Management
14
Stock Assessment in Practice What We Measure
  • Population Size
  • Age Structure
  • Proportional Stock Density
  • Minimum Viable Population Size
  • Effective Population Size
  • Recruitment
  • Stock-Recruitment Relationships
  • Natural Mortality
  • Fishing Mortality
  • Movement
  • Growth Rates
  • Diet
  • Condition
  • Habitat Use

Models to Predict Fish Population Dynamics Under
Various Management Scenarios
Write a Comment
User Comments (0)
About PowerShow.com