Fish Population Dynamics and Stock Assessment


Dr. Devanand T N


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Course Name : Fish Population dynamics and Stock Assessment

Code(Credit) : FSRM3108(2-1-0)

Course Objectives

  • Population dynamics is a branch of life science which is concerned with the short and long-term changes in the size and age composition of populations, and the biological and environmental processes influencing those changes. It deals with the way populations are affected by birth and death rates, and by immigration and emigration, and studies topics such as ageing populations or population decline.
  • Stock assessment is an important tool in fisheries management. In particular, to ensure contained, healthy, fish stocks, measurements of the Spawning Stock Biomass (the stock population capable of reproducing) allows sensible conservation strategies to be developed and maintained through the application of sustainable fishing quotas.

Learning Outcomes

  • The student will have idea about Biological distribution of the catches by species, by length, by ages, etc.
  • Estimation of age and growth in tropical fishes
  • Fishing effort or CPUE
  • Softwares used in fish stock assessment
  • Mortality parameters
  • Growth parameters
  • Recruitment parameters

Course Syllabus

The concept of population and unit stock. Biological structure of fisheries resource in space and time. Indicators of dynamics in a fishery resource. Characteristics of unit and mixed stock. Data requirements for stock assessment. Segregation of stocks. Principles of stock assessment. Population age structure. Theory of life tables. Von Bertalanffy growth parameters. Graphical models. Monte Cario simulation model and ECOPATH model. Estimation of total fishing and natural mortality. The concept of yield, yield in number and yield in weight, yield per recruit, yield curve. Yield models. The concept of Maximum Sustainable Yield and Maximum Economic Yield. Biological symptoms of under-fishing and over-fishing. Growth over-fishing and recruitment over-fishing. Eumetric fishing. Open access fisheries. Fisheries regulations. CPUE. Trawl selection and gillnet selection. Analytical models of fish stocks.

Study of length – weight relationship, segregation of stock using direct methods. Study of analytical models: Beverton and Holt model. VBGF, Pauly’s integrated methods, graphical models. Estimation of Z, F and M. estimation of net selectivity coefficient. Fitting of surplus production model: Schaeffer model, Fox model. Study of yield isopleth diagrams. Micro-computer packages ELEFAN, FISAT.


Prescribed Book
1. Gulland, J.A. 1989. Fish Stock Assessment. John Wiley & Sons Inc., New York.

Reference Books
1. Hilborn, R. and Walters, J.W. 1992. Quantitative Fisheries Stock Assessment. Chapman & Hall Press, London.
2. Kuderskii, L.A. 1995. Population Dynamics of Commercial fish in Inland Reservoirs. Oxonian Press Pvt. Ltd., New Delhi.
3. Sakgawa, T.G. (Ed.) 1995. Assessment Methodologies and Management. Oxford & IBH Publishing Pvt. Ltd., New Delhi.

Session Plan

Session 1

Theory 1. Introduction to fish population dynamics and stock assessment- Introduction

1. Introduction_to_fish_population_dynamics_and_stock_assessment

Session 2

Session 3

Practice 1. Age Determination using length frequency method and Estimation of mean length and growth rate

Session 4

Session 5

Session 6

Practice 2. Gulland and Holt Equation and Estimation of growth parameters by Chapman and Ford – Walford

Session 7

Session 8

Theory 6. Biological structure of fisheries resource in space and time

6. Biological structure of fisheries resource in space and time

Session 9

Practice 3. Estimation of growth parameters by Bagenel’s least square method and Estimation of ‘Z’ using Beaverton and Holt equation based on length data

Session 10

Session 11

Session 12

Practice 4. Ricker’s catch curve and Powell and Wetherall method

Session 13

Theory 9. Population Age Structure and Theory of life tables

9. Population_age_structure and Theory of life tables

Session 14

Session 15

Session 16

Theory 11. Growth models:  von Bertalanffy’s growth equation

11. Growth models- von Bertalanffy’s growth equation

Session 17

Session 18

Practice 6. Schaefer’s and Fox model and Estimation of yield / recruit by analytical model

Session 19

Session 20

Session 21

Session 24

Practice 8. Swept area method and Computer Packages for Stock Assessment Studies

Session 26

18. Ecosystem and computer based software models- Ecopath and Monte carlo simulation model

18. Ecopath

18. Monte carlo simulation model

Session 27

Theory 19. Stock recruitment relationship- Models used for  stock recruits and parent stock

19. Stock recruitment relationship- Models used for  stock recruits and parent stock

Session 28

Case Studies

Case Studies

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    Dr. Devanand T N

    Assistant Professor

                  School of Fisheries Centurion University of Technology and Management (CUTM)  Paralakhemundi- 761211 Odisha, INDIA     Cleared ICAR – ASRB NET in FISHERIES RESOURCE MANAGEMENT   B.F.Sc. (Fisheries Science)- 2013, College of Fisheries, Mangaluru, Karnataka Veterinary, Animal and Fisheries Sciences University (Bidar), Karnataka, India M.F.Sc. in Department of […]