Sustainalbe Fishery Management / Fishery Resource and Stock

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Fishery Resource is Aquatic Animals and Plants which is good for fishery
Fishery resource is a renewable resource.
Stock is an unit of fishery management.
Various method of stock identification
A stock has its sex, length and age composition.
Chi-square test is used for test the difference of sex ratio.
Age determination is conducted from various age character (scale, otolith, shell etc)
Length composition will be converted to age composition by using ALK

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Sustainalbe Fishery Management / Fishery Resource and Stock

  1. 1. Fishery Resource and Stock Takashi Matsuishi At SERD, AIT, Thailand 24Feb-14Mar, 2014 1
  2. 2. Resource 2
  3. 3. 3 Resource  Things that human do NOT use : things, garbage  Things that human use: resource  Fish: good for use / not good for use  Fishery Resource  Aquatic Animals and Plants which is good for fishery
  4. 4. 4 Categories of Resource  Environmental Resource  Non Renewable Resource  Renewable Resource
  5. 5. Environmental Resource 5  Water,Air, etc  It circulate as it is.  Usage: Use it without pollution or contamination Stock
  6. 6. Non-Renewable Resource 6  Finite Resource  Resource that does not renew itself at a sufficient rate for sustainable economic extraction  Oil, Gas , metal ores  Usage: Use it as small as possible to use it longer Stock
  7. 7. 7 Renewable Resource  Resource which can fill up again with the passage of time, either through biological reproduction or other naturally recurring processes.  Fish, Forest, Crops,Animal husbandry  Usage: Use as much as its reproduction Stock Reproduction
  8. 8. 8 Fishery Resource is a Renewable Resource  Reproducible  Unlimited sustainable Use  May deplete if the usage is wrong
  9. 9. Stock 9
  10. 10. 10 Resource and Stock  Resource  a stock or supply of materials or assets  Stock  a supply of goods or materials available for sale or use  (Concise Oxford Dictionary)  CONFUSING  If resource is gathered for use, it is called Stock.
  11. 11. 11 The unit of stock  Stock : the population that made same population dynamics  Species / population / sub-population etc.  Genetic definition: Mendelian population with a same gene pool(Numachi1974)  Stock = the object of stock assessment = the object of fishery management
  12. 12. 12 Stocks of Walleye Pollock around Japan Sea of Japan Catch (2009) 15,000t Nemuro Catch (2009) 9,500t Pacific Catch (2009) 169,000t Okhotsuku Catch (2009) 26,000t
  13. 13. 13 Walleye Pollock J-stock P-stock Catch(1000t)
  14. 14. 14 Stock Identification  Morphological Method  Proportion, number of bones  Morphometric / Meristic Character  Ecological Method  Difference of Spawning season, Spawning area, Length composition  Mark-Recapture Method  Confirm the existence of mixture  Fishery Condition  Consistency of the catch trends  Genetic Method  Test the samples are from same Mendelian Population  Genetic difference made by mutation
  15. 15. 15 Example of Herring around Hokkaido Hotta, Matsuishi, Sakano, Kanno, 1999, Nissuishi
  16. 16. 16 Japanese Sand Smelt Suzuki, Kobayashi, Matsuishi, Numachi (2000) Nissuishi
  17. 17. 17 Property of stock  The stock will described in the item  Habitat Area / Fishing Ground  Morphological Features (Body Length, Pictures, Colour)  Ecological Features (Prey, Predator)  Life History (Age at Maturity, Longevity)  Composition  Sex composition  Length composition  Age composition
  18. 18. Sex ratio 18
  19. 19. 19 Sex ratio  Ratio of male to female.  Basically it is near One for fish.  If the behaviour of the fish is different in sex, the sex ratio in a certain fishing ground would not be one  If the growth of the fish is different in sex, the sex ratio in a certain fishery with length dependent selectivity would not be one.
  20. 20. 20 Statistical test of that the sex ratio  Number of male : n1(≥5)  Number of female: n2 (≥5)  If then the sex ratio is significantly different from one. (p<0.05, chi-square test)  It is difficult to test that the sex ratio is EQUAL to one. You may find some difference from one if you collect more samples.     84.305.0,12 21 2 212 0      nn nn
  21. 21. Age determination 21
  22. 22. 22 Methods of Age determination  In captivity  The growth speed may different to the wild situation  Mark- Recapture Method  Can not estimated absolute age  Length Composition  Difficult to determine the older age  Can not estimated absolute age  Age Character  Labourious but accurate and precise
  23. 23. 23 Age Characteristics  Scale  Otolith  vertebra  Fin ray  Shell Scale of Rosy seabasshttp://www.pref.niigata.jp/norin/chiiki/suikai/joho/dayori/9gou/akamutu.htm Otolith of Kichiji Rockfish http://hnf.fra.affrc.go.jp/H-jouhou/seika/hnf98008.html Shell of Abalone http://www.pref.kyoto.jp/kaiyo/kenkyu-koborebanashi-awabinenrei.html
  24. 24. 24 Age composition  A stock contains many year class or cohorts  Age composition is the relative abundance of the year classes at a certain year
  25. 25. 25 Walleye Pollock Pacific Ocean Biomass displayed by Year Class http://abchan.job.affrc.go.jp/digests19/details/1913.pdf Biomass(1000t) Year
  26. 26. 26 Dominant Year Class  a year class that predominates in the fishery, often continuing over several years  It appears frequently in Herring,Walleye Pollock etc  It may be difficult to the appearance of the dominant class just after the appearance when the young fish are not targeted for fishery.
  27. 27. 27 Catch at age  Catch at age is the number of fish caught by year by age.  It is not a age composition of the stock, because the catch at age is the result of fishery with selectivity  Age based population estimation method (eg.VPA) uses Catch at Age  Catch at Age is often calculated from Length Composition and Age length Key
  28. 28. 28 Length Composition  Length composition / Length frequency distribution  In Stock / In Catch fish  It reflects stock status  If exploitation is too strong, the frequency is moved to small side  If dominant year class is appeared, the length composition has a peak  Peaks sometimes represents year class  In younger age, it is clear  In older age, it is not clear because of the slow growth  In Crastacetean, the peak reflects the molting age
  29. 29. 29 0 500 1000 1500 2000 2500 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 CatchinNumber Body Length Age Composition of Yellowback seabream Dentex tumifrons Akamine(2007) P5
  30. 30. How to measure the body length 30 Fish Measurement Board
  31. 31. Fish Length 31
  32. 32. 32 Age – Length Key (ALK)  Key matrix to convert catch at length to catch at age  Procedure  1. Making ALK  Get sample  Measure length, and aging (e.g. 20 fish for each length class)  Make ALK  2. Length Composition  Get many measurement (e.g. 1000) and get length composition  Estimate total # fish caught (Total Catch / average weight)  Make catch at length table from length comp. and total # catch  3. Calculate Catch at Age by using ALK
  33. 33. 33 Simple example of ALK Virtual data BL (mm) ALK 1 2 3 [80-100) 100% 0 0 [100-120) 20% 70% 10% [120-140) 0 20% 80%
  34. 34. 34 Catch at Length BL (mm) Length Composition Catch at Length [80-100) 30% 3,000 [100-120) 50% 5,000 [120-140) 20% 2,000 合計 100% 10,000
  35. 35. 35 Calculation of catch at age BL(mm) Age Total 1 2 3 [80-100) ALK 100% 0 0 100% #fish 3000 0 0 3,000 [100-120) ALK 20% 70% 10% 100% #fish 1000 3500 500 5,000 [120-140) ALK 0 20% 80% 100% #fish 0 400 1600 2,000 Total 4000 3900 2100 10,000
  36. 36. 36 Size Category Composition  Size Category Composition: a kind of size class decided in market or middleman to classify the fish size for sale  Example: Size Category of Sea Bream in Nagasaki, Japan  You can convert the size category to age composition if you make the age category key 3S 2S S M L -15cm 15-20 20-30 30-40 40-
  37. 37. 37 Summary  Fishery Resource is Aquatic Animals and Plants which is good for fishery  Fishery resource is a renewable resource.  Stock is an unit of fishery management.  Various method of stock identification  A stock has its sex, length and age composition.  Chi-square test is used for test the difference of sex ratio.  Age determination is conducted from various age character (scale, otolith, shell etc)  Length composition will be converted to age composition by using ALK

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