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The Great Lakes Fisheries Leadership Institute Introduction to Fisheries Management Daniel Hayes Department of Fisheries and Wildlife Michigan State University
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What is Fisheries Management? The manipulation of aquatic organisms (POPULATIONS), aquatic environments (HABITAT), and human users (PEOPLE) to produce sustained benefits for humanity (Nielsen 1999 in “Inland Fisheries Management in North America, edited by Kohler and Hubert)
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Because we are managing for human benefits, we need to decide what is “beneficial”
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1. Set Goals 2. Examine the Resource 3. Analyze the Situation and Set Objectives 4. Prescribe Treatment 5. Organize Personnel and Resources 6. Implement 7. Evaluate 8. Maintain 9. Publish The Eight (Nine) Steps of Management
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The Eight Steps of Management 1. Set Goals 2. Examine the Resource 3. Analyze the Situation and Set Objectives 4. Prescribe Treatment 5. Organize Personnel and Resources 6. Implement 7. Evaluate 8. Maintain 9. Publish Critical Points For Public Involvement
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The Eight Steps of Management What is “the” most critical step?
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The Eight Steps of Management What is “the” most critical step? Setting Goals and Objectives
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The Eight Steps of Management Goals: Broad statement of desired outcome of management Healthy ecosystem Good fishing Productive forest Safe water
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Evolution of Fishery Management Goals Maximum utilization (fisheries are unlimited) Maximum sustainable yield (MSY) Optimum sustainable yield (OSY) OSY + Healthy ecosystem/Biotic Integrity
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The Public Trust Doctrine is a common law doctrine. The essence of the Doctrine is the legal right of the public to use certain lands and waters. The right may be concurrent with private ownership. The legal interest of the public is not absolute; it is determined by a balancing of interests. The rights of the public are vested in each STATE as owner and trustee of Trust lands. The Public Trust Doctrine arises from the fact that Trust lands are special in nature physically and legally. Historically, the public use of these waters and lands was crucial for sustenance, travel, and commerce. B. Black’s Law Dictionary defines the public trust doctrine as a doctrine which, "Provides that submerged and submersible lands are preserved for public use in navigation, fishing, and recreation and the state, as trustee for the people, bears responsibility of preserving and protecting the right of the public to the use of the these lands and the waters above them for those purposes." Public Trust Doctrine
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Fishery Management Objectives S pecific M easurable A chievable R elated to goal T ime-constrained
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Fishery Management Objectives “Better Fishing” –Not S, Marginally M, A, R, Not T Increase catch rates of Chinook salmon –Marginally S, M, A, R, not T Increase average catch rates of Chinook salmon to 0.5 fish/hour or more by 2007 –S, M, maybe A, R, T
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Fishery Management Objectives Increase average catch rates of Chinook salmon to 0.5 fish/hour or more by 2007 by implementing bag limits –By adding the phrase “by implementing bag limits”, we are mixing an objective with a method to achieve the objective –We don’t want to do this because it constrains the way we think about achieving the objective
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Fishery Management Tools Populations –Stocking –Fish Community Manipulation People –Fishing Regulations –Allocation issues Habitat –Wetland preservation –River restoration –Water quality management
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Population Dynamics
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Time Steady Irregular Numbers
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Irruption Time Spasmodic Cyclical Numbers
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Time Numbers Increasing
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Thought Question You stock a pond with 10 fish. What factors would influence the population dynamics of this new population?
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Factors affecting population Birth rate Death rate Immigration/Emigration
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Time Numbers B = DB > DB < D
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Factors affecting population Birth rate –Sex Ratio –Fecundity (number of eggs) –Age structure –Spawning habitat Death rate –Predators (including people!) –Environment –Food Resources –Age structure
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A B A B C
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Key Points What is the rate of increase when population is reduced What is the eventual number that is achieved How does the rate of increase and number achieved vary in response to the fishery, habitat changes, or changes in other aquatic populations?
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Birth Rates
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Birth Rates: Fecundity Yellow Perch 12345 0 1,000 2,000 3,000 4,000 5,000 Age 123456789101112 0 200,000 400,000 600,000 800,000 1,000,000 1,200,000 Age Number of Eggs Haddock
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Reproductive Guilds A. Nonguarders -open substrate spawners -brood hiders - lots of small eggs B. Guarders -substrate choosers -nest spawners -larger eggs C. Bearers -external bearers -internal bearers -larger offspring
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Hermaphroditism Protandry Start life as a male, then become female Sea basses and groupers Protogyny Start life as a female, then become male Wrasses, parrot fish Self-fertilizing Simultaneously male and female Sea basses and grouper Parthenogenesis Female only Some mollies – in this case, male is needed to initiate egg development but no gene transfer Very common in Cladocerans (Daphnia, or “water fleas”)
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Survival Rate
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Survival Curves Time Numbers in Cohort Mammals Birds Fish
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Lifetime Changes in Size Birth Weight Adult Weight Ratio Mammals (Humans) 3,000 g68,000 g23 Birds (Mallard) 50 g1,100 g22 Fish (Yellow Perch) 0.001 g300 g300,000
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Time Number in Cohort Chinook Salmon Yellow Perch Chinook Salmon - Semelparous Yellow Perch - Iterparous
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0.00010.01110010,0001,000,000 0 20 40 60 80 100 Weight (grams) Percent Survival 0.00010.01110010,0001,000,000 0 2 4 6 8 10 12 14 Weight (grams) Mortality Rate
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Longevity: Age 20 Age 8 Age 4 Age Number in Cohort 20% mortality50% mortality80% mortality
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Natural Mortality=20% Fishing Mortality=10% NaturalWeight (g)Yield (kg) AgePopulationCatchMortalityTotal Deaths 1100086173259675.8 27416412819248330.9 35494795142117755.8 44073570105196869.1 5301265278271470.6 6223193958335464.7 7165142943386155.1 8122112132426945.2 99181624456935.8 106761217480327.9 460.9
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Natural Mortality=20% Fishing Mortality=50% Natural Mortality=20%
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Fishing Mortality=50% NaturalWeight (g)Yield (kg) AgePopulationCatchMortalityTotal Deaths 110003601445036724.1 24971797125048386.2 324789351241177104.4 4122441862196886.7 56122931271459.3 63011415335436.4 715528386120.8 87314426911.4 9411245696.1 10210148033.2 438.6 Natural Mortality=20% Fishing Mortality=20% NaturalWeight (g)Yield (kg) AgePopulationCatchMortalityTotal Deaths 11000165 3306711.0 2670110 22148353.3 344974 148117787.2 430150 99196897.7 520233 67271490.3 613522 45335474.8 79115 30386157.7 86110 20426942.8 9417713456930.7 1027559480321.6 567.3
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Natural Mortality=20% Fishing Mortality=50% beginning at age 3 NaturalWeight (g)Yield (kg) AgePopulationCatchMortalityTotal Deaths 110000181 670.0 28190148 4830.0 3670241963371177283.8 4333120481681968235.6 51655924832714161.3 682301241335499.0 74115621386156.6 8207310426931.1 910415456916.5 10521348038.6 892.5 Fishing Mortality=50% beginning at age 7 NaturalWeight (g)Yield (kg) AgePopulationCatchMortalityTotal Deaths 110000181 670.0 28190148 4830.0 36700122 11770.0 4549099 19680.0 5449081 27140.0 6368067 33540.0 7301108431523861418.2 81505422754269229.6 9742711374569122.0 103713519480363.7 833.5
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Surplus Production Fishing Effort Yield per newborn Growth > MortalityGrowth < Mortality
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Yield Effort Age 1 Age 2 Age 3 Surplus Production
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Adults Number of Young Adults Reproduction Revisited: Stock and Recruitment
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Integrating Population Dynamics with Fishery Management Tools Populations –Stocking increases births –Fish Community Manipulation alters survival rate and age structure People –Fishing Regulations alters survival rate and age structure –Allocation issues * Primarily a human issue* Habitat –Wetland preservation alters birth rate –River restoration alters birth rate –Water quality management alters birth rate and survival rate
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