Ecological and Economic Considerations in the Conservation and

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Ecological and Economic Considerations in the Conservation and Powered By Docstoc
					Ecological and Economic Considerations
in Management of the U.S. Pacific sardine
                Fishery

          Samuel F. Herrick Jr
            NOAA Fisheries
    Southwest Fisheries Science Center




                                         1
• Report on ongoing work in collaboration with Rognvaldur
  Hannesson, Norwegian School of Economics and
  Business Administration and John Field, NOAA
  Fisheries, Southwest Fisheries Science Center

• Publications:
   – Hannesson, R., S. Herrick and J. Field. 2009. Ecological and
     economic considerations in the conservation and management
     of the Pacific sardine (Sardinops sagax). Ca. J. Fish. Aquat. Sci.
     66: 859-868.
   – Hannesson, R. and S.F. Herrick Jr. 2010. The value of Pacific
     sardine as forage fish. Marine Policy 34: 935–942




                                                                      2
• Account for the total value sardines provide in
  terms of their function in the California Current
  Ecosystem
• Basically a matter of balancing the economic
  benefits from harvesting sardines against the
  economic benefits from leaving sardines in the
  water
• At this point
   – Present the analytical framework for evaluating
     the tradeoffs
   – Show what has been done with existing data
   – Draw some conclusions
                                                   3
Uses of the Pacific sardine resource in the
      California Current Ecosystem

                                                              Direct use
                 Other ?                                      as harvest


                                                                              - Human Consumption
                                                                              - Bait: commercial, recreational
                                                                              - Aquafeed: fresh/frozen, meal/oil
                                   Sardine Ecosystem Sevices in
                                       the California Current
                                            Ecosystem



Forage for ecologically                                                    Forage for commercial
important species: gulls, orcas,               Indirect Use                predators: salmon,
toothed whales, sea lions, fur                   as forage                 albacore, coastal sharks,
seals, baleen whales                                                       whiting


                                       Forage for recreational
                                       predators:salmon,
                                       albacore, coastal sharks




                                                                                                                   4
• Summarize as follows


 $


         Marginal Net Benefit
         from Harvest
                                     Marginal Net Benefit
                                     from Forage


 $*




                                H'
      Quantity of Harvest             Quantity of Forage




                                                            5
• The analytical framework to address this issue:
  – Suppose that the catch of sardines is reduced by S
  – The value of this incremental sardine stock as forage would be
    given by

      (1)    a i
              S Pib
                i
                 i


    • Where:
       – i indexes species that feed on the sardine,
    – Pi is the price (net of fishing costs) of species i,
       – ai is the share of the incremental sardine stock that is eaten by
         species i, and      
       – bi is the transfer efficiency, the fraction converted to predator
         biomass

  – If the sardine is more valuable as commercial landings than as
    forage fish the following must hold:

      (2)   P 
             ii i
                 b
            s S SPa
                     i

      • Where Ps is the market price of sardine, net of fishing costs.       6
• The predators of the sardine are not all
  commercially valuable
   – Dividing the right hand side of (2) into commercial and non-
     commercial predators, and canceling the S on both sides, gives

           s 
             iii j j
              ba
       (3) P P vb  a
                i        j


     Where:
       • v is a non-market average value per unit of biomass growth of non-
         commercial predators attributable to sardine consumption
       • i is an index for the commercially valuable species
       • j is an index for the non-commercial species
       The right hand side is the value of the increase in the amount of
         sardine predators provided by a unit increase in the sardine stock
   – The Pi’s and v have to be large enough to reverse the inequality
     for sardine to be more valuable as forage species
• Calculate the critical value of v, that turns (3) into
  an equality
                                                                          7
• We used the data published in Field et al. (2006)
  to identify sardine predators and to calculate
  values for the parameters a and b for each
  predator k
• Prices, P, are real average exvessel prices over
  the 1998-2006 period




                                                  8
•    Critical value of v under different pricing scenarios:
    1. Base case, v = $6.78/kg
       •   The annual net benefit of a one kg increase in the biomass
           of all non-commercial predators induced by the incremental
           supply of sardines as forage.
    2. Five-fold increase in the price of sharks to reflect
       their potential recreational value: from $1.73 to
       $8.47/kg, v = $0.0/kg
       •   The increase in the value of sharks would suffice to make
           the sardine more valuable as forage.
    3. 20% increase in salmon and albacore prices with a
       20% decrease in price of sardines, v < $0.0/kg
       •   These price differences are within the range of prices for
           the 1998-2002 period, indicating that the value of sardine as
           forage is quite sensitive to realistic changes in its own price
           and those of commercially relevant predators.


                                                                        9
•    Critical value of v under different
     biological/ecological parameter scenarios:
    1. Increase the transfer efficiency, b, to .02 for salmon,
       albacore and coastal sharks, v = $3.81/kg
       •   A higher transfer efficiency by itself would not make
           sardine sufficiently valuable as forage for the commercial
           predators alone at the assumed baseline biological
           parameter values and exvessel prices.
    2. Increase the share of sardines in the diets of
       salmon, albacore and coastal sharks by 40%,
       v < $0.0
       •   If increased consumption of sardines by commercial
           predators is realistic, it would imply that the sardine stock is
           more valuable as forage fish than as commercial catches.


                                                                         10
• Conclusions:
   – The total value of forage species is derived from their commercial
     harvest value and their value as prey for commercially, recreationally
     and ecologically important stocks

   – To quantitatively model this situation requires a great deal of detailed
     economic and ecological data
       • On the economic side
           – Market values
                 » the net benefits of harvesting sardines and their commercial predators rely
                    on market prices and costs associated with their harvest
           – Non-market values
                 » recreational catches are not sold
                 » ecologically important species are public goods
       • On the ecological side
           – Identify sardine predators
                 » the proportion of the sardine biomass that is consumed by each predator
                 » transfer efficiencies

   – The relationships that have been modeled here are likely to be non-
     linear and dependent on the relative abundance of sardines and their
     predators

   – Management strategy likely to vary with the composition of the forage
     base
       • Composition of forage base determined by environment
                                                                                            11
                                  Pacific sardine, Pacific mackerel and Northern anchovy biomass estimates (mt) and NE Pacific Ocean cumulative
                                  sea surface temperature, 1932-2009.

               6,000,000                                                                                                                                                 12.0000

                                                                                                                                                                         10.0000
                                                                                                           Sardine Biomass
               5,000,000                                                                                                                                                 8.0000
                                                                                                           Anchovy Biomass

                                                                                                           Mackerel Biomass                                              6.0000
               4,000,000                                                                                   Cumulative SST                                                4.0000




                                                                                                                                                                                   Cumulative Anomaly
                                                                                                           Anomaly
Biomass (mt)




                                                                                                                                                                         2.0000
               3,000,000
                                                                                                                                                                         0.0000

                                                                                                                                                                         -2.0000
               2,000,000
                                                                                                                                                                         -4.0000

               1,000,000                                                                                                                                                 -6.0000

                                                                                                                                                                         -8.0000

                      0                                                                                                                                                  -10.0000
                           1932

                                  1936

                                         1940

                                                1944

                                                       1948

                                                              1952

                                                                     1956

                                                                            1960

                                                                                   1964

                                                                                          1968

                                                                                                   1972

                                                                                                          1976

                                                                                                                 1980

                                                                                                                        1984

                                                                                                                               1988

                                                                                                                                      1992

                                                                                                                                             1996

                                                                                                                                                    2000

                                                                                                                                                           2004

                                                                                                                                                                  2008
                                                                                                 Year


                                                                                                                                                                                                        12
• Species by trophic level and trophic category.




                                                   13
Regression of the average trophic level of California commercial fishery landings
on forage stock biomass, 1932-2009.
Stock                Coefficient           P-value|            N
P. sardine           -1.52e-07             0.000               78
P. mackerel           2.04e-07             0.030               78
N. anchovy            2.08e-07             0.022               46




                                                                                    14
• Ecological data:
   – Field, J.C., R.C. Francis and K. Aydin. 2006. Top-down modeling
     and bottom-up dynamics: Linking a fisheries-based ecosystem
     model with climate hypotheses in the California Current.
     Progress in Oceanography 68:238-270.




                                                                  15
Predators, ecological parameters, shares of sardine eaten by predators
(a), and prices of sardine and its predators.
                                                                  Price
    Predator          d      S/km2     g        b        a       ($/kg)
Salmon               0.010    0.367 0.930 0.1600      0.13168      3.50
Albacore             0.050    0.014 0.360 0.0500      0.03111      1.76
Coastal sharks       0.050    0.050 0.180 0.0600      0.04630      1.73
Common murres        0.001    0.009 0.100 0.0008      0.00694
Gulls                0.001    0.002 0.120 0.0010      0.00148
Orcas                0.005    0.001 0.020 0.0020      0.00031
Toothed whales       0.050    0.052 0.070 0.0025      0.44939
Sea lions            0.010    0.012 0.074 0.0050      0.01096
Fur seals            0.010    0.006 0.091 0.0025      0.01348
Baleen whales        0.090    0.075 0.037 0.0050      0.30834
Sardine                       0.663                                0.10

				
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