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Can fisheries under catch shares better track management targets ?. Michael Melnychuk, Tim Essington, Olaf Jensen, Trevor Branch, Ana Parma, John Pope, Tony Smith, Jason Link, Selina Heppell, Steve Martell . Pew Charitable Trusts Webinar November 3, 2011.
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Can fisheries under catch shares better track management targets ? Michael Melnychuk, Tim Essington, Olaf Jensen, Trevor Branch, Ana Parma, John Pope, Tony Smith, Jason Link, Selina Heppell, Steve Martell Pew Charitable Trusts Webinar November 3, 2011
Catch shares →Allocation of quota to individuals such that competition among individuals is reduced
Do catch share fisheries better track management targets • than fisheries not under catch shares ? • targets: annual quota (C/Q) • exploitation rate target (F/Ftarget) • biomass target (B/Btarget) • Hypotheses: • Adherence to targets: catch shares > quota only > effort controls • Strength of response: C/Q > F/Ftarget > B/Btarget
Target F F F 4 metrics: Mean SD(target) Minor exceedance Major exceedance F : Ftarget
Summary of response variables C/Q n = 259 stocks F/Ftarget n = 172 B/Btarget n = 205 Frequency Mean C/Q Mean F/Ftarget Mean B/Btarget
Variables of interest Responses Predictors 3 ratios with management targets: Catch/quota F/Ftarget B/Btarget Catch control type Other covariates accounted for: Region Taxonomic/habitat-association Year of fishery development Average catch Lmax Propensity for being under catch shares X 4 metrics: Mean SD(target) Minor exceedance Major exceedance
C/Q analysis SD(target C/Q) Mean C/Q Minor (10%) overages Major (25%) overages Catch shares Partial catch shares Quota only * * Coefficient estimate
F/Ftarget analysis Minor (10%) over-exploitation Major (50%) over-exploitation SD(target F/Ftarget) Mean F/Ftarget Catch shares Partial catch shares Quota only Effort regulations * Coefficient estimate
B/Btarget analysis Minor (10%) depletion Major (50%) depletion SD(target B/Btarget) Mean B/Btarget Catch shares Partial catch shares Quota only Effort regulations Coefficient estimate
Summary • Compared to non-catch shares, catch share fisheries had: • less variability in C/Q • less frequent (major) overfishing • Effects of both quota management and catch shares • Catch shares are one of many possible tools that can be used to help meet management objectives • Next step: what particular aspects of catch share systems tend to lead to the outcomes we’ve observed ?
Thank you: Data collection: Kate Stanton, Rachel Finley, Jordan Watson RAM Legacy database: Dan Ricard and all contributors Interviews: U.S. – Alaska: J. DiCosimo, J. Heltzel, M. Fina, S. Hare, S. Kelley, J. Regnart; U.S. – W Coast: J. DeVore, M. Burner, C. Niles, I. Stewart; U.S. – NE/Mid-Atl. Coast: C. Legault, T. Chute, D. Hart, J. Idoine, G. Shepherd, B. Beal, N. Meserve, K. Taylor, B. Spear, D. Boelke, T. Hoff, K. West, J. McNamee; U.S. – SE Coast/G. Mexico: J. McGovern, P. Hood, A. Strelcheck, S. Gerhart, J. Kimmel, J. Smith; Canada – W Coast: A. Keizer, B. Ackerman, W. Li Ou, P. Ridings, J. Rogers, J. Schweigert, E. Wylie, M. James; Canada – E Coast: P. Cahill, V. Docherty, J. Hansen, D. Coffin, M. Baker, D. Ball, H. Bishop, J. Buie, S. Campana, G. Chouinard, J. Conlin, P. Couillard, A. Frechet, J. Gaudette, C. Hendry, P. Koeller, M. LeCouffre, L. Legere, D. Lemelin, B. Lester, C. MacDonald, B. Morin, M. Moriyasu, D. Pezzack, D. Roddick, A. Rumbolt, T. Siferd, J. Simon, S. Smith, G. Stevens, H. Stone, C. Waters, R. Federizon; Europe: J. Sigurjónsson, J. Horwood, B. Deas, A. LeGarrec, C. Olesen, M. Anderson, M. Welvaert, G. van Balsfoort, P. Breckling, N. Holdsworth; Australia: C. Dichmont, N. Klaer, G. Tuck, S. Wayte, S. Auld, S. Gaddes, S. Koh, S. Weekes, B. Taylor, K. Crosthwaite, T. Ward, C. Gardner; New Zealand: D. Foster, D. Sykes, G. Clement; Argentina: J. Hansen, A. Giussi, M. Renzi; South Africa: A. Brandao, D. Butterworth, S. Halloway, S. Johnston, C. de Moor, R. Rademeyer, G. Maharaj, R. Bross, A. Badenhorst. Funding: Lenfest Ocean Program
Catch/quota ratios n = 130 Probability density ▬ Alaska, U.S. ▬ West coast, U.S. ▬ West coast, Canada ▬ East coast, Canada ▬ Europe ▬Australia ▬New Zealand ▬ Other n = 41 ▬ Frequency n = 88 Mean C/Q SD(target C/Q)
F/Ftarget ratios n = 54 Probability density n = 24 ▬ Alaska, U.S. ▬ West coast, U.S. ▬ NE & mid-Atl., U.S ▬ Europe ▬New Zealand ▬ Other ▬ Frequency n = 67 n = 27 Mean F/Ftarget SD(target F/Ftarget)
B/Btarget ratios n = 67 Probability density n = 28 ▬ Alaska, U.S. ▬ West coast, U.S. ▬ West coast, Canada ▬ NE & mid-Atl., U.S. ▬ Europe ▬Australia ▬New Zealand ▬ Other ▬ Frequency n = 82 n = 28 Mean B/Btarget SD(target B/Btarget)
Catch share propensity scores • Controls for non-random application of catch share “treatments” • Logistic regression: • CS ~ Region + Habitat + avCatch + devYear + Lmax • Use estimated coefficients to predict probability of each fishery being under full catch shares during 2000–2004 • Use propensity scores as covariates in subsequent analyses
Catch share propensity scores Habitat Region Catch control Average propensity score
Propensity score matching ● Actual full CS X Actual non-CS
Propensity score matching Mean C/Q SD(target C/Q) Minor (10%) overages Major (25%) overages 2.5th %ile 97.5th %ile Mean F/Ftarget SD(target F/Ftarget) Minor (10%) overfishing Major (50%) overfishing Grand mean of: ResponseCS – ResponseNon-CS Mean B/Btarget SD(target B/Btarget) Minor (10%) depletion Major (50%) depletion Mean difference of response variable
Proportion of stocks in some undesirable state C/Q Probability of exceedance F/Ftarget B/Btarget (OK) (Bad)
C/Q Minor (10%) overages Major (25%) overages SD(target C/Q) Mean C/Q Catch shares Partial catch shares Quota only Average catch Development year Lmax Propensity score * * Fixed effect coefficients (full model) Random effect conditional modes
F/Ftarget Minor (10%) over-exploitation Major (50%) over-exploitation SD(target F/Ftarget) Mean F/Ftarget Catch shares Partial catch shares Quota only Effort regulations Average catch Development year Lmax Propensity score Fixed effect coefficients (full model) Random effect conditional modes
B/Btarget Minor (10%) depletion Major (50%) depletion SD(target B/Btarget) Mean B/Btarget Catch shares Partial catch shares Quota only Effort regulations Average catch Development year Lmax Propensity score Fixed effect coefficients (full model) Random effect conditional modes
Filters applied • Excluded oceanic sharks/tunas • Excluded rarely targeted stocks • Excluded stocks with catch shares or TACs established during 2000-2004 • Excluded stocks with missing time series data or reference points • Excluded stocks whose assessments were not trustworthy (F, B only) • Excluded stocks with >50% landings in recreational sector • Excluded fisheries under moratorium 2000-2004 (C/Q, F only)
Sensitivity tests • Removed propensity score covariate • Excluded stocks whose Ftarget or Btarget reference points were estimated with Schaefer model • Excluded ICES/NAFO-managed stocks • Excluded stocks with C/Q < 0.5 • Excluded stocks under moratorium (biomass analyses) • Considered only full catch share and quota-only categories big reduction in sample size
Mixed-effects model analysis Y ~ (CControl + PS) + avCatch + devYear + Lmax+ Region + Habitat Y ~ (CControl + PS) + devYear + Lmax+ Region + Habitat Y ~ (CControl + PS) + avCatch + devYear+ Region + Habitat Y ~ (CControl + PS) + avCatch + Lmax+ Region + Habitat Y ~ (CControl + PS)+ Region + Habitat Y ~ Intercept + avCatch + devYear + Lmax+ Region + Habitat Y ~ Intercept + devYear + Lmax+ Region + Habitat Y ~ Intercept + avCatch + devYear+ Region + Habitat Y ~ Intercept + avCatch + Lmax+ Region + Habitat Y ~ Intercept+ Region + Habitat Catch control included Catch control not included
Current exploitation rate to target exploitation rate (F/Ftarget) Current catch to current quota (C/Q) Current biomass to target biomass (B/Btarget) Type of response variable : Metric for each response variable : Exceedance of major undesirable threshold e.g. P(C/Q > 1.25) Standard deviation around target e.g. SD(target C/Q) Exceedance of minor undesirable threshold e.g. P(C/Q > 1.1) 5-year mean e.g. mean C/Q