1. Retrospective bioeconomic analysis of Fraser River sockeye salmon fisheries management
Dale Marsden, Steve Martell and Rashid Sumaila Fisheries Economics Research Unit Fisheries Centre University of British Columbia

2. Background: Sockeye salmon
Life cycle:
Anadromous and semelparous;
Migrate to the ocean during second spring;
Return to natal stream after two years of ocean life.
A key part of British Columbia’s economy and culture for centuries.
The core of the BC salmon fishery.
Drawing: Tim Knepp

3. Variability

4. Cause of variability: hypotheses
Depensatory fishing hypothesis
Historical ‘accident’ led to slight variability between years;
Strong fishing pressure reinforced and exacerbated variability through depensatory fishing mortality.

5. Cause of variability: hypotheses
Delayed density dependence
Large runs create poor growing conditions on freshwater rearing grounds;
These conditions then suppress several following years of juveniles;
System ‘resets’ after several years.

6. Question:
How much more profitable could the fishery have been if managed differently?

7. Modeling the hypotheses
For each of the nine “stock complexes”:
Depensatory fishing mortality hypothesis: Ricker model
Delayed density dependence hypothesis: Larkin model

8. Methods (1)
Use historical data to estimate parameters of Ricker and Larkin models (including wt).

9. Methods (1)
Use historical data to estimate parameters of Ricker and Larkin models (including wt).
Calculate management parameters
Optimal harvest rate (umsy)
Optimal escapement (Smsy)

10. Methods (1)
Use historical data to estimate parameters of Ricker and Larkin models (including wt).
Calculate management parameters
Optimal harvest rate (umsy)
Optimal escapement (Smsy)
Simulate the fishery using Ricker or Larkin to drive the biological dynamics, and using one of several harvest rules…

11. Methods (2) Harvest rules:
Fixed exploitation rate = umsy
Target escapement = Smsy
“Omniscient” yield-maximizing manager
“Omniscient” profit-maximizing manager
Use cost, price, catch and effort data to assess profitability of different scenarios.

12. Results…

13. Current profit (million 2000 CAD)
Ricker
Current profit (million 2000 CAD)
Larkin

15. Conclusions
Substantially more (35-200%) profit could have been generated if managers had known (and applied) in 1952 what we know today (umsy and Smsy).
Knowledge of recruitment anomalies (wt) would have had little impact.

16. Next steps Refine fishery model;
Bayesian decision analysis of future management options
incorporate uncertainty in parameters & models
Quantify trade-offs among objectives (e.g., profit, employment, conservation risks);

17. Thanks to:
Social Sciences and Humanities Research Council (SSHRC), Canada
Al Cass (Fisheries and Oceans Canada) for data