Table 3.
Optimal harvest control rules (HCRs) for three alternative management objectives, maximizing either total welfare, total profit, or total yield, for different discount rates (0%, 2%, and 4%). Emerging harvesting properties for 2004–2053 are given as temporal means (with coefficients of temporal variation in parentheses) for catch ratio, total allowable catch (TAC), spawning-stock biomass (SSB), total profit, and total welfare. The catch ratio is the emerging ratio between TAC and total biomass of individuals aged 3 years or older.
| Objective | Fmax (yr−1) | Bmax (1000 tonnes) | Catch ratio | TAC (1000 tonnes) | SSB (1000 tonnes) | Total profit (million NOK) | Total welfare (million NOK) |
|---|---|---|---|---|---|---|---|
| Maximize total welfare | |||||||
| 0% discount ratea | 0.54 | 640 | 0.248 (0.039) | 431 (0.064) | 571 (0.058) | 3410 (0.049) | 4520 (0.065) |
| 2% discount ratea | 0.54 | 640 | 0.248 (0.039) | 431 (0.064) | 571 (0.058) | 3410 (0.049) | 4520 (0.065) |
| 4% discount rate | 0.58 | 160 | 0.260 (0.026) | 436 (0.051) | 526 (0.057) | 3375 (0.042) | 4512 (0.055) |
| Maximize total profit | |||||||
| 0% discount ratea | 0.43 | 460 | 0.214 (0.027) | 408 (0.062) | 709 (0.09) | 3466 (0.053) | 4465 (0.067) |
| 2% discount ratea | 0.43 | 460 | 0.214 (0.027) | 408 (0.062) | 709 (0.09) | 3466 (0.053) | 4465 (0.067) |
| 4% discount ratea | 0.43 | 460 | 0.214 (0.027) | 408 (0.062) | 709 (0.09) | 3466 (0.053) | 4465 (0.067) |
| Maximize yield | |||||||
| 0% discount rate | 1.18 | 740 | 0.301 (0.038) | 445 (0.057) | 383 (0.029) | 3190 (0.043) | 4374 (0.058) |
| 2% discount rate | 0.79 | 200 | 0.307 (0.028) | 445 (0.047) | 367 (0.044) | 3164 (0.04) | 4347 (0.051) |
| 4% discount rate | 0.84 | 360 | 0.316 (0.03) | 444 (0.049) | 340 (0.052) | 3110 (0.04) | 4288 (0.053) |
a
The same optimal HCR is obtained for different discount rates.