Fig 1.
The study area of the application examples.
The Yucatan Peninsula, fishing grounds of the Mexican octopus fishery, and main communities involved in octopus fishing (CH, Champotón; SYB, Seybaplaya; CAMP, Campeche; IAR, Isla Arena; SI, Sisal; PR, Progreso; DB, Dzilam de Bravo; RL, Río Lagartos; CY, El Cuyo). Colored shaded areas and adjacent continental shelf correspond to the Campeche Bank.
Fig 2.
Maximum likelihood estimates of parameters and two standard errors bars of intra-annual generalized depletion models selected as best fits for the O. maya and O. americanus fisheries database in the Yucatan Peninsula, Mexico. a) Natural mortality rate, b) initial abundance, c) sum of abundance inputs during the season, d) scaling (note different multipliers for each species), e) effort response, f) abundance response.
Fig 3.
Weekly instantaneous exploitation rate (100*F/(F + M)) from intra-annual generalized depletion models applied to catch, effort and mean weight data in the fisheries for O. maya and O. americanus in the Yucatan Peninsula, Mexico. The thick black line marks the 40% exploitation rate.
Fig 4.
Biomass dynamics (green dots and lines, black lines and surrounding bands) and realized (blue bars) and sustainable annual harvest rates (TLP: total latent productivity) of two octopus species in the Yucatan Peninsula, Mexico. The arrow points to the timing set to trigger changes in parameters of the biomass dynamics, the symmetry of the production function (p) in O. maya and the carrying capacity of the environment (K) in O. americanus. CatDyn biomass are weighted by q(1/CV(Biomass))/(1/min(CV(Biomass))) where q = 0.3 and 0.15 in O. maya and O. americanus respectively, so more precise estimates appear bigger.
Table 1.
Model selection, surplus production model.
Comparison of surplus production model variants fitted to biomass and biomass standard errors predicted by intra-annual generalized depletion models applied to the fisheries for O. maya and O. americanus in the Yucatan Peninsula, Mexico. In both species changes in some parameter values happen from 2010 to 2011. Nº is the number of parameters. Best working model marked in bold.
Table 2.
Parameter estimates, surplus production model.
Maximum likelihood estimates of directly estimated parameters (K, p, and r) and derived reference points (MSY, BMSY, average total latent productivity (TLP)) of the best Pella-Tomlinson models for each octopus species, O. maya and O. americanus, in the Yucatan Peninsula, Mexico. MLE: maximum likelihood estimate; CV: coefficient of variation; TLP: annually averaged total latent productivity; : annually averaged landings.
Fig 5.
Stochastic biomass projections of the stock of O. maya and O. americanus in the Yucatan Peninsula 10 years into the future under five landings scenarios. Uncertainty bands (light blue polygons) correspond to two standard errors above and below the mean (blue lines) over 1000 replicates of the projections. These projections are implemented with parameters and standard errors of the selected Pella-Tomlinson model of each octopus species (Table 2). MSY: maximum sustainable yield; TLP: average total latent productivity; AL: average landings over the period 2000 to 2021.
Fig 6.
Spatial distribution of fishing effort.
Spatial coverage of octopus fishing events over four periods in the VMS database for octopus fishing in the Yucatan Peninsula. The top left panel shows the coverage in the pre-expansion period while the other three panels show the coverage during the post-expansion period.