South Africa Region |

Region Summary Plots | Individual Stock Summary Plots (PDF)

Number of individual stocks:	21
Number of taxonomy groups represented by stocks:	8
Earliest year with available data in this region:	1900
Latest year with available data in this region:	2020

REGION SUMMARY PLOTS

Biomass Coverage (all stocks combined) — This describes the year range of data covered in the most recent assessment for each stock, beginning in 1950. Each bar represents an individual stock, sorted vertically from largest to smallest by average biomass over the time series.

Relative Biomass, Exploitation Rate, and Catch Trends (all stocks in region) — This describes the trend in ratios of B/Bmsy, U/Umsy, and catch/(mean catch) across assessed stocks in the region. These trends are based on outputs from a state-space model developed during the Science for Nature and People Partnership (SNAPP) working group “Measuring the status of fisheries and factors leading to success” (method implemented by Cóilín Minto). Regional mean trends follow a random walk on the log scale with fixed-effect deviations per stock and autoregressive observation error within a stock. Not all stocks have estimates of B/Bmsy, U/Umsy, or catch/(mean catch) in every year, so mean trends account for which stocks are represented in any given year (the fraction of stocks represented is shown as ‘Coverage’). Boxplots and medians (red points) reflect available data in each year. Geometric means (orange line) are rescaled to the median in years of high coverage, as we require a robust measure of central tendency that should be close to the median in high coverage years.

Status of Assessed Stocks — The left panel shows the most recent estimate of status for individual stocks relative to MSY-based reference points. Circle areas are proportional to MSY for the stock. The ‘+’ and ‘x’ symbols show the bivariate geometric mean and bivariate median values, respectively, across all stocks in the region. The right panel shows temporal trends in regional mean biomass and fishing mortality relative to MSY-based reference points, based on state-space model outputs.

Added Productivity Time Series (top 4 individual stocks) — This describes annual surplus production (net increase of biomass plus catch) over time since 1950 for the four stocks with the highest average biomass in the region.

Added Productivity vs. Biomass (top 4 individual stocks) — This shows annual surplus production compared to annual biomass over time (beginning in 1950) for the four stocks that contribute the most to surplus production in the region.

To download all plots for this region in one pdf, click here: Summary Plots – South Africa

Biomass Coverage

All stocks in region

The below plot identifies the individual stocks from the above plot sorted from highest to lowest average biomass without scaling.

Relative Biomass, Exploitation Rate, and Catch Trends

Trends of all stocks in the region (Coverage variable indicates how many stocks are represented in each year)

Status of Assessed Stocks

On the left: the most recent estimate of status for individual stocks relative to MSY-based reference points. Circle areas are proportional to MSY.

On the right: trends in regional mean biomass and fishing mortality relative to MSY-based reference points