What specific ecological metric must be rigorously tracked and maintained within defined thresholds to ensure 'Mizan' (balance) is upheld and overexploitation is prevented in a targeted fishery?

The specific ecological metric that must be rigorously tracked and maintained within defined thresholds to ensure 'Mizan' (balance) is upheld and overexploitation is prevented in a targeted fishery is Fishing Mortality (F), also known as the Exploitation Rate. Fishing Mortality quantifies the rate at which fish are removed from a population due to fishing activities. It measures the proportion of a fish stock that is harvested by fishing gear over a specific period, thereby directly indicating the fishing pressure exerted on the stock. In the context of fisheries, 'Mizan' represents the ecological equilibrium where the rate of fish removal through harvesting does not exceed the fish stock's natural capacity to replenish itself, ensuring the long-term health and productivity of the marine ecosystem. Tracking Fishing Mortality requires comprehensive data collection, including detailed records of catch (species, quantity, size, age), fishing effort (e.g., number of fishing days, gear types deployed), and biological surveys to understand stock structure. This data is then utilized in stock assessments, which are scientific analyses that estimate the current status of a fish population, including its size, biomass, growth rates, and the impact of fishing. To prevent overexploitation, Fishing Mortality must be kept below scientifically determined reference points. These reference points define the sustainable thresholds for fishing pressure. A key example is F_MSY, which represents the fishing mortality rate that yields the Maximum Sustainable Yield. This is the largest average catch that can be continuously taken from a stock over the long term without impairing its future productivity. Another critical threshold is a Limit Reference Point (LRP), such as F_lim, which signifies a fishing mortality rate that, if exceeded, carries a high risk of causing the stock to collapse or become severely depleted. Management interventions are directly linked to these thresholds. If the current Fishing Mortality is assessed to be above F_MSY or approaching F_lim, specific management measures are implemented to reduce fishing pressure. These measures can include setting Total Allowable Catches (TACs), which are limits on the total amount of fish that can be caught; restricting fishing effort, such as limiting the number of fishing vessels or days at sea; or adjusting technical measures like minimum landing sizes or gear specifications (e.g., mesh sizes to allow juvenile fish to escape). By actively managing Fishing Mortality to stay within these defined sustainable thresholds, managers ensure that the fish stock can adequately reproduce and grow, thereby preventing overexploitation and maintaining ecological 'Mizan'.