An ichthyologist tags 48 fish in a reef and later captures a sample of 60 fish, finding that 6 are tagged. Using the capture-recapture method, estimate the total fish population in the reef.

Mon, 04 May 2026 13:34:33 +0000

**Why Tracking Fish Populations Matters—And How Scientists Estimate Reef Abundance** Ocean researchers are constantly seeking better ways to understand marine ecosystems, and one of the most reliable methods used today is the capture-recapture approach. This technique helps estimate wildlife populations using simple, repeatable fieldwork—without requiring invasive techniques or compromising animal welfare. Recent interest in this method has grown, fueled by global efforts to monitor reef health, track fish movement, and inform conservation policies. Through real-world experiments, like tagging and recapturing reef fish, scientists now offer practical insights into how restoration and biodiversity are measured. **The Science of Tracking Reef Fish Populations**
An ichthyologist tags 48 fish in a vibrant reef ecosystem and returns weeks later to capture a sample of 60 fish, uncovering that 6 bear those identifying tags. Using the capture-recapture method—a widely accepted statistical approach—this simple observation helps estimate the total fish population in the reef. The math is grounded in probability: if 6 out of 60 sampled fish are tagged, and 48 were originally tagged, the expected proportion represents the ratio of tagged to total fish. From there, scientists apply a formula to project the full population, offering a transparent and repeatable measure of biodiversity. This process is not theoretical. Field research across coral reefs, including tropical and temperate zones along the U.S. coastline, relies on these principles to assess population stability and resilience. The method is especially valuable in environments where direct counts are impossible due to fish mobility, reef complexity, and visibility constraints. By anchoring population estimates in observable data, researchers support sustainable management of marine protected areas.