Anchovy Population Growth

by Eric Edinger

 

Submitted : Fall 2018

In 2018 Floridians were affected by a massive red tide event centered around Sarasota and all along the gulf coast in varying concentrations. Red tide is an event caused by an increase in unicellular microorganisms caused by excess nutrients in the water (Alcock, 2007). The large die offs of fish have been shown to kill off nearly 90 percent of reef and sport fish (Alcock, 2007). The focus of this project is to measure the time it takes for a population of Anchovies to recover from a devastated state to a healthy one. I used Verhulst’s logarithmic growth model to estimate population growth rate of Anchovies over their spawning season from May to August . I determined the total the K value as 1.5 million representing the number of anchovies to be considered a healthy population (CES, 1992). I then removed 90% of the K value (representing the 90% that was mentioned earlier) in order to get an initial value representing the aftermath of a red tide event (CES, 1992). Then based on the information that anchovies are capable of breeding at 2 months of age representing the r value, I used this to graph the population over a period of 16 weeks (Lisovenko, 1996). The anchovies multiply rapidly and as they reach physical maturity in 2 months new generations are capable of reproduction in the same spawning season (Lisovenko, 1996). This leads to the issue that this specie’s proliferation rate makes them resistant to long term damage but not immune from red tide.

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