Abstract

Nassau grouper (Epinephelus striatus) and Tiger grouper (Mycteroperca tigris) are species of reef fish known to form spawning aggregations. Throughout the year, these fish are solitary, posing a challenge for local fisherman, but during their annual mass aggregation they are easily exploited; resulting in declines of many Nassau grouper aggregations throughout their range. This study takes place on Little Cayman Island in the Cayman Islands. The Cayman Islands have passed strong protections for Nassau grouper spawning aggregations, resulting in one of the largest known aggregations being located on Little Cayman Island. Despite protections elsewhere, other aggregations have failed to recover. Some hypothesize that fertilization rates could be a cause of the populations’ failure to increase. This study focuses on analyzing the fertilization rates of the grouper populations in Little Cayman from 2014 - 2017 using various methods. A series of statistical analyses were used to evaluate the method of egg collection; compare egg morphometrics between spawning batches, and measure overall fertilization rates. Fertilization rates for Nassau grouper and Tiger grouper, during this time period on Little Cayman, represent an optimal rate for recovering unexploited populations. These rates can be used as a baseline to compare against other populations and to also aid in recovery plans.

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