Fish assemblage in Arecibo, Puerto Rico

Background/Question/Methods

The mouth of the Arecibo River feeds directly into the Atlantic Ocean through the beautiful town of Arecibo, Puerto Rico. This river supports a diverse assemblage of salt water and fresh water fish including many amphidromous fish. Amphidromous fish migrate from salt water to fresh water or vice versa at some point in their lifespan. One amphidromous species in particular, Sirajo Gobies, or ceti as locals call it, has high cultural and economic value in Puerto Rico.  These ceti travel from fresh water to salt water to spawn and then the post larval fish travel back to fresh water to live. This migration to fresh waters is directly associated with the lunar cycle. My research revolved around these ceti by using bag seines and gill nets to get a sample and tally of fish assemblage close to the mouth of the river before, during, and after the ceti run. We wanted to see how these protein filled fish larvae affected the assemblage and diet of other fish in the area. After gathering all the data, it was entered and organized based on date, fish species, and number of fish.

Results/Conclusions

We found no strong, definite patterns of fish assemblage change associated with migrating post-larval ceti based on the 3^rd quarter lunar phase. There were, however, numerous accounts of a variety of predators feeding on the ceti. This proves that these ceti are not only valuable to humans but also an important source of food for the several predators in the Arecibo River. This study demonstrates that additional management regulations associated with short-term changers in the estuary fish assemblage of the Arecibo River may not be warranted.