Fish Abundance in Charlotte Harbor Estuary

Written by Dr. Lisa Beever | 02 November 2009

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Having an understanding of the health, diversity and abundance of fish in our estuaries is a key to understanding the health of the estuary itself.

In Charlotte Harbor, we are very fortunate to have long-term scientific monitoring of fish. The Fisheries-Independent Monitoring (FIM) program was established in Charlotte Harbor in 1989 by the Florida Marine Research Institute (FMRI). Although FMRI is now the Fish and Wildlife Research Institute (FWRI) and is now housed in the Florida Fish and Wildlife Conservation Commission,data collection has been consistent

From time to time, collection areas have been expanded and special studies have been conducted in places such as Estero Bay and Lemon Bay. This provides a rich source of data that spans two decades in some areas.

Fish Abundance 2004-2007 (fish per 100 square meters) - Average fish abundance by bay segment is shown on the map. Fish data were collected in Charlotte Harbor (A, B and C), Pine Island Sound (D), Pine Island (E), Matlacha Pass (G), and the 3 large rivers which feed Charlotte Harbor, the Caloosahatchee River (H), the Myakka (M) and the Peace (P).

I recently had the pleasure of performing statistical analysis on the data compiled from 1989 through 2008. Thank you to Phil Stevens with FWRI for providing me the data and supporting information! To evaluate fish community structure, we controlled for the type of gear and the unit effort (fish per 100 square meters); therefore, the analysis was limited to 1996 to present.

Pictured above, juvenile snook in shallow river. Those areas that have lower diversity and abundance, such as the lower rivers, are very important nursery habitat. In fact, the low diversity and abundance is what allows the little guys to better avoid being eaten and survive to maturity.

From 1989–1994, fish data were collected in Charlotte Harbor A, B and C as well as Myakka (M) and Peace (P). Then in 1994, Pine Island Sound (D) is added, though the type of gear that we are using in this analysis was not started until November 2003. By 2003, data collection was expanded to include Pine Island (E), Matlacha Pass (G) and Caloosahatchee (H).

In 1996, new gear was added to expand the search for fish. Since 1996, both fish diversity and abundance has declined at a statistically significant level.

Abundance and diversity tend to run counter to one another. Places of high abundance tend to be places of low diversity. As shown on the map, Pine Island Sound has relatively high fish abundance between 2004 and 2007. Fish abundance is also high around inlets.

I would be interested to hear from anglers. Is what I have shown consistent with your experience? I am also interested in getting additional data sets from area scientists. For me, a day with data is like a day of sunshine!