How fish sense the world around them

Fish sense the world around them in many ways. While most fish possess sight, hearing, taste, and smell senses, all of which we can easily relate to, they also have sensory means for detecting stimuli, such as water particle displacement, and in some fish, electrical currents. These later sensory perceptions, take advantage of the physical and chemical properties of water, and work in conjunction with the more conventional sight, hearing, taste, and smell sensory modes. Let’s explore them!

The lateral line – In an effort to help you visualize the structures that make up a lateral line, picture the lateral line as being a river. On a fish, this river is a lateral line canal. The lateral line canal is filled with endolymph; the same fluid that’s in our inner ear. Below the river, running parallel to it is ground water. This, on a fish is nerves. At various locations along the river there are springs connecting the ground water to surface water. That point of connection is the spring heads, which on fish are called neuromasts. Neuromasts connect the nerves to the lateral line canal, and that connection through the neuromasts allow fish to sense mechanical changes in water.

Each neuromast is comprised of hair cells. Like all hair cells, those of the lateral line are contained in hair bundles. The hair bundles grow longer from one edge of the bundle to the other. These hair bundles are covered by a flexible and jellylike cupula (essentially a cup) that connects the bundles with canal fluid, or in some cases with the water surrounding the fish. The cupula are sensitive to movements of the watery endolymph fluid through the canal. Pressure changes bend the cupula, and in turn bend the hair cells inside.

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Schooling Fish

Who hasn’t sat in awe, watching large coordinated schools of fish, shimmering in unison through complicated maneuvers with each member precisely spaced apart? These schools seem to effortlessly turn, expand, contract, wishbone apart and then come back together…all without missing a beat.

There are actually two types of fish aggregations – schools and shoals. A shoal is a loose aggregation and sometimes comprises different species. These fish hang out together for social reasons but are not organized. Schools, are shoals on steroids. They are highly structured and coordinated. There is no clear rule for calling a shoal a shoal and a school a school, since all schools are shoals by definition.

The shape of a shoal can vary widely. Traveling shoals, may appear as long, thin lines, or they may be oval, square, or akin to an oozing splat. However, fast moving, traveling schools are generally wedge shaped. And, feeding shoals tend to be circular.

Why do fish Shoal/school? There’s a few theories on this. First, the regular spacing of fish in schools suggests that there’s probably a hydrodynamic advantage to being in a school – at least for fish that are behind other fish. Another advantage is increased ability for finding food. Fish that shoal throughout their lifetimes also have a reproductive advantage. They don’t have to expend energy to find a mate, its right there.

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Baby sport fish need Estuaries



Perhaps the most well-known function of estuaries, such as Charlotte Harbor, is their role as nursery grounds for growing fish, shrimp and shellfish. Very few marine species spawn in estuaries, but estuaries are used extensively as nursery grounds.

Most fish and crustaceans (crabs, shrimp, etc.) spawn offshore. The eggs are typically planktonic (free floating). Eggs develop into larvae that depend upon tides and currents to transport them to suitable habitats to settle out and grow within. Settling young fish and crustaceans utilize a number of different survival strategies, but common to all is a quest to not be eaten.

Redfish, sand sea trout, southern kingfish and spot larvae for example, when ready to settle as juveniles, look for low salinity waters associated with river mouths. Low salinity waters tend to support less predator fish than higher salinity waters. In fact, three times as many piscivores (fish eaters) are found in lower Charlotte Harbor – where the water is deeper and saltier – than are found in the upper harbor. So, if your survival strategy is not to be eaten, river mouths associated with the upper harbor are good places to be – that is, if you can tolerate low salinities.

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2017 Earth Day Mail Art Competition

UF/IFAS Extension Pinellas County invites you to celebrate Earth Day by getting in touch with your artistic side! Pick up your colored pencil, paintbrush, or scissors and get creative! The 2017 Earth Day Mail Art Competition is currently accepting submissions of original, handmade artwork from all ages in 3 categories- Love Tampa Bay, To Earth With Love, and Plastic Aware. Residents of Tampa Bay counties may submit one distinct creative piece per category. Age groups are broken down into youth (<12 years old), teens (13-18 years), and adult (18+). There will be 3 prizes awarded in each category.  For full contest rules and prize details click here.


#LoveTampaBay – Show us why you love Tampa Bay’s waters and wildlife
#ToEarthWithLove – Show us how you give back to the earth, whether it is through recycling, composting, conserving water, educating, etc.
#PlasticAware – Show us how plastics are impacting the environment and/or communities (people)

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The Cortez Commercial Fishing Festival: Fishing for our Future

This year marks the 35th anniversary of the annual Cortez Commercial Fishing Festival. For one weekend in February, this tough and tiny village will open its doors to thousands of visitors to share the proud history and culture of one of Florida’s last true working waterfronts.

Settled by fishermen from North Carolina in the late 1800s, Cortez has never stopped fishing. Its people have withstood hurricanes, wars, recessions and storms of regulations. The village has had to adapt to shifting sands – but the perseverance and grit of the people have never wavered. Today it remains a true testament to the “real” Florida.

This region has supplied bountiful seafood to humans for thousands of years. Fishing here is good for a reason. Nestled among mangroves on Sarasota Bay, Cortez is positioned between two nationally accredited estuaries. Quick translation: the habitat here is pretty special. However, like so much of Florida, Cortez faces threats associated with an increasing human population and ever-encroaching development. But unlike so much of Florida, where similar places have simply been swallowed by the concrete, Cortez has been fighting back.

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A Salty Heritage: Celebrating the Fishing History of Tampa Bay

The National Sea Grant Program is celebrating 50 years of Science Serving America’s Coasts (for a 30 second video, or even better, a 10 minute video). To commemorate Sea Grant’s cherished history of working with fishing communities, UF/IFAS Extension Florida Sea Grant Agents Libby Carnahan (Pinellas) and Angela Collins (Manatee, Hillsborough, Sarasota) hosted “A Salty Heritage: Celebrating the Fishing History of Tampa Bay.” The program, held at Weedon Island Preserve in December 2016, was open to the public and highlighted the bounty and diversity of fishing opportunities within the Tampa Bay region. Invited panelists included commercial and recreational representatives, and featured crabbers, seafood wholesalers, and fishermen. Each speaker told tales from their past, provided insight into their industries, and shared their visions for the future.

John Stevely, UF/IFAS Extension Florida Sea Grant Agent emeritus, talks about the history local working waterfronts in Tampa Bay; notably the sponge industry in Tarpon Springs and mullet in Cortez. Other panelists included (from left to right) Dawn Ayelsworth, Bob Ayelsworth, Jason DeLaCruz, Larry Borden and Gus Muench.

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Sea Grant 50th Anniversary Program: Celebrating the Fishing History of Tampa Bay


Photo credit: Hubbard’s Marina

Sea Grant is turning 50! Come and Celebrate 50 Years of Putting Science to Work for America’s Coastal Communities.

What: A Salty Heritage: Celebrating the Fishing History of Tampa Bay

When: Saturday, December 3, 2016

Where: Weedon Island Preserve Cultural and Natural History Center, 1800 Weedon Drive, St. Petersburg, FL 33702

About: Tampa Bay has a rich heritage as a fishing community. To celebrate Sea Grant’s 50th Anniversary, we are holding a Marine Science Open Classroom (10 am – 12 pm) that will be fun for the whole family! Then we’ll have cake and refreshments in the lobby (12 – 1 pm), and will proudly finish the day by hosting some of the saltiest fishermen in the bay for an open panel discussion (1 – 3 pm) with the audience! Invited panelists range from crabbers, spearfishers, wholesalers, and recreational and commercial anglers. Each speaker will tell tales from the past, provide insights into their profession, and give us a glimpse of what they see as they look to the future. A question and answer session will follow the panel discussion.

We hope that you will join us for part (or all) of the day to learn about the resources Tampa Bay provides to our community.

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2016 Annual Cortez Fishing Festival Celebrates Community’s Commercial Fishing Heritage

A fishing boat docks along the working waterfront of Cortez

A fishing boat docks along the working waterfront of Cortez village.

If you love seafood and want to savor a taste of Florida’s history, then you don’t want to miss the annual Cortez Commercial Fishing Festival (February 13 & 14, 2016).

Cortez village represents one of the last working waterfronts on Florida’s Gulf coast that is dedicated to commercial fishing. Each year, tough and ingenious Cortezians join together to celebrate and share the history and proud heritage of their community at the Cortez Commercial Fishing Festival. This two-day event allows festival-goers to enjoy live music, clog dancing, boat rides, marine life exhibits, nautical arts & crafts, beautiful waterfront vistas – and of course, plenty of delicious local seafood! Trust me, you do not want to miss out on the mullet hot dog. This year’s Festival marks its 34th anniversary.

Cortez has been a center of commercial fishing since the Spanish colonial era, and prior to that, Native Americans depended upon the region for its abundant marine life. This little village has withstood the test of time, surviving hurricanes, red tides and storms of regulations, habitat degradation and economic upheavals. The annual festival showcases how the pioneering spirit of fishermen past continues today in the industrious locals who carry on the community’s legacy.

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Water Quality: Who’s Monitoring Charlotte Harbor’s Water?

hands holding up globeMaintaining good water quality is essential to maintaining the health of our harbor. Water quality refers to the condition of water relative to legal standards, social expectations or ecological health. In order to track water quality conditions in the harbor and identify specific areas of concern, long term water quality monitoring is a must.

A number of organizations conduct water quality monitoring water quality in Charlotte Harbor and its adjacent tributaries. What follows is a look at some of the organizations who conduct water quality monitoring and the reasons why:

FDEP, Charlotte Harbor Aquatic Preserves Volunteers – Conduct monthly sunrise sampling at 40+ fixed locations from Lemon Bay to Estero Bay. Initiated in 1996, trained volunteers sample mostly near shore shallow waters. Sunrise sampling serves to identify Dissolved Oxygen levels (necessary for plant & animal survival) at their lowest levels.

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Attention Captains – Join Us for a For-Hire Fishing Workshop

Click on image to enlarge

Click on image to enlarge

Join us for an exciting opportunity! This “For-Hire” fishing workshop from Florida Sea Grant and UF/IFAS Extension will give you new ideas and proven advice that will help you grow your fishing business! You will connect with experts in your community, learn how to get involved in fisheries research opportunities, and get answers to the business questions and challenges that will keep you ahead of the competition. Workshop topics will include: Accounting practices to help you at tax time, Using the Visitors Bureau to market your business, Fish health and how you can help researchers, State and Federal fisheries management updates, And much, much more! New this year: Join us for our Captain’s panel and share time! Captains Ralph Allen, Dan Cambern, Mike Myers and Jay Withers will be on deck to answer your questions and lead everyone in some active discussion.

Need to know: The workshop will take place from 8:30 a.m. – 3:30 p.m. on Wednesday, September 9th, at the Charlotte County Eastport Environmental Campus, 25550 Harborview Rd., Port Charlotte, FL 33980. The cost is $20 and includes materials, lunch and refreshments. Registration is online at: https://for-hire15.eventbrite.com or contact the organizer at staugler@ufl.edu or (941) 764-4346.

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