Barotrauma Basics

The arrow is pointing to an
inflated swim bladder

Many marine reef fish have a unique organ called a swimbladder. The gas-filled sac, which is attached to a fish's backbone beneath the dorsal fin, helps control buoyancy and allows the fish to maintain various depths in the water column. When a fish is brought up from depth during fishing, the decreasing pressure can cause the gases (mostly oxygen, nitrogen, and carbon dioxide) inside it's swimbladder to expand and rupture the organ. The escaped gases will continue to expand into the fish's body cavity, and the pressure exerted by them is sufficient to push the stomach out the mouth and the intestines out of the anus. Other symptoms may include a swollen belly or buldging eyes.




A grouper showing the signs of
barotrauma

This process, known as barotrauma, can result in serious injury to the fish and prevent if from returning back down to depth on its own if left in this state. Fish released in this condition may float away and die from exposure to the elements or become an easy target for predators.
Dealing with barotrauma has become as major challenge to fisheries managers. Allowing fish to simply float off after being released defeats the purpose of having regulations for minimum size restrictions and bag limits.
Several tools have been developed by researchers and fishermen to help address the issue of barotrauma.Venting involves inserting a hollow, sharpened needle into the side of a fish to release trapped gases so the fish is able to quickly return to a safe depth. Recompression involves returning a bloated fish to a safe depth with the aid of a cage, basket, or weighted hook or lip device.
Neither method is full proof or applicable in all conditions (or for all fish), but research studies have shown that when used in the right conditions venting and recompression can play an important role in  reducing mortality rates associated with fish suffering from barotrauma.
Stay tuned to learn more about these efforts as there are several initiatives at the local, state, regional, and national level to investigate the continued use of the conservation tools. In the meantime if you'd like to learn more about venting and recompression visit: catchandrelease.org

venting a red grouper

Returning a red grouper with a recompression device

FAO/ WHO Report of the Risks and Benefits of Fish Consumption Available

Interested in learning more about the relative health benefits and risks associated with eating seafood?

Recently a report by the Joint Food and Agriculture Organization (FAO) and the World Health Organization (WHO) Expert Consultation on the Risks and Benefits of Fish Consumption was published that provides a framework for assessing the net health benefits or risks of fish consumption. While the report itself it too long to share, below is a summary of what the report's expert panel concluded.

1. Consumption of fish provides energy, protein and a range of other important nutrients, including the long-chain n-3 polyunsaturated fatty acids (LCn3PUFAs).

2. Eating fish is part of the cultural traditions of many peoples. In some populations, fish is a major source of food and essential nutrients.

 

3. Among the general adult population, consumption of fish, particularly fatty fish, lowers the risk of mortality from coronary heart disease. There is an absence of probable or convincing evidence of risk of coronary heart disease associated with methylmercury. Potential cancer risks associated with dioxins are well below established coronary heart disease benefits from fish consumption.

4. When comparing the benefits of LCn3PUFAs with the risks of methylmercury among women of childbearing age, maternal fish consumption lowers the risk of suboptimal neurodevelopment in their offspring compared with the offspring of women not eating fish in most circumstances evaluated.

5. At levels of maternal exposure to dioxins (from fish and other dietary sources) that do not exceed the provisional tolerable monthly intake (PTMI) of 70 pg/kg body weight established by JECFA (for PCDDs, PCDFs and coplanar PCBs), neurodevelopmental risk for the fetus is negligible. At levels of maternal exposure to dioxins (from fish and other dietary sources) that exceed the PTMI, neurodevelopmental risk for the fetus may no longer be negligible.

6. Among infants, young children and adolescents, the available data are currently insufficient to derive a quantitative framework of the health risks and health benefits of eating fish. However, healthy dietary patterns that include fish consumption and are established early in life influence dietary habits and health during adult life.

To view the entire report visit:

http://www.fao.org/docrep/014/ba0136e/ba0136e00.pdf

Exploring the flats at low tide

Seagrass and mudflat communities at low tide are an excellent opportunity for curious onlookers to explore and see up close the myriad of coastal life these dynamic environments can support. In particular, these environments harbor a high diversity of invertebrates (animals lacking backbones) from egg sack-producing  worms to predatory snails hunting in the mud for a snack. For those who aren't afraid to get a little wet and muddy, they won't be disappointed at what they can find. I thought I'd "wet" your appetite by starting you off with a quiz of some of the invertebrates you might discover in these communities. Good luck! (I've provided you with some clues to help name them.) Answers are on the bottom.

1. Hint: this is nether an equine's support apparatus nor a true crustacean as the name implies.

2. Hint: Perhaps not a pretty as the flower that shares its name, but cool nonetheless.

3. Hint: check out its royal head gear.

4. Hint: No spinning webs for this crustacean.

5. Hint: Don't let the electrifying streaks in the sky prevent you from naming this one.

6. Hint: Count the arms to help you with its name.

7. Hint. Think "fragile celestial body"

8. Hint: The mollusk has within its name, another word for swine.

ANSWERS

1. Horseshoe Crab
2. True Tulip Snail
3. Crown Conch
4. Spider Crab
5. Lightning whelk
6. 9-armed sea star
7. Banded Brittle Star
8. Quahog Clam

If you would like to learn more about these animals  and  other marine life that inhabit Florida's coastal waters, consider taking the Florida Master Natural Program Coastal Module. Details and Schedules and can found at: http://www.masternaturalist.ifas.ufl.edu/