Viewing entries tagged
bonefish

Carleton University Research at CEI

Researchers from Carleton University (Cooke Lab) was at CEI last week studying flats ecology. The team is determining whether radio tags can be used to track the movements of checkered puffers in shallow mangrove habitats. Radio tags normally are used only in freshwater because signals are attenuated by sea water. However, the researchers have modified the tags such that the antenna points vertically and breaks the water surface as puffers swim about in tidal creeks. In addition, the researchers placed tri-axial accelerometer loggers on bonefish in McKinney Creek at CEI. The loggers record information on swimming (e.g., tail beats) and feeding (e.g., tilting as they dip their heads to feed) activity. This is the first time that such loggers have been used on bonefish and will provide information that will serve as the basis for a bonefish bioenergetics model. The same loggers were also placed on some fish in Kemps Creek to evaluate the effects of different handling techniques on post-release behaviour. The Carleton team includes Jake Brownscombe, Felicia St. Louis, Charles Hatry, Jason Thiem, and Dr. Steven Cooke. [slideshow]

Update from CEI's Flats Ecology Research

[slideshow]

So everyone has heard of climate change/global warming- increased anthropogenic CO2 in the Earth’s atmosphere shifts annual global climate, which then leads to other catastrophic events within the Earth’s ecosphere. An increase in oceanic temperature and acidity is among the most pressing and readily apparent effects of climate change. Past research has shown fish of tropical reefs to be particularly sensitive to changes in ocean temperature and pH. In the flats department, we aim to determine whether common teleost occupants of tropical mangroves exhibit a similar sensitivity to such changes. Using bonefish (Albula spp.), checkered puffers (Sphoeroides tetudineus), juvenile yellowfin mojarra (Gerres cinereus), and juvenile yellowtail snapper (Ocyurus chrysurus), we aim to determine the Critical maximum and minimum temperature and pH at which each species looses equilibrium (“goes belly up”). With the help of visiting students from the Maine School of Science and Mathmatics, we have already determined the critical maximum temperature for puffers, mojarra, and snapper by observing behavior of test subjects while gradually increasing the ambient temperature. With our recently engineered water-cooling system, we plan on determining critical minimum temperature this week! Once completed this study will help us to predict the phenotypic plasticity of these mangrove species in response to rising oceanic temperatures and acidity.

A Bonefish Expedition

[slideshow] By C.J., Noah, Hannah, Ellen, Heather, and Chris D.

The Flats Research team recently traveled by boat to Kemp’s Creek to catch bonefish. Our research group is studying bonefish, among other species, because there have been very few studies on them.  This is surprising, considering the important ecological role played by bonefish, as well as their appeal for sport fishing in the Bahamas. Bonefish are mainly found in shallow flats ecosystems, since this is where they hunt for prey. At low tide, however, bonefish tend to swim into open ocean. Recognizing that bonefish would be making this transition during the change in tides, we headed to Kemp Creek to collect some for our research.

The process by which we caught the bonefish was a method known as seining.  This method involves setting up a large net that covers the opening where the creek meets the ocean.  Many fish enter tidal creeks during high tide to forage for food.  We purposefully set the net during a time when the tide was leaving the creek, because the bonefish would be following the tide and retreating into deeper waters at this time. As the fish left the mouth of the creek, they were caught in the seine net that impeded their exit.  We also used an additional “booster” method to lure as many bonefish into the net as possible:  those who weren’t holding the net stood in a line that stretched the width of the creek, and slowly walked towards the net while splashing and making as much noise as possible to scare the fish into the seine net.  The net-operators then immediately closed the net into a circle surrounding the fish.  Using smaller dip nets, we then did our best to catch all of the bonefish that had been trapped. After collecting all of the bonefish from the net, our “by-catch” – which included a lemon shark, a cow fish, and many barracuda – was safely returned to its habitat in the creek.