Archive | June, 2013

Bottom water temperature off of New Jersey

Have you ever wondered what the water temperature was like at the bottom of the ocean?  Recently we were wondering this same question.  If winter flounder move into estuaries in the late fall to spawn and out of the estuaries in the spring, using temperature as a trigger, would an offshore resident population feel this temperature change?  What would be their cue when it came time to spawn?  In the deep water, greater than 100m light is greatly diminished so they would not be able to tell if there was a change in season.

Here is a video made with model data from the Regional Ocean Modeling System (ROMS) based out of Rutgers.  Currently this is made with model data that are a few degrees warmer at the bottom than in actuality but you still get the idea…The red box on the movie is where we released our tagged winter flounder 



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Searching for winter flounder after Sandy

(Sorry this was written in January but not posted…)

I hope everyone was able to pull through after the storm, and hopefully everything is starting to get back to normal again.

While the storm caused horrible damage, a lot can be learned from such a tremendous force.  Rutgers University had an autonomous under water vehicle called a glider out during Sandy to look at how storms affect the ocean temperatures and sedimentation, in an effort to enhance models for future predictions of storms and to understand how they effect the ocean.  Two graduate students, Travis Miles and Greg Seroka, are tackling this data goldmine… you can read more about their daring mission here

My curiosity however is what do the fish do when a storm comes through?  Fishermen say that the fish move offshore when a storm comes.  Since our tags were out during the storm, once we get them back we will be able to look into these questions like what environmental parameters might trigger the fish to move offshore?  How soon before the storm do they leave?  How soon after the storm leaves do they come back?

Additionally this week we pulled all of our hydrophones out of the water since the batteries in both the hydrophones and the acoustic tags in the fish are dead.  We had one minor set back when we realized the rope for the hydrophone in Point Pleasant had frayed and the hydrophone was no longer attached to the dock.  First I tried to swim and search for the hydrophone with no luck.  Next my advisor Motz tried, and since he used to be a free diver he was able to find it within a minute! Surprisingly, we had NO tagged fish swim into the estuaries via Shark River, Manasquan River, or the Navesink River. This is one of those cases though that no data is still good data, because our hypothesis is that the fish we tagged are part of a resident population that does not come into the estuary to spawn.  Since they didn’t come in this could be the case! However this is not a method that can give us a definitive answer because those fish could’ve died, been eaten, or swam to another estuary further away. We’ll just need to keep looking for our archival tags and hope someone finds one soon!


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