SC Offshore Water Temperatures, Currents, and Fish

SC Offshore Water Temperatures, Currents, and Fish

Tim Kent

5/25/17

Spring is here, signaling the annual run of Dolphin fish off the Southeast Coast.  This fishery provides a large economic impact to coastal communities and coincides with warm water from the Gulf Stream shifting over the continental shelf where it interacts with cooler shelf water.  We will look at a couple days with different conditions to compare and discuss, where the fish may or may not have been.

Relavant factors

  • Water Temperature >70F (preferred 74F-80F).
  • Water Color – Blue to Cobalt Blue (related to chlorophyll).
  • Edges/Rips – Concentrate debris and baitfish.
  • Bottom topography in relation to the above factors.

 

4/18 SST

credit: Hiltons Offshore

  • Note warm water (74F-76F) eddy pushed in to the shelf waters inshore of the main Gulf Stream edge.
  • Also not finger of cooler (72F) upwelling water between the two water masses.

4/18 Chlorophyll (water color)

credit: Hiltons Offshore

  • Note color of water in corresponding warm eddy vs color of water in Gulf Stream and finger of cooler water between the two water masses.
  • Often chlorophyll, which indicates the presence of marine plant life, is higher (yellow) along boundaries between cool and warm waters, where currents are mixing up nutrient-rich water from deep in the ocean. Many of the temperature boundaries along the loops in the Gulf Stream are mirrored in the chlorophyll image with a stripe of lighter blue or yellow, indicating elevated chlorophyll.
  • Finished a stupidly long day with 8 dolphin and 1 skippy

5/16 SST

credit: Hiltons Offshore

  • Same area nearly a month later – note how much warmer the shelf water has become.
  • There is a finger of warm water (78F) pushed in to the SWB area extending down toward the 380 hole, but aside from that the main feature appears to be the gulf stream edge out deep.

5/16 Chlorophyll (Water Color)

credit: Hiltons Offshore

  • Note water color of finger of warm water inside the 380 hole vs surrounding water color vs Gulf stream edge water.
  • Finished a regular trolling day with 10 dolphin.

Now for the weather portion of the discussion, as both days were “fishable” by recreational boaters.

4/18 Sea State at Edisto Buoy 41004

 

  • Fading SW’rly wind chop from prior day with mild ~2ft of nicely spaced  (10-11s) SE’rly Swell.
  • Translated to pretty rough ride out into the first 10NM due to pinched coastal front laying right along the coast producing 15kts of NE’rly winds along beaches,  but pretty nice thereafter, and a very nice ride back.
  • Heading was of no concern as we were able to go directly where we though we should.

5/16 Sea State at Edisto Buoy 41004

  • Relatively light wind most of the day with a mild SE’rly swell (9s) and a pesky SW’rly wind swell from prior afternoon then again in the afternoon as Sea Breeze circulation expanded.
  • Translated to a relatively bumpy ride out, and pretty smooth return trip not counting the last 10NM in crappy SW’rly Sea Breeze chop.
  • Primary issue was not being able to take a more E’rly heading in the morning due to fear of plowing into SW’rly wind chop on return trip.

Morale of the story is that although we have lots of data to help narrow down the likely location of fish in the region, we are subject to sea conditions and the actual availability/density of fish in the region.  Two different trips yielded similar results, but in general the fish were not here in good numbers yet back in mid April, and we fished the wrong area most of the day in mid May.  Thats why they call it fishing and not catching!

Posted in Cape Cod