Tracking fish movement at Redfish Rocks: Larval Dispersal (Where do the newborn fish go?)

*DRIFTER UPDATES: In 2014 we dropped nine drifters from Redfish Rocks Marine Reserve.  To find out where they have traveled and learn more about what we are discovering, check the Fishtracker blog, here.*

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Rockfish Larvae

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Black Rockfish

To determine the effectiveness of Redfish Rocks Marine Reserve and  Marine Protected Area, there are many important questions that can be asked and researched.   Some of the most important questions that can be asked are those of connections between the protected area other habitats along the coast.  They are questions about the to the movement of fishes.  How big are their home or territorial ranges? How far do they travel?  Where do the fishes come from?  Where do the larval fish go once they are born?

Some work on movement patterns of adult fishes has already been done by OSU grade student Tom Calvanese.  He worked for two-and-a-half years to track the movement patterns of adult fish at Redfish Rocks.  The project is known as the “Fishtracker Program”.  When his thesis is published, it will give some insight to movement patterns of different fishes in the marine reserve and whether or not those fishes are staying within the protective boundaries.

Today, OSU Professor Dr. Scott Heppell is collaborating with Port Orford Sustainable Seafood, Redfish Rocks Community Team and other partners to pilot a program to track currents that are dispersing rockfish larvae from Redfish Rocks.  Tracking currents and the fish within them will help us to explore the questions, “Where do the larvae (baby fish) go?  How does Redfish Rocks connect with other habitats along the coast?”

To track the currents and where those larvae are going, passive drifters are being used.  A drifter is a buoy containing a satellite transmitter that will allow us to track its position as it drifts with the currents. We will be launching three drifters from the Redfish Rocks Marine Reserve. Signals from a satellite transmitter reveal the direction and speed of currents that also carry larval rockfish to their destination, and each drifter carries a temperature sensor.

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The surface float the passive drifter rides on the ocean surface and transmits its coordinates and water temperature information via satellite.

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A look inside the drifter with hardware exposed.

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The sock drogue attaches to the bottom of the surface float and extends 30ft below the surface. The sock catches the water currents that transport the device.

         To know when to deploy the passive drifters, ovaries of female rockfish are examined.  The ovaries provide information on development of the larvae or if the fish has already given birth to those larvae.  As fish are found to have given birth, that signals that it is time to release the passive drifters in an attempt to track those newly released larvae.

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The above photo shows eggs from a three pound female Black Rockfish (the target species for this project). You can see the tiny fish curled within the eggs. They’re not yet ready to be released.

Interesting facts:

  • All rockfish give birth to live Larvae!  For about their first 90 days in the water, these larvae are passively drifting with the currents, until they develop enough to begin actively swimming.
  • Females will store sperm for several months until fertilization.  Female rockfish have the ability to control when they fertilize their eggs and give birth.
  • Black rockfish live to about 50 years.  The older they are, the more larvae they can produce.
  • Black rockfish produce between 125,000 to 1,200,000 eggs per season. After mating,. Larvae are released alive from January to May along the Pacific coast..

For this project, local Port Orford commercial fishermen have provided the samples of female fish ovaries, the fish fillets were sent to market. Of the twelve fish examined that lead up the release of the drifters, ten were females, and two of these had recently given birth. The samples were taken from fish captured by local commercial fisherman Jeff Miles and processed by Aaron Longton of Port Orford Sustainable Seafood.

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The eyes of a larval Black Rockfish

 

The first of three passive drifters was launched on Saturday morning, March 1st from the Redfish Rocks Marine Reserve by the Redfish Rocks Community Team.  Community Team members (Tom Calvanese, a graduate student in the Heppell Lab at Oregon State University, Tyson Rasor, Project Coordinator for the Redfish Rocks Community Team,  Captain Lyle Keeler) and  volunteers Beth Pietrzak and First Mate Rich Hill launched the fishing vessel Dominion from the Port of Port Orford.   The drifter carries a satellite transmitter and temperature sensor that will transmit its location and sea surface temperature every ten minutes for the next three months.

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Tom preparing the drifter to be deployed.

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Tom and Rich stop for to pose with the drifter.

It was released at the Northwest corner of the Redfish Rocks Marine Reserve to track ocean currents that carry larval fish from that location.

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Splash down! The drifter is let loose to track the currents leaving Redfish Rocks.

 

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Above you can see the path the drifter was taken.

 

Drifter 1 - Final Location

This drifter’s 90 day expedition was cut short as it was washed ashore in a small cove on the Port Orford Headlands after just a few days at sea.

After “shooting the gate,” drifter #1 was retained in Tichenor Cove for several days before drifting north through a narrow channel between a small island and the headland. It remained there for several days before going aground in the second cove. We recovered the drifter and transported it to the OSU field station lab. Positioning errors were produced while the drifter was aground in the cove, the final labeled  position is the location of the OSU field station lab.

A second drifter was deployed on 3/12/14.  Once again, the Redfish Rocks Community Team members (Tom Calvanese, a graduate student in the Heppell Lab at Oregon State University, Tyson Rasor, Project Coordinator for the Redfish Rocks Community Team,  Captain Lyle Keeler, and Maryanne Holcomb) and  volunteer and First Mate Rich Hill lead the effort for deployment.

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Maryann taking a moment with Drifter #2.

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Tyson getting fired up for deployment!

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Drifter #2 is set to sea.

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As of March 13, 2014 , this is the path of drifter #2.

*Update: The Track of Drifter #2*

As these drifters float with the currents for the next 90 days, there courses will be plotted and watched by the lead of this project, Dr. Scott Heppell.  He will scrutinize the data and make determinations on how to proceed with this project into the future.  If all goes as planned, and hoped, this project will be repeated in the coming years.  The more data that is collected, the more information we have.  The more information we have, the more we will know about the currents interacting with Redfish Rocks.  We can then begin to better understand where and how the larvae of Black Rockfish are connecting with other habitats along our coast!

Stay tuned!  We will be providing updates as research and monitoring progress.

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Pictured: Captain Lyle Keeler and First Mate Rich Hill are headed out to sea aboard the F/V Dominion.

Many thanks to the commercial fisherman, community members, professionals and researchers who are collaborating on this project in order to better understand the ocean we all depend upon.