1. Recover satellite data from 5 tags scheduled to detach from halibut on June 15, 2001 and 3 tags scheduled to detach November 15, 2001.
2. Tag and release additional halibut in the Gulf of Alaska in spring 2001 outside of Resurrection Bay.
3. Analyze light data and geolocation estimates for all tags recovered from live fish.
4. Recover remote data from ARGOS satellite system and analyze halibut movement.

1.  Recover satellite data from 5 tags scheduled to detach from halibut on June 15, 2001 and 3 tags scheduled to detach November 15, 2001.

Analysis from the returned April 2001 tag (737a) caught in the commercial fishery found that the remaining four tags from the November 2000 release had a programming error effecting the release date.  These four tags will remain attached to the halibut essentially acting as archival tags until recovered by sport or commercial fisherman.  Wildlife Computers replaced the four tags which were deployed on halibut in July 2001 with a release date scheduled for November 2001. 

2.  Tag and release additional halibut in the Gulf of Alaska in spring 2001 outside of Resurrection Bay.

In conjunction with the opening of the commercial halibut fishery season, March 2001, biologist successfully captured, tagged and released three mature halibut by longline on-board the F/V Rocinante.  During a second on-board tagging operation, July 2001, the two remaining halibut at the ASLC were re-tagged and released at the mouth of Resurrection Bay using previously described methods.  In addition, four halibut were capture, tagged and released into Resurrection Bay, via longline and the F/V Rocinante.    

3.  Analyze light data and geolocation estimates for all tags recovered from live fish.

The PSAT tags attached to free roaming halibut collected valuable habitat data (temperature, depth and ambient light) every minute until release.  After detachment, the PSAT tags began transmitting 12-hour depth and temperature data summaries as well as daily ambient light conditions at depth, used for producing geolocation estimates using Wildlife Computers geolocation program.  The transmitting data was received by the ARGOS satellite system and then downloaded to the Alaska Science Center for data analysis.  

The graph, top right,  is an example of a light curve produced by Wildlife Computers geolocation program.  The bell shaped curve is key in producing a geolocation estimate.  A sudden increase in light intensity provides an approximate sunrise where as a sudden decrease in light intensity produces an approximate sunset on the light curve.  Using navigational algorithms and the known sun angle (zenith angle) relative to the time of year, a latitude and longitude estimate can be produced.  The data for this curve was collected from a tagged halibut while being held at the ASLC for observations in a two-meter deep outdoor holding tank. The graph, bottom right,  represents a light curve produced from a tagged halibut in its natural habitat.  Note that a clear bell shaped curve was produced from the recorded light data, as the halibut appeared to remain at a nearly constant depth as indicated by the blue light.

The two graphs to the left depict geolocation estimates (Longitude-Latitude) produced from a tagged halibut held at the ASLC.  Each red dot represents an individual day in which a bell shaped curve was produced, there by allowing for a geolocation estimate.  These data are being used to validate the accuracy of geolocation estimates produced at northern latitudes in and around the Gulf of Alaska and to compare with estimates produced from tags on halibut in the wild at depth.  The solid black line in each graph represents the actual ASLC longitude and latitude.  The error difference between the mean longitude estimates and the actual longitude of the ASLC was approximately 19 km.  The error difference between the mean latitude estimates and the actual ASLC latitude was approximately 300 km with the spring equinox variation and approximately 237 km with out.  Geolocation estimates produced in near proximity of the spring or fall equinox periods (+/-14days) have a greater margin of error because of the globally uniform 12 hours with and without daylight. The blue squares on the latitude graph represent the 14 days on either side of the spring equinox.

4.  Recover remote data from ARGOS satellite system and analyze halibut movement.

A total of 14 halibut were tagged with PSAT tags from October 200 to July 2001 resulting in data being collected from seven tags.  Two halibut were caught in the commercial longline fishery (April and November 2001), each yielding an entire data set.  Five out of eight tags scheduled to pop-off in November 2001 transmitted data to the ARGOS system, producing 12-hour histogram data sets.  

The map below shows the locations of tagged halibut release, recapture and PSAT pop-off sites.  Note that three of the tagged halibut indicated by the tag numbers (737b, 741, 10047) traveled considerable distances from their release sites.  The distance traveled category, below, represents a straight line distance between the release and pop-up points. The locations of the November pop-off placed these three halibut on or near the continental slope in waters greater than 250m  suggesting a possible spawning migration to areas off the continental shelf. Tags 737a and 821 were the two halibut captured in the commercial  fishery after being tagged and released. 

Tag # 818 819 737b 741 047	Release Date 3-16-01 3-16-01 7-5-01 7-5-01 7-5-01	Pop-off Date 11-15-01 11-15-01 11-15-01 11-15-01 11-15-01	Distance Traveled 6 kilometers 112 kilometers 338 kilometers 189 kilometers 356 kilometers

Observed Behaviors:

Future Research:

Pacific halibut movements will be plotted and analyzed using a unified database created from the pop-up tags and bathymetric data.  The geolocation data from the PSAT tags on the buoy array will be collected in March 2002 and compared to the actual buoy position to test light attenuation levels at depth and insitu light gradients during the equinox periods at northern latitudes.  Data from the two tags held at the ASLC will act as a baseline for the non-captive tags and validity for the geolocation estimates at a fixed position.  These data collected from the PSAT tags will be used to assess critical habitat in the Gulf of Alaska.

DNA from the Pacific halibut fin clips will be used to examine biogeographic relationships and evolutionary history of halibut using microsatellite analysis.  Development of the laboratory procedures is underway at the USGS Molecular Ecology Lab in Anchorage.  Populations from Resurrection Bay, Glacier Bay, and the Bering Sea will be compared genetically.

A collaborative project between the USGS and the International Pacific Halibut Commission (IPHC) will use PSAT tags in looking at Pacific halibut migrations and assessing critical habitat areas in the Bering Sea and other locations in the Gulf of Alaska, summer 2002.  Similar techniques as previously described will be used for capture and tagging of halibut along with the collection of data using the ARGOS system.

Anchorage Daily News Featured Article 3/24/02

Alaska Public Radio Network Article from the Alaska Economic Report 5/29/01

Fish Information and Services Web Article 5/24/01

Alaska Magazine Featured Article April 2001 by Les Palmer

Anchorage Daily News Featured Article 11/26/00