SEA Pink Salmon Survival Model Quarterly Tasks
2005 Quarterly Project Tasks:
1st Quarter Tasks (October 1, 2004 - December 31, 2004)
Tasks to be performed:
October: Project funding approved by Trustee Council
2nd Quarter Tasks (January 1, 2005 - March 31, 2005)
Tasks to be performed:
January 12-16 (tentative): Annual GEM Workshop
Second quarter objective was met.
3rd Quarter Tasks (April 1, 2005 - June 30, 2005)
Tasks to be performed:
April 1: Purchase PIT tags and recruit technicians
June 15: Train technicians to operate PIT tag scanning equipment
Third quarter objectives have been met.
4th Quarter Tasks (July 1, 2005 - September 30, 2005)
Tasks to be performed:
July 1-15: Conduct PIT tag loss and mortality studies
July 15-August 15: Conduct PIT tag detection studies at processors
September 30: Submit project final report to Trustee Council (actually due 4/15/06)
Update from PI:
The first task was completed in early July 2005. We used the ADF&G research vessel R/V Solstice to capture juvenile salmon near Shelter Bay on 5 and 6 July 2005. An anchovy purse seine net (25 m deep with 1.5 cm stretch mesh) was deployed to capture fish, and the net was held open for 20 minutes each set. Two hundred juvenile pink salmon were PIT tagged and the tagged fish ranged from 66 to 129 mm snout to fork length (mean = 91 mm). One hundred and eighty-five fish (92.5%) survived to 96 hours; however, 2 more fish would have not have survived because of caudal fin erosion and external skin and scale loss. None of the remaining fish (n = 183) had obvious external injuries that would have affected their survival. Forty percent (6 of 15) mortalities in 96 hours were in the first 25 fish tagged. This suggests a lack of tagging and handling experience contributed to early mortalities. Cadual fin erosion and associated skin and scale loss were documented on 47% (7 of 15) of the mortalities. The cause of these injuries is unknown, but they are probably related to handling during the tagging process. They could also be related to damage from sea lice or from swimming near the sides of the tote; however, only one of the seven mortalities with external injuries had sea lice at the time of tagging and visual observations suggest the circulating sea water in the tote kept fish from swimming near the sides of the tote.
Two changes from the original project procedures were 1) MS-222 was used instead of clove oil and 2) the tagged fish were maintained in a tote on board the vessel instead of a net pen near Armin F. Koernig Hatchery. The tagging personnel had more experience using MS-222 and the fish were not to be released or used as food, so MS-222 was appropriate. The fish were maintained in a tote onboard the R/V Solstice because this allowed more control over the water parameters (temperature, salinity), food availability, and protection from predators.
The second task for the fourth quarter was to determine the optimal configurations of PIT scanning equipment at each salmon processor in PWS and estimate tag detection rates at each processor. This method of recovering PIT tagged fish was used by Willette et al. (2003) in Cook Inlet. However, they injected PIT tags into the cheek muscle of adult salmon and were able to scan at PVC chutes just after the heading machine while our objective was to test configurations for scanning of adult salmon with the PIT tag in the body cavity.
During July and early August 2005 we visually examined the Cordova processing plants for locations along the processing lines without excessive metal or electric motors that would interfere with tag detection. Unlike the experience of Willette et al. (2003) there did not appear to be processing line locations that would work without extensive modifications. On 17 August 2005 we ran some PIT tag detection tests at the Ocean Beauty Seafoods plant in Cordova. We ran tests at two locations: 1) a nonmetal conveyor belt in an aluminum frame, and 2) an aluminum belt with plastic conveyor sides. These appeared to be locations that would have the least interference from metal or electric motors. Fifty-one commercially harvested adult pink salmon were injected with PIT tags (12 mm x 2.1 mm, 134.2 kHz) in the body cavity (described earlier for juvenile pink salmon). The fish were scanned with an electronic tag detector to ensure the tags were working. The fish were then placed on the moving conveyor, one at a time, and transported past a handheld racket antenna and electronic tag detector. The antenna power, distance from the fish, and location of the antenna (under the conveyor belt vs. over the conveyor belt) was varied with a small number of fish to find a configuration that maximized the antenna current. Two different electronic detectors and racket antennas were tried for multiple configurations. The antenna current was lower than suggested by manufacturer for all configurations examined. Three tests with all 51 tagged fish were then completed and the numbers of tags detected were documented. The first test was completed on the nonmetal conveyor belt with a single antenna (100% antenna power) about 0.3 m above the belt. Only 7 of 51 PIT tags (14%) were detected. The next test was again on the nonmetal conveyor belt with a single antenna (70% antenna power) about 0.15 m above the belt. Only 12 of 51 PIT tags (24%) were detected. The third test was completed on the aluminum belt with plastic sides with a single antenna (70% antenna power) about 0.3 m above the belt. Only 3 of 51 PIT tags (6%) were detected. These results match our expectations given the low antenna currents with the configurations tested.
There were several changes from our original procedures outlined to meet this objective. Visual examination of processing plants in Cordova suggested that the detection rates would be too low without plant modifications. Because this was a one year project, it is unlikely that processing plants would make the necessary modifications to allow us to increase tag detection rates. Therefore no attempt was made to conduct detection tests at plants in Valdez or Seward. Additionally, we conducted our tests with 51 tagged fish rather than 100 fish as outlined in our procedures because our preliminary configuration testing suggested we would not get good detection rates. If a large scale tagging study was conducted, processing plant modifications should allow a much higher tag detection rate than was documented in this study. For example, replacing the aluminum chutes that funnel fish to the line with heavy, food grade plastic chutes would provide an antenna location with less metal interference.
The third project task for the fourth quarter was to submit the final report by 30 September. An annual report was submitted on 30 September; however, I would request that the due date for the final report be delayed until 30 December. Preparations for the State of Alaska Board of Fisheries meeting (1-6 December) has required more time than I anticipated.
*Notified PI that final report is actually not due until 4/15/06. PI requested an extension to June 1 2006; this was approved by the EVOSTC Executive Director on 4/15/06.
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