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Movement Patterns of Sub-Adult Coho in Puget Sound
 

Movement Patterns of Sub-Adult Coho in Puget Sound

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Migration is a central mechanism affecting the distribution of mobile populations, and intra-specific variation in migration patterns can affect many aspects of their ecology and conservation. Most ...

Migration is a central mechanism affecting the distribution of mobile populations, and intra-specific variation in migration patterns can affect many aspects of their ecology and conservation. Most sub-adult Chinook and coho salmon rear over the continental shelf or offshore waters of the North Pacific Ocean, but some Puget Sound salmon exhibit an alternative migratory pattern, spending all or part of their marine lives within Puget Sound. This “resident” behavior has been linked to decreased growth and increased contaminant accumulation. However, little is known about the movements of individual salmon and duration of their residency in Puget Sound. Accordingly, we tagged 45 sub-adult coho salmon in central Puget Sound with acoustic transmitters and tracked their movements using the array of moored receivers throughout the Salish Sea. Our initial results indicated that most individuals remained in Puget Sound, though several individuals were detected leaving through the Strait of Juan de Fuca and the San Juan Islands. Additionally, between basin movement was minimal; no individuals were detected entering Hood Canal or southern Puget Sound, but there was some movement into the Whidbey Basin. Overall, these results indicate that coho salmon found within Puget Sound in winter-spring are largely separated from those rearing off the coast. Thus resident and migratory individuals seem to be distinct categories, though the factors determining these two pathways are unclear.

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  • GOOD AFTERNOON My name is Jessica, and this is my co-host the cohoI just completed my first year of my master’s at SAFSMy research is part of a larger body of research on the migratory behavior of puget sound salmonids being conducted by several organizations using acoustic telemetryMy focus is on the movement of coho, popular with sport fishermen in the area
  • Pugetsalmonids have a range of intra-specific variation in migration patterns These can affect many aspects of their the ecology and conservation. This figure shows examples of life-history classifications that can be made based on the geographic extent of migrationCLICK 1Most coho salmon rear over the continental shelf or offshore waters of the North Pacific Ocean where they grow rapidlyCLICK 2but some exhibit an alternative migratory pattern, spending all or part of their marine lives within Puget Sound. This behavior where some members of a species migrate and others do not is known as partial migration and is well studied in some terrestrial species, especially birdsIt is important to understand this behavior in salmonids because it has been linked to decreased growth and increased contaminant accumulation.CLICK3 Although we know that there are residents in Puget Sound we are unaware of the movements of individual residentsAnd whether residents spend their entire lives in PS It’s possible that some may make quick trips out of PS and back, which might indicate and intermediate life-history type which we could call a semi-residentone of the goals of this research is to determine whether migrants and residents have discrete migratory behavior patterns.
  • Theobjective of this research is to characterize the movements of sub adult coho both spatially and temporallyCLICK1At the largest spatial scale, we want to find out if coho leave Puget SoundWithin Puget Sound, we want to know if they movebetween basins We also wanted to know where they go within basinsAs well as how they use vertical spaceCLICK 2Finally, we want to see if there are seasonal and dielpaterns to these movements
  • We tagged coho in central puget sound basin,using V7, V9 and V13 acoustic transmittersWe targeted resident coho by tagging them between November and June, avoiding summer months when migrant coho return to from the open ocean and both residents and migrants are present in Puget SoundBecause we tagged them in the central basin after they have already had time to disperse, we don’t know what population they are fromCLICK 1These fish were then detected by moored receivers throughout Puget Sound and the Salish SeaCLICK 2We were able to monitor movements of coho at larger scales by way of the network of “curtain” receivers deployed by the Pacific Ocean Shelf Tracking ProjectThe line across the SJDF was deployed throughout our study period and able to detect all fish that passed throughCLICK 3To monitor smaller scale movements we utilized receivers deployed throughout Puget Sound by various agenciesThis map shows a snapshot of 2008 when there was high coverage, but the deployments of receivers varied throughout our study periodCLICK 4
  • We tagged coho in central puget sound basin,using V7, V9 and V13 acoustic transmittersWe targeted resident coho by tagging them between November and June, avoiding summer months when migrant coho return to from the open ocean and both residents and migrants are present in Puget SoundBecause we tagged them in the central basin after they have already had time to disperse, we don’t know what population they are fromCLICK 1These fish were then detected by moored receivers throughout Puget Sound and the Salish SeaCLICK 2We were able to monitor movements of coho at larger scales by way of the network of “curtain” receivers deployed by the Pacific Ocean Shelf Tracking ProjectThe line across the SJDF was deployed throughout our study period and able to detect all fish that passed throughCLICK 3To monitor smaller scale movements we utilized receivers deployed throughout Puget Sound by various agenciesThis map shows a snapshot of 2008 when there was high coverage, but the deployments of receivers varied throughout our study periodCLICK 4
  • This table shows an overview of our resultsEach row represents a tagged fish, each column a month during the study38coho were tagged in the central basin during 6 different expeditions at approximately 6 month increments between 2006 and 2008.Length of each gray bar shows the months that an individual could have been detected (based on tag battery life)And x denotes that individual was actually detected that month.A red x indicates that the fish was detected outside of puget sound that monthYou’ll see that the time between detections can span several monthsAnd that once they were detected outside of Puget Sound, we didn’t detect them coming backLargest release in march of 2008, also the period when we had the best coverage of receivers
  • At the largest spatial scale of my research, we found that some assumed resident coho do in fact leave Puget SoundIn this map, purple dots show receivers that detected our cohoCircled x’s show receivers that did not detect any of our coho and were deployed for at least 3 months during the study periodFinally, stars indicate tagging sitesCLICK1There are two ways to exit puget sounddeception pass, a narrow high speed channel, where no coho were detected And admiralty inlet, where multiple coho were detectedCLICK 2The curtain of receivers at JDF was deployed entire studyWe recognized a detection at this point as an indicator of a coho’s complete departure from puget soundCLICK 38 detected outside of puget sound2 of those down coast1 in SJI
  • Data analysis revealed a trend suggesting a potential threshold afterwhich sub-adult coho do not leave puget soundBetween mid-april and mid-june, with a peak early to mid-mayAfter entering, they spend 18 months in marine waters the coho that we tagged entered puget sound 1 to 10 months before taggingFor those that did leave, there did not seem to be a pattern in the date that they exited puget soundHowever, we found that coho that had been in marine waters for less than six months when tagged, left puget sound more often than those that had been in marine waters for more than six monthsThis suggests that there may be a date after which coho found in the central basin are less likely to leave and more likely to remain resident.
  • Next, we found that there was some movement between basinsIn general, the tagged coho were mostly detected in Central Puget Sound.However, 1 was detected in south puget sound and another in hood canalAdditionally 9 entered whidbey basinIt’s interesting that we detected so little between basin movement when swimming speed would allow quick movement between.Admiralty inlet can be considered a sub-basin of central puget soundThe average depth of admiralty is less than half that of the main basinLarge amount of tidal energy causes turbulent mixing at outer sillA curtain of receivers was deployed at the northern end of admiralty between April and July of 2008, This was the time of our greatest release of 18 coho10 fish were detected there, and 5 of those returned to central puget sound within 5 days
  • We approached within basin distribution from a receiver based perspective, assessing the popularity of each receiver through several different “activity” measurements”Including the number of fish detected at each receiver and their residence time, or time continuously detected at a receiverThese maps indicate receiver sites in central puget sound active continuously for 30 days after the release of 18 fish of march 2008Receivers in the middle of the channel tend to have high numbers of fish and residence timeBut some sites differ in these measurements, For example,CLICK 1in the shallow, reef like area just west of the entrance to whidbey basin, there was a below average number of fish detected and an above average mean residence timeAdditionally, sites within close proximity can vary in these measurementsFor example CLICK 2just east of bainbridge island. Receivers within a couple km detected different numbers of individuals, indicating possible small scale habitat preference I’m in the process of developing both univariate and multivariate approaches to relating these activity measurements to habitat measurements such as depth, distance to shore, shape of shoreline, east or west side of sound, and local currents Additionally, I plan to see if these measurements vary over time or if there are different activity patterns for fish that left puget sound versus those that stayed
  • Vertical movements of coho showed clear diel and seasonal patternsCLICK 1These are our raw data for 9 fish tagged with depth sensing transmitters mar 08 releasedepth of detections (y-axis) by the time of day they occurred (x-axis) for spring months of march through mayDepth transmitters aren’t accurate below 100 meters, so it is likely that coho were deeper than thisThis shows a clear pattern of ascent during daylight hours, and descent at night. This is exactly the opposite of tradiationaldvm theory: In which fish move deeper during the day to avoid predationAnd ascend at night to feedCLICK 2By summer fewer fish were still being detectedStill, In the summer, the pattern seems to weaken with fewer deep detections at nightIn the future I plan to develop methods that determine if there are differences between depth at different temporal scales while accounting for variation of individual cohoSeparate into categories of deep, med, shallow receiversLook at rate of individual movement, are each of these a string of detectons at one receiver or at different receiversUse this for hypothesis, take out potential for this to be different fish on different receiversNormalize by using same fish for entire chart, say whether it was a different receiver or notKelly categorized receivers by shallowness, asked what times of the day those detected fishWhen in the day do they detect fish? first and last detectionsFish that are moving from deep to shallow vs. from shallow to deep, then fish that are on the same receiver but moving up and downCoho go close to shore during day?
  • Some assumed residents leave puget soundLittle movement between basinsWithin basin activity differs between sitesVertical movements show clear diel and season patterns
  • Our results indicate that Coho salmon found within Puget Sound later in marine phase are largely separated from those rearing off the coast.Thus resident and migratory individuals seem to be distinct categoriesFuture work will further investigate the behavioral differences between the two categories

Movement Patterns of Sub-Adult Coho in Puget Sound Movement Patterns of Sub-Adult Coho in Puget Sound Presentation Transcript

  • Movement Patternsof
    Sub-Adult Coho Salmon
    in Puget Sound
    Jessica Rohde1, Tom Quinn1, Fred Goetz1,Kurt Fresh2, Anna Kagley2
    1School of Aquatic and Fishery Sciences, University of Washington2Northwest Fisheries Science Center, NOAA
  • Puget Sound Coho Life-Histories
    • Contaminant accumulation
    • decreased growth
    ?
    • Are there semi-residents?
    Figure provided by Fred Goetz
  • ObjectivesCharacterize the movements of individual sub-adult coho
    Spatial scales:
    Do they leave Puget Sound?
    Within Puget Sound, do they move between basins?
    Within basins, what habitats do they use?
    What is their vertical distribution?
    Temporal scales:
    Does movement vary with season?
    Are there diel patterns?
  • Methods
    • Coho tagged with acoustic transmitters in central basin
    • Targeted residents by tagging between November and June
    • Population unknown
    • Detected by moored hydrophonic receivers
  • Methods
    • POST line of receivers in the Strait of Juan de Fuca
    • Data from receivers in Puget Sound shared through Hydra Database
    • Gray bars indicate when a fish could be detected
    • Black x indicates detection
    • Red x indicates detection outside of Puget Sound
  • Do they leave Puget Sound?
    • 2 exits
    • Deception Pass
    • Admiralty Inlet
    • Strait of Juan de Fuca (JDF) line
    • deployed throughout study
    • 8 individuals total left Puget Sound
    • 7 at JDF line
    • 2 at Willipa Bay
    • 1 in San Juan Islands
    Coho Detected
    No Coho Detected
    Tagging Sites
  • Is there a date threshold after which
    sub-adult coho do not leave Puget Sound?
    Left Puget Sound
    • Coho enter Puget Sound around May 1.
    • Spend 18 months in marine waters.
    • We tagged coho in Central Puget Sound that had been in marine waters for 1-10 months.
    • No pattern in the date of exit.
    Did not leave
    # Individuals
    < 6 months
    > 6 months
    Time in marine waters prior to tagging
  • Do they move between basins?
    • Limited between basin movement
    • 1 South Puget Sound
    • 1 Hood Canal
    • 9 Whidbey
    • Admiralty Inlet
    • Sub-basin
    • Curtain April - July 2008
    • 10 fish detected
    • 5 of those returned to central within 5 days
    • Semi-resident unlikely
    Coho Detected
    Tagging Sites
  • Within basin distribution
    # Fish Detected
    0 - 2
    3 - 5
    6 - 10
    11 - 14
    Mean Residence
    Time (hours)
    < 1
    1 - 3
    3 - 10
    24
    Tag Site
    Depth (m)
    30
    100
    200
    295
  • Vertical distribution
    Diel and
    Seasonal patterns
    Spring
    Summer
    Depth (m)
    Hour of Day
  • Summary
    Some assumed residents leave Puget Sound
    Coho tagged in Puget Sound in late marine phase less likely to leave
    Limited movement between basins
    Some use of Whidbey basin and Admiralty Inlet
    Within basins, activity differs between sites
    May reside longer in shallower habitats
    Clear vertical movement
    Diel: deep at night, shallow during day
    Seasonal: pattern stronger in spring than summer
  • Conclusions
    Resident and migratory individuals seem to be distinct categories.
    Future work will further investigate the behavioral differences between these two groups.
    http://www.emeraldwateranglers.com
  • Acknowledgements
    Rachel Hovel
    Josh Chamberlin
    Chloe Bracis
    Halley Nelson
    Megan Stachura
    Curry Cunningham
    Tom Quinn
    Kurt Fresh
    Anna Kagley
    Fred Goetz
    Kelly Andrews
    Dawn SpilsburyPucci
    Miles Logsdon
    Julian Olden
    Loveday Conquest
    Neala Kendall
    Morgan Bond
    Thomas Buehrens