Encounter Rates and Catch-and- Release Mortality of Wild ... Annual Meeting/… · Release Mortality of Wild Steelhead in Idaho ... They are present in a non-anadromous form, which
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Encounter Rates and Catch - and - Release Mortality of Wild Steelhead in Idaho William J. Lubenau Idaho Cooperative Fish and Wildlife Research Unit Department of Fish and Wildlife Sciences University of Idaho
Encounter Rates and Catch-and-Release Mortality of Wild Steelhead
in Idaho
William J. LubenauIdaho Cooperative Fish and Wildlife Research Unit
Department of Fish and Wildlife Sciences University of Idaho
Diverse life history • Non-anadromous
• Rainbow Trout• Anadromous
• Steelhead
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O. Mykiss exhibits a very diverse array of life history strategies. They are present in a non-anadromous form, which is known as the rainbow trout, and an anadromous form which are known as steelhead. Within this life history form, varying degrees of anadromy are present and life history execution is independent between generations. O. mykiss has been widely introduced throughout north america, but their native range in north America…. Change slide
Steelhead Distribution
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in North America spans from southern California into a portion of Alaska. They additionally span inland through the Columbia and Snake River basins.
Decline in abundance • Water development • Land use activities • Ocean conditions
Many protected under the Endangered Species Act
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In the Columbia and Snake river basins steelhead populations have declined from a combination of factors, but are primarily attributed to the construction of dams, timber harvest, mining, and urbanization, and poor ocean conditions. As a result of this decline, steelhead have been listed as threatened and are protected under the endangered species act. Though wild stocks are protected, In 1997, 6 distinct population segments of steelhead were listed as threatened under the ESA for the Columbia and Snake river basins. They currently remain listed as threatened.
0 100 km
Clearwater RiverColumbia River Snake River
Salmon River
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Steelhead have a wide distribution in the Columbia and Snake river basins with a major population in Idaho.
These recreational fisheries are supported by hatchery stocks that are released to mitigate negative effects of the hydro system. In Idaho, there is eight primary hatchery stocks that are released. Hatchery stocks may be harvested, and are identified by the absence of an adipose fin. Wild stocks, which are identified by the presence of an adipose fin must be release immediately after capture, but little is know about how often angler actually encounter wild steelhead and the subsequent mortality rates of steelhead that occur from catch and release angling. So…
Encounter rate • Number of hatchery and wild fish• Hatchery fish harvested • Hatchery fish caught and released • Hatchery and wild encounter rates are equal
The objective of my research will be to provide an estimate of how often Idaho anglers are encountering wild steelhead and estimate the mortality that occurs from those encounters
Clearwater RiverColumbia RiverSnake River
0 100 km
Salmon River
Lower Granite Dam
Bonneville Dam
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Many steelhead are PIT tagged as Juveniles prior to outmigrating. These PIT tags allow us to identify individual fish as they return from the ocean with PIT arrays that are integrated into the fish ladders of each dam. When Identifying those fish, we can also identify the natal tributary that it will be returning to.. For a portion of my sampling I will use the integrated PIT arrays at Bonneville dam to identify fish that will be returning to Idaho. They will be identified at Bonneville dam, then later sampled at lower Granite dam using separation by code. Steelhead are PIT-tagged as juveniles prior to their out-migration. PIT-tags uniquely identify individual fish and they can be traced back to their natal streams. As juveniles they out-migrate to the ocean from the Clearwater River, passing through eight dams. Returning adult steelhead are detected at each dam by PT-tag arrays. These arrays are located in the adult fish ladders. Bonneville dam is important to the study because this is where I can select PIT-Tagged steelhead passing over Bonneville dam online through Columbia River DART. I can send a list of selected PIT-tagged fish to Lower Granite where there is a trap that selects for my pre-selected PIT-tags. Once a PIT_tagged fish is identified by a PIT-Tag array at Lower granite then a door would open selecting for that fish and will be placed into a trap box where it can then be radio tagged
Separation by code• Sample individual fish• Limited sample size
Random sample
1000 adipose intact• 200 adipose-intact hatchery fish• 800 wild fish
200 adipose clipped Sample throughout run
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In total, I will be sampling 1000 adipose intact steelhead at lower granite dam. These steelhead can be farther broken down into 200 adipose intact hatchery stock steelhead and 800 wild stock. These steelhead will be sampled throughout the run, using spawn year 2017 as a guide for estimating the proportion of the population that has passed lower granite dam at a given time. I will talk more about my tagging methods in later slides, but the oint of this sampling method is to allow my tags to reflect the population proportion that is available in the fishery. When we sample these fish,
Angling • Variety of gear types • Distribute effort • Steelhead caught at least once • Multiple capture events
200 adipose intact
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In total, I will be sampling 1000 adipose intact steelhead at lower granite dam. These steelhead can be farther broken down into 200 adipose intact hatchery stock steelhead and 800 wild stock. These steelhead will be sampled throughout the run, using spawn year 2017 as a guide for estimating the proportion of the population that has passed lower granite dam at a given time. I will talk more about my tagging methods in later slides, but the point of this sampling method is to allow my tags to reflect the population proportion that is available in the fishery. When we sample these fish,
Anesthetize Examine
• Marks• Injuries• External tags
Scan for internal tag Fork length Tissue sample
• Stock identification
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We will take biometrics and a fin clip for stock identification
T-bar anchor tag • Tag-You’re-It information • Unique identifying number • Reporting incentive
• Non-reward • $25• $50• $100• $200
• 20% double tagged PIT tag
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We will also implant at least one visible tag in each fish. These tags will be labeled with information for reporting the tag, a unique identifying number for the individual fish, and a various reporting incentives. Just to clarify, Non reward tags will not be labeled as such. We will also implant a PIT tag in the pelvic girdle of the fish that do not already have a PIT tag. After processing, the fish will be released, and hopefully reported…
Contact information Number of tags on fish Individual tag number(s) Date Location Environmental conditions
• USGS National WaterInformation System
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By steelhead anglers that encounter the tagged fish. When a tag is reported, we ask for simple data including the anglers contact information, the number of tags on the fish, the individual tag number(s), and the date and location the fish was encountered. The date and location can later be used to gather data on the environmental conditions using the USGS national water information system. Unfortunately, not all tags that are encountered will be reported.
So we will use the method suggested by Nichols et al. (1991) in which we use reporting rates of our reward tags to estimate non reporting rates using a linear-logistic model . Our reward tags will also be used… To provide a direct estimate of Angler- Wild steelhead encounter rates because literature suggests $100 and $200 rewards elicit a reporting rate of %100
Moving on to estimating catch and release mortality, to obtain an estimate of this, we will be comparing the return rates of caught and uncaught steelhead to instream PIT arrays and weirs that will be present in spawning tributaries throughout the snake river basin. We will use this model that was developed by Josh mccormick from Idaho Department of Fish and Game. Taking a closer look at that model,
Caught fish-reported
Uncaught fish
Caught fish-not reported
Idaho Department of Fish and GameBrett BowersoxJoshua McCormick Joe Dupont Timothy Copeland Daniel SchillJeff Dillon
