Contract Title:
2002-031-00 EXP GROWTH MODULATION IN SALMON SUPPLEMENTATION
Contract Start Date:
6/1/2011
Contract End Date:
5/31/2012
Title:
D: 157 - Growth rate modulation experiment #6 (URB Fall Chinook)
Description:
Objective 2b) Develop protocols to reduce minijack rates and optimize smolt development in URB Fall Chinook salmon.
As noted in Objective 2a, a major focus of this project is to improve hatchery-rearing protocols to produce fish with life history characters similar to wild fish, and minimize artificial selection due to altered phenotypes of juvenile fish at release. The knowledge gained from this work will be used to help develop rearing guidelines that allow hatchery programs to take advantage of the increased survival found in yearling release without the disadvantage of un-naturally high rates of early male maturation. In this study the effects of two environmental factors, photoperiod (at emergence) and food availability (growth during early rearing) will be assessed with regard to seasonal timing of smolting, and age of male maturity in URB fall Chinook salmon. This is the first time such studies have been conducted with Fall (rather than spring) Chinook salmon. This Growth Modulation Experiment #6 will be initiated during this contract period.
The experiment will be conducted using Umatilla River URB eyed eggs obtained from the Bonneville Hatchery in autumn 2011 and reared at the Northwest Fisheries Science Center Research Hatchery, NOAA Fisheries Seattle. At the time of ponding replicate treatments will be exposed to Early, Middle or Late Emergence photoperiod regimes and fed under either a High or Low ration according to the method of Beckman et al. (2007). This range of rearing regimes will allow us to examine the full range and proportion of life-history phenotypes expressed by URB Fall Chinook with regard to age of smoltification and early male maturation. Furthermore, monitoring of growth and development of treatment groups throughout the study will allow for a comprehensive understanding of the causative physiology driving the various life-histories.
H01: Photoperiod at emergence does not alter seasonal timing of smoltification or age of male maturation in URB fall Chinook salmon
H02: Growth (ration) after ponding does not alter seasonal timing of smoltification or age of male maturation in URB fall Chinook salmon
Emergence timing of hatchery salmonids is often earlier than found in wild fish because of elevated water temperatures used for early incubation in hatchery programs. These practices may inadvertently affect later timing of smolting and prevalence of early male maturation in hatchery-produced fish relative to wild fish. Delayed or advanced emergence exposes fry to a seasonally advanced or delayed photoperiod, respectively, and alters the time allowed for growth prior to release. In Sacramento River winter-run Chinook salmon and Yakima River spring Chinook salmon, both factors influence life history phenotype in terms of smolt timing and occurrence of early male maturation (Beckman et al. 2007; Beckman unpublished). Under this work element an experiment will be conducted to examine the independent and interactive effects of photoperiod at emergence (3 different regimes) and growth (2 rations) post-ponding.
Methods:
Buttoned up fry will be placed into each of three different photoperiods: Early Emergence (EE, photoperiod equivalent to that found on 1 December), Middle Emergence (ME, photoperiod equivalent to that found on 15 February), and Late Emergence (LE, photoperiod equivalent to that found on 1 May). Throughout the rest of this proposal calendar day (day #) will refer to when events take place, months will refer to seasonal photoperiod (for each calendar day there will be 3 different photoperiods). Early emergence represents hatchery/captive broodstock programs that accelerate emergence by incubating eggs in relatively warm water (~ 10oC) and late emergence represents conditions found in cold, higher elevation Snake River tributaries. This range of photoperiods should provoke the entire range of phenotypic responses found for URB fall Chinook salmon under current environmental conditions.
Ponding will occur on day # 45 (mid-February). Because of this design fish will be the same age throughout the experiment even though they are exposed to different photoperiods. Within each photoperiod treatment fish will be fed under two feeding regimes: HiFeed and LoFeed. Target sizes after first year will be 10 and 25g on day # 270 (1 October) for LoFeed and HiFeed treatments, respectively. Target sizes in spring of the second year (at 1+ age smolting) will be 25 and 50g on day # 485 (1 May) for LoFeed and HiFeed treatments, respectively. Feeding rate will be adjusted so that fish from a given feeding treatment (HiFeed or LoFeed) will be the same size regardless of photoperiod treatment. Each treatment (photoperiod x feeding rate) will be conducted in replicate (3 photoperiods x two feeding rates x 2 replicate tanks = 12 tanks).
During the experiment fish will be monitored for growth, smoltification and male maturation as we anticipate the treatments to alter these three parameters (see sampling below).
Sampling
At approximately 4-week intervals after ponding, size will be assessed (3 batch weights of 50 fish) and sub-samples of fish (8 fish/tank, 16 fish/treatment) will be sacrificed to obtain gill tissue and blood plasma. Gill Na-K ATPase activity will be measured as an index of smolting and plasma 11-ketotestosterone (11-KT) will be measured as an early index of male maturation (Larsen et al. 2004). Gonads will be weighed from all sacrificed males to assess degree of male maturation. Seawater challenges will be conducted monthly (72 hours in 37.5 ppt seawater) as another assessment of smolting. On approximately day 225 of the experiment (1 August) 100 fish from each tank will be sacrificed to assess age-1 male maturation (testis weight and plasma 11-KT levels). All remaining fish will be sacrificed and testis will be examined to determine male maturation at age 2 at approximately day # 590 (30 August of year 2). Maturing males will be readily identified by gonado-somatic indices (GSIs), however the stage of testis development of immature males will aid in determining whether some males are maturing in the subsequent year (age 3). Plasma 11-ketotestosterone (11-KT) levels will be determined using an enzyme-linked immunosorbant assay according to Cuisset et al. (1994). Gill Na-K-ATPase (ATPase) activities will be measured using the method of McCormick (1993).
All data will be collected on pre-formatted data sheets by hand and entered into electronic spreadsheets (Microsoft Excel or File Maker Pro). Data will be double-checked for accuracy. Data will be analyzed and graphed electronically (Excel, Prism, JMP and Powerpoint). Differences in smolting between groups will be assessed by comparing mean gill Na-K ATPase activities and arcsin square root transformed % seawater survival data in a 3-way ANOVA with date, photoperiod and feeding rate the main affects, with replicates nested within the major effects. If significant differences among the main effects are found, a multiple range test will be used to assess differences between treatments on specific dates. Differences in the proportion of males maturing at age 1 or 2, will be assessed with a 2-way ANOVA containing photoperiod and feeding rate as the main effects. Males maturing at age 1 will be assessed and enumerated through normal physiological sampling (testis size, plasma 11-KT levels, 8 fish/tank, monthly), seawater challenges (testis size ,12 fish/tank, monthly), the August sampling for age 1 males (testis size, 100 fish/tank) and the visual census (all fish throughout the experiment). We are not sure that simple visual examination will allow us to assess maturation with 100% efficiency, necessitating the additional terminal sampling at age 1. Again, if significant differences among the main ANOVA effects are found, a multiple range test will be used to assess differences among treatments. We donÕt anticipate a strict statistical test of differences between the two populations; rather, we will assess overall differences or similarities in patterns (seasonal timing of smolting) and magnitude (% early maturing males at each age) of life history variation.
Expected Results and Timeline
We expect that early-emerging, fast-growing fish will smolt as under-yearlings and males will undergo a high percentage of precocious maturation (age 1). Conversely, we expect that late emerging, slow-growing fish will undergo smolting in the spring at 1+ age and have low rates of early male maturation (at either age 1 or 2). We expect both populations will display variability in both smolting and early male maturation with respect to photoperiod at emergence.
Experiments will be conducted on the following timeline:
During this contract period: (October 2011-May 31 2012)
Fall 2011: obtain eyed eggs, incubate embryos
Spring 2012: pond fry, begin experiment, initiate treatments, monitor growth rate for first couple months of the experiment.
During following contract period (June 1 2012-May 31 2013)
Spring/Summer 2012 continue monitoring
Fall 2012-assess age 1 male maturation
Summer 2013: terminate experiment and assess age 2 male maturation
Summer/Winter 2013: run samples
Winter 2014/Spring 2015: analyze data and write report
WE Agreement Type:
Contracted
Deliverable Specification:
Assist NOAA personnel with sibling contract #CR-187019 from acquisition, transport and incubation of gametes (Fall 2011), ponding under experimental treatments (Feb 2012) and monitoring growth and development until end of the contract period 31 May 2012.
WSE Effective Budget:
$10,000
% of Total WSE Effective Budget:
11.74%
WSE Completion:
05/24/2012
WSE ID Continued From:
n/a
Finite or Recurring:
Recurring
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