Title: Studies of Reproductive Maturity among Age Cohorts of Pacific Herring (Clupea pallasii) in Prince William Sound, Alaska
Project Year and Number: 2019: 19120111-D
Other Fiscal Years and Numbers for this Project: None
Principal Investigator (PI): Kristen Gorman, Prince William Sound Science Center
Assisting Personnel: None
Restoration Category: Research
Abstract: To address the lack of recovery of Pacific herring (Clupea pallasii, hereafter herring) in Prince William Sound (PWS), Alaska, research by the Herring Research and Monitoring (HRM) Program has been focused on improving predictive models of PWS herring stocks through observations and research. To this end, the goal of the project described here is to test the PWS herring Bayesian Age-Structured Assessment model’s age at maturity schedule with empirical data. The main objectives of the study originally proposed in FY17 are fourfold: 1) Assess the seasonal timing (spring, summer, fall, and winter) that allows for determination of both previously spawned and maturing female herring, and maturing male herring, based on direct measures of gonad development to assess reproductive maturation states per age cohort of interest (ages two through five) in PWS. The proportion of immature and mature herring per age cohort of interest can then be determined using the information obtained on maturation states. 2) Assess inter-annual variability in the proportion of immature and mature herring per age cohort of interest in PWS collected at the optimal seasonal time as determined by Objective 1 using direct measures of gonad maturation. 3) Couple histological analysis of gonad maturity with annual scale growth information at the individual level, within specific age cohorts of interest, to understand if scale growth patterns reflect reproductive investment; and 4) Assess annual variation in herring age at maturity schedules before and after 1997 using Alaska Department of Fish & Game’s (ADF&G) PWS herring scale image library, which allows for understanding maturity schedules of past cohorts. The work to be conducted in FY19 is focused on Objectives 2-4, namely (2) assessing inter-annual variability in the proportion of immature and mature PWS herring per age cohort of interest (ages 2-5) collected at the optimal seasonal time as determined by Objective 1. Methods for determining the proportion of immature and mature herring at the optimal seasonal time in FY19 will follow those employed in FY17 and FY18. The work on Objective 3 couples histology results with annual scale growth information at the individual level, within specific age cohorts of interest, to understand if scale growth patterns reflect reproductive investment. The work on Objective 4 will focus on evaluating the potential of the scale technique for estimating past maturity schedules using ADF&G’s PWS herring scale image library. This analysis will examine the progression of bimodal distributions in scale growth as a cohort of herring passes through time. The prediction is that if scale growth is related to investment in reproduction, then the frequency of fish showing reduced scale growth should increase as a cohort of fish matures over time from age 1 through age 6. Methods for conducting the scale image library analysis have been included in this proposal.
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Proposal: View PDF (441 KB)
Funding Recommendations: View
Funding Detail For: 2019
Quarterly Project Tasks For: 2019
Annual Report: 2019: Due 03/01/2020
Final Report: Draft Final Report Due 4/15/20
Publications from this Project: None Available