University Events

Description: The School for Marine Science and Technology

The Department of Fisheries Oceanography

PhD Dissertation Defense

Title: Modeling Index Selectivity for Fishery Stock Assessments

by Cole Carrano

Abstract: Abundance indices are crucial components of fishery stock assessments because they provide a time series of relative abundance for estimating absolute stock size. Selectivity is the relative vulnerability to a fishery or fishery-independent survey for each species or demographic group within a species (e.g., size or age class). In an age-based assessment model, selectivity relates observed stock indices to model estimates of abundance at age. Thus, selectivity estimates must be carefully modeled to ensure an accurate depiction of the stock's age structure. The objectives of this research are to improve the accuracy and utilization of indices in fisheries stock assessment models by understanding the effect of alternative approaches to estimating index selectivity. Chapter One provides a general introduction to the topic and a review of the relevant literature. Chapter Two involves splitting a fishery-independent survey into two series to account for vessel and methodological changes by estimating distinct catchability and selectivity parameters for each series. Chapter Three develops fleet-structured assessment models to improve selectivity estimates for the fishery and the fishery-dependent indices. Chapter Four involves simulation cross-testing as a method to evaluate the effect of key structural differences in stock assessment models. This work examines how decisions about modeling fleet structure or changes in survey systems affect the performance of an assessment model and how sensitive models are to these decisions. This research will emphasize the importance of selectivity estimates to stock assessment and advance our understanding of how to effectively utilize abundance indices in an assessment model.

Dissertation Committee: Steve Cadrin (SMAST, Advisor), Pingguo He (SMAST), Gavin Fay (SMAST), Lisa Kerr (University of Maine)

East 101-103 and via Zoom

Join Zoom Meeting
https://umassd.zoom.us/j/99067360217?pwd=Z1RVVUx3eUo4K0YrY3QzNGU2Si9Tdz09
Meeting ID: 990 6736 0217
Passcode: 002519
---
One tap mobile
+13052241968,,99067360217#,,,,*002519# US
+13092053325,,99067360217#,,,,*002519# US
---
Dial by your location
+1 305 224 1968 US
+1 309 205 3325 US
+1 312 626 6799 US (Chicago)
+1 646 876 9923 US (New York)
+1 646 931 3860 US
+1 301 715 8592 US (Washington DC)
+1 719 359 4580 US
+1 253 205 0468 US
+1 253 215 8782 US (Tacoma)
+1 346 248 7799 US (Houston)
+1 360 209 5623 US
+1 386 347 5053 US
+1 507 473 4847 US
+1 564 217 2000 US
+1 669 444 9171 US
+1 669 900 6833 US (San Jose)
+1 689 278 1000 US

Meeting ID: 990 6736 0217
Passcode: 002519

Find your local number: https://umassd.zoom.us/u/adYOmDImeT
---

Join by SIP

99067360217@zoomcrc.com

---

Join by H.323

162.255.37.11 (US West)
162.255.36.11 (US East)
115.114.131.7 (India Mumbai)
115.114.115.7 (India Hyderabad)
213.19.144.110 (Amsterdam Netherlands)
213.244.140.110 (Germany)
103.122.166.55 (Australia Sydney)
103.122.167.55 (Australia Melbourne)
149.137.40.110 (Singapore)
64.211.144.160 (Brazil)
149.137.68.253 (Mexico)
69.174.57.160 (Canada Toronto)
65.39.152.160 (Canada Vancouver)
207.226.132.110 (Japan Tokyo)
149.137.24.110 (Japan Osaka)

Meeting ID: 990 6736 0217
Passcode: 002519

Please contact: Scarreiro1@umassd.edu with any questions