Presentation Abstract

In 2010, three species of rockfish in the Puget Sound/Georgia Basin (PSGB) region were listed under the Endangered Species Act (ESA). Subsequent genetic analyses revealed that yelloweye rockfish in PSGB were genetically differentiated from individuals on the outer coast; while canary rockfish showed no population structure among these geographic regions. These results confirmed the listing status of yelloweye rockfish in PSGB as a “distinct population segment” (DPS), but suggested that canary rockfish in PSGB were not a DPS, which led to their removal from the endangered species list. Here, we test whether larval dispersal could be a mechanism for the differences observed in population structure between these species. We used an oceanographic model to track larvae of each species released from sites inside and outside the PSGB DPS. Results were similar among both species. Larvae released from sites on the outer coast rarely settled within the boundaries of the DPS and larvae released from sites within Puget Sound proper and the Strait of Georgia rarely settled outside of the boundaries of the DPS. However, larvae released from the Strait of Juan de Fuca and the San Juan Islands settled outside of their natal DPS region at levels that would suggest genetic migration between the regions. For yelloweye rockfish, this potential exchange of larvae across regions is inconsistent with the finding that the DPS is genetically isolated. In contrast, the exchange of larvae across DPS boundaries for canary rockfish is consistent with their population structure of genetic continuity across the regions. We also found no differences in the proportion of larvae settling inside vs. outside the DPS depending on the day of parturition or the age of settlement. These results suggest that larval dispersal does not fully explain the observed differences in population structure for these two ESA-listed species in PSGB.

Session Title

Rockfish Conservation via Collaborative Research and Ecosystem-Based Management in the Salish Sea

Conference Track

Trophic Interactions - Zooplankton, Phytoplankton, Salmon, Forage Fish & Invasive Species

Conference Name

Salish Sea Ecosystem Conference (2020 : Online)

Document Type

Event

SSEC Identifier

2020_abstractID_3007

Start Date

21-4-2020 9:00 AM

End Date

22-4-2020 4:45 PM

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

Language

English

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Apr 21st, 9:00 AM Apr 22nd, 4:45 PM

Can larval dispersal explain differences in population structure of ESA-listed rockfish in Puget Sound?

In 2010, three species of rockfish in the Puget Sound/Georgia Basin (PSGB) region were listed under the Endangered Species Act (ESA). Subsequent genetic analyses revealed that yelloweye rockfish in PSGB were genetically differentiated from individuals on the outer coast; while canary rockfish showed no population structure among these geographic regions. These results confirmed the listing status of yelloweye rockfish in PSGB as a “distinct population segment” (DPS), but suggested that canary rockfish in PSGB were not a DPS, which led to their removal from the endangered species list. Here, we test whether larval dispersal could be a mechanism for the differences observed in population structure between these species. We used an oceanographic model to track larvae of each species released from sites inside and outside the PSGB DPS. Results were similar among both species. Larvae released from sites on the outer coast rarely settled within the boundaries of the DPS and larvae released from sites within Puget Sound proper and the Strait of Georgia rarely settled outside of the boundaries of the DPS. However, larvae released from the Strait of Juan de Fuca and the San Juan Islands settled outside of their natal DPS region at levels that would suggest genetic migration between the regions. For yelloweye rockfish, this potential exchange of larvae across regions is inconsistent with the finding that the DPS is genetically isolated. In contrast, the exchange of larvae across DPS boundaries for canary rockfish is consistent with their population structure of genetic continuity across the regions. We also found no differences in the proportion of larvae settling inside vs. outside the DPS depending on the day of parturition or the age of settlement. These results suggest that larval dispersal does not fully explain the observed differences in population structure for these two ESA-listed species in PSGB.