Evaluating the effects of Southern Resident orcas recovery actions and external threats in the marine ecosystem of Puget Sound

• Main Author: Morzaria-Luna, Dr. Hem Nalini
• Format: Text
• Language: English
• Published: Western CEDAR 2022
• Subjects: Orca
• Online Access: https://cedar.wwu.edu/ssec/2022ssec/allsessions/406; https://cedar.wwu.edu/context/ssec/article/3568/type/native/viewcontent/Morzaria_Luna_et_al_Salish_Sea_Conf_April_28_2022_2020_04_2022_2008_59_19_958.pptx_AWSAccessKeyId_AKIAYVUS7KB2I6J5NAUO_Signature_smg4sn7Mu55wZfh6UYOkUg6g0Cw_3D_Expires_1690487938

We apply two ecosystem models, the Atlantis Model for Puget Sound and the Salish Sea Atlantis Model, to simulate the recommendations of the Southern Resident Orca Task Force for recovery of the endangered Southern Resident Killer Whales (“Southern Residents”) in the Salish Sea. The downturn of the Southern Residents has been attributed to multiple, co-occurring anthropogenic and ecological pressures that are being addressed through the recommendations of the Orca Task Force. Atlantis is a spatially-explicit ecosystem modeling platform that simulates oceanography and biochemistry, food-web interactions, fisheries, and dependence of species on biogenic and physical habitat. We are evaluating the ecosystem-level impacts of recovery actions aimed at enhancing population growth and long-term sustainability of the Southern Residents and the future cumulative impacts from human population growth, oil spills, and climate change. We are addressing three objectives by simulating long-term dynamics using the two ecosystem models built in the Atlantis framework that span the full Salish Sea range of Southern Residents: (1) Analyze whether recovery actions for Southern Residents will support or hinder other conservation objectives; (2) Reveal potential tradeoffs inherent in the proposed recovery actions, both via direct effects and indirect (trophic) pathways; (3) Examine future cumulative threats from population growth, ocean warming, and oil spills. We are evaluating these scenarios in terms of abundance, size, diets, catch, and ecosystem indicators. We are generating information on ecosystem-level tradeoffs, the probability of success of recovery actions, and economic impacts, that can help managers and policy makers reconcile potentially conflicting unintended consequences that are likely to arise in response to bold conservation actions for Southern Resident recovery and from future cumulative threats.