Growth and dispersal of early life history stages of Arctic cod and saffron cod under variable climate forcing

Project Description

The main goal of this project is to develop biophysical transport models for both Arctic cod (Boreogadus saida) and saffron cod (Eleginus gracilis) in the Pacific Arctic to better understand the early life histories of these species and model their growth and dispersal under variable climate forcing. The model builds on a recently developed Pacific Arctic ocean model, field observations from the Arctic Ecosystem Integrated Survey and laboratory studies on temperature-dependent growth of both species. Results will contribute to a better understanding of the relative competitiveness of these two key forage species in a changing Arctic. Specific Project Objectives: 1. Quantify the vertical and horizontal distribution of early life stages of Arctic cod and saffron cod and synthesize available literature on their early life history with emphasis on growth dynamics. 2. Parameterize the development and growth of eggs and larvae of Arctic cod and saffron cod under different temperature conditions from spawning until the early juvenile stage (approximately 70 mm total length). 3. Develop a biophysical, individual-based model that uses output from a high-resolution circulation model to simulate the growth and transport of early life history stages of Arctic cod and saffron cod. 4. Identify possible spawning locations of Arctic cod and saffron cod in the Chukchi Sea using the biophysical transport model. 5. Identify likely pathways of dispersal of larval and early juvenile Arctic cod and saffron cod from their known summer distributions in the Northeast Chukchi Sea in 2012 and 2013 to test the hypothesis that observed aggregations of Arctic cod are a source for Arctic cod in the Beaufort Sea, while saffron cod are retained within the Chukchi Sea. 6. Model growth and dispersal of Arctic and saffron cod under variable climate conditions using hindcasts from 2004-2013. Broader Relevance: Our proposed research contributes to pressing information needs in at least these important ways: 1. Improving our understanding of the biology, life history and population dynamics of two of the three potential target species in the Arctic Fisheries Management Plan directly contributes to the research needs identified in the Plan. 2. Better information on the early life stages of these key species is required by the Bureau of Ocean Energy Management and other agencies to enhance environmental impact assessments, to develop indices and benchmarks against which to compare future changes and to identify the distribution and movements of these vulnerable life stages to facilitate development of effective mitigation measures. 3. Understanding the connectivity between the Chukchi Sea and Beaufort Sea provides a critical understanding of the risks associated with development and climate change in the Chukchi Sea, where large aggregations of young-of-year Arctic cod and saffron cod have been observed, which may influence potentially connected “downstream populations” in the Beaufort Sea. 4. Finally, a better understanding of climate change impacts on these key forage species helps communities whose livelihood depends on seabirds and marine mammals, which in turn depend on Arctic cod and saffron cod as principal prey items, to manage impacts and adapt to changes.