Doryteuthis opalescens aggregate and migrate to the continental shelf during the last stage of their life presumably to select spawning sites that optimize the survival and fitness of their offspring. This dissertation examined the timing and site selection of spawning aggregations, and essential habitat requirements for their embryos. Squid embryos occurred every year for five years, across all seasons during most years (Winter 2009-Summer 2013) and were commonly observed to occur on coarse sands and on submarine canyon walls. Essential embryo habitat was defined by observed depth (10-100 m depth), embryo density (0.1-350.1 capsules*m⁻²), area (0.15-7.32*10⁶ m²), by repeated use, and by association with high [O²] and pH (and low pCO₂). ROV observations of embryos recorded [O²] from 70-280 [mu]M, pH from 7.65-8.10, T from 9.8-18.1 °C, and S from 33.3-33.9 PSU and that [O²], pH and T were higher (and S lower) in areas where embryos were present. Embryos exposed to combined low pH and low [O²] in the laboratory had a 16.7 % longer development time, remained at earlier development stages and had 54.7 % smaller statolith area. Embryo dorsal mantle length and statoliths were bigger and yolk reserves were smaller in a low pH only laboratory treatment relative to those in a low [O²] only treatment. Geochemical testing for pH and [O²] effects evaluated element ratios (B:Ca, Mg:Ca, Sr:Ca, Ba: Ca, Pb:Ca, U:Ca) of embryonic statoliths. Uranium:Ca was eight-times higher in statoliths exposed to low pH and low [O²] than those exposed to high pH and [O²] . This thesis provides evidence that squid spawn and hatch continuously on the SCB, that adults select sites that are exposed to relatively higher [O²] and pH, embryos develop poorly when exposed to low [O²] and pH, and that embryo statolith geochemistry can reflect sublethal levels of [O²] and pH. Several options are available for inclusion of climate change into adaptive management policy including mapping and monitoring embryo habitat over the range of D. opalescens and development of research initiatives inclusive of commercial fishers

The market squid, Doryteuthis opalescens, is an important forage species for the inshore ecosystems of the California Current System. Due to increased upwelling and expansion of the oxygen minimum zone in the California Current Ecosystem, the inshore environment is expected to experience lower pH and [O2] conditions in the future, potentially impacting the development of seafloor-attached encapsulated embryos. To understand the consequences of this co-occurring environmental pH and [O2] stress for D. opalescens encapsulated embryos, we performed two laboratory experiments. In Experiment 1, embryo capsules were chronically exposed to a treatment of higher (normal) pH (7.93) and [O2] (242 μM) or a treatment of low pH (7.57) and [O2] (80 μM), characteristic of upwelling events and/or La Niña conditions. The low pH and low [O2] treatment extended embryo development duration by 5-7 days; embryos remained at less developed stages more often and had 54.7% smaller statolith area at a given embryo size. Importantly, the embryos that did develop to mature embryonic stages grew to sizes that were similar (non-distinct) to those exposed to the high pH and high [O2] treatment. In Experiment 2, we exposed encapsulated embryos to a single stressor, low pH (7.56) or low [O2] (85 μM), to understand the importance of environmental pH and [O2] rising and falling together for squid embryogenesis. Embryos in the low pH only treatment had smaller yolk reserves and bigger statoliths compared to those in low [O2] only treatment. These results suggest that D. opalescens developmental duration and statolith size are impacted by exposure to environmental [O2] and pH (pCO2) and provide insight into embryo resilience to these effects.

The market squid, Doryteuthis opalescens, is an important forage species for the inshore ecosystems of the California Current System. Due to increased upwelling and expansion of the oxygen minimum zone in the California Current Ecosystem, the inshore environment is expected to experience lower pH and [O2] conditions in the future, potentially impacting the development of seafloor-attached encapsulated embryos. To understand the consequences of this co-occurring environmental pH and [O2] stress for D. opalescens encapsulated embryos, we performed two laboratory experiments. In Experiment 1, embryo capsules were chronically exposed to a treatment of higher (normal) pH (7.93) and [O2] (242 μM) or a treatment of low pH (7.57) and [O2] (80 μM), characteristic of upwelling events and/or La Niña conditions. The low pH and low [O2] treatment extended embryo development duration by 5-7 days; embryos remained at less developed stages more often and had 54.7% smaller statolith area at a given embryo size. Importantly, the embryos that did develop to mature embryonic stages grew to sizes that were similar (non-distinct) to those exposed to the high pH and high [O2] treatment. In Experiment 2, we exposed encapsulated embryos to a single stressor, low pH (7.56) or low [O2] (85 μM), to understand the importance of environmental pH and [O2] rising and falling together for squid embryogenesis. Embryos in the low pH only treatment had smaller yolk reserves and bigger statoliths compared to those in low [O2] only treatment. These results suggest that D. opalescens developmental duration and statolith size are impacted by exposure to environmental [O2] and pH (pCO2) and provide insight into embryo resilience to these effects.

Marine heatwaves are increasingly affecting marine ecosystems, with cascading impacts on coastal economies, communities, and food systems. Studies of heatwaves provide crucial insights into potential ecosystem shifts under future climate change and put fisheries social-ecological systems through “stress tests” that expose both vulnerabilities and resilience. The 2014–16 Northeast Pacific heatwave was the strongest and longest marine heatwave on record and resulted in profound ecological changes that impacted fisheries, fisheries management, and human livelihoods. Here, we synthesize the impacts of the 2014–2016 marine heatwave on US and Canada West Coast fisheries and extract key lessons for preparing global fisheries science, management, and industries for the future. We set the stage with a brief review of the impacts of the heatwave on marine ecosystems and the first systematic analysis of the economic impacts of these changes on commercial and recreational fisheries. We then examine ten key case studies that provide instructive examples of the complex and surprising challenges that heatwaves pose to fisheries social-ecological systems. These reveal important insights into improving the resilience of monitoring and management and increasing adaptive capacity to future stressors. Key recommendations include: (1) expanding monitoring to enhance mechanistic understanding, provide early warning signals, and improve predictions of impacts; (2) increasing the flexibility, adaptiveness, and inclusiveness of management where possible; (3) using simulation testing to help guide management decisions; and (4) enhancing the adaptive capacity of fishing communities by promoting engagement, flexibility, experimentation, and failsafes. These advancements are important as global fisheries prepare for a changing ocean.