National Sea Grant College Program Amendments Act of 2017 This bill amends the National Sea Grant College Program Act to reauthorize through FY2023 the National Sea Grant College Program. The bill requires the National Oceanic and Atmospheric Administration (NOAA) to award Dean John A. Knauss Marine Policy Fellowships. Currently, NOAA has discretion in awarding such fellowships. Those fellowships support the placement of graduate students in fields related to ocean, coastal, and Great Lakes resources in positions with the executive and legislative branches. NOAA must establish priorities for the use of donations given for the National Sea Grant Program. An agency may appoint a recipient of a Dean John A. Knauss Marine Policy Fellowship to a federal position within five years after such recipient successfully completes a fellowship. The bill authorizes through FY2023 grants for university research on: (1) the biology, prevention, and control of aquatic nonnative species; (2) oyster diseases, oyster restoration, and oyster-related human health risks; (3) the biology, prevention, and forecasting of harmful algal blooms; and (4) sustainable aquaculture techniques and technologies. The bill also authorizes through FY2023 grants for: (1) fishery extension activities conducted by sea grant colleges or sea grant institutes to enhance existing core program funding; and (2) priority issues identified in the National Sea Grant Program's strategic plan.