Barbara Muhling John Lamkin NMFS: Southeast Center

Potential impacts of climate change on marine fish and fisheries Warming sea temperatures o Changes in species dominance, occurrence and distribution o Changes in reproductive behaviors and spawning effort Changing current patterns o Alteration of larval dispersal pathways o Changes to larval survival and recruitment to adult populations, and fisheries Rising sea levels o Loss or degradation of nearshore habitat Changing precipitation regimes o Changes in nearshore water quality

The Florida Keys National Marine Sanctuary Linked to the Dry Tortugas, Gulf of Mexico and Caribbean via the Loop Current The degree of northward penetration of the Loop Current is highly variable Flow from the intra-American seas through the Gulf of Mexico and onto the Florida Keys The Loop Current and Tortugas Gyre

The Florida Keys National Marine Sanctuary Freshwater inflow enters Florida Bay from the Everglades Water quality in Florida Bay and the Florida Keys influences the health of seagrass meadows and coral reefs These are important habitats for adult and juvenile fishes Mean surface salinity across Florida Bay in summer, and winter

Climate change impacts of primary concern to fish and fisheries in the FKNMS 1) Changes in species occurrence and distribution 2) Changes in spawning behaviors and recruitment 3) Changes in larval supply to nursery habitats Potential changes are most likely to be linked to changes in water temperatures, Loop Current dynamics, and health of fish habitats Examples demonstrating these mechanisms follow, highlighting research capacity at the SEFSC

Potential impacts on fish and fisheries - 1 Changes in species dominance, occurrence or distributions Example: Increasing abundances of tropical Lane Snapper (Lutjanus synagris) in the northern Gulf of Mexico NMFS Trawl survey area: Northwest GOMChanging abundance of L. synagris in summer trawl surveys

Potential impacts on fish and fisheries - 2 Changes in spawning behaviors and thus recruitment Example: Spawning habitat of bluefin tuna (Thunnus thynnus) in the northern Gulf of Mexico Probability of collecting larval bluefin tuna vs. sea surface temperature Change in suitable spawning habitat with 2°C increase in SST Actual May 2003 SST 2°C increase Probability of larvae

Potential impacts on fish and fisheries - 3 Changes in larval supply to nursery habitats in the FKNMS Example: Changes in magnitude and timing of connection between Yucatan Peninsula, Dry Tortugas and Florida Keys Snapper larvae collected off YucatanGeneralized Loop Current flowEddies provide retention and transport mechanisms for larvae

Data and modeling needs 1) To predict and quantify the types of mechanisms described, we need better information on how climate change would affect: Water temperatures Current patterns Freshwater inflows A downscaled climate model would be very helpful in addressing these points 2) To help explain past trends and predict future trajectories, access to historical datasets and collaboration with scientists within and outside of NOAA is essential

Downscaled climate models Coarse-scale (~100km) climate models have already been produced through the IPCC Downscaling these to a regional level allows the predictions of temperature, rainfall, and regional oceanographic conditions under various climate change scenarios A downscaled model covering the Gulf of Mexico and Florida Keys would help to predict water temperatures, precipitation and Loop Current flow across the region under future CO2 emission scenarios These parameters are highly important for predicting future stressors to the FKNMS, and fish populations