Flow, Fish and Fishing Dave Siegel, Chris Costello, Steve Gaines, Bruce Kendall, Satoshi Mitarai & Bob Warner [UCSB] Ray Hilborn [UW] Steve Polasky [UMn] Kraig Winters [SIO/UCSD] A Biocomplexity in the Environment Project

U.S. West Coast Rockfish Source: Pacific Fisheries Management Council

How did we get here? Poorly managed rates of fishing mortality Do we know how to best manage a fishery? Do we know understand the dynamics of fish stocks under uncertainty?

Flow, Fish & Fishing Human-natural system biocomplexity project Oceanography, population dynamics, marine ecology, fishery management, fisherman behavior & economics all wrapped up together Focus on California nearshore fisheries & role of uncertainty in management [but in a general way] Today – environmental uncertainties & their role on the stocks & harvest of a long-lived fish

Who are we talking about?? Harvested species with limited home ranges Rockfish, kelp bass, urchin, … Not whales, tuna, sardine,...

Key is the Analysis of Fish Life Cycle

The Planktonic Larval Stage Many organisms considered have a planktonic larval life stage Plankton disperse with the currents Planktonic larval durations (PLD) range from hours to months During this time larvae can disperse 10’s m to 100’s of km

Dispersal & Time in Plankton Siegel et al. [2003; Marine Ecology Progress Series 260: 83-96] Plankton Larval Duration (days) Genetic Dispersal Scale (km)

Time/Space Scales of Larval Transport Duration of larval releases is short (>months) Fecundity rates are huge Probability of successful settlement is tiny Planktonic larval durations are weeks to months -> leads to stochastic larval settlement

Stirred, Not Mixed?? PISCO / SBC-LTER [UCSB] Invert Settlement Time Series - Ellwood

The Flow, Fish & Fishing Idea Larval transport is stochastic driven by stirring Fish stocks, yields, profits & their assessment are directly affected by this stochastic forcing Management under this uncertainty must be accounted for in real & robust ways Key ingredients are notion of scale and the flows & values of information

What sets the scales for fish stocks & harvest? bathymetry, coastal circulation, habitat structure, larval settlement, adult migration, primary production, community interactions, fishery regulations, natural & fishing mortality, fisherman knowledge, choice & attitudes, spatial costs for harvest, etc… ??

Flow Fish Settlement Habitat Recruitment Harvest Regulation Fishermen Market INFO Climate

The F 3 Modeling Approach Circulation & Larval Transport – assess time / space scales of larval transport & their settlement Stock / Harvest Dynamics – assess implications of stochastic settlement (& ??) on stocks, yields & profits Fleet Dynamics – How do fishermen choose when, where & how to fish? Value of Information – How does amount & quality of data available inform the management process?

CONNECTIVITY MATRIX Summer Winter

Stock / Harvest Modeling Next generation stocks = survivors - harvest + new recruits SURVIVORS are naturally surviving adults HARVEST are those extracted NEW RECRUITS are a function of fecundity of the survivors, larval dispersal & mortality, settlement & recruitment to adult stages

Mathematically...

Stock / Harvest Model Example Periodic domain MPA at center Spatial fishing TAC policy Stochastic dispersal Long-lived Post-settlement density depend

Flow, Fish & Fishing in a Nutshell Larval transport is stochastic which impacts fish stock dynamics, harvest yields & their assessment Keys are notions of scale and the flows & values of information in the management of a fishery Our approach is to conduct coupled natural – human model investigations of process Our goal is to help change the best science that drives fishery management

Thank You!! Photo credit: Steve Churchill