flowchart TB Ice["Ice and bloom timing"] --> Prey["Lipid-rich prey"] Mix["Summer nutrient flux"] --> Prey Prey --> Energy["Age-0 total energy"] Energy --> Winter["Winter survival"] Winter --> R["Age-3 recruits"]
Infographics
Compact visual summaries of alternative causal pathways for a science audience.
Recruitment as a sequence of survival gates
The literature points to a sequence: spawners produce eggs, environment and transport set larval distribution, prey and production determine age-0 condition, winter filters age-0 fish into age 1, and predation overlap filters age-1 and age-2 fish into age 3.
Spawners
SSB, maturity, spawning location
→
Eggs and larvae
Temperature, transport, local prey
→
Age-0 fall fish
Size, diet lipid, total energy
→
Age-1 and age-2
Cannibalism and predator overlap
→
Age-3 recruits
Year-class signal
Alternative Causal Explanations
A. Bottom-up energy
Most diagnostic indicators: age-0 total energy, diet lipid, Calanus/euphausiid biomass.
B. Top-down overlap
flowchart TB Adults["Adult pollock"] --> Overlap["Predator overlap"] Arrow["Arrowtooth flounder"] --> Overlap Cold["Cold pool"] --> Overlap Overlap --> Mort["Age-1/2 mortality"] Mort --> R["Age-3 recruits"]
Most diagnostic indicators: juvenile-adult overlap, arrowtooth overlap, age-1 predation mortality.
C. Transport match-mismatch
flowchart TB Spawn["Spawning location"] --> Dist["Larval distribution"] Wind["Wind and currents"] --> Dist Dist --> Match["Prey match"] Dist --> Refuge["Predator separation"] Match --> R["Age-3 recruits"] Refuge --> R
Most diagnostic indicators: particle-tracking output, observed spawning distribution, prey/predator collocation.
D. Switching control
flowchart TB Climate["Climate state"] --> Prey["Bottom-up prey field"] Prey --> Age0["Age-0 condition"] Prior["Prior cohorts"] --> Pred["Predator field"] Age0 --> Overlap["Later overlap"] Pred --> Overlap Overlap --> R["Age-3 recruits"]
Most diagnostic indicators: climate-state interactions, adult biomass, predator biomass, repeated cold/warm year sequences.
Evidence Weight
Age-0 energy gate
Strongest mediator. Fall total energy, lipid-rich prey, and energy density repeatedly link to overwinter survival (Heintz et al. 2013; Siddon et al. 2013; Sogard and Olla 2000).
Age-1 predation gate
Strong support from adult-juvenile overlap, cannibalism, and arrowtooth predation models (Mueter et al. 2006; Spencer et al. 2016).
Transport and spawning
Moderate support. Spawning-area shifts improve modeled distributions, but transport, temperature, and prey are confounded (Petrik et al. 2015).
Simple cold-pool effect
Mixed support. Cold pool matters for predator distributions, but a direct cold-pool recruitment mechanism is weak (Mueter et al. 2006; Spencer et al. 2016).
References
Heintz, Ron A., Elizabeth C. Siddon, Edward V. Farley, and Jeffrey M. Napp. 2013. “Correlation Between Recruitment and Fall Condition of Age-0 Pollock (Theragra chalcogramma) from the Eastern Bering Sea Under Varying Climate Conditions.” Deep-Sea Research Part II: Topical Studies in Oceanography 94: 150–56. https://doi.org/10.1016/j.dsr2.2013.04.006.
Mueter, Franz J., Carol Ladd, Michael C. Palmer, and Brenda L. Norcross. 2006. “Bottom-up and Top-down Controls of Walleye Pollock (Theragra chalcogramma) on the Eastern Bering Sea Shelf.” Progress in Oceanography 68 (2–4): 152–83. https://doi.org/10.1016/j.pocean.2006.02.012.
Petrik, Colleen M., Janet T. Duffy-Anderson, Franz J. Mueter, Katherine Hedstrom, and Enrique N. Curchitser. 2015. “Biophysical Transport Model Suggests Climate Variability Determines Distribution of Walleye Pollock Early Life Stages in the Eastern Bering Sea Through Effects on Spawning.” Progress in Oceanography 138: 459–74. https://doi.org/10.1016/j.pocean.2014.06.004.
Siddon, Elizabeth C., Ron A. Heintz, and Franz J. Mueter. 2013. “Conceptual Model of Energy Allocation in Walleye Pollock (Theragra chalcogramma) from Age-0 to Age-1 in the Southeastern Bering Sea.” Deep-Sea Research Part II: Topical Studies in Oceanography 94: 140–49. https://doi.org/10.1016/j.dsr2.2012.12.007.
Sogard, Susan M., and Bori L. Olla. 2000. “Endurance of Simulated Winter Conditions by Age-0 Walleye Pollock: Effects of Body Size, Water Temperature and Energy Stores.” Journal of Fish Biology 56: 1–21. https://doi.org/10.1111/j.1095-8649.2000.tb02083.x.
Spencer, Paul D., Kirstin K. Holsman, Stephani Zador, et al. 2016. “Modelling Spatially Dependent Predation Mortality of Eastern Bering Sea Walleye Pollock, and Its Implications for Stock Dynamics Under Future Climate Scenarios.” ICES Journal of Marine Science 73 (5): 1330–42. https://doi.org/10.1093/icesjms/fsw040.