timing of food producing events. For cod that might be a match (or not) of their
hatching with spawning of Calanus to provide the larvae with early and abundant
nauplii to eat. Critical periods for finding food before starvation are a related
conceptual template, one making matches (as opposed to mismatches) a survival
necessity.
(^) Those two concepts are closely similar to Lasker windows. Reuben Lasker
emphasized the need for larvae to find sufficient food and associated that with the
need for strong vertical layering of zooplankton prey. Finding suitable concentrations
would be a “window” to growth beyond the prey sizes of planktonic predators, to
juvenile status and to mobility. Lasker coupled this to the importance of ocean
stratification so that layers of prey for larvae would not be disturbed in the larva’s
critical period.
(^) Connectivity (Michael Sinclair and others) – egg and larval drift must connect
planktonic young with suitable locations for juvenile development. As detailed above
for the term “hydrographic containment”, spawning sites become selected as places
usually providing that connectivity. It can fail if currents are unusual (another sort of
match–mismatch requirement). This relates to ocean triads, Bakun’s notion that large
stocks can develop in areas where: (i) the ocean is enriched (upwelling, mixing, iron
available, etc.), (ii) concentrations are sustained (convergences, fronts, etc.), and (iii)
flow connects larvae to juvenile habitat.
(^) P2P loop (Bakun) – “prey to predator” reversed interaction. The notion is that in
marine ecosystems forage fish can prey heavily on the eggs and larvae of their
predators (e.g. cod, hake, bluefish, ... ), thus protecting themselves because those
potential predators do not grow up. Bakun suggests, for example, that the recently
booming herring stocks in the northwest Atlantic may be eating cod spawn, slowing
cod stock recovery, sustaining their own peak abundance. Quantifying the importance
of P2P can be difficult.
(^) Loopholes (Bakun and Kenneth Broad) – places where predation on eggs or larvae
is low enough to overcome their disadvantages as habitat. Bakun and Broad (2003)
give the example of tuna spawning in regions of minimal production relative to the
rest of their adult range, possibly to lower the predation threat to larvae. Emphasis on
not being eaten can be as important as eating well.
(^) Predator pits (Bakun) – at low density, of say a forage fish, its predators will ignore
it and survival will be high. To reach high density, the stock must cross a level of
abundance (a low level, but not the lowest possible, the “pit”) in which it is controlled
by its attentive predators. If good conditions allow a breakout above the “critical
point” at which predation becomes saturated, then the population can have low per
capita mortality and reach very high abundance.
(^) School trap (Bakun, again) – a far from dominant species of fish may school with