Dataset for: Spawning fish maintain trophic synchrony across time and space beyond thermal drivers

Increasing ocean temperature will speed up physiological rates of
ectotherms. In fish, this is suggested to cause earlier spawning, due to
faster oocyte growth rates, causing spawning time to potentially become
decoupled to the timing of the offspring’s food resources. A phenomenom
referred to as trophic asynchrony. We used biological data, including body
length, otolith information, and gonad developmental stages collected from
> 125,000 individual Northeast Arctic cod (Gadus morhua) sampled
between 59 and 73 °N in 1980-2019. Combined with experimental data of
oocyte growth rates, our analysis shows that cod spawned progressively
earlier by about a week per decade, partly due to ocean warming. It also
appears that spawning times vary by more than 40 days, depending on year
and spawning location. The significant plasticity in spawning time seems
to be fine-tuned to the local phytoplankton spring bloom phenology. This
ability to partly overcome thermal drivers could allow individuals to
phenologically modulate their spawning time to maximize fitness by closely
tracking local environmental conditions important for offspring survival.
This finding highlights a new dimension for trophic match-mismatch and
should be an important consideration in models used to predict phenology
dynamics in a warmer climate.