Spring temperature gave no clear common day-night richness interaction in four CalCOFI samples from 1978-2022

We tested whether spring sea temperature changes the night-minus-day contrast in recorded fish larva richness. We used spring bongo tows in two California sectors and two periods, 1978-1999 and 2000-2022. Expected richness at 20 larvae reduced differences in individual counts. Station and year effects, season terms and tow volume reduced sampling bias. The analysis retained 1,316 of 2,147 selected tows. Four interaction slopes ranged from -0.651 to +0.292 taxa per C. All four adjusted 95% intervals included zero. A stricter light rule gave a negative interval in the later south, but the direction did not repeat in all samples. This does not prove that sampling time has no bias. Sparse catches, taxon labels, selected stations, broad uncertainty and shared water masses limit inference. We did not test air pollution or attribute change to human warming. The package gives code, aggregate results, source hashes, checks and instructions. External data and record-level panels stay outside the package.

CalCOFI · observation bias · day-night sampling · rarefaction · fish larvae · temperature · null result