Traditional At-Sea Surveys

Traditional survey methods — bottom trawls, midwater trawls, visual transects by divers or remotely operated vehicles, and ship-based hydroacoustic surveys — have been the primary source of marine biodiversity data for decades. They provide directly observed species identifications, abundance counts, and size measurements that form the calibration baseline for all newer approaches.

Why traditional methods matter

No satellite image or water-column DNA sample yet replaces the taxonomic resolution, ecological context, and direct biological measurement that a skilled observer or net tow can provide. Long-running trawl survey time series are irreplaceable for detecting change, because they span decades with consistent methodology.

The cost problem

The fundamental limitation of ship-based surveys is scale. A research cruise covers a finite geographic area over a finite window of time at significant cost per sample. MBON’s strategic investment in genomics, acoustics, and remote sensing is explicitly motivated by the need to extend coverage between cruises — not to replace them.

Integration with modern methods

MBON uses traditional survey stations as calibration points for:

• eDNA — comparing metabarcoding species lists against trawl catches at the same station
• Active acoustics — groundtruthing echosounder biomass estimates with trawl-confirmed species
• Remote sensing — linking satellite-derived chlorophyll and habitat maps to observed species assemblages

This integration allows the network to extrapolate from point observations to basin-scale understanding.