Instrument: Squidpop

The squidpop assay is described in detail in Duffy et al., 2015 (doi: 10.1371/journal.pone.0142994).

In summary, the squidpop consists of a standard prey item: a small piece of dried squid mantle tissue, tethered to a fiberglass plant stake with light monofilament fishing line. The squidpop is assembled by first punching a 1.3-centimeter (cm) diameter disc from the squid mantle using a cork borer. A length of monofilament line is threaded through the squid disc and tied to it securely, then the other end of the line is attached to the end of the plant stake with electrical tape, leaving 1-2 cm of line with the squid piece on the end. The short length of the line helps prevent tangling the tethers when squidpops are bundled together.

Squidpops are deployed by pushing the stakes securely into the substratum. The stakes are typically arranged in one or two rows, but the spatial arrangement is of secondary importance to ensuring that the squidpops can be reliably relocated and retrieved at the end of the deployment. Squidpops are assessed for the presence or absence of the squid bait after some period of time.