Do Angler Moves Carry Invasive Fish Between Waters? Inconclusive on Current Data

The earlier finding from 4,370 moves between waters with a native-species negative control, that there is no evidence angler movement spreads invasive species, is withdrawn. In the 2026-09-26 snapshot, 6,016 times an angler's consecutive catches fall in different waters (1,486 anglers, 3,327 waters); but the snapshot has no verified invasive-species classification and no effort or unsuccessful-trip record, so the link between angler movement and invasive spread is currently inconclusive.

Inconclusive: without a pinned invasive classification the negative control and time split cannot be rebuilt, and catch locations only show where fish were caught.

Reviewed 2026-09-30 | Data 2025-01-01 to 2026-09-25

The earlier version drew a network of each angler's moves between waters, compared invasive and native species over 4,370 moves from 2025-01-01 to 2026-09-04, and concluded that the network predicts both equally, finding no evidence that angler movement spreads invasive species. That conclusion is withdrawn.

There are three reasons. The pinned species catalogue (3,479 rows) has no invasive or native field and the external list the earlier study used was never pinned, so the negative control cannot be rebuilt. Moves can only be inferred from the places of consecutive catches, so places visited without a catch are invisible. The earlier time split and first-appearance rule have not been rebuilt on the current data.

So whether angler movement spreads invasive species is currently inconclusive. This is neither a finding of no link nor a finding of a link.

Of 14,424 eligible catches from 2025-01-01 to 2026-09-25, 3,549 anglers have catches with a water body. Ordered by verified capture time, an angler's consecutive catches fall in different waters 6,016 times, from 1,486 anglers, across 3,327 waters and 5,532 distinct origin-destination pairs.

Moves are inferred from catch records only and are not complete itineraries; the water-body link is used only to tell whether consecutive catches are in different waters, and no record was excluded because of it.

A versioned invasive-species list that can be pinned and mapped species by species to the site's species identity.

Location records for every trip, including trips with no catch, hypotheses written down before looking at the data, then a rebuilt negative control and time split.

Source: a read-only point-in-time snapshot taken 2026-09-26 (38,040 catch records), recomputed offline with no production reads or writes.

Records count from 2025-01-01 when the current record, species identity and context rules all pass and both upload and verified capture time are on or before 2026-09-25; shrimp-fishing, managed-pond and non-fish records are excluded. Water class is used only for grouping; no record was excluded because of it.