Authors
Matthew David Taylor, Stephen Grant Morris, Rowan Campbell Chick
Published in
PeerJ. Volume 14. Pages e21665. Epub Aug 24, 2026.
Abstract
Cockles (ark clams) are infaunal molluscs that support important fisheries worldwide, but often occur across a complex range of strata. This creates challenges for designing independent survey programs to support fisheries management, and there is a need for additional published studies to aid development of such programs. Here, we improve the basal information available to inform the design of sampling programs for cockles, using Sydney Cockle (Anadara trapezia) as a case study. The combination of small quadrats and systematic searching of the quadrat area using the 'finger dredge' approach was highly effective. In a typical nested design (including quadrats, transects, subsites and sites), a considerable proportion of the overall variation in cockle abundance was detected at intermediate distances, with an upper limit of spatial dependence of <700 m. Approximately 77% of quadrats had all cockles visible upon initial observation (without 'finger dredging'), meaning visible cockles provided a reasonable proxy for total (visible + buried) abundance. However, patterns were not consistent among subsites, suggesting site-specific factors may influence cockle burial. Presence of epiphytic algae ('cockle weed') provided a poor proxy for both presence and abundance, as algae was absent when cockles were present in 75% of observations. Analyses indicated that sampling effort should prioritise a greater number of shorter transects with fewer quadrats, allocated across a grid with <350 m centres. The patterns resolved are broadly useful for developing sampling programs for both cockles, and other infaunal bivalve molluscs.
PMID:
42668952
Bibliographic data and abstract were imported from PubMed on 30 Aug 2026.
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