Seine nets and beam trawls compared by day and night for sampling fish and crustaceans in shallow seagrass habitat

By Ma Guest, Rod M. Connolly, N. Loneragan. 2003

112 citations recorded by the source corpus.

Densities of nekton were estimated by comparing catch rates of two previously uncompared gear types, a beam trawl and a seine net, by day and night in a shallow seagrass (Zostera capricorni) habitat in Moreton Bay, Queensland, Australia. A total of 39,676 fish and crustaceans representing 42 species was caught. The catch rates of nekton were 1.4-68.1 times higher at night than in the day for 8 of the 17 common species, and were 1.4-9.2 times higher in seines than trawls for 11 of the common species. None of the common species had higher catch rates in the day than the night, or in the trawls than the seines. For some species there was no significant difference in catch rates amongst the sampling combinations. Night-time seine collections had a greater proportion of larger individuals than day and trawl samples. The differences in catch rates and size of nekton are probably a consequence of both gear avoidance and the movement of nekton out of seagrass during the day. Catch rates were estimated more accurately and precisely with the seine than the trawl, with higher catch rates at night. An analysis of the overall composition of the catch (based on presence/absence data) by multi-dimensional scaling separated the samples into four main groups: day-trawl, night-trawl, day-seine and night-seine. The results suggest that seine nets are a better choice for determining the relative proportion of species in a seagrass habitat, and estimating the density of most species. Such sampling should also be done by day and night, or by night alone.

Subfields: Global and Planetary Change, Oceanography

View Paper: https://www.semanticscholar.org/paper/b4b09a0910fd0d7f272350d86dbd27ccdc5b6c0b

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Citations in the corpus

Fish assemblages in seagrass beds are influenced by the proximity of mangrove forests (2007, background): “Previous research demonstrated that four drags of the net gave an adequate estimation of the fish assemblage (Jelbart 2004), and the net design has previously been demonstrated to be effective at capturing seagrass fish (Connolly 1994b; Guest et al. 2003 ).”
Review of nekton patterns and ecological processes in seagrass landscapes (2006, background): “Collection techniques for nekton in seagrass have been well described (Rozas and Minello, 1997; Edgar et al., 2001; Guest et al., 2003), but landscape studies often require novel techniques that are effective at scales small enough to sample different microhabitats within patches (Connolly, 1994d).”
The role of seagrass meadows, mangrove forests, salt marshes and reed beds as nursery areas and food sources for fishes in estuaries (2017, background): “However, overall night-time catches of fishes in seagrass (Zostera capricorni) beds in Moreton Bay (Australia) were considerably higher than day-time catches (Guest et al. 2003), and the number of fish species were nocturnally greater in Ruppia megacarpa habitats in the Wilson Inlet (Australia) than”
Diel trophic structuring of seagrass bed fish assemblages in the Wakatobi Marine National Park, Indonesia (2007, methodology): “Foods, such as epibenthic crustaceans, whilst available in the day, have been found to nocturnally increase in abundance, both locally (Unsworth et al., unpublished data) and in other localities ( Guest et al., 2003 ).”
High connectivity of Indo-Pacific seagrass fish assemblages with mangrove and coral reef habitats (2008, background): “Despite the spatial imbalance of the 3 habitat types (all Sg Cor sites were located around Hoga Island, as mangroves still remain dominant in most coastal areas with low human impact), we do not consider this to be a major reason for our observed results.”