Habitat structure in soft-sediment environments and abundance of juvenile snapper Pagrus auratus

Abstract

Small-scale biogenic or physical features, such as depressions, burrows, shells, boulders, cobbles and sand waves, dominate soft-sediment coastal and shelf environments. Such structures may provide refuge from predation and feeding areas for juvenile fish. We investigated the potential for juvenile snapper Pagrus auratus to utilise areas characterised by small-scale structures by sampling soft-sediment habitats that varied in both sediment characteristics and biogenic structure. Juvenile snapper abundance was estimated at each site using opera house traps, while variations in small-scale benthic habitat structure were quantified from video transects of the seafloor. The captured fish had 172 ± 43 mm fork length, indicating that they were 1 to 2 yr old. Statistical modelling revealed that complex habitat structure had a positive influence on the abundance of juvenile snapper, suggesting that these areas are preferentially utilised. This finding highlights the potential for disturbance of such structures (by, for example, trawling or dredging) to affect the abundance of juvenile snapper.

Catchability and selectivity of juvenile snapper (Pagrus auratus, Sparidae) and western butterfish (Pentapodus vitta, Nemipteridae) from prawn trawling in a large marine embayment in Western Australia

“…These findings concur with studies on snapper from other localities where the preferred habitat for juvenile snapper, less than 2 years of age, is on silt substratum ideal for trawling (e.g. Lenanton, 1974;Francis, 1995;Thrush et al, 2002;Fowler and Jennings, 2003). Typically, at 18-24 months of age snapper move to non-trawlable habitat along reef margins of nearshore marine embayments (Moran and Kangas, 2003).…”

Feeding ecology of red snapper Lutjanus campechanus in the northern Gulf of Mexico

“…Small-scale biogenic and physical habitat features (e.g. shells, cobbles, sand waves) have been shown to be important for demersal fishes and have been suggested to increase juvenile survivorship (Lindholm et al 1999, Thrush et al 2002). An assumption in our approach is that natural mortality is growth rate-dependent and faster growing juveniles have lower mortality rates due to reduced exposure time to predators (Cowan et al 1996).…”

Presence of larger flatfish modifies habitat preference by Age-0 northern rock sole Lepidopsetta polyxystra

“…Sediment preferences often change with ontogeny, reflecting burial capabilities (Gibson & Robb 1992, Stoner & Ottmar 2003. However, within broad areas of suitable sediment characteristics, some species of juvenile flatfish, as well as other fishes, aggregate on bottom with secondary emergent features, such as shells, cobble, burrows, feeding pits and sand waves (Auster et al 1996, Thrush et al 2002, Abookire et al 2007), which presumably enhance habitat quality (Gibson 1994). For example, juvenile winter flounder Pseudopleuronectes americanus settle onto muddy sediments, but by the time they reach 55 mm often associate with drift algae Ulva lactuna and Gracilaria sp.…”