Use of artificial shelter structures by individual Penaeus monodon broodstock prawns

Optimising the housing and management conditions for aquaculture species is becoming increasingly important. Determining what resources animals prefer can inform captive management decisions for positive impacts on the individual’s welfare. The black tiger prawn ( Penaeus monodon ) aquaculture industry is prominent in Australia and is the second most farmed prawn species internationally, however there is little information on resource preferences of broodstock animals in hatcheries. The objective of this study was to assess the use of three different shelter structures, including a rectangular box, a cylindrical tube, and a vertical piece of plastic mesh, by 21 individual male P. monodon . It was hypothesised that prawns would utilise these objects and would prefer to be hidden rather than out on the open sandy substrate. Observations were made from video-recordings of individual prawns in separate tanks across 72 h. Scan sampling every 15 min included the location of the prawn in the tank (visually divided into thirds), proximity to a shelter structure, and contact with a shelter structure. Analyses across 12-h time blocks showed no effect of time on location (both P ≥ 0.13). There were only 6 instances where the prawns were observed in contact with the shelter structures and no significant difference in proximity preferences for the three shelter structures ( P = 0.26). Large standard deviations across measures of location preference and proximity indicated high variability between the tested individuals. Contrary to predictions, this study indicates these selected objects did not provide sufficient value to individual prawns to facilitate engagement with them in the experimental context tested. It is possible the sandy substrate in the tanks was sufficient enrichment for the prawns or that use may have increased if there was conspecific competition for access. Further work should continue to explore what resources may be utilised by this species that may inform on practical additions in the commercial hatchery environment. Future identification of resources that are of value to P. monodon prawns should continue to assess preferences while taking into account communal settings, individual variation and the potential benefits of providing a choice of resources that can cater to differing preferences. • Adult male Peneaus monodon prawns did not utilise shelter structures. • High individual variability in tank exploration and shelter proximity. • Identifying valued enrichments could improve broodstock management.