No abstract

The effect of environmental variables on movement of aquatic organisms can be examined using preferenceavoidance behaviors. Fluviariums have been used to examine such preference-avoidance behaviors in fish, including choices associated with various water quality variables. The sharp gradient in fluviariums provides aquatic organisms with a choice of (usually) two water qualities, sharply demarcated at a relatively narrow boundary zone. A detailed description of a recently constructed and up-dated fluviarium, however, is missing from the literature. The fluviarium described in this paper integrates hydrodynamic design and extensive control of water quality to provide consistent experimental conditions, while at the same time being affordable. The system described was designed and used to examine acid avoidance behavior in juvenile fish and prawns, as part of a larger study on migration barriers in aquatic environments. An assessment of the fluviarium with juvenile snapper, Pagrus auratus, showed that the system worked as desired. The design described here, however, can be used or modified to study behavioral responses of aquatic biota to a wide variety of environmental variables, including habitat quality or combinations of two or more environmental variables.

No abstract

Neonatal predation in multispecies aquarium exhibits can prevent detection of captive breeding by wobbegong sharks. We used ultrasonography and isolation strategies to prevent neonatal predation and maximize survival/growth of the dwarf ornate wobbegong (Orectolobus ornatus de Vis, 1883). We captured seven free‐living wobbegongs (two males and five females) and subjected each animal to a health assessment which led to the euthanasia of one female with a retained hook. Ultrasonography showed that females were pregnant, one was preovulatory, and one was in a resting phase. Two females (one pregnant) and one male were placed in isolation in each of two tanks. In October 2006, 25 neonates were born overnight with the two litters placed into separate neonate tanks. Over the ∼6.5‐month monitoring period, four neonates with reduced body condition died without premonitory signs resulting in a 63.0% annual survival rate. Finite growth rates did not differ between sexes or litters and averaged (±SE) 12.2 (1.5) cm/year and 156.4 (26.4) g/year. At the cessation of monitoring, total length had increased by ∼30%, whereas total weight had almost doubled with neonatal body condition in line with free‐living wobbegongs. Our efficacious, six‐step manipulative, the approach should be applicable with all wobbegongs given their reproductive similarities, but we recommend that efforts focus on the dwarf ornate, tasselled and Japanese wobbegongs because all are small in size and have bred in aquaria. Ultimately, this approach should produce self‐sustaining aquarium populations, place less reliance on the wild acquisition and provide animals for other aquaria, population restocking, or scientific research.