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Abstract: We aimed to identify spatial variability in estuarine trophic pathways and to elucidate their role as a nursery for juvenile fishes along Chikugo River estuary, Japan. First, we investigated [...]

Abstract: A comprehensive framework for modelling data from multiyear tagging experiments in a fishery context is presented that incorporates catch data into the traditional Brownie tag-recapture model. Incorporation of catch [...]

Teleost fishes capture prey using ram, suction, and biting behaviors. The relative use of these behaviors in feeding on midwater prey is well studied, but few attempts have been made to determine how benthic prey are captured. This issue was addressed in the wrasses (Labridae), a trophically diverse lineage of marine reef fishes that feed extensively on prey that take refuge in the benthos. Most species possess strong jaws with stout conical teeth that appear well-suited to gripping prey. Mechanisms of prey capture were evaluated in five species encompassing a diversity of feeding ecologies: Choerodon anchorago (Bloch, 1791), Coris gaimard (Quoy and Gaimard, 1824), Hologymnosus doliatus (Lacepede, 1801), Novaculichthys taeniourus (Lacepede, 1801) and Oxycheilinus digrammus (Lacepede, 1801). Prey capture sequences were filmed with high-speed video at the Lizard Island Field Station (14[degrees]40'S, 145[degrees]28'E) during April and May 1998. Recordings were made of feeding on pieces of prawn suspended in the midwater and similar pieces of prawn held in a clip that was fixed to the substratum. Variation was quantified among species and between prey types for kinematic variables describing the magnitude and timing of jaw, hyoid, and head motion. Species differed in prey capture kinematics with mean values of most variables ranging between two and four-fold among species and angular velocity of the opening jaw differing seven-fold. The kinematics of attached prey feeding could be differentiated from that of midwater captures on the basis of faster angular velocities of the jaws and smaller movements of cranial structures which were of shorter duration. All five species used ram and suction in combination during the capture of midwater prey. Surprisingly, ram and suction also dominated feedings on attached prey, with only one species making greater use of biting than suction to remove attached prey. These data suggest an important role for suction in the capture of benthic prey by wrasses. Trade-offs in skull design associated with suction and biting may be particularly relevant to understanding the evolution of feeding mechanisms in this group.

The sensory brain areas of a sample of

Analysis of stable isotopes of oxygen and carbon in the otolith carbonate of pink snapper, Pagrus auratus, from several locations in Shark Bay, Western Australia, indicated that snapper are highly location specific. The hypersaline (36 to > 60 [per thousand]) Shark Bay, on the coast of Western Australia, generated strongly characteristic isotopic signatures in the otolith carbonate of snapper collected from the various locations indicating low levels of individual movement of the species. Oxygen isotopes showed enrichment in [sup.18.O] in otolith carbonate with salinity (0.10: [DELTA] [delta][sup.18.O]/[DELTA] salinity [per thousand]) typical for the evaporation of seawater. The enrichment in [sup.13.C] (up to 1.75[per thousand]) was attributed to the incorporation of metabolically derived C[O.sub.2] from an enrichment of [sup.13.C] in the food web within Shark Bay. This was possibly a result of lower concentrations of dissolved C[O.sub.2] with increasing salinity causing a reduction in isotope fractionation during photosynthesis. Results complement recent genetic and tagging studies and provide further evidence of the complex nature of snapper stock structure in the Shark Bay region.

Research has been conducted on association between genetic diversity and fitness in bullhead populations. Results demonstrate that both environmental and genetic variables can affect bullhead population condition factor.