Ben Fitzpatrick

We studied the persistence of fishing impacts on coral reef fish assemblages by sampling 2 protected and 2 fished locations, using random replicate stereo baited remote underwater video. At each location we sampled a variety of coral reef habitats on 4 separate occasions between 2006 and 2007. We tested for consistency in differences in the biomass of target and non-target species, trophic groups and overall assemblages. Generally, target species were more abundant and/or larger at protected… Show more

We studied the persistence of fishing impacts on coral reef fish assemblages by sampling 2 protected and 2 fished locations, using random replicate stereo baited remote underwater video. At each location we sampled a variety of coral reef habitats on 4 separate occasions between 2006 and 2007. We tested for consistency in differences in the biomass of target and non-target species, trophic groups and overall assemblages. Generally, target species were more abundant and/or larger at protected locations. Many non-target species were either more abundant or depleted at protected sites, and some of these species were significantly larger or smaller. Trophic groups such as piscivores, piscivore invertivores, invertivores and planktivores were consistently more abundant within protected locations. Generally, greater numbers of species and individuals were found on protected reefs, though this was not consistent in all cases across all 4 sampling periods. These findings are consistent with the theory that protected areas can increase the abundance of not just target species but overall fish assemblages. These findings provide evidence for ecological mechanisms such as predator–prey interactions, competitive release, and benefits to invertivores, omnivores and other non-target groups from the presence of more abundant and larger target species within marine protected areas. Show less

The implications of shallow water impacts such as fishing and climate change on fish assemblages are generally considered in isolation from the distribution and abundance of these fish assemblages in adjacent deeper waters. We investigate the abundance and length of demersal fish assemblages across a section of tropical continental shelf at Ningaloo Reef, Western Australia, to identify fish and fish habitat relationships across steep gradients in depth and in different benthic habitat types… Show more

The implications of shallow water impacts such as fishing and climate change on fish assemblages are generally considered in isolation from the distribution and abundance of these fish assemblages in adjacent deeper waters. We investigate the abundance and length of demersal fish assemblages across a section of tropical continental shelf at Ningaloo Reef, Western Australia, to identify fish and fish habitat relationships across steep gradients in depth and in different benthic habitat types. The assemblage composition of demersal fish were assessed from baited remote underwater stereo-video samples (n = 304) collected from 16 depth and habitat combinations. Samples were collected across a depth range poorly represented in the literature from the fringing reef lagoon (1–10 m depth), down the fore reef slope to the reef base (10–30 m depth) then across the adjacent continental shelf (30–110 m depth). Multivariate analyses showed that there were distinctive fish assemblages and different sized fish were associated with each habitat/depth category. Species richness, MaxN and diversity declined with depth, while average length and trophic level increased. The assemblage structure, diversity, size and trophic structure of demersal fishes changes from shallow inshore habitats to deeper water habitats. More habitat specialists (unique species per habitat/depth category) were associated with the reef slope and reef base than other habitats, but offshore sponge-dominated habitats and inshore coral-dominated reef also supported unique species. This suggests that marine protected areas in shallow coral-dominated reef habitats may not adequately protect those species whose depth distribution extends beyond shallow habitats, or other significant elements of demersal fish biodiversity. The ontogenetic habitat partitioning which is characteristic of many species, suggests that to maintain entire species life histories it is necessary to protect corridors of connected habitats. Show less

Measures of fish abundance, assemblage composition and length were compared when sampled by baited remote underwater stereo-video (stereo BRUV) and diver-operated stereo-video transects (stereo DOV) at the Houtman Abrolhos Islands and Ningaloo Reef. Species richness counts were 40% higher on stereo BRUV than stereo DOV. Stereo BRUVs also recorded a greater number of large-bodied targeted species in higher abundance than stereo DOV (e.g. Lethrinus nebulosus, Plectropomus leopardus) at the… Show more

Measures of fish abundance, assemblage composition and length were compared when sampled by baited remote underwater stereo-video (stereo BRUV) and diver-operated stereo-video transects (stereo DOV) at the Houtman Abrolhos Islands and Ningaloo Reef. Species richness counts were 40% higher on stereo BRUV than stereo DOV. Stereo BRUVs also recorded a greater number of large-bodied targeted species in higher abundance than stereo DOV (e.g. Lethrinus nebulosus, Plectropomus leopardus) at the Houtman Abrolhos and at Ningaloo Reef. Many non-targeted species were also recorded in greater abundances on stereo BRUV than stereo DOV (e.g. Coris auricularis, Gymnothorax spp). Stereo DOV transects recorded a greater abundance of some small-bodied Pomacentridae, Labridae and Scaridae species than did stereo BRUV, particularly at Ningaloo Reef. This study demonstrates that choice of sampling technique for surveys of reef fish can lead to very different biological interpretations of fish assemblage structure. Show less

Baited remote underwater stereo-video (stereo-BRUV) stations and diver operated stereo-video (stereo-DOV) transects are increasingly used to sample both tropical and temperate fish assemblages. Compared to in situ visual census methods, the use of stereo-video reduces inter-observer variability, improves definition of the sample unit area, increases accuracy of fish length estimates and provides a permanent record of the assemblage that can be validated where required or independently… Show more

Baited remote underwater stereo-video (stereo-BRUV) stations and diver operated stereo-video (stereo-DOV) transects are increasingly used to sample both tropical and temperate fish assemblages. Compared to in situ visual census methods, the use of stereo-video reduces inter-observer variability, improves definition of the sample unit area, increases accuracy of fish length estimates and provides a permanent record of the assemblage that can be validated where required or independently reanalysed. Previous studies have suggested that stereo-BRUV collects representative data on both carnivorous and herbivorous species and can be more cost-efficient than diver-based survey methods. This study compares estimates of common fish assemblage metrics obtained with stereo-BRUV stations and stereo-DOV transects across 3 biogeographic regions, and uses a cost-optimization procedure to compare the efficiency of these 2 methods. Stereo-BRUV stations were found to sample greater species richness and obtain greater estimates of relative biomass of generalist carnivores, but no differences occurred in the biomass of herbivores sampled by the 2 techniques. Stereo-BRUV stations generally obtained estimates of assemblage metrics with less variance, resulting in greater power to detect spatial and temporal changes in the fish assemblage metrics. Cost–benefit analyses found that stereo-BRUV was generally more time efficient than stereo-DOV transects in terms of smaller standard error around the mean of the various metrics considered. However, across the 3 biogeographic regions sampled there was considerable variation in the magnitude of these differences. Results suggest that stereo-BRUV stations are, in general, a more cost-effective method for monitoring fish assemblages than stereo-DOV transects. Show less

Seasonal observations of whalesharkabundance recorded by ecotourist operators at NingalooReef, WesternAustralia from 1999 to 2004 were compared with weekly regional and global oceanographic and atmospheric variables, including average sea surface temperatures, along-shelf wind shear, sea level and the Southern Oscillation Index (SOI). Estimates of these physical variables were derived from either ground-based data or from remote sensing instruments. A generalised linear mixed-effects modelling… Show more

Seasonal observations of whalesharkabundance recorded by ecotourist operators at NingalooReef, WesternAustralia from 1999 to 2004 were compared with weekly regional and global oceanographic and atmospheric variables, including average sea surface temperatures, along-shelf wind shear, sea level and the Southern Oscillation Index (SOI). Estimates of these physical variables were derived from either ground-based data or from remote sensing instruments. A generalised linear mixed-effects modelling (GLMM) approach with random sampling and model simulation was used to determine the relationships between the number of whalesharks and all model variants of the environmental parameters, using information-theoretic weights of evidence to rank models. SOI and wind shear had the most support for explaining the deviance in weekly whalesharkabundance at NingalooReef during a season. The SOI and wind shear variables positively influenced whalesharkabundance such that more sharks were sighted when the Southern Oscillation was stronger and along-shelf winds were increasingly prevalent. This may reflect changes in the strength of oceanographic processes such as the Leeuwin Current (in response to the Southern Oscillation) and wind/current driven upwelling which may affect the abundance of whalesharks transported to the region and/or the availability of their prey by driving productivity changes. Show less

Over-exploitation of whalesharks threatens the future of these wide-ranging pelagic fish. A long-term continuous record (4436 sightings) from a large aggregation (300–500 resident individuals) of whalesharks at NingalooReef, Western Australia shows that mean shark length declined linearly by nearly 2.0 m and relative abundance measured from ecotourism sightings (corrected for variation in search effort and environmental stochasticity) has fallen by approximately 40% over the last decade. This… Show more

Over-exploitation of whalesharks threatens the future of these wide-ranging pelagic fish. A long-term continuous record (4436 sightings) from a large aggregation (300–500 resident individuals) of whalesharks at NingalooReef, Western Australia shows that mean shark length declined linearly by nearly 2.0 m and relative abundance measured from ecotourism sightings (corrected for variation in search effort and environmental stochasticity) has fallen by approximately 40% over the last decade. This population-level result confirms previous predictions of population decline based on projection models parameterised using mark-recapture estimates of survival. The majority of these changes are driven by reductions in the number of large individuals in the population. Phenomenological time series models support a deterministic (extrinsic) decline in large females, although there was some evidence for density dependence in large males. These reductions have occurred despite the total protection of whalesharks in Australian waters. As this species is highly migratory, the rapid change in population composition over a decade (<1 whaleshark generation) supports the hypothesis of unsustainable mortality in other parts of their range (e.g., overfishing), rather than the alternative of long-term abiotic or biotic shifts in the environment. As such, effective conservation of whalesharks will require international protection, and collaborative tagging studies to identify and monitor migratory pathways. Show less

Ningaloo Reef in Western Australia hosts an aggregation of whale sharks in coastal waters from March to June. The predictable arrival of whale sharks has led to the development of a lucrative ecotourism industry that allows divers to observe sharks in shallow waters on the seaward edges of the fringing coral reef. During these whale shark encounters, attacks by a predator, possibly a tiger shark, Galeocerdo cuvier (Péron and Lesueur in Lesueur, 1822), or great white shark, Carcharodon… Show more

Ningaloo Reef in Western Australia hosts an aggregation of whale sharks in coastal waters from March to June. The predictable arrival of whale sharks has led to the development of a lucrative ecotourism industry that allows divers to observe sharks in shallow waters on the seaward edges of the fringing coral reef. During these whale shark encounters, attacks by a predator, possibly a tiger shark, Galeocerdo cuvier (Péron and Lesueur in Lesueur, 1822), or great white shark, Carcharodon carcharias
(Linnaeus, 1758), and ectoparasitic sharks (Isistius spp.) were documented. Encounters with the same whale shark 3 mo and then 1 yr later recorded wound healing. This time series provides insight into the predation risk faced by whale sharks despite their size and their ability to recover from attacks that cause substantial wounds. Show less

This paper presents results from a benthic survey testing for differences in benthic habitat variability between sanctuary zones and adjacent areas of two coastal Marine Protected Areas (MPAs) of New South Wales (NSW), Australia; Jervis Bay Marine Park (JBMP) and Solitary Islands Marine Park (SIMP); and within the newly established Cape Byron Marine Park (CBMP) and adjacent waters. This addresses a need to better define habitat to support management and conservation of unique, spatially… Show more

This paper presents results from a benthic survey testing for differences in benthic habitat variability between sanctuary zones and adjacent areas of two coastal Marine Protected Areas (MPAs) of New South Wales (NSW), Australia; Jervis Bay Marine Park (JBMP) and Solitary Islands Marine Park (SIMP); and within the newly established Cape Byron Marine Park (CBMP) and adjacent waters. This addresses a need to better define habitat to support management and conservation of unique, spatially restricted or threatened species including grey nurse sharks, Charcharias taurus, black cod, Epinephelus daemelii, eastern blue devil fish, Parapleisiops bleekeri, ballina angelfish Chaetodontoplus ballinae, and broad banded anemonefish, Amphiprion latezonatus (NSWMPA et. al. 2001). Non destructive towed video and echo sounding measured habitat along randomized 250m transects in 10 and 60m depths (Oxley 1997). Video were analyzed and percent cover of 14 biophysical benthic habitat types derived. Within Jervis Bay Marine Park, coralline-turf and macro algae, sponge, sponge-ascidian complex, Jervis Bay oyster, polychaete, sand, silt and rubble habitat were observed in various combinations of which it was found that sand, sponge and sea-whip habitat was significantly underrepresented within sanctuary zones. Solitary Islands Marine Park was found to contain coralline-turf algae, macro algae, sponge, hard coral, soft coral, black coral, ascidian, sand, silt and rubble habitat in various combinations of which rubble, sponge, soft coral and turf/coralline algae habitat deeper than 35m was underrepresented within sanctuary zones. This study addresses preliminary information needs describing habitat heterogeneity within MPAs of NSW and represents one approach for planning and assessing a representative network of MPAs at the habitat level. Show less