R. Keller Kopf's research while affiliated with Charles Darwin University and other places

Publications (32)

Article
Full-text available
The likelihood of extinction within the next 20 years was determined for 47 Australian mammal, bird, reptile, frog and freshwater fish taxa previously identified as being highly imperilled. A 14-member expert elicitation panel, consisting of a mix of taxon experts and government managers of threatened species, estimated that there was a > 50% chanc...
Article
Supporting the recovery of large carnivores is a popular yet challenging endeavour. Estuarine crocodiles in Australia are a large carnivore conservation success story, with the population having extensively recovered from past heavy exploitation. Here, we explored if dietary changes had accompanied this large population recovery by comparing the is...
Article
Full-text available
This study aimed to investigate the links between parasites and behavioural traits of juvenile Murray cod (Maccullochella peelii). The Murray cod is an endangered Australian freshwater fish for which restocking programs are in place and there is a growing human consumption market. However, little is known about the parasites of these fish and how t...
Article
Full-text available
The aim of this study was test whether maximum body mass and jaw length are reliable predictors of trophic position (TP) in fishes, and to compare linear and nonlinear machine‐learning (ML) models incorporating biogeography, habitat and other morphological traits. Global. Modern. Fishes. We compiled a global database of TP (2.0–4.5), maximum body m...
Article
In the World's rivers, alteration of flow is a major driver of biodiversity decline. Global warming is now affecting the thermal and hydrological regimes of rivers, compounding the threat and complicating conservation planning. To inform management under a non-stationary climate we must improve our understanding of how flow and thermal regimes inte...
Article
• Dam construction is a major driver of ecological change in freshwater ecosystems. Fish populations have been shown to diverge in response to different flow velocity habitats, yet adaptations of fish populations to river and reservoir habitats created by dams remains poorly understood. • We aimed to evaluate divergence of morphological traits and...
Article
Full-text available
Animals show various behavioural, neural and physiological changes in response to losing aggressive encounters. Here, we investigated affective state, which are emotion-like processes influenced by positive or negative experiences, in a territorial fish following aggressive encounters and explore links to bold/shy behavioural traits. Eighteen 15-mo...
Article
Full-text available
Aim The only factor in the fossil record that consistently buffers against extinction risk is large geographical range. We ask whether extant vertebrate species with the smallest geographical range for their body size have a higher extinction risk, and thus whether the lower bound of the modern range–body size relationship could serve as an effecti...
Article
Most fish recruitment models consider only one or a few drivers in isolation, rarely include species’ traits and have limited relevance to riverine environments. Despite their diversity, riverine fishes share sufficient characteristics that should enable predictions of recruitment. Here we synthesize the essential components of fish recruitment hyp...
Article
Full-text available
The Australian Government is considering Cyprinid herpesvirus 3 (CyHV-3) for biocontrol of invasive common carp (Cyprinus carpio L.). We review the evidence-base for its potential ecological risks, benefits and effectiveness. Lower carp abundance may boost native fish biomass and improve water clarity, but there is little evidence available to sugg...
Article
Although the effects of mass fish mortality (MFM) events on fish populations and water quality are frequently reported, the effects on consumers of fish and other water-dependent fauna are relatively poorly understood. Managing the effects of MFM events on other fauna is important when they occur in ecologically or culturally sensitive locations, o...
Article
The biomass of organisms of different sizes is increasingly being used to explore macroscale variation in food-web and community structure. Here we examine how invasive species and river flow regulation affect native fish biomass and fish community log10 biomass – body mass scaling relationships in Australia’s largest river system, the Murray–Darli...
Article
Full-text available
Widespread flooding in south-eastern Australia in 2010 resulted in a hypoxic (low dissolved oxygen, DO) blackwater (high dissolved carbon) event affecting 1800 kilometres of the Murray–Darling Basin. There was concern that prolonged low DO would result in death of aquatic biota. Australian federal and state governments and local stakeholders collab...
Article
Different populations of organisms can vary widely in their responses to environmental conditions and this variation is fundamental to the persistence of species. Using a common garden experiment, we examined temperature-specific growth and survival responses of larvae among populations of Murray cod (Maccullochella peelii) from four regions of the...
Article
Full-text available
Large-scale invasive species control initiatives are motivated by laudable desires for native species recovery and economic benefits, but they are not without risk. Management interventions and policies should include evidence-based risk–benefit assessment and mitigation planning.
Article
Full-text available
en Small body size is generally correlated with r‐selected life‐history traits, including early maturation, short‐generation times, and rapid growth rates, that result in high population turnover and a reduced risk of extinction. Unlike other classes of vertebrates, however, small freshwater fishes appear to have an equal or greater risk of extinct...
Article
Full-text available
Global ecosystems have shifted from historical conditions, but it is unclear from what baselines change should be assessed. Scientists and managers have increasingly accepted the impossibility of returning ecosystems to a “pristine” state; however, historical conditions remain the cornerstone for restoration and management. We explore the rationale...
Article
Full-text available
Hypoxia represents a growing threat to biodiversity in freshwater ecosystems. Here, aquatic surface respiration (ASR) and oxygen thresholds required for survival in freshwater and simulated blackwater are evaluated for four lowland river fishes native to the Murray-Darling Basin (MDB), Australia. Juvenile stages of predatory species including golde...
Article
This study presents the first histology-based assessment of the reproductive dynamics of south-west Pacific striped marlin Kajikia audax. Maturity and reproductive status were assessed from histological sections of ovaries (n = 234) and testes (n = 243) of fish caught in commercial longline and recreational fisheries between 2006 and 2009. Spawning...
Book
Fish marking and tracking is a fundamental tool for fisheries management and research. In recent years the technologies and analytical procedures available for marking and monitoring fisheries have evolved. The 31 chapters in this volume include papers on integrated approaches, conventional tagging, acoustic tags and arrays, radio telemetry, chemic...
Article
Kopf, R. K., Davie, P. S., Bromhead, D., and Pepperell, J. G. 2011. Age and growth of striped marlin (Kajikia audax) in the Southwest Pacific Ocean. – ICES Journal of Marine Science, 68: 1884–1895. This study describes the first validated model of age and growth developed for striped marlin (Kajikia audax). Daily periodicity of otolith microincreme...
Article
Annulus counts were compared between four sectioned levels of first dorsal-fin spines (D1-6) and anal-fin spines (A1-3) of Striped Marlin (Kajikia audax) caught in the southwest Pacific Ocean. The number of annuli observed in transverse sections varied significantly between spines of individual fish and between sections cut at varying distances alo...
Article
Sailfish (Istiophorus platypterus) appear annually off northwestern Australia in large numbers, supporting substantial recreational and charter fisheries in which almost all fish are released. The main centres for this activity are the towns of Broome, Dampier and Exmouth. Examination of historic Japanese longline catch data from northwestern Austr...
Article
This study describes the first validated model of age and growth developed for striped marlin (Kajikia audax). Daily periodicity of otolith microincrements was corroborated by back-calculated hatch dates that matched the known spawning season in the Southwest Pacific Ocean (SWPO). Yearly annulus formation in fin-spine sections was corroborated by d...
Article
Full-text available
Fin spine ageing is the most common technique used to estimate age and growth parameters of large pelagic billfishes from the families Istiophoridae and Xiphiidae. The most suitable methods for processing and interpreting these calcified structures for age estimation have not been clearly defined. Methodological differences between unvalidated agei...
Article
Full-text available
This review investigates how recreational fishing affects the physiology, behaviour, and welfare of fish. Sentience and the capacity of fish to experience pain, suffering and fear are discussed, and practical recommendations for improving the treatment of fish during recreational fishing are provided. Handling procedures used in recreational fishin...
Article
Full-text available
Size trends and population characteristics of striped marlin, Tetrapturus audax (Philippi, 1887) caught in the New Zealand recreational fishery were evaluated using club records from the Bay of Islands Swordfish Club (BOISC) from 1925 to 2003 (n = 15,114) and biological samples from northern New Zealand collected from 1985 to 1994 (n = 684). Averag...
Article
Full-text available
which tries to explain natural phenomena in terms of underlying causes. These underlying causal relationships in science are required to be self consistent and to correspond with actual reality and differ subtly from the philosophical enquiries which inform the questions but not necessarily the answers. Whether or not other animals are conscious an...

Citations

... R Core Team, 2021) and the package rfishbase (Boettiger et al., 2012). Trophic position estimates from FishBase are often crude but have reasonable correlation levels with more precise estimates from stable isotope analyses (Carscallen et al., 2012;Mancinelli et al., 2013) and have been used extensively by other studies (e.g., Romanuk et al., 2011;Dantas et al., 2019;Kopf et al., 2021). The fish traits measured here were selected based on well-documented associations with feeding, locomotion, and habitat use (Toussaint et al., 2016;Bower and Winemiller, 2019;Keppeler and Winemiller, 2020; see Tables S1 and S2 for definition, function, and references). ...
... Individual growth strongly influences ultimate body size and reproductive fitness (Barneche et al. 2018;Tréhin et al. 2021), and is thus an important aspect of population dynamics (Plard et al. 2015). Abiotic and biotic drivers of fish growth, and/or the direction and magnitude of their effects, are likely to vary between life stages as habitat and resource requirements, physiological tolerances and sexual maturity, shift during ontogeny (Lange et al. 2018;Stoffels et al. 2020). For example, the relationship between energy acquired and somatic growth changes profoundly at maturation, whereafter much of the energy acquired is allocated to reproduction, with a concomitant decline in somatic growth (Lester et al. 2004). ...
... A limitation of this study was that only ecomorphological traits were used for characterizing functional originality. Although ecomorphological traits mirror evolutionary processes and can be used as a proxy of functional niche and ecological functions, we believe that a more direct quantification of species functions is warranted (Villéger et al., 2017;Svozil et al., 2020). In fact, the exact relationships between ecomorphological traits and ecosystem functions have been studied in detail only for a few traits and taxa (Wainwright, 1991;Higham, 2007a;Higham, 2007b;Cochran-Biederman & Winemiller, 2010;Villéger et al., 2017;Svozil et al., 2020;). ...
... Short-term emotional responses can shape an animal's affective state, which are long-term states that reflect the valence, positive or negative, of emotions over time (Mendl et al. 2010). Affective states can influence the way an animal makes decisions (cognitive bias) (Kleinginna and Kleinginna 1981;Lazarus 1982;Paul et al. 2005;Millot et al. 2014;Dolcos and Denkova 2015;Roelofs et al. 2016;Cerqueira et al. 2017;Laubu et al. 2019;Rogers et al. 2020). Cognitive bias tests are a well-validated indicator of animal welfare for a variety of terrestrial species, however, there is little evidence of this type of test being employed in an aquatic setting for farmed fish (Baciadonna and McElligott 2015;Bethell 2015;Crump et al. 2020). ...
... However, currently available phylogenetic comparative methods are still limited with respect to allowing for simultaneous tests for multiple correlates of evolutionary rates, but this area seems like a particularly interesting area for further investigation. Together with body size, range size is a strong predictor of anthropogenic extinction risk (Newsome et al., 2020). We hope that our results might contribute to a more mechanistic understanding of range size evolution, as well as to predict the impacts of global climate change on the future distribution of terrestrial vertebrates. ...
... While misinformation is not a new phenomenon, the complexity and scale of misinformation in today's digitally networked world is unmatched (Wardle and Derakhshan 2017). Environmental misinformation and the potential impacts of misinformation about environmental initiatives, including MPAs, have begun to garner some attention in academic research and will likely continue to increase as more ambitious MPA targets are set worldwide (Davis et al. 2014;Farrell 2019;Kopf et al. 2019;Munro 2019;Lees et al. 2020;Hart et al. 2020). The implications for environmental policy processes can be profound, negatively influencing people's behaviours and attitudes about conservation initiatives and redirecting conversations away from relevant issues that require greater attention and analysis (Davis et al. 2014). ...
... By retreating water and creating additional slackwater habitats, major flood pulses generally result in increased nutrient enrichment and concentration in nursery areas. This boosts primary production and food availability for newly-hatched fishes (Reckendorfer et al., 1999;Hoagstrom and Turner, 2015), and could lead to strong cohorts and increased abundances of certain fish species (Górski et al., 2011;Cruz et al., 2020;Humphries et al., 2020). Following the major flooding of 2020, we observed highest overall YOY abundances whereas in 2017, we found low fish numbers. ...
... A reasonable critique of our modelling to identify areas for the prioritisation of the release of CyHV-3 is that it does not directly address the complex issue of weighing the pros and cons of using the virus for carp population control. However, as has been discussed extensively, this is an extremely complex and controversial issue with little current consensus McColl and Sunarto, 2020;McGinness et al., 2019). One of the most often stated arguments against release of the virus is the uncertainty of achieving ecological restoration at the same time as limiting detrimental effects to the environment and other species . ...
... The virus is specific to common carp and is considered harmless to other species of fish, other animals and humans (McColl et al. 2014(McColl et al. , 2018. Transmitted through water, CyHV-3 infects carp causing lesions and necrosis in the fish's gills, resulting in a high rate of mortality within just a few days of infection (Boutier et al. 2019;McColl et al. 2018;Michel et al. 2010). Components of the NCCP feasibility study included extensive testing on the susceptibility of native animals to infection, modelling of potential ecological consequences, and a study of social and economic risks and benefits, including the social risk acceptability of the proposed biocontrol method (Commonwealth Department of Agriculture, Water and the Environment 2020; McColl et al. 2018). ...
... Although the authors generally agree that myxomatosis should not be released today, the voice of compassionate conservation stated that there were plans to do very similar things to carp (Cyprinus carpio) [68], to cats (Felis catus) and to many other species, even knowing how traumatic death was for the affected rabbits. We are still releasing new strains of calicivirus, a hemorrhagic disease, to kill those rabbits that myxomatosis missed. ...