Comparison of efficiency of direct observations by scuba diver and indirect observations via video camera for measuring reef-fish behaviour

Comparing remote and hand-held video observation methods for quantifying a cleaning mutualism

Field studies of cleaning mutualisms use a variety of methods to quantify behavioral dynamics. Studies in marine systems typically utilize data recorded by human observers on scuba or snorkel or via remote underwater video. The effects of these different methods on cleaner-client behaviors have not been rigorously assessed. We quantified cleaner-client interactions at 13 bluestreak cleaner wrasse (Labroides dimidiatus) cleaning stations in Moorea, French Polynesia using hand-held and remote videos. We found that cleaning, cheating, and client posing rates, cleaning duration, and client species richness were all greater in the remote than in the hand-held videos, suggesting that human presence disrupts cleaning interactions by inducing antipredator responses among clients. Some metrics, such as the ratio of cleaner chasing to cleaning behavior and the cleaners' benthic feeding rate, were higher for the hand-held than the remote videos, possibly due to limited access of cleaners to clients in the presence of humans. Other metrics, such as cleaner and client chasing rates, the ratio of cleaning to cheating behaviors, and the duration of cleaner chases, did not differ between video types. Finally, piscivorous clients were far more abundant in the remote than the hand-held videos, suggesting that piscivores are particularly sensitive to human presence, likely because they are targeted by fishers. Overall, our study suggests that human presence can bias studies of cleaning behavior and cleaner-client interactions, and that remote cameras should be used to conduct behavioral studies. These potential biases should be considered when interpreting existing behavioral data.

Point for Enrichment, Point for Welfare-Testing Use of a Laser Pointer with Arapaima gigas

The arapaima (Arapaima gigas) is one of the largest freshwater fish species, known to exceed 3 m in total length. It is listed as Data Deficient by the IUCN. A. gigas is native to the Amazon River basin where they are an important food source. Arapaimas are also farmed for meat and for live specimens in various South American and Asian countries. Despite decades of keeping the species in public aquariums, little is known of its behaviour and cognitive abilities. This pilot study provides baseline data on using a green laser pointer as environmental enrichment for this species under human care. The data collection included 18 observations before the use of the laser pointer (baseline) and 18 observations during the use of the laser pointer (test). Ten behaviours were monitored, investigating physical contact, activity pattern and habitat use by the fish. During the test, the fish significantly increased their presence in the tank, their level of activity and their use of the habitat. This pilot study provides valuable baseline data for further investigations demonstrating the value of a laser pointer as environmental enrichment for A. gigas under human care.

Frequent visits to various anvils during tool use by the graphic tuskfish Choerodon graphicus (Labridae)

This study investigated tool use by the graphic tuskfish Choerodon graphicus in New Caledonia. Anvils included rocks, a conical shell, flat dead corals and a concrete mooring. Sixteen tool-use events were observed in 10 h. A tool-use event often involved more than one anvil (44%). On average, C. graphicus struck prey six times and spent 84 s at an anvil. The only prey items brought to anvils were bivalve and gastropod molluscs. These results provide a foundation for future research on tool use in fishes.

Damselfishes alleviate the impacts of sediments on host corals

Mutualisms play a critical role in ecological communities; however, the importance and prevalence of mutualistic associations can be modified by external stressors. On coral reefs, elevated sediment deposition can be a major stressor reducing the health of corals and reef resilience. Here, we investigated the influence of severe sedimentation on the mutualistic relationship between small damselfishes (Pomacentrus moluccensis and Dascyllus aruanus) and their coral host (Pocillopora damicornis). In an aquarium experiment, corals were exposed to sedimentation rates of approximately 100 mg cm-2 d-1, with and without fishes present, to test whether: (i) fishes influence the accumulation of sediments on coral hosts, and (ii) fishes moderate partial colony mortality and/or coral tissue condition. Colonies with fishes accumulated much less sediment compared with colonies without fishes, and this effect was strongest for colonies with D. aruanus (fivefold less sediment than controls) as opposed to P. moluccensis (twofold less sediment than controls). Colonies with symbiont fishes also had up to 10-fold less sediment-induced partial mortality, as well as higher chlorophyll and protein concentrations. These results demonstrate that fish mutualisms vary in the strength of their benefits, and indicate that some mutualistic or facilitative interactions might become more important for species health and resilience at high-stress levels.

Ethical considerations in fish research

Fishes are used in a wide range of scientific studies, from conservation research with potential benefits to the species used to biomedical research with potential human benefits. Fish research can take place in both laboratories and field environments and methods used represent a continuum from non-invasive observations, handling, through to experimental manipulation. While some countries have legislation or guidance regarding the use of fish in research, many do not and there exists a diversity of scientific opinions on the sentience of fish and how we determine welfare. Nevertheless, there is a growing pressure on the scientific community to take more responsibility for the animals they work with through maximising the benefits of their research to humans or animals while minimising welfare or survival costs to their study animals. In this review, we focus primarily on the refinement of common methods used in fish research based on emerging knowledge with the aim of improving the welfare of fish used in scientific studies. We consider the use of anaesthetics and analgesics and how we mark individuals for identification purposes. We highlight the main ethical concerns facing researchers in both laboratory and field environments and identify areas that need urgent future research. We hope that this review will help inform those who wish to refine their ethical practices and stimulate thought among fish researchers for further avenues of refinement. Improved ethics and welfare of fishes will inevitably lead to increased scientific rigour and is in the best interests of both fishes and scientists.