Marine Wildlife Research Articles

Analysis of two whale shark watching destinations in Indonesia: status and ecotourism potential

Abstract. Djunaidi A, Jompa J, Nadiarti N, Bahar A, Tilahunga SD, Lilienfeld D, Hani MS. 2020. Analysis of two whale shark watching destinations in Indonesia: status and ecotourism potential. Biodiversitas 21: 4511-4523. Botubarani in Gorontalo, on the northern coast of Tomini Bay and Labuhan Jambu in Teluk Saleh, Sumbawa recently became whale shark tourism destinations in Indonesia. Both sites offer visitors opportunities to interact with whale sharks, either watching from canoes or snorkelling and diving. In this study, we investigated the status and ecotourism potential of whale shark watching as a form of marine wildlife tourism development in eastern Indonesia by examining the existing operations in both sites. Data were collected using questionnaires administered to local community members and visitors to understand their perceptions, and how this opportunity was valued. Secondary data were collected to explore and understand influencing factors. Findings revealed that whale sharks commonly emerge near bagan lift-nets and other interactive areas as a response to the presence of their favorite prey, anchovies, and rebon shrimp. In general, whale sharks most commonly visit bagan lift nets and can be found in the interaction areas in the morning and stay for couple of hours before swimming away to deeper waters. Out of 119 community respondents in Labuhan Jambu village (Teluk Saleh) and Botubarani, Gorontalo, 80.7% knew about the occurrence of whale sharks in their locality. Of the 111 visitor respondents, 67.6% knew about the whale shark watching sites from word of mouth. The study results also suggest a correlation between chlorophyll-a concentration, anchovies, rebon shrimp and whale sharks. Regarding management approaches to this type of tourism, a local community-based management model is strongly recommended, with 87.4% of respondents showing interest in this approach. The roles and responsibility of local government in developing such tourism is very significant, especially with respect to facilitating appropriate competency within the local community throughout training and education, as suggested by nearly 26% of respondents.

Leftover drug disposal: Customer behavior, pharmacist recommendations, and obstacles to drug take-back box implementation

Production and use of pharmaceuticals in the United States is high and continues to grow. This, combined with poor wastewater removal rates for drugs in excreted waste, and improper pharmaceutical disposal leads to the presence of pharmaceuticals in fresh- and marine waters and wildlife. In the United States, safe drug take-back boxes, or dropboxes, were established in pharmacies after federal legislation passed in 2014, allowing for year-round safe collection of leftover pharmaceuticals. The overarching objective of this work was to identify opportunities for improving access to proper pharmaceutical disposal. We assessed consumer behavior regarding drug disposal choices and knowledge of dropboxes at pharmacies, investigated pharmacist attitudes toward and recommendations about leftover drug disposal, and compared responses at locations with and without dropboxes. We also explored obstacles to dropbox adoption and usage. We found that customer awareness of dropboxes as well as knowledge about risks of improper disposal are low, however awareness was greater at pharmacies with dropboxes. Additionally, pharmacists at dropbox locations were more consistent in their messaging to customers, more likely to recommend proper disposal methods, and more supportive of drug take-back programs. Through a focus group, we learned that further consumer education would overwhelm the capacity of the existing dropboxes. Based on our findings, we recommend solutions to improper disposal focus on legislation mandating dropboxes at pharmacies and pressure on the pharmaceutical industry to fund proper disposal of unused pharmaceuticals.

Development and application of species-specific cell-based bioassays to assess toxicity in green sea turtles

Despite the detection of a wide range of contaminants in the blood of green turtle populations foraging in three locations of northern Queensland – Upstart Bay, Cleveland Bay and the Howick Group of Reefs, little is known about the effects of these contaminants on turtle health. Newly developed cell-based bioassays using green turtle primary cell cultures provide an ethical, reproducible, and high-throughput method for assessing the risk of chemical exposure sea turtles. In this project, the toxicity of six priority metals (Mn, Co, Mo, As, Sb, Cu) and blood extracts from foraging turtles were tested in two bioassays adapted to green turtle primary skin and liver cells. Cytotoxicity of metals and blood extracts was measured in primary skin fibroblast cells using a resazurin assay. Glutathione-S-transferase (GST) activity was measured in primary skin fibroblasts and primary liver epithelial cells following exposure to metals and blood extracts. Arsenic, molybdenum, cobalt and copper were found to be cytotoxic to green turtle skin cells. Only manganese, cobalt and copper were found to alter GST activity, predominantly in skin cells, indicating a higher sensitivity of green turtle skin cells compared to liver cells. Effect concentrations of metals in both bioassays were above concentrations found in turtle blood. Turtle blood extracts from the three foraging grounds showed differences in cytotoxicity and GST activity. In both assays, blood extracts of turtles from Upstart Bay were the most toxic, followed by those from Cleveland Bay, then the Howick Reefs, suggesting turtles from Upstart Bay and Cleveland Bay may be at risk from current concentrations of organic contaminants. This study demonstrates that species-specific cell-based bioassays can be used effectively to assess chemical risk in sea turtles and their foraging grounds, and could be applied to assess chemical risk in other marine wildlife.

Marine Wildlife Experiences and Beliefs: Towards Reciprocal Benefits

The concept of reciprocal healing invites consideration of how experiences in nature and with wildlife encourage mutual benefits via well-being for humans and the earth. This contrasts with using n...

How safe are the new green energy resources for marine wildlife? The case of lithium

Considering the increasing use of Lithium (Li) and the necessity to fulfil this demand, labile Li occurrence in the environment will be enhanced. Thus, additional research is needed regarding the presence of this element in marine environment and its potential toxic impacts towards inhabiting wildlife. The aim of the present study was to evaluate Li toxicity based on the exposure of Mytilus galloprovincialis to this metal, assessing the biochemical changes related with mussels’ metabolism, oxidative stress and neurotoxicity. For this, organisms were exposed to different Li concentrations (100, 250, 750 μg/L) for 28 days. The results obtained clearly demonstrated that Li lead to mussels’ metabolism depression. The present study also revealed that, especially at the highest concentrations, antioxidant and biotransformation enzymes were not activated, leading to the occurrence of lipid peroxidation and loss of redox homeostasis, with increased content in oxidized glutathione in comparison to the reduced form. Furthermore, after 28 days, higher Li exposure concentrations induced neurotoxic effects in mussels, with a decrease in acetylcholinesterase enzyme activity. The responses observed were closely related with Li concentrations in mussels’ tissues, which were more pronounced at higher exposure concentrations. Such results highlight the potential toxic effects of Li to marine species, which may even be higher under predicted climate changes and/or in the presence of other pollutants.

Risk assessment of atmospheric and liquid discharges of radionuclides on humans, marine biota and terrestrial wildlife

Egypt is currently considering building a nuclear power plant (NPP). Consequently, an environmental impact assessment is required for potential releases to the environment. The aim of this work is to implement an environmental impact assessment for a nuclear power plant to assess radiation doses to man and the wildlife, to aid the decision-making related to the environment effects of that facility. This study focused on atmospheric dispersion modeling code cap88-Pc, ERICA Tool version 1.2 and R&D128 approach for predicting the activity concentrations of released radionuclides and the corresponding dose rates to human, as well as terrestrial and marine wildlife at different distances from the reactor at normal operation. The results of total dose rate to marine wildlife, recommended that the release point to be beyond 1600 m offshore for such organisms to be protected and the summing risk quotient to be well below unity. The risk quotients for terrestrial organisms from deposited radionuclides on the ground and the emitted noble gases were well below unity. The total effective dose rate to man from air emissions and from consumption of contaminated marine species (fish and crustaceans) from liquid discharges combined was 5.19E−3 mSv y−1 corresponding to 2.6E−7 cancer risk factor, which is acceptably low risk. The radionuclide Co-60 was one of the major contributors of dose rate to marine organisms (beside Co-58 and Mn-54) and of total effective dose for human together with Ag-110m and C-14. The current study considered to provide the baseline information for further implementation of regulatory policies when site specific data is available.

Transboundary marine mammal management in the Northern Bering-Chukchi Sea Large Marine area

ABSTRACT Indigenous arctic communities access terrestrial and marine wildlife. This access contributes to their food sovereignty. Ineffective management of wildlife that migrate internationally jeopardizes local and regional access to these species and subsequently hunting practices and human health. Despite general recognition of the role of effective transboundary management in food security, the issue remains under-studied. One puzzle is why some food sources (i.e. marine mammals) with transboundary policies have been sustainably managed, while others have not. Guided by Mitchell’s ‘four factors’ framework, this research compares the effectiveness of the transboundary management of the Bering-Chukchi-Beaufort bowhead whale population and the Chukchi Sea polar bear population in the Northern Bering-Chukchi Sea Large Marine Ecosystem. We find that the cases diverged in terms of governance and transparency. Regarding the management of the Chukchi Sea polar bear population, information and incentives were only sometimes present and capacities were rarely present. Based on the effective aspects of the evaluated transboundary agreements, we recommend the following for transboundary marine mammal management in the Arctic: 1) that local and regional financial, administrative, and technical capacities are included at the decision-making table, and 2) that western science is used in conjunction with Indigenous Knowledge or to co-produce knowledge.

The Role of Temperature on the Impact of Remediated Water towards Marine Organisms

Marine organisms are frequently exposed to pollutants, including trace metals, derived from natural and anthropogenic activities. In order to prevent environmental pollution, different approaches have been applied to remove pollutants from waste water and avoid their discharge into aquatic systems. However, organisms in their natural aquatic environments are also exposed to physico-chemical changes derived from climate change-related factors, including temperature increase. According to recent studies, warming has a negative impact on marine wildlife, with known effects on organisms physiological and biochemical performance. Recently, a material based on graphene oxide (GO) functionalized with polyethyleneimine (PEI) proved to be effective in the remediation of mercury (Hg) contaminated water. Nevertheless, no information is available on the toxic impacts of such remediated water towards aquatic systems, neither under actual nor predicted temperature conditions. For this, the present study assessed the toxicity of seawater, previously contaminated with Hg and remediated by GO-PEI, using the clam species Ruditapes philippinarum exposed to actual and a predicted temperature conditions. The results obtained demonstrated that seawater contaminated with Hg and/or Hg+GO-PEI induced higher toxicity in clams exposed to 17 and 22 °C compared to organisms exposed to remediated seawater at the same temperatures. Moreover, similar histological and biochemical results were observed between organisms exposed to control and remediated seawater, independently of the temperatures (17 and 21 °C), highlighting the potential use of GO-PEI to remediate Hg from seawater without significant toxicity issues to the selected marine species.

Beach-user perceptions and attitudes towards drone surveillance as a shark-bite mitigation tool

Management of human-wildlife conflict is often challenging and complex, particularly when the conflict involves sharks. New technologies are being trialled in New South Wales, on Australia's east coast, to accommodate the community demand for increased beach-user protection that does not harm marine wildlife. Drones (or unmanned aerial vehicles), are one of a suite of potential tools that can address both these demands. We released an online survey to assess beach-user perceptions and attitudes toward drones on NSW beaches as a shark surveillance tool. From 439 respondents, we found the use of drones on coastal beaches was accepted by the majority of people surveyed (88%) due to perceptions of reduced impact on sharks, and the relatively low cost. Drone surveillance was also the preferred approach for bather protection overall. Arguably the most vulnerable beach-user group for a shark bite incident, surfers, claimed the highest level of awareness of the use of drones for shark surveillance, but also indicated lower confidence in their utility compared to other groups. The study demonstrates an overall social licence regarding the use of drones for shark surveillance purposes, with the levels of support likely to increase with further public education efforts and improvements to the efficacy of drone-based surveillance.

Plastic-derived contaminants in Aleutian Archipelago seabirds with varied foraging strategies

Phthalates, plastic-derived contaminants, are of increasing global concern. This study quantified phthalates in seabirds collected across >1700 km of the Aleutian Islands, Alaska, and contributes to a body of knowledge on plastic contaminants in marine wildlife. We measured six phthalate congeners in seabirds representing ten species and four feeding guilds. Phthalates were detected in 100% of specimens (n = 115), but varied among individuals (3.64–539.64 ng/g). DEHP and DBP occurred at an order of magnitude higher than other congeners. Total phthalates did not vary geographically, but differed among feeding guilds, with significantly higher concentrations in diving plankton-feeders compared to others. Plastic particles were detected in 36.5% of randomly subsampled seabird stomachs (n = 74), suggesting plastic ingestion as a potential route of phthalate exposure. Our findings suggest feeding behavior could influence exposure risk for seabirds and lend further evidence to the ubiquity of plastic pollutants in marine ecosystems.

A Scientific Basis for Designation of the Northeast Canyons and Seamounts Marine National Monument

The Northeast Canyons and Seamounts Marine National Monument (NEC&SMNM) was designated by President Barack Obama in 2016, using his authority under the Antiquities Act of 1906. The Act allows a President to proclaim as national monuments “historic landmarks, historic and prehistoric structures, and other objects of historic or scientific interest” that are “upon the lands owned or controlled” by the United States but to reserve each designation to “the smallest area compatible with the proper care and management of the objects to be protected.” Protection in general excludes commercial scale extraction and is in perpetuity. Analyses of physiographic and ecological data sets facilitated assessment of the conservation benefits of protections for the NEC&SMNM and syntheses of the ecological literature describe processes that operate in continental margin and deep-sea settings. Results indicate that the current monument designation is an area of high diversity and ecological connectivity across depths and along the continental margin. The monument boundaries contain hot spots (areas of high abundance and species richness) for seafloor communities (inclusive of benthic invertebrate and demersal fish) as well as marine mammals in the epipelagic. Many species are sensitive to disturbance and vulnerable to human activities (e.g., deep-sea corals, sponges) with very long recovery times and extremely low resilience. The monument contains at least nine exemplars of offshore northwest Atlantic marine wildlife communities and habitats (e.g., deep shelf invertebrates, shelf fish, deep sea corals and sponges in canyons and on seamounts, deep sea fish, chemosynthetic communities, deep sea soft sediment, shelf edge cetaceans & seabirds). The region is relatively undisturbed and can serve as a reference site to focus future research on ecological processes in an increasingly industrialized ocean and one subject to the synergies of regional climate effects. These results suggest that there is great potential for discovery and novel research in this first Atlantic Ocean Marine National Monument.

From Human Wellbeing to an Ecocentric Perspective: How Nature-Connectedness Can Extend the Benefits of Marine Wildlife Experiences

ABSTRACT Contact with nature and experiences with nonhuman animals have been shown to contribute to nature connection and human wellbeing, both of which are innate needs according to the biophilia hypothesis. This study explores what marine mammal encounters mean to people and how they affect connection to and understanding of nature. It was hypothesized that individuals who had wild random vs ecotour vs captive marine mammal experiences would report differing degrees of meaning and nature-connectedness. The paper draws on responses to three survey questions, two quantitative and one qualitative, by 625 predominantly Australian participants. Significant differences were found between the three types of marine mammal experiences on subjective meaning, with highest levels in the wild random, then ecotour, then captive experience. Similarly, participants with wild experiences were more likely to report that the experience had influenced their nature connection than those who had captive mammal experiences. The five themes of Positive Emotion, Engagement, Relationships, Meaning, and Accomplishment that make up Seligman’s PERMA wellbeing model were used to inform thematic template analyses of the short answer responses and highlighted the relationship between wellbeing and connection to nature. Importantly, the addition of Perspective as a sixth theme captured the expressed changes in participants’ points of view and attitudes, including humans’ place in the world and their impacts. Collectively the results point to how, through nature-connectedness and wellbeing, marine mammal experiences can contribute to an ecocentric view and humans can realize their effects on nature and wildlife. A model is proposed for understanding how marine mammal experiences can facilitate the quest for human wellbeing and meaning.

Concentrations of some legacy pollutants have increased in South Australian bottlenose dolphins from 1989 to 2014

Information about pollution and its potential impact in Australian marine wildlife is scarce. To fill this knowledge gap, our study investigated concentrations of legacy pollutants as well as naturally produced methoxylated polybrominated diphenyl ethers (MeO-PBDEs) in blubber, liver, kidney and muscle of Indo-Pacific bottlenose dolphins (Tursiops aduncus) from two large inverse estuaries in South Australia from 1989 to 1995 and 2009–2014. Our results show that concentrations of most pollutant classes are relatively low compared to the literature but at the higher end of the ranges reported for marine mammals in Australia. Results for some individuals exceed toxicity thresholds indicative of immunotoxicity in marine mammals. It is important to note that concentrations of some compound classes, particularly PBDEs and polychlorinated biphenyls (PCBs), increased over a time interval of 20 years thereby placing more individuals at risk in recent years. Some of the highest concentrations of persistent organic pollutants (POPs) were measured in juveniles, which may jeopardize their development and the success of future generations. These results indicate that legacy pollutants may play a role in the long-term health of T. aduncus and should be included in biomonitoring efforts.

Seasonal productivity drives aggregations of killer whales and other cetaceans over submarine canyons of the Bremer Sub-Basin, south-western Australia

Cetaceans are iconic predators that serve as important indicators of marine ecosystem health. The Bremer Sub-Basin, south-western Australia, supports a diverse cetacean community including the largest documented aggregation of killer whales (Orcinus orca) in Australian waters. Knowledge of cetacean distributions is critical for managing the area’s thriving ecotourism industry, yet is largely sporadic. Here we combined aerial with opportunistic ship-borne surveys during 2015–2017 to describe the occurrence of multiple cetacean species on a regional scale. We used generalised estimating equations to model variation in killer whale relative density as a function of both static and dynamic covariates, including seabed depth, slope, and chlorophyll a concentration, while accounting for autocorrelation. Encountered cetacean groups included: killer (n = 177), sperm (n = 69), long-finned pilot (n = 29), false killer (n = 2), and strap-toothed beaked (n = 1) whales, as well as bottlenose (n = 12) and common (n = 5) dolphins. Killer whale numbers peaked in areas of low temperatures and high primary productivity, likely due to seasonal upwelling of nutrient-rich waters supporting high prey biomass. The best predictive model highlighted potential killer whale ‘hotspots’ in the Henry, Hood, Pallinup and Bremer Canyons. This study demonstrates the value of abundance data from platforms of opportunity for marine planning and wildlife management in the open ocean.

Tourists’ willingness to pay for Blue Flag's new ecolabel for sustainable boating: the case of whale-watching in Iceland

ABSTRACT Despite its positive image boat-based marine wildlife tourism, including whale-watching, endangers animals’ habitats and populations. This highlights the importance of transitioning towards more sustainable forms of boating. This could be achieved through certification with ecolabels that establish clear guidelines for operators, and ensure compliance, while informing tourists of these higher standards. Ecolabelled operators should be able to gain a competitive edge by offering a more sustainable product. The aim of this paper is to analyse tourists’ willingness to pay for a new ecolabel for sustainable boating in the case of whale-watching in Iceland using the Contingent Valuation Method. Results of a survey of 337 whale-watchers show that 60% were very likely to choose an ecolabelled tour, and that 65.9% were likely or very likely to be willing to pay ∼20% more for an ecolabelled tour. Considering the intention-behaviour gap, the low importance of environmental issues for choosing the operator, and other biases, it is probable that the ecolabel would only influence preferences in a limited market niche. We suggest that the new ecolabel has a high potential for promoting sustainability in boating tourism if it develops into a full-blown CSR approach that covers a content broader than just environmental issues.

Unraveling the white shark observation tourism at Guadalupe Island, Mexico: Actors, needs and sustainability

White Shark watching tourism at natural aggregation sites is an increasingly popular activity globally among marine wildlife enthusiasts. This wildlife tourism activity promotes conservation and economic development but information on the design of adequate and sustainable management practices is missing. Management of the White Shark Observation Activity (WSOA) at Guadalupe Island, Mexico, in an international context was explored. The actors involved in the WSOA as well as the power relationships among them were investigated. Actors helped to elucidate the strengths, weaknesses, opportunities and threats of the WSOA. Tourist Operators, Tourists, a Fishing Cooperative, Non-Governmental Organizations, Academia, and Federal Government institutions were identified as the main groups of actors. All the actors agreed that they have an interest in the use of resources and their conservation but their needs and some perspectives of management differed. An imbalance of power among actors was found, with Federal Governmental institutions holding most power, possibly hindering collective management actions. It is necessary to adapt a management plan that promotes a vision for the future and the integration of the concerns and perspectives of the stakeholders to ensure the sustainability of the WSOA.

Estimating the effects of pile driving sounds on seals: Pitfalls and possibilities.

Understanding the potential effects of pile driving sounds on marine wildlife is essential for regulating offshore wind developments. Here, tracking data from 24 harbour seals were used to quantify effects and investigate sensitivity to the methods used to predict these. The Aquarius pile driving model was used to model source characteristics and acoustic propagation loss (16 Hz-20 kHz). Predicted cumulative sound exposure levels (SELcums) experienced by each seal were compared to different auditory weighting functions and damage thresholds to estimate temporary (TTS) and permanent (PTS) threshold shift occurrence. Each approach produced markedly different results; however, the most recent criteria established by Southall et al. [(2019) Aquat. Mamm. 45, 125-232] suggests that TTS occurrence was low (17% of seals). Predictions of seal density during pile driving made by Russell et al. [(2016) J. Appl. Ecol. 53, 1642-1652] were compared to distance from the wind farm and predicted single-strike sound exposure levels (SELss) by multiple approaches. Predicted seal density significantly decreased within 25 km or above SELss (averaged across depths and pile installations) of 145 dB re 1 μPa2⋅s. However, there was substantial variation in SELss with depth and installation, and thus in the predicted relationship with seal density. These results highlight uncertainty in estimated effects, which should be considered in future assessments.

Preferential adsorption of Cd, Cs and Zn onto virgin polyethylene microplastic versus sediment particles

Plastic pollution has become a major environmental concern worldwide, and marine ecosystems have become polluted with ubiquitous microplastic particles (MP). MP can contain chemical additives and can also scavenge pollutants from the surrounding environment, and these co-contaminants may threaten the marine biota when MP become inadvertently ingested and transferred up the food chain. However, our understanding of the sorption-desorption kinetics of chemical compounds bound to MP remains limited. Moreover, whether MP are better transport vectors of co-contaminants than other natural particles (e.g. sediment) has not received much attention. Here, we used radiotracers to examine the partition coefficients (Kd) of three trace metals (109Cd, 134Cs, and 65Zn) to virgin MP (32–75 μm polyethylene beads) and to natural sediment particles of a similar size (35–91 μm) in seawater. After 72 h, sediment particles adsorbed 2.5% of 109Cd, 68.0% of 134Cs, and 71.0% of 65Zn, while MP adsorbed <0.8% of these three elements. Results highlight that under these experimental conditions, virgin polyethylene MP may not be effective transport vectors for these trace metals. Important variations in Kd were observed between elements, inciting for further studies to decipher how chemical characteristics, MP composition, and associated-biofilms, all interact in these biokinetic processes. These results demonstrate how radiotracers can allow us to address important knowledge gaps and broaden our understanding regarding the interactions between waterborne contaminants, naturally occurring particles and marine wildlife.

A global review of elasmobranch tourism activities, management and risk

Elasmobranch tourism is a rapidly expanding global industry. While this industry can provide community and conservation benefits, it presents risks to target species, environments and humans when inappropriately managed. To ensure appropriate management is implemented, there is a need to identify the prevalence of elasmobranch tourism globally, the types of operations occurring and the controls used to mitigate risk. This study undertook a global literature review to develop an industry activity typology and establish the types of management controls present across elasmobranch tourism operations. In total, 151 unique species-activity-location conditions were identified, with four broad activity types categorised: diving, snorkelling, provisioning and cage diving. Spanning 42 countries and 49 different species, 32% of conditions identified lacked evidence of management. Further to this, many of the prevailing management controls in place (e.g. MPAs, shark sanctuaries, protected species status), were secondary in nature, having not been designed or implemented to manage elasmobranch tourism explicitly. Therefore, avoidable risks are likely widespread throughout the industry. Encouragingly, the application of activity specific management controls is likely to be effective at reducing risks across activity types. The theoretical case studies and management tools investigated herein provide operators and industry managers with guidance on how to reduce risk and safeguard industry benefits. With the elasmobranch tourism industry likely to continue expanding, it is important that appropriate management and regulatory frameworks are in place so that marine wildlife tourism can continue in a beneficial and sustainable manner.

Fish density estimation using unbaited cameras: Accounting for environmental-dependent detectability

The fast development of camera technologies opens a breakthrough opportunity for animal ecology, particularly at the marine realm where observing wildlife is challenging. These outstanding technological advances are meeting with the impressive capabilities of artificial intelligence for enabling automatic extraction of relevant information from videos and images. Altogether, this may be a unique opportunity for a qualitative jump in marine wildlife assessment but substantial strengthening of the links between theorists, empiricists and engineers is still required. Specifically, a recent theory proposes that animal density can be estimated from (1) the counted animals per frame, (2) the area surveyed by the camera and (3) the probability of detecting an animal that is actually within the area surveyed by the camera. However, a potential drawback for applying this theory to the real world is that environmental dependencies of camera's detection probability may lead to biased estimates of animal density. Therefore, here we propose a sampling protocol and a statistical model of general application for estimating (and accounting for) the environmental factors affecting fish detectability when estimating fish density with cameras. The method implies one calibration sampling with cameras and with the preferred reference method at the same time and place. The relevance of this method is that, once calibrated, it can be used to obtain unbiased estimates of fish density at new sites and moments using only cameras. Thus, fish density could be estimated at the temporal and the spatial scale needed, but with substantially less cost-effort than any other reference methods (e.g., underwater visual censuses). As a proof of concept, we evaluated the dependence of camera's detection probability on habitat complexity (e.g., cavities, rocks, seagrass, etc.) as a proxy for the hiding capability of a small serranid. In that specific case, probability of detection seems to be independent of habitat complexity. However, the sampling protocol and the statistical model provided here open the opportunity to estimate fish density using underwater cameras at wider temporal and/or spatial scales, which will help to better understanding the ultimate drivers of marine fish population dynamics and further development of science-based management.