Documented and Potential Biological Impacts of Recreational Fishing: Insights for Management and Conservation

Analysis of Public Comments on Experimental Regulations for Protecting Black Bass during The Spawning Period in Eastern Ontario Reveals Both Stakeholder Acceptance and Skepticism

Recreational angling of nesting largemouth bass (Micropterus nigricans) and smallmouth bass (M. dolomieu) can greatly increase nest abandonment, and in the northern clines of their range, decrease recruitment. This is the case in eastern Ontario, where high levels of non-compliance and difficult to enforce regulations have impacted black bass (Micropterus spp.) conservation and management. Effective January 1, 2024 until December 31st, 2025, novel and experimental fishing sanctuaries were imposed on portions of Charleston Lake and Opinicon Lake that prohibit recreational fishing of all types from April 15th to the Friday before the first Saturday in July (encompassing the full bass reproductive season). As part of the formal process to institute these experimental regulations, public comments were collected on the Environmental Registry of Ontario. We examined those comments and identified supportive and non-supportive themes related to these experimental regulations. While a majority of stakeholders were in support of the new regulations, we also noted sub-themes that may hinder regulation acceptance. Those sub-themes include: a perceived lack of enforcement negating the potential benefits of the sanctuaries, under-estimation of the extent of non-compliance with existing regulations such that new regulations are unnecessary, misunderstanding and misinformation, as well as distrust of government and the academic research community. Understanding and addressing these stakeholder perspectives will help researchers studying the new sanctuary areas and managers understand any lack of compliance while informing future decisions about bass management in eastern Ontario and beyond.

Demographic patterns of walleye (Sander vitreus) reproductive success in a Wisconsin population

Harvest in walleye Sander vitreus fisheries is size-selective and could influence phenotypic traits of spawners; however, contributions of individual spawners to recruitment are unknown. We used parentage analyses using single nucleotide polymorphisms to test whether parental traits were related to the probability of offspring survival in Escanaba Lake, Wisconsin. From 2017 to 2020, 1339 adults and 1138 juveniles were genotyped and 66% of the offspring were assigned to at least one parent. Logistic regression indicated the probability of reproductive success (survival of age-0 to first fall) was positively (but weakly) related to total length and growth rate in females, but not age. No traits analyzed were related to reproductive success for males. Our analysis identified the model with the predictors' growth rate and year for females and the models with year and age and year for males as the most likely models to explain variation in reproductive success. Our findings indicate that interannual variation (i.e., environmental conditions) likely plays a key role in determining the probability of reproductive success in this population and provide limited support that female age, length, and growth rate influence recruitment.

Does size-selective harvesting erode adaptive potential to thermal stress?

Overharvesting is a serious threat to many fish populations. High mortality and directional selection on body size can cause evolutionary change in exploited populations via selection for a specific phenotype and a potential reduction in phenotypic diversity. Whether the loss of phenotypic diversity that accompanies directional selection impairs response to environmental stress is not known. To address this question, we exposed three zebrafish selection lines to thermal stress. Two lines had experienced directional selection for (1) large and (2) small body size, and one was (3) subject to random removal of individuals with respect to body size (i.e. line with no directional selection). Selection lines were exposed to three temperatures (elevated, 34°C; ambient, 28°C; low, 22°C) to determine the response to an environmental stressor (thermal stress). We assessed differences among selection lines in their life history (growth and reproduction), physiological traits (metabolic rate and critical thermal max) and behaviour (activity and feeding behaviour) when reared at different temperatures. Lines experiencing directional selection (i.e. size selected) showed reduced growth rate and a shift in average phenotype in response to lower or elevated thermal stress compared with fish from the random-selected line. Our data indicate that populations exposed to directional selection can have a more limited capacity to respond to thermal stress compared with fish that experience a comparable reduction in population size (but without directional selection). Future studies should aim to understand the impacts of environmental stressors on natural fish stocks.

How involvement drives decision rules behind stated preferences for recreational-fisheries management

This paper connects the concept of involvement with recreational fishing and decision rules, namely regret-minimizing vs. utility-maximizing when making choices related to the activity. We hypothesized that people who are more involved show regret-minimizing rather than utility-maximizing behavior. In support, we found that behavioral commitment, measured as avidity in fishing, and psychological involvement (measured by centrality of angling in the lifestyle of the respondent) was significantly related to the decision rule, correlating with regret-minimizing behavior, while skill, specific attitudes toward the catch and place attachment were unrelated to the decision rules that respondents followed. In our sample, regret-minimizers were dominant and preferred more restrictive harvest policies (i.e., lower daily bag limits or harvest slots over minimum-size limits). Welfare estimates of policy changes were sensitive to the decision rule and were substantially lower when assuming regret minimizing behavior than when assuming utility maximization. We conclude that regret-minimizing behavior may be a characteristic of more involved anglers, with relevant implications for welfare estimation and derivation of policy advice.

Acute effects of angler's groundbaits: nutrient flux to water column

Although ground-baiting related nutrient loading has been widely studied, we do not know what proportion of these nutrients release into the water column, affecting primary production directly. We conducted short-term (24-h, 5-day) experiments at wide temperature range, in presence and absence of fish using fish meal-based (FM-GB) and plant-based groundbait (PB-GB), to assess the nitrogen (N) and phosphorus (P) fluxes from GB into the water column. Nitrogen release from unconsumed FM-GB was negligible in the first 3 days, then increased abruptly, releasing 32% of its total N content by the fifth day. In contrast, PB-GB acted as temporary sink for inorganic N forms. Considerable (18-21%) inorganic P release was observed in both GB types in the first twelve hours. Consumed GBs induced considerable inorganic N release and its rate increased with temperature. Particulate forms predominated the released N in PB-GB, suggesting impaired digestion. Phosphorus-dominated by particulate forms-release was similar or lower than in unconsumed GB. Based on our results, excessive use of GB-when high amount of it remains unconsumed-can enhance eutrophication in P-limited ecosystems. Although less digestible GBs may have less abrupt effect on the primary production, undigested nutrients remain unavailable for removal through fish harvest.

Are the effects of catch-and-release angling evident in changes to mRNA abundances related to metabolism, acid-base regulation and stress in lake trout (Salvelinus namaycush) gills?

Catch-and-release (C&R) angling is a conservation-oriented practice intended to reduce the impact recreational angling has on fish populations. Even though most recreationally angled fish are released, little is known about how C&R angling impacts fish at the cellular or tissue level. As the first to explore the impacts of C&R angling on mRNA abundances, our study aimed to identify how the stress of angling influenced metabolism, acid-base regulation and cellular stress in the gills of lake trout (Salvelinus namaycush). Because gills are responsible for metabolic gas exchange, are crucial sites of acid-base homeostasis and respond to stressors quickly, we hypothesized that the relative mRNA abundance of genes related to these three physiological processes would be altered after angling. We took gill samples of live lake trout at 0, 2 or 48 h after fish were angled by rod and reel, and then used quantitative PCR (qPCR) to measure the relative abundance of nine candidate mRNA transcripts. Heat shock protein 70 (hsp70) mRNA levels significantly increased over 5-fold 2 h after angling, indicating a potential activation of a cytoprotective response. However, contrary to our hypothesis, we observed no change in the relative mRNA abundance of genes related to metabolism or acid-base regulation in response to C&R angling within a 48-h period. As C&R angling can negatively impact fish populations, further use of transcript-level studies will allow us to understand the impact C&R has on specific tissues and improve our knowledge of how C&R influences overall fish health.

Short-term responses of macroinvertebrate assemblages to the "ten-year fishing ban" in the largest highland lake of the Yangtze basin

The rapid decline of freshwater biodiversity caused by overfishing has led to the implementation of a series of conservation measures, including fishing bans. However, existing studies have mostly focused on the effects of fishing bans on economically important species, while impacts on freshwater macroinvertebrates in lake ecosystems have been rarely studied. This study used a before-and-after methodology to determine the short-term effects of the "ten-year fishing ban" on the macroinvertebrates of the Dianchi Lake, the largest highland freshwater lake in the upper Yangtze basin, between 2015 and 2022. Following the fishing ban, the overall macroinvertebrate species richness (median [interquartile]) across sites increased from 4 [2-6] to 5 [4-7]. The total density increased from 128 [80-272] to 212 [140-325] n/m². The median biomass increased from 0.18 [0.08-0.41] to 0.51 [0.26-2.36] g/m². In particular, the Chironomidae density in the offshore sites increased from 16.00 [0.00-32.00] to 33.30 [16.00-48.00] n/m², and the biomass increased from 0.03 [0.00-0.09] to 0.16 [0.07-0.22] g/m². Within the inshore sites, the aquatic insect density increased from 4 [1.33-15.33] to 56 [22.00-86.67] n/m². The Malacostraca density increased from 34.67 [11.67-95.33] to 110 [53.33-223.33] n/m², and the biomass increased from 0.43 [0.11-1.00] to 1.48 [0.50-2.00] g/m². Two endangered Margarya species were rediscovered at multiple sites compared to the pre-fishing ban period. A significant change in macroinvertebrate community structure across the lake was observed, which can be largely attributed to the fishing ban. The immediate increase in species richness, density, and biomass of most macroinvertebrate species suggests a combination of effects from both reduced exploitation pressure and lessened disturbances on lake habitats. The findings indicate that the fishing ban is beneficial for the recovery of most macroinvertebrate species in freshwater lakes.

Interactions between breeding gulls and monofilament lines at one of the main recreational fishing sites in Argentina

Monofilament fishing lines lost or discarded during recreational fishing activities often result in negative impacts on marine organisms. We assessed the interactions between Kelp and Olrog's gulls (Larus dominicanus and L. atlanticus, respectively) and recreational fishing at Bahía San Blas, Argentina. Monofilament lines constituted 61 and 29 % of total debris items recorded along beaches in the low and high fishing seasons, respectively. A total of 61 balls of tangled lines were also found within Kelp and Olrog's gull colonies. No Olrog's Gulls but nine Kelp Gulls were found tangled with monofilament lines within colony boundaries, seven of which were caught in vegetation. No Kelp or Olrog's gulls foraging in recreational fishing areas were observed tangled with lines. Monofilament lines did not negatively affect gull populations during the study period, but actions are needed to correctly manage their disposal given the relevance of Bahía San Blas as a recreational fishing area in the region.

Cascading effects of climate change on recreational marine flats fishes and fisheries

Tropical and subtropical coastal flats are shallow regions of the marine environment at the intersection of land and sea. These regions provide myriad ecological goods and services, including recreational fisheries focused on flats-inhabiting fishes such as bonefish, tarpon, and permit. The cascading effects of climate change have the potential to negatively impact coastal flats around the globe and to reduce their ecological and economic value. In this paper, we consider how the combined effects of climate change, including extremes in temperature and precipitation regimes, sea level rise, and changes in nutrient dynamics, are causing rapid and potentially permanent changes to the structure and function of tropical and subtropical flats ecosystems. We then apply the available science on recreationally targeted fishes to reveal how these changes can cascade through layers of biological organization-from individuals, to populations, to communities-and ultimately impact the coastal systems that depend on them. We identify critical gaps in knowledge related to the extent and severity of these effects, and how such gaps influence the effectiveness of conservation, management, policy, and grassroots stewardship efforts.

Phylogenomics and species delimitation of the economically important Black Basses (Micropterus)

Informed management and conservation efforts are vital to sustainable recreational fishing and biodiversity conservation. Because the taxonomic rank of species is important in conservation and management strategies, success of these efforts depends on accurate species delimitation. The Black Basses (Micropterus) are an iconic lineage of freshwater fishes that include some of the world’s most popular species for recreational fishing and world's most invasive species. Despite their popularity, previous studies to delimit species and lineages in Micropterus suffer from insufficient geographic coverage and uninformative molecular markers. Our phylogenomic analyses of ddRAD data result in the delimitation of 19 species of Micropterus, which includes 14 described species, the undescribed but well-known Altamaha, Bartram’s, and Choctaw basses, and two additional undescribed species currently classified as Smallmouth Bass (M. dolomieu). We provide a revised delimitation of species in the Largemouth Bass complex that necessitates a change in scientific nomenclature: Micropterus salmoides is retained for the Florida Bass and Micropterus nigricans is elevated from synonymy for the Largemouth Bass. The new understanding of diversity, distribution, and systematics of Black Basses will serve as important basis for the management and conservation of this charismatic and economically important clade of fishes.

The impact of the COVID-19 pandemic on a recreational rainbow trout (Oncorhynchus mykiss) fishery

There has been a recent flurry of publications describing the potential effects of the COVID-19 pandemic on both commercial and recreational fisheries. As of yet, studies have only provided insights from researchers or industry experts detailing perceived consequences, or from survey data indicating modifications in angler activity levels and behaviours. Using real recreational fisheries data from an ongoing radio telemetry study (2018-present), we explored changes in the relative exploitation rates of rainbow trout (Oncorhynchus mykiss; Walbaum 1792) in the Saugeen River, Ontario, a tributary to Lake Huron, before compared to during the pandemic. Restrictions on site access that affected the implementation of important management activities that usually support this popular fishery are also discussed. During the initial phase of complete public lock-downs imposed during spring 2020, angler exploitation rates decreased to half that reported prior to the pandemic. Fishway operations were temporarily suspended and hatchery efforts were interrupted. Once restrictions began to ease in fall 2020, there was an eight-fold increase in overall exploitation rate and a four and a half-fold increase in harvest rate compared to seasons prior to the pandemic. While the full impact of the ongoing pandemic on the Lake Huron fishery is not likely to be fully realized for several years, the potential effects on future return run sizes may need to be considered by fisheries managers monitoring trends in population escapement.

Capture vulnerability of sea turtles on recreational fishing piers

Capture vulnerability of commercial and recreational fishes has been associated with behavioral, morphological, and life-history traits; however, relationships with non-target species, such as sea turtles, have not been adequately studied. We examined species composition, timing of captures, morphological variables including body size and head width, and body condition of sea turtles captured from a recreational fishing pier in the northern Gulf of Mexico and of sea turtles captured in the waters adjacent to the pier. From 2014 to 2019, 148 net captures and 112 pier captures of three sea turtle species were documented. Green turtles were captured most frequently in the net and on the pier. Turtles captured from the pier were larger than those captured in the net. There was no difference in head width between net-caught and pier-caught turtles; however, small sample sizes limited those comparisons. The body condition index was lower for pier-caught than net-caught Kemp';s ridleys but did not differ with green turtles or loggerheads. Differences were also observed in the timing of capture on the pier as compared to in the net. Finally, the relationship between size, body condition, and pier-capture vulnerability suggests these are complex interactions. Mortality of sea turtles captured from fishing piers could be selecting against bolder individuals, which may result in changes in sea turtle population demographics over a long time period.

Known but not called by name: recreational fishers' ecological knowledge of freshwater plants in Hungary

BACKGROUND

Documenting local ecological knowledge (LEK) has recently become a topic of considerable interest. LEK can contribute to various areas of ecology, including habitat management and conservation biology. It has been recently revealed that recreational fishers' ecological knowledge (FEK) can also provide valuable information about different organisms and habitats, while recreational fishers' ecological knowledge is understudied in many aspects and regions of the world.

METHODS

We aimed to record Hungarian recreational FEK on plant species related to freshwater habitats. Our research was conducted in three regularly fished water bodies in Hungary, namely Lake Velence, Keleti Main Canal, and Lake Látóképi, where a total of 72 interviews were conducted with recreational anglers. During interviews, 24 plant species occurring at freshwater habitats with common or sporadic distribution were shown to anglers as single species or in congeneric pairs. Miscellaneous plant-related knowledge of anglers was also collected.

RESULTS

Anglers identified a total of 16 plant species. They used 45 botanical or folk names. An angler knew the name of 4.6 plants on average and recognized 7.4 other species without naming it. According to our detailed analysis, anglers were able to name or at least recognize those plant species which are somehow related to fishing activities, are salient, and/or common. Moreover, anglers at Lake Velence recognized less plant species; however, they also had less years of fishing experience compared to anglers of the other two locations.

CONCLUSION

We found that recreational FEK exists even in the case of freshwater plants which are not the main focus of anglers. It is highly presumable that recreational fishers would be able to provide reliable ecologically related data for scientific research establishing future citizen science projects of nature conservation.

Global assessment of marine and freshwater recreational fish reveals mismatch in climate change vulnerability and conservation effort

Recreational fisheries contribute substantially to the sociocultural and economic well-being of coastal and riparian regions worldwide, but climate change threatens their sustainability. Fishery managers require information on how climate change will impact key recreational species; however, the absence of a global assessment hinders both directed and widespread conservation efforts. In this study, we present the first global climate change vulnerability assessment of recreationally targeted fish species from marine and freshwater environments (including diadromous fishes). We use climate change projections and data on species' physiological and ecological traits to quantify and map global climate vulnerability and analyze these patterns alongside the indices of socioeconomic value and conservation effort to determine where efforts are sufficient and where they might fall short. We found that over 20% of recreationally targeted fishes are vulnerable to climate change under a high emission scenario. Overall, marine fishes had the highest number of vulnerable species, concentrated in regions with sensitive habitat types (e.g., coral reefs). However, freshwater fishes had higher proportions of species at risk from climate change, with concentrations in northern Europe, Australia, and southern Africa. Mismatches in conservation effort and vulnerability were found within all regions and life-history groups. A key pattern was that current conservation effort focused primarily on marine fishes of high socioeconomic value rather than on the freshwater and diadromous fishes that were predicted to be proportionately more vulnerable. While several marine regions were notably lacking in protection (e.g., Caribbean Sea, Banda Sea), only 19% of vulnerable marine species were without conservation effort. By contrast, 72% of freshwater fishes and 33% of diadromous fishes had no measures in place, despite their high vulnerability and cultural value. The spatial and taxonomic analyses presented here provide guidance for the future conservation and management of recreational fisheries as climate change progresses.

Ecological impacts of water-based recreational activities on freshwater ecosystems: a global meta-analysis

Human presence at water bodies can have a range of ecological impacts, creating trade-offs between recreation as an ecosystem service and conservation. Conservation policies could be improved by relying on robust knowledge about the relative ecological impacts of water-based recreation. We present the first global synthesis on recreation ecology in aquatic ecosystems, differentiating the ecological impacts of shore use, (shoreline) angling, swimming and boating. Impacts were assessed at three levels of biological organization (individuals, populations and communities) for several taxa. We screened over 13 000 articles and identified 94 suitable studies that met the inclusion criteria, providing 701 effect sizes. Impacts of boating and shore use resulted in consistently negative, significant ecological impacts across all levels of biological organization. The results were less consistent for angling and swimming. The strongest negative effects were observed in invertebrates and plants. Recreational impacts on birds were most pronounced at the individual level, but not significant at the community level. Due to publication bias and knowledge gaps, generalizations of the ecological impacts of aquatic recreation are challenging. Impacts depend less on the form of recreation. Thus, selectively constraining specific types of recreation may have little conservation value, as long as other forms of water-based recreation continue.

Changes in angler demography and angling patterns during the Covid-19 lockdown in spring 2020 measured through a citizen science platform

From 11 March to end of May 2020 a lockdown was imposed in Denmark due to the Covid-19 outbreak. Concurrently a 20% increase in sales of mandatory national angling licenses was reported in Denmark, suggesting an increase in angling participation. Here, we use data collected from a citizen science platform for recreational anglers to a) explore whether the increase in participation affected multiple characteristics of the anglers that registered to the citizen science platform in spring 2020, and b) explore changes in angling effort and catch patterns during the lockdown as reported to the platform. The results indicate that the platform was able to detect changes in the characteristics of the participants in the Danish recreational angling during the Covid-19 lockdown, i.e. participants were younger, more likely to live in urban areas, less experienced, stated angling as a less important hobby, and less likely to be from outside of Denmark. The spring 2020 participants did not conduct more fishing trips compared to previous years, but their effort patterns differed. The effort patterns revealed a shift in fishing activity from weekend to weekday and, during the day, a shift in fishing activity from midday to early evening. These changes most likely reflect the extraordinary conditions that most Danes experienced during the lockdown. We found relatively lower catch rates and a trend towards retaining more fish, among the participants that registered in spring 2020. The results are discussed in relation to biological implications and lessons learned about data collection from citizen science platforms.

A role for lakes in revealing the nature of animal movement using high dimensional telemetry systems

Movement ecology is increasingly relying on experimental approaches and hypothesis testing to reveal how, when, where, why, and which animals move. Movement of megafauna is inherently interesting but many of the fundamental questions of movement ecology can be efficiently tested in study systems with high degrees of control. Lakes can be seen as microcosms for studying ecological processes and the use of high-resolution positioning systems to triangulate exact coordinates of fish, along with sensors that relay information about depth, temperature, acceleration, predation, and more, can be used to answer some of movement ecology's most pressing questions. We describe how key questions in animal movement have been approached and how experiments can be designed to gather information about movement processes to answer questions about the physiological, genetic, and environmental drivers of movement using lakes. We submit that whole lake telemetry studies have a key role to play not only in movement ecology but more broadly in biology as key scientific arenas for knowledge advancement. New hardware for tracking aquatic animals and statistical tools for understanding the processes underlying detection data will continue to advance the potential for revealing the paradigms that govern movement and biological phenomena not just within lakes but in other realms spanning lands and oceans.

Fishing for food: Values and benefits associated with coastal infrastructure

While there is substantial literature about the socio-cultural characteristics and values associated with recreational and commercial fisheries in the U.S., studies directed at those who ‘fish for food’—those who depend on consuming their catch to various degrees—are relatively sparse. Using qualitative data collected through 80 semi-structured interviews with fishers in the summer and fall of 2018 in Carteret County, North Carolina, this study aims to better understand the group of recreational fishers who consume their catch by describing social and cultural dimensions and values associated with fishing for food, examining the role of infrastructure in facilitating access to benefits associated with this activity, and considering how knowledge of existing licensing regulations surrounding subsistence license waivers affect this fishing community. Interviews conducted at free public fishing structures in the region revealed that fishers derive a variety of values and benefits from fishing at these sites, including access to recreation, nutrition, a social community, and mental health benefits, which were found to be negatively impacted by Hurricane Florence in September 2018. We also found an informal economy of sharing catch on- and off-site that extends the reach and benefits facilitated by public infrastructure to people beyond those using it directly. Overall, we call for conceptualizations of ‘fishing for food’ that include aspects that go beyond traditional definitions of ‘subsistence’ or ‘recreational’ fishing such as food security, access, and less obvious social and cultural motivations behind the activity. These findings are a compelling rationalization for the creation and maintenance of formal and informal fishing places locally and, by extension, in other coastal areas, given the array of benefits provided by access to these types of locations.

Fishery reforms for the management of non-indigenous species

Marine ecosystems are undergoing major transformations due to the establishment and spread of Non-Indigenous Species (NIS). Some of these organisms have adverse effects, for example by reducing biodiversity and causing ecosystem shifts. Others have upsides, such as benefits to fisheries or replacing lost ecological functions and strengthening biogenic complexity. Stopping the spread of NIS is virtually impossible and so the societal challenge is how to limit the socioeconomic, health, and ecological risks, and sustainably exploit the benefits provided by these organisms. We propose a move away from the notion that NIS have only negative effects, and suggest a turn towards an Ecosystem-Based Fishery Management approach for NIS (EBFM-NIS) in the Mediterranean Sea, the world's most invaded marine region. A structured, iterative, and adaptive framework that considers the range of costs and benefits to ecosystems, ecosystem services, and fisheries is set out to determine whether NIS stocks should be managed using sustainable or unsustainable exploitation. We propose fishery reforms such as multiannual plans, annual catch limits, technical measures for sustainable exploitation, and legitimization of unlimited fishing of selected NIS and introduction of a radical new license for NIS fishing for unsustainable exploitation. Depending on local conditions, investment strategies can be included within the EBFM-NIS framework to protect/enhance natural assets to improve ecosystem resilience against NIS, as well as fishery assets to improve the performance of NIS fisheries. Examples of the former include the enhancement of Marine Protected Areas, harvesting of invasive NIS within MPAs, and protection of overfished predators and key species. Examples of the latter include market promotion and valorisation of NIS products, development of novel NIS products, and innovative/alternative NIS fishing such as fishery-related tourism ('pescatourism'). The application of the suggested EBFM-NIS would create jobs, protect and enhance ecosystem services, and help to meet the United Nations Sustainable Development Goal 14: Conserve and sustainably use the oceans, seas, and marine resources for sustainable development.

Modeling recreational fishing intensity in a complex urbanised estuary

Urbanised estuaries, ports and harbours are often utilised for recreational purposes, notably recreational angling. Yet there has been little quantitative assessment of the footprint and intensity of these activities at scales suitable for spatial management. Urban and industrialised estuaries have previously been considered as having low conservation value, perhaps due to issues with contamination and disturbance. Studies in recent decades have demonstrated that many of these systems are still highly biodiverse and of high value to local residents. As a response, urbanised estuaries are now being considered by coastal spatial management initiatives, where assessments of recreational use in these areas can help avoid 'user-environmental' and 'user-user' conflict. The models of these activities need to be developed at a scale relevant to governments and regulatory authorities, but the few human-use models that do exist integrate fishing intensity to a regional or even continental scale; too large to capture the fine scale variation inherent in complex urban fisheries. Species Distribution Modeling (SDM) is a tool commonly used to assess drivers of species range, but can be applied to models of recreational fishing in complex environments, at a scale relevant to regulatory bodies. Using point-data from 573 visual surveys with recently developed Poisson point process models, we examine the recreational fishery in Australia's busiest estuarine port, Sydney Harbour. We demonstrate the utility of these models for understanding the distribution of boat and shore-based fishers, and the effects of a range of temporally static (geographical) and dynamic (weather) predictors on these distributions.

Evolutionary responses of marine organisms to urbanized seascapes

Many of the world's major cities are located in coastal zones, resulting in urban and industrial impacts on adjacent marine ecosystems. These pressures, which include pollutants, sewage, runoff and debris, temperature increases, hardened shorelines/structures, and light and acoustic pollution, have resulted in new evolutionary landscapes for coastal marine organisms. Marine environmental changes influenced by urbanization may create new selective regimes or may influence neutral evolution via impacts on gene flow or partitioning of genetic diversity across seascapes. While some urban selective pressures, such as hardened surfaces, are similar to those experienced by terrestrial species, others, such as oxidative stress, are specific to aquatic environments. Moreover, spatial and temporal scales of evolutionary responses may differ in the ocean due to the spatial extent of selective pressures and greater capacity for dispersal/gene flow. Here, we present a conceptual framework and synthesis of current research on evolutionary responses of marine organisms to urban pressures. We review urban impacts on genetic diversity and gene flow and examine evidence that marine species are adapting, or are predicted to adapt, to urbanization over rapid evolutionary time frames. Our findings indicate that in the majority of studies, urban stressors are correlated with reduced genetic diversity. Genetic structure is often increased in urbanized settings, but artificial structures can also act as stepping stones for some hard-surface specialists, promoting range expansion. Most evidence for rapid adaptation to urban stressors comes from studies of heritable tolerance to pollutants in a relatively small number of species; however, the majority of marine ecotoxicology studies do not test directly for heritability. Finally, we highlight current gaps in our understanding of evolutionary processes in marine urban environments and present a framework for future research to address these gaps.

A spatiotemporal comparison of length-at-age in the coral reef fish Acanthurus nigrofuscus between marine reserves and fished reefs

Quantitative assessments of the capacity of marine reserves to restore historical fish body-size distributions require extensive repeated sampling to map the phenotypic responses of target populations to protection. However, the “no take” status of marine reserves oftentimes precludes repeated sampling within their borders and, as a result, our current understanding of the capacity of marine reserves to restore historical body-size distributions remains almost entirely reliant on independent, static visual surveys. To overcome this challenge, we promote the application of a traditional fisheries tool known as a “back-calculation”, which allows for the estimation of fish body lengths from otolith annuli distances. This practical application was pursued in this study, using data collected in five marine reserves and adjacent fished reefs in the Philippines, to investigate spatiotemporal disparities in length-at-age of the brown surgeonfish, Acanthurus nigrofuscus. The spatial component of our analyses revealed that 1) A. nigrofuscus were phenotypically similar between marine reserves and fished reefs during their early life history; 2) marine reserve and fished reef populations diverged into significantly different length-at-age morphs between ages three and six, in which protected fish were predominantly larger than conspecifics in fished reefs; and 3) A. nigrofuscus returned to a state of general phenotypic similarity during later life. The temporal component of our analyses revealed that younger generations of A. nigrofuscus exhibited significant, positive year effects that were maintained until age eight, indicating that, within the significant age cohorts, younger generations were significantly larger than older generations.

When an advantageous reproductive trait turns bad: Eggs of the threatened fish Genidens barbus as a natural bait in recreational fisheries

This study describes a recreational fishing method focused on marine catfish, Genidens barbus (Endangered-EN), through the adoption of its eggs as a natural bait during its reproductive period in southern Brazilian ecosystems. Male G. barbus perform parental care, collecting eggs released by females after the fertilization process. Owing to this male behavioural pattern during the reproductive period, these individuals are easily caught in recreational fisheries that use eggs of the same species as a natural bait. The current adoption of G. barbus eggs as bait may intensify the fishing pressure on its populations.

Life in the fast lane: Temperature, density and host species impact survival and growth of the fish ectoparasite Argulus foliaceus

With expanding human populations, the food sector has faced constant pressure to sustainably expand and meet global production demands. In aquaculture this frequently manifests in an animal welfare crisis, with fish increasingly farmed under high production, high stress conditions. These intense environments can result in fish stocks having a high susceptibility to infection, with parasites and associated disease one of the main factors limiting industry growth. Prediction of infection dynamics is key to preventative treatment and mitigation. Considering the climatic and technology driven changes facing aquaculture, an understanding of how parasites react across a spectrum of conditions is required. Here we assessed the impact of temperature, infection density and host species on the life history traits of Argulus foliaceus, a common palearctic fish louse, representative of a parasite group problematic in freshwater aquaculture and fisheries worldwide. Temperature significantly affected development, growth and survival; parasites hatched and developed faster at higher temperatures, but also experienced shorter lifespans when maintained off the host. At high temperatures, these parasites will likely experience a short generation time as their life history traits are completed more rapidly. A. foliaceus additionally grew faster on natural hosts and at lower infection densities. Ultimately such results contribute to prediction of population dynamics, aiding development of effective control to improve animal welfare and reduce industry loss.

Storms promote ecosystem resilience by alleviating fishing

Marine ecosystems face numerous challenges from natural and anthropogenic sources. For example, excessive rainfall from storms rapidly lowers salinity, which can destroy coastal foundation species and their associated fauna [1], while fishing can alter coastal food webs, reduce biodiversity, and lower ecosystem resilience [2]. Concurrently, mass disruptions to fishing activity are common following disasters such as hurricanes, oil spills, and tsunamis, which may lead to increased populations of harvested species [3]. However, our understanding of how these disturbances interact to affect communities remains limited. We examined effects on estuarine communities following fishing disruptions and salinity changes caused by a tropical cyclone. Our results indicate that recreational fishing had large effects on fish populations that cascaded down the food web. Further, although destructive, hurricanes and other disturbances that simultaneously curtail human activities may promote recovery. VIDEO ABSTRACT.

Population status and ecology of the Salmo trutta complex in an Italian river basin under multiple anthropogenic pressures

Salmonids inhabiting Mediterranean rivers are of particular concern for biodiversity conservation, as they are threatened by various stressors, including habitat alterations, overfishing, climate change, and introgressive hybridization with alien species. In the Tiber River basin (Central Italy), genetic introgression phenomena of the native Salmo cettii with the non-native Salmo trutta hinder the separate analysis of the two species, which are both included in the S. trutta complex. Little is known about the factors currently limiting the trout populations in this area, particularly with respect to climate change. With the intention of filling this gap, the aims of the current study were to (a) quantify changes in the climate and (b) analyze the distribution, status, and ecology of trout populations, in the context of changing abiotic conditions over the last decades. Fish stock assessments were carried out by electrofishing during three census periods (1998-2004, 2005-2011, and 2012-2018) at 129 sites. The trend over time of meteorological parameters provided evidence for increased air temperature and decreased rainfall. Multivariate analysis of trout densities and environmental data highlighted the close direct correlation of trout abundance with water quality, altitude, and current speed. Climate-induced effects observed over time in the sites where trout were sampled have not yet led to local extinctions or distribution shifts, indicating a marked resilience of trout, probably due to the buffering effect of intrinsic population dynamics. Decreasing body conditions over time and unbalanced age structures support the hypothesis that variations in hydraulic regime and water temperature could overcome these compensatory effects, which may lead to a severe decline in trout populations in the near future. In a climate change context, habitat availability plays a key role in the distribution of cold-water species, which often do not have the possibility to move upstream to reach their thermal optimum because of water scarcity in the upper river stretches.

Size- and stage-dependence in cause-specific mortality of migratory brown trout

Evidence-based management of natural populations under strong human influence frequently requires not only estimates of survival but also knowledge about how much mortality is due to anthropogenic vs. natural causes. This is the case particularly when individuals vary in their vulnerability to different causes of mortality due to traits, life history stages, or locations. Here, we estimated harvest and background (other cause) mortality of landlocked migratory salmonids over half a century. In doing so, we quantified among-individual variation in vulnerability to cause-specific mortality resulting from differences in body size and spawning location relative to a hydropower dam. We constructed a multistate mark-recapture model to estimate harvest and background mortality hazard rates as functions of a discrete state (spawning location) and an individual time-varying covariate (body size). We further accounted for among-year variation in mortality and migratory behaviour and fit the model to a unique 50-year time series of mark-recapture-recovery data on brown trout (Salmo trutta) in Norway. Harvest mortality was highest for intermediate-sized trout, and outweighed background mortality for most of the observed size range. Background mortality decreased with body size for trout spawning above the dam and increased for those spawning below. All vital rates varied substantially over time, but a trend was evident only in estimates of fishers' reporting rate, which decreased from over 50% to less than 10% throughout the study period. We highlight the importance of body size for cause-specific mortality and demonstrate how this can be estimated using a novel hazard rate parameterization for mark-recapture models. Our approach allows estimating effects of individual traits and environment on cause-specific mortality without confounding, and provides an intuitive way to estimate temporal patterns within and correlation among different mortality sources.

Leveraging public harvest to reduce invasive hybridization in Yellowstone National Park: field identification and harvest of cutthroat × rainbow trout hybrids

Leveraging public harvest can be a cost-effective invasive species management tool, but target taxa must be correctly identified and removed at rates that achieve biological objectives. We explored the potential role of recreational anglers to curtail expanding hybridization between invasive rainbow trout (Oncorhynchus mykiss; RT) and native Yellowstone cutthroat trout (O. clarkii bouvieri; YCT) in the Lamar River watershed in Yellowstone National Park. We sought to (1) develop a hybrid identification key that could be used by anglers and (2) estimate angler participation, catch, and potential exploitation rates. We assessed seven morphological features of trout in the field (n = 251, 15 locations) and collected fin clips to estimate RT ancestry proportion using genetic analysis. An identification key was built using recursive partitioning to objectively distinguish YCT from RT and hybrids. A single-choice dichotomous key (white pelvic fin tip present/absent) correctly classified 93% of fish as native (YCT) or containing RT ancestry (RT or hybrid). Success increased to 97% when a second criterion was added (head spot count ≥ 6). Using angler surveys (2013–2017), we estimated that 10,000 anglers catch 50,000 trout annually. In a popular road-accessible area, most trout are probably caught and released ~ 5 times each year. The combination of high angler participation, substantial annual catch, and an accurate and easy to use identification method indicate that leveraging public harvest is a promising management tool. Invasive hybridization is a global conservation issue threatening many native taxa; this case study highlights some factors for resource managers to consider prior to implementing public harvest regulations and the benefits of standardized keys to distinguish hybrids in the field.

Effects of multiple stressors on the distribution of fish communities in 203 headwater streams of Rhine, Elbe and Danube

Fishes in European rivers are threatened by manifold stressors such as structural degradation, water pollution, overexploitation, land-use changes in the catchment, invasive species and global processes including climate change. Identifying main stressors in a stream/river system is of utterly importance for efficiently utilizing the scarce funds for conservation measures in order to achieve the best possible outcome. Within 203 headwater streams of Rhine, Elbe and Danube, we quantified the relative influence of different environmental stressors (water chemistry, food availability (macroinvertebrates), terrestrial predators) and anthropogenic stressors (land use, structural modification of streams) on fish assemblages at different spatial scales based on multivariate biota-environment models. In our analyses, the predictor variables percentage of impoundments, crop farming (especially erosion-prone crops such as maize) and ground sealing in the catchments, the number of wastewater treatment plants and biogas plants in the catchments as well as structural modifications of river banks were most often identified as stressors influencing fish community composition. However, the effects of the stressors varied between the investigated survey-area scales (two different catchments sizes and riparian strips) and regionally (entire study area, major drainage systems, river catchments, stream sizes, geographical subregions). In most cases, fish community composition was simultaneously affected by multiple stressors, underpinning the need for a more holistic and ecosystem-based approach in freshwater conservation and restoration.

The pros and cons of the invasive freshwater apex predator, European catfish Silurus glanis, and powerful angling technique for its population control

Catfish have spread across Europe and several countries out of this region within the last decades. Basic knowledge of this apex predator has revealed concerns of invasive behaviour and questions regarding its utilization as a biomanipulation species. However, a method enabling its regulation to a required level has not yet been developed. We simulated the impact of angling on the catfish population by method of hook-lines in two post-mining lakes with a monitored population consisting of tagged individuals and in two reservoirs as reference sites. Further, the efficiency of hook-lines as a reducing device was examined and the economic aspects were determined. Catfish population in localities where the species is unwanted or invasive may be efficiently reduced to a harmless level by hook-lines and angling (depending on the approach of anglers). The most efficient time of the year seems to be spring to early summer with catch efficiency of 5.4 individuals per 10 baits in one day. The catch efficiency markedly decreased during the second part of the year and did not exceed 2.8 individuals per 10 baits in one day. Mean size of catfish had negative impact whereas catfish biomass had positive impact on the catch efficiency. Trophic status and number of catfish in the locality had no impact on the catch efficiency. According to model, 11-18 bait-days per 1 ha per season is efficient to decrease catfish population to 10% of the original size. Both angling and hook-lines are very simple, they are financially and time bearable mechanisms of catfish regulation in any condition. However, catfish play an important role as a biomanipulative species in many localities. In this case where catfish is beneficial, angling presents a real threat of population collapse and loss of the biomanipulative effect.

Searching for responsible and sustainable recreational fisheries in the Anthropocene

Recreational fisheries that use rod and reel (i.e., angling) operate around the globe in diverse freshwater and marine habitats, targeting many different gamefish species and engaging at least 220 million participants. The motivations for fishing vary extensively; whether anglers engage in catch-and-release or are harvest-oriented, there is strong potential for recreational fisheries to be conducted in a manner that is both responsible and sustainable. There are many examples of recreational fisheries that are well-managed where anglers, the angling industry and managers engage in responsible behaviours that both contribute to long-term sustainability of fish populations and the sector. Yet, recreational fisheries do not operate in a vacuum; fish populations face threats and stressors including harvest from other sectors as well as environmental change, a defining characteristic of the Anthropocene. We argue that the future of recreational fisheries and indeed many wild fish populations and aquatic ecosystems depends on having responsible and sustainable (R&S) recreational fisheries whilst, where possible, addressing, or at least lobbying for increased awareness about the threats to recreational fisheries emanating from outside the sector (e.g., climate change). Here, we first consider how the concepts of R&S intersect in the recreational fishing sector in an increasingly complex socio-cultural context. Next, we explore the role of the angler, angling industry and decision-makers in achieving R&S fisheries. We extend this idea further by considering the consequences of a future without recreational fisheries (either because of failures related to R&S) and explore a pertinent case study situated in Uttarakahand, India. Unlike other fisheries sectors where the number of participants is relatively small, recreational angling participants are numerous and widespread, such that if their actions are responsible, they have the potential to be a key voice for conservation and serve as a major force for good in the Anthropocene. What remains to be seen is whether this will be achieved, or if failure will occur to the point that recreational fisheries face increasing pressure to cease, as a result of external environmental threats, the environmental effects of recreational fishing and emerging ethical concerns about the welfare of angled fish.

Density dependent attributes of fish aggregative behaviour

Grouping behaviour, as fascinating as it is unclear, has lately drawn the attention of numerous researchers. While most of the authors focused their work on a mechanistic approach to the matter of schooling, this study explores the issue from a population point of view. Present camera observation study on the fish community carried out in the epipelagic habitat of a European temperate reservoir in the Czech Republic explored the relationship between density and aggregative features of predominantly cyprinid fish stock. Results demonstrated that schooling behaviour is triggered by the ‘critical density’ of fish in the habitat. School size as well as counts of schools and proportion of schooling individuals increased with the density of fish. Counts of clusters (observed units in time, including singletons, pairs and schools) and cluster size, on the other hand, showed a slowing tendency to increase. The slower increase implies the tendency of fish for not being frequent but rather to create larger groups. Altogether, our findings suggest that fish density is a triggering factor in the formation of large fish schools. As the tendency of cyprinid species for school formation could be an evolutional advantage responsible for dominance in later succession phases of water bodies, we suggest that more in situ studies should be encouraged for the proper understanding of the ecological interactions that drive the structure of aquatic ecosystems and for ensuring unbiased assessment.

Do Metabolic Traits, Vulnerability to Angling, or Capture Method Explain Boldness Variation in Eurasian Perch?

The pace-of-life syndrome (POLS) concept predicts that individuals with high baseline metabolic rates demonstrate high boldness, aggressiveness, and activity, especially in food acquisition, with associated relatively greater energy requirements. In fishes, these behaviors may increase individual vulnerability to angling. To test the predictions of the POLS concept, we quantified individual standard metabolic rate (SMR) and boldness in both wild-caught and hatchery-reared Eurasian perch (Perca fluviatilis). We found both SMR and boldness to be repeatable traits but detected no correlation between them. Individual vulnerability to angling was assessed in the hatchery-reared perch, but we found no difference in boldness or SMR between vulnerable and nonvulnerable perch. Wild-caught perch were ice fished using either natural or artificial bait, and we observed no differences in boldness or SMR with respect to bait type or capture order. Our findings do not support the predictions of the POLS concept and, consistent with earlier studies in perch, suggest that angling may not drive selection against boldness in this species.

Heterogeneous public and local knowledge provides a qualitative indicator of coastal use by marine recreational fishers

Marine recreational fishing (MRF) benefits individuals and economies, but can also impact fish stocks and associated ecosystems. Fish are an important resource providing direct economic benefit through commercial and recreational exploitation, and more esoteric ecosystem services. It is important to consider recreational fishing in marine spatial planning, but spatial information on coastal utilisation for MRF is frequently lacking. Public sources of local knowledge were reviewed and the frequency of unique references to sites extracted. Sites were georeferenced using a gazetteer compiled from the Ordnance Survey and United Kingdom Hydrographic Office named sea features gazetteer and local knowledge sources. Recreational fishing site densities were calculated across 2700 km of coastline and this proxy indicator of coastal utilisation validated against two independent surveys using permutative Monte Carlo sampling to control for sparse and non-independent data. Site density had fair agreement with independent surveys, but standardization by shore length reduced this agreement. Applying a 3 by 3 box filter convolution to the spatial layers improved the agreement between local knowledge derived predictions of activity and those of directed surveys, and permutation testing showed that agreement did not arise as a result of the convolution itself. High and low activity areas were more accurately predicted than areas of intermediate activity. Site density derived from heterogeneous participant and local knowledge can produce qualitative predictions of where recreational fishers fish, and applying a convolution can improve the predictive power of data so derived. However, this approach will be subject to unquantifiable bias and may fail to identify areas highly valued by marine recreational fishers. Thus it should be used in conjunction with other information in decision making and may be best suited to inform the early stage sampling design of on-site surveys or to complement other data sets in mapping areas of importance to recreational fishers.

How ecological processes shape the outcomes of stock enhancement and harvest regulations in recreational fisheries

Fish stocking and harvest regulations are frequently used to maintain or enhance freshwater recreational fisheries and contribute to fish conservation. However, their relative effectiveness has rarely been systematically evaluated using quantitative models that account for key size- and density-dependent ecological processes and adaptive responses of anglers. We present an integrated model of freshwater recreational fisheries where the population dynamics of two model species affect the effort dynamics of recreational anglers. With this model, we examined how stocking various fish densities and sizes (fry, fingerlings, and adults) performed relative to minimum-length limits using a variety of biological, social, and economic performance measures, while evaluating trade-offs. Four key findings are highlighted. First, stocking often augmented the exploited fish population, but size- and density-dependent bottlenecks limited the number of fry and fingerlings surviving to a catchable size in self-sustaining populations. The greatest enhancement of the catchable fish population occurred when large fish that escaped early bottlenecks were stocked, but this came at the cost of wild-stock replacement, thereby demonstrating a fundamental trade-off between fisheries benefits and conservation. Second, the relative performance of stocking naturally reproducing populations was largely independent of habitat quality and was generally low. Third, stocking was only economically advisable when natural reproduction was impaired or absent, stocking rates were low, and enough anglers benefitted from stocking to offset the associated costs. Fourth, in self-sustaining fish populations, minimum-length limits generally outperformed stocking when judged against a range of biological, social and economic objectives. By contrast, stocking in culture-based fisheries often generated substantial benefits. Collectively, our study demonstrates that size- and density-dependent processes, and broadly the degree of natural recruitment, drive the biological, social, and economic outcomes of popular management actions in recreational fisheries. To evaluate these outcomes and the resulting trade-offs, integrated fisheries-management models that explicitly consider the feedbacks among ecological and social processes are needed.

Angling-induced injuries have a negative impact on suction feeding performance and hydrodynamics in marine shiner perch, Cymatogaster aggregata

Fishing is a popular and lucrative sport around the world and, in some cases, may contribute to declining fish stocks. To mediate this problem and maintain fish biomass in aquatic ecosystems, catch-and-release fishing, whereby a fish is caught and immediately released, has been implemented in many countries. It is unclear whether the injuries to the mouth that are caused by the hook have an impact on feeding performance of fishes. Using high-speed video and computational fluid dynamics (CFD), we asked whether injuries around the mouth caused by fishing hooks have a negative impact on suction feeding performance (measured as maximum prey velocity) of the commonly angled marine shiner perch (Cymatogaster aggregata). We hypothesized that fish with mouth injuries would exhibit decreased feeding performance compared with controls. Ten shiner perch were caught using scientific angling and 10 were caught using a seine net. Feeding events were then recorded at 500 frames per second using a high-speed camera. Compared with the control group, maximum prey velocity was significantly lower in the injured group (P<0.01). Maximum gape, time to peak gape, maximum jaw protrusion and predator-prey distance were comparable between the control and injured groups, leading us to conclude that the injury-induced hole in the buccal cavity wall reduced the pressure gradient during mouth expansion, thereby reducing the velocity of water entering the fish's mouth. This was confirmed with our CFD modelling. Fishing injuries in nature are likely to depress feeding performance of fish after they have been released, although it is currently unclear whether this has a significant impact on survival.

Status-quo management of marine recreational fisheries undermines angler welfare

Recreational fisheries can have a significant impact on fish populations and can suffer from the same symptoms of open access as commercial fisheries. However, recreational fisheries receive little attention compared with their commercial counterparts. Regulations designed to allocate scarce fish, such as seasonal closures and bag limits, can result in significant losses of value to anglers. We provide an estimate of these foregone benefits by estimating the potential gains to implementing management reforms of the headboat portion of the recreational red snapper fishery in the US Gulf of Mexico. This fishery has suffered from a regulatory spiral of shortened seasons and lowered bag limits in spite of rebuilding stocks. We gather primary survey data of headboat anglers that elicit trip behavior and their planned number and seasonal distribution of trips under status-quo and alternative management approaches. We use these data to estimate a model of anglers' seasonal trip demand as a function of the ability to retain red snapper, bag limits, and fees. We find that a hypothetical rights-based policy, whereby vessels with secure rights to a portion of annual catch could offer their customers year-round fishing in exchange for lower per-angler retention and increased fees, could raise the average angler's welfare by $139/y. When placed in the global context of recreational fishing, these estimates suggest that status-quo management may deprive anglers of billions of dollars of lost economic value per year.

Gigapixel big data movies provide cost-effective seascape scale direct measurements of open-access coastal human use such as recreational fisheries

Collecting data on unlicensed open-access coastal activities, such as some types of recreational fishing, has often relied on telephone interviews selected from landline directories. However, this approach is becoming obsolete due to changes in communication technology such as a switch to unlisted mobile phones. Other methods, such as boat ramp interviews, are often impractical due to high labor cost. We trialed an autonomous, ultra-high-resolution photosampling method as a cost effect solution for direct measurements of a recreational fishery. Our sequential photosampling was batched processed using a novel software application to produce "big data" time series movies from a spatial subset of the fishery, and we validated this with a regional bus-route survey and interviews with participants at access points. We also compared labor costs between these two methods. Most trailer boat users were recreational fishers targeting tuna spp. Our camera system closely matched trends in temporal variation from the larger scale regional survey, but as the camera data were at much higher frequency, we could additionally describe strong, daily variability in effort. Peaks were normally associated with weekends, but consecutive weekend tuna fishing competitions led to an anomaly of high effort across the normal weekday lulls. By reducing field time and batch processing imagery, Monthly labor costs for the camera sampling were a quarter of the bus-route survey; and individual camera samples cost 2.5% of bus route samples to obtain. Gigapixel panoramic camera observations of fishing were representative of the temporal variability of regional fishing effort and could be used to develop a cost-efficient index. High-frequency sampling had the added benefit of being more likely to detect abnormal patterns of use. Combinations of remote sensing and on-site interviews may provide a solution to describing highly variable effort in recreational fisheries while also validating activity and catch.