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De-hooking depredation: Exploring multiple fisher perceptions about marine depredation in Florida
Abstract
Marine depredation involves the removal of or damage to captured fish by predators, and recent evidence suggests it is increasing globally likely due to increasing fishing effort and changes in predator behavior. Anecdotal reports indicate that marine depredation in Florida may be especially severe, given the high number of fishers and predator species. However, the magnitude of marine depredation in Florida and fisher perceptions of these events are poorly understood. We employed a survey of commercial, private recreational, and for-hire saltwater license holders to explore the extent and magnitude of fishing experiences and perceptions related to marine depredation across Florida, highlighting differences among fisher groups using closed-and open-ended survey questions. We found few to no significant differences between fishing sector groups, meaning depredation was prevalent across all locations, gear types, and target species. Most user groups experienced depredation by more than one predator, but sharks and dolphins were reported as the most common predators. Commercial and for-hire operators were more likely to have very negative and negative sentiments toward predators, while private recreational fishers were more likely to view their depredation experiences as neutral. The need for improved management of predators and other fish stocks was expressed across all sectors, especially among commercial fishers. Our results support the growing literature on increased depredation experiences statewide and the need to devise a solution for all marine fisheries users in Florida. We anticipate our exploratory findings to be used as a starting point for researchers and fisheries management agencies to understand fishing sector perceptions and attempt to mitigate negative depredation experiences.
Overfishing, habitat degradation, and climate change have caused declines in shark populations throughout the world's oceans. However, in the United States Gulf of Mexico (GoM), populations of several coastal shark species are starting to stabilize following decades of successful regulations and enforcement. The stabilization of coastal shark populations, coupled with increases in recreational fishing effort, has the potential to escalate human-wildlife interactions. The most often reported conflict is shark depredation, the partial or complete removal of a hooked species by a shark. Reported increases in shark depredation within the last several years have begun to erode angler support for shark conservation, potentially undermining decades of previous work. To address these concerns, we implemented a GoM-wide online survey to characterize the impact of depredation on recreational reef fish anglers' fishing satisfaction and perceptions of shark management and conservation. Our results revealed that most recreational anglers in the GoM have witnessed depredation but have not changed their fishing behaviors. In contrast, anglers' viewpoints on managing shark populations were split between reducing population sizes and maintaining current population levels. As coastal shark populations in the GoM continue to recover, shark depredation is likely to increase. Consequently, efforts to characterize anglers' satisfaction and perceptions are a critical component of future shark conservation initiatives.
Shark depredation is a complex social-ecological issue that affects a range of fisheries worldwide. Increasing concern about the impacts of shark depredation, and how it intersects with the broader context of fisheries management, has driven recent research in this area, especially in Australia and the United States. This review synthesises these recent advances and provides strategic guidance for researchers aiming to characterise the occurrence of depredation, identify the shark species responsible, and test deterrent and management approaches to reduce its impacts. Specifically, the review covers the application of social science approaches, as well as advances in video camera and genetic methods for identifying depredating species. The practicalities and considerations for testing magnetic, electrical, and acoustic deterrent devices are discussed in light of recent research. Key concepts for the management of shark depredation are reviewed, with recommendations made to guide future research and policy development. Specific management responses to address shark depredation are lacking, and this review emphasizes that a “silver bullet” approach for mitigating depredation does not yet exist. Rather, future efforts to manage shark depredation must rely on a diverse range of integrated approaches involving those in the fishery (fishers, scientists and fishery managers), social scientists, educators, and other stakeholders.
We developed and applied a method to quantify spearfisher effort and catch, shark interac- tions and shark depredation in a boat-based recreational spearfishing competition in the Great Barrier Reef Marine Park in Queensland. Survey questions were designed to collect targeted quantitative data whilst minimising the survey burden of spearfishers. We provide the first known scientific study of shark depredation during a recreational spearfishing competition and the first scientific study of shark depredation in the Great Barrier Reef region. During the two-day spearfishing competition, nine vessels with a total of 33 spearfishers reported a catch of 144 fish for 115 h of effort (1.25 fish per hour). A subset of the catch comprised nine eligible species under competition rules, of which 47 pelagic fish were weighed. The largest fish captured was a 34.4 kg Sailfish (Istiophorus platypterus). The most common species captured and weighed was Spanish Mackerel (Scomberomorus commerson). The total weight of eligible fish was 332 kg and the average weight of each fish was 7.1 kg. During the two-day event, spearfishers functioned as citizen scientists and counted 358 sharks (115 h effort), averaging 3.11 sharks per hour. Grey Reef Sharks (Carcharhinus amblyrhynchos) comprised 64% of sightings. Nine speared fish were fully depredated by sharks as spearfishers attempted to retrieve their catch, which equates to a depredation rate of 5.9%. The depredated fish included four pelagic fish and five reef fish. The shark species responsible were Grey Reef Shark (C. amblyrhynchos) (66%), Bull Shark (Carcharhinus leucas) (11%), Whitetip Reef Shark (Triaenodon obesus) (11%) and Great Ham- merhead (Sphyrna mokarran) (11%). There were spatial differences in fish catch, shark sightings and rates of depredation. We developed a report card that compared average catch of fish, sightings of sharks per hour and depredation rate by survey area, which assists recreational fishers and marine park managers to assess spatio-temporal changes. The participating spearfishers can be regarded as experienced (average 18 days a year for average 13.4 years). Sixty percent of interviewees perceived that shark numbers have increased in the past 10 years, 33% indicated no change and 7% indicated shark numbers had decreased. Total fuel use of all vessels was 2819 L and was equivalent to 6.48 tons of greenhouse gas emissions for the competition.
Forage fish — small, low trophic level, pelagic fish such as herrings, sardines, and anchovies — are important prey species in marine ecosystems and also support large commercial fisheries. In many parts of the world, forage fish fisheries are managed using precautionary principles that target catch limits below the maximum sustainable yield. However, there are increasing calls to further limit forage fish catch to safeguard their fish, seabird, and marine mammal predators. The effectiveness of these extra‐precautionary regulations, which assume that increasing prey abundance increases predator productivity, are under debate. In this study, we used prey‐linked population models to measure the influence of forage fish abundance on the population growth rates of 45 marine predator populations representing 32 fish, seabird, and mammal species from five regions around the world. We used simulated data to confirm the ability of the statistical model to accurately detect prey influences under varying levels of influence strength and process variability. Our results indicate that predator productivity was rarely influenced by the abundance of their forage fish prey. Only six predator populations (13% of the total) were positively influenced by increasing prey abundance and the model exhibited high power to detect prey influences when they existed. These results suggest that additional limitation of forage fish harvest to levels well below sustainable yields would rarely result in detectable increases in marine predator populations. This article is protected by copyright. All rights reserved
Coding is a ubiquitous part of the qualitative research process, but it is often under-considered in research methods training and literature. This article explores a number of questions about the coding process which are often raised by beginning researchers, in the light of the recommendations of methods textbooks and the factors which contribute to an answer to these questions. I argue for a conceptualisation of coding as a decision-making process, in which decisions about aspects of coding such as density, frequency, size of data pieces to be coded, are all made by individual researchers in line with their methodological background, their research design and research questions, and the practicalities of their study. This has implications for the way that coding is carried out by researchers at all stages of their careers, as it requires that coding decisions should be made in the context of an individual study, not once and for all.
Ecosystem-based fisheries management (EBFM) is increasingly recognized as the future of fisheries conservation and stewardship, appearing prominently in policy documents internationally. Although considerable progress has been made to translate EBFM from theory to practice, limited attention has been given to assessing the theoretical and practical linkages between EBFM and fisheries co-management. While EBFM and fisheries co-management are not new ideas, growing interest in both compels reflection on the interplay of these concepts, even though they have traditionally been viewed as disparate approaches. We report on the results of a literature review that explored the extent to which EBFM and fisheries co-management are linked. We describe the fundamental drivers, attributes, and desired outcomes commonly used to characterize these management concepts and quantify the degree of overlap in the literature. To illustrate how EBFM and co-management are integrated in practice, we present three examples. These examples highlight that these concepts exist on a continuum, with elements of co-management regularly appearing in conventional management regimes and elements of EBFM appearing in fisheries co-management initiatives.
Over recent years there have been rapid changes occurring across marine ecosystems worldwide, with high latitude systems seeing ecosystem shifts emerging at unprecedented rates. The Gulf of Alaska and Bering Sea marine ecosystems have experienced substantial fluctuation in fish stocks, with some species experiencing considerable decreases while others thrive. Following the marine heatwave of 2014, sablefish ( Anoplopoma fimbria ) had a historically unparalleled juvenile recruitment class that is now dominating the stock composition. While this recruitment class bodes well for future fisheries, it is currently undermining the value of the fishery with limited incentives to retain the smaller and less valuable fish, compounding adverse effects on earnings in the fishery due to whale depredation that has been occurring for years. This study examines the well-being implications of fishermen’s adaptive strategies to these ecosystem conditions within the Alaska sablefish fishery using a socio-ecological system framework, operationalized as a qualitative network model (QNMs) and quantitative indicators. We examine the extent to which adaptation strategies, derived from a literature review and stakeholder interviews, are being utilized in the fishery with quantitative indicators. These strategies are then examined with QNMs that explore their impacts across the spectrum of well-being. By coupling quantitative indicators and QNMs, we were able to demonstrate how adaptive strategies can be examined to capture the multi-faceted well-being effects of fisheries participants’ adaptations to changing conditions. This study directly addresses several of the key guiding principles of the U.S. EBFM Road Map, including advancing our understanding of ecosystem processes, exploring trade-offs within an ecosystem, and maintaining resilient ecosystems, inclusive of community well-being. Thus this paper demonstrates how coupled socio-ecological models can elevate the inclusion of human adaptive behaviors, providing a framework for the development of policymaking that can mitigate adverse effects on both the participants and the resource by facilitating the mixture of adaptive strategies that maximizes desired well-being outcomes.
The U.S. Congress is currently discussing the Shark Fin Sales Elimination Act to eliminate shark fin trade at the federal level. This bill was introduced in 2017 and has been proceeding very slowly in Congress because of mixed reviews from the scientific community. Debate exists on whether shark conservation and management are effectively addressed with tightened trade controls for imported shark products or blanket bans that outright end U.S. participation in the shark fin trade. Here we contribute to this debate with a review and analysis of economic, nutritional, ethical, and legal arguments, as well as of the shark fisheries status and shark fin trade. We show that the United States has a limited commercial interest in shark fisheries and contributes to the shark fin trade mainly as a facilitator. A fin trade ban has few tangible economic drawbacks but would have a considerable conservation impact. While making all shark fisheries sustainable is the ultimate goal, in practice this objective is far from achievable everywhere in the world. Conversely, banning shark fin trade is an interim measure that nations like the United States can take with negligible cost and can truly impact the biggest driver of shark exploitation globally.
Fishers aim to optimise cost-benefit ratios of their behaviour when exploiting resources. Avoidance of interactions with marine predators (i.e. their feeding on catches in fishing gear, known as depredation), has recently become an important component of their decisions. How fishers minimise these interactions whilst maximising fishing success is poorly understood. This issue is addressed in a sub-Antarctic, long-line fishery confronted with extensive depredation by sperm whales Physeter macrocephalus and killer whales Orcinus orca by examining a 15-year dataset. Whereas a broad range of behaviours was identified from spatio-temporal and operational descriptors, none combined high fishing success with low frequency of interactions. With experience, fishers favoured exploitation of productive patches with high frequencies of interactions over avoidance behaviours. Such decisions, although potentially optimal in the short-term, are likely to intensify pressures on fish stocks and impact depredating whales. Therefore, the present study provides additional evidence to inform management decisions pertaining to the coexistence between fisheries and marine predators.
The Atlantic Goliath Grouper Epinephelus itajara, a large indigenous tropical reef fish, approached local extinction in U. S. waters by the 1980s as a result of intense fishing pressure. In 1990, federal and state laws intervened to protect this species. The resulting fishery closure, over the intervening years, allowed limited, slow population recovery in Florida waters while populations outside of the United States remained vulnerable (IUCN). The closure led to the blossoming of a dive ecotourism industry catering to local and international divers seeking opportunities to see and photograph these enormous fish. This fundamentally changes the paradigm for Goliath Grouper from a fishery resource to a non‐extractive resource with a commercial value vastly greater than that gained through fishing. While federal and state agencies attempted to re‐establish the fishery, all three stock assessments were rejected. Here, we discuss Goliath Grouper's biology, the controversy surrounding its protection, and the drawbacks of re‐establishing a fishery including: loss of nursery habitat, increasingly destructive episodic events like red tide and cold snaps, and the effects of mercury contamination on survival. Add to this the human health risk of consuming mercury‐contaminated fishes, and the argument supporting re‐opening the fishery evaporates. This article is protected by copyright. All rights reserved.
Depredation of demersal longlines by killer and sperm whales is a widespread behaviour that impacts fisheries and whale populations. To better understand how depredating whales behave in response to fishing activity, we deployed satellite-linked location and dive-profile tags on a sperm and killer whale that were depredating Patagonian toothfish from commercial longlines off South Georgia. The sperm and killer whale followed one fishing vessel for >180 km and >300 km and repeatedly depredated when longlines were being retrieved over periods of 6 and 7 d, respectively. Their behaviours were also sometimes correlated with the depths and locations of deployed gear. They both dove significantly
deeper and faster when depredating compared with when foraging naturally. The killer whale dove >750m on five occasions while depredating (maximum: 1087 m), but these deep dives were always followed by long periods (3.9–4.6 h) of shallow (<100 m) diving. We hypothesize that energetically and physiologically costly dive behaviour while depredating is driven by intra- and inter-specific competition due to the limited availability of this abundant resource.
Shark depredation, where a shark partially or completely consumes an animal caught by fishing gear before it can be retrieved to the fishing vessel, occurs in commercial and recreational fisheries worldwide, causing a range of negative biological and economic impacts. Despite this, it remains relatively understudied compared to other fisheries issues. This is the first review of the literature relating to shark depredation, which also includes an overview of the potential mechanisms underlying its occurrence and options for mitigation. Furthermore, this review highlights key research gaps that remain to be investigated, thereby providing impetus for future research. In total, 61 studies have been published between 1955 and 2018, which include information on shark depredation. These studies recorded quantitative rates of depredation between 0.9 and 26% in commercial and recreational fisheries and during research fishing, identified 27 shark species from seven families that were responsible for depredation and discussed potential factors influencing its occurrence. Information from research into bycatch mitigation and the testing of shark deterrent approaches and technologies is also presented, in the context of applying these approaches to the reduction of shark depredation. This review presents an holistic overview of shark depredation in fisheries globally and, in doing so, provides a central resource for fisheries researchers and managers focusing on this topic to stimulate further collaborative research on this important fisheries issue.
Shark depredation, where a shark consumes a hooked fish before it can be retrieved to the fishing vessel, can occur in recreational fisheries. This may cause higher mortality rates in target fish species, injuries to sharks from fishing gear and negatively impact the recreational fishing experience. This study quantified spatial variation and frequency of shark depredation in a recreational fishery in the Ningaloo Marine Park and Exmouth Gulf, Western Australia, by surveying 248 fishing boats at west coast boat ramps and 155 boats at Exmouth Gulf boat ramps from July 2015 to May 2016. Shark depredation occurred on 38.7% of fishing trips from west coast boat ramps and 41.9% of trips from Exmouth Gulf boat ramps. The mean (±95% CI) shark depredation rate per trip was 13.7 ± 3.3% for demersal fishing (n = 185) and 11.8 ± 6.8% for trolling (n = 63) for west coast boat ramps, compared to 11.5 ± 2.8% (n = 128) and 7.2 ± 8.4% (n = 27) for Exmouth Gulf ramps. Depredation rates varied spatially, with higher depredation in areas which received greater fishing pressure. A novel application of Tweedie generalised additive mixed models indicated that depth, the number of other boats fishing within 5 km and survey period influenced depredation rates for fishing trips from west coast boat ramps. For the Exmouth Gulf ramps, fishing pressure and decreasing latitude positively affected the number of fish depredated. These results highlight the important influence of spatial variation in fishing pressure. The occurrence of higher depredation rates in areas which receive greater fishing pressure may indicate the formation of a behavioural association in the depredating sharks. This study is the first quantitative assessment of shark depredation in an Australian recreational fishery, and provides important insights that can assist recreational fishers and managers in reducing depredation.
A recent global quantitative assessment suggested that “the majority of shark populations will continue to decline under current fishing pressure” (Worm et al. 2013:198) and concluded that global shark mortality needs to be drastically reduced to rebuild populations and restore marine ecosystems with functional top predators. The high exploitation rates inferred by the authors are alarming and, if accurate, justify the increased concern of the global conservation community. To assess the generality and accuracy of this work, I critically evaluate the assumptions and validity of the extrapolations made by the authors. This global study provided a valuable overall perspective on the highly relevant topic of shark conservation; however, the generalizations made carry substantial uncertainty that was not accounted for. My review aims to place the
conclusions drawn by the authors into perspective, highlighting numerous factors that, having been considered, would have significantly affected their claims.
Demersal and pelagic longline fisheries involve frequent and geographically widespread interactions with many individuals, populations, and species of marine mammals. Animals sometimes suffer mortality and serious injury following these interactions, attracted mainly to longlines as a source of food. This depredating behaviour can have serious consequences for fishermen, especially when they lose valuable catch and face other associated operational and regulatory challenges. Using input from a group of international experts in the science, fishing industry, and government sectors, we produced a list of methods for mitigating depredation and bycatch of marine mammals in longline fisheries, collectively assessed their potential as a solution, and determined priorities for further research. The intention of this review is to help synthesize our current understanding about potential solutions, to provide an introduction to the articles that appear in this themed set of the ICES Journal of Marine Science, and to help fishermen, fisheries managers, and research scientists advance solutions to this global problem. © 2015 International Council for the Exploration of the Sea 2015. All rights reserved. For Permissions, please email: [email protected]
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Interactions between killer whales (Orcinus orca), sperm whales (Physeter macrocephalus), fur seals (Arctocephalus spp.) and longline fishing operations were reported by observers on board fishing vessels targeting Patagonian toothfish (Dissostichus eleginoides) in the Crozet and Kerguelen Islands Exclusive Economic Zones (EEZs) between 2003 and 2005. In the Crozet EEZ, the reported interactions involved killer whales and sperm whales. These two species, alone or in co-occurrence with each other, were observed in 71% of the 1 308 longlines set. In the Kerguelen EEZ, the reported interactions involved sperm whales and fur seals. These two species, alone or in co-occurrence with each other, were observed in 54% of the 6 262 longlines monitored. Interactions were observed in all fishing areas. The effect of depredation was assessed by comparing catch-per-unit-effort (CPUE) (fish weight/hook) of each longline set in the absence/presence of marine mammal species alone or in co-occurrence. In the Crozet EEZ, CPUE was found to be reduced by 22.5% in the presence of killer whales, 12.1% by sperm whales, and 42.5% when both species were present together. An extensive photo-identification effort, primarily focussing on killer whales, allowed a total of 103 individual whales to be identified. The analysis of photo-identification indicated that a small number of individual killer whales were responsible for most of the interactions with the fishery. In the Kerguelen EEZ only sperm whales, alone or in co-occurrence with fur seals, were found to impact negatively on CPUE.
Large sharks are top predators in most coastal and marine ecosystems throughout the world, and evidence of their reduced prominence in marine ecosystems has been a serious concern for fisheries and ecosystem management. Unfortunately, quantitative data to document the extent, timing, and consequences of changes in shark populations are scarce, thwarting examination of long‐term (decadal, century) trends, and reconstructions based on incomplete data sets have been the subject of debate. Absence of quantitative descriptors of past ecological conditions is a generic problem facing many fields of science but is particularly troublesome for fisheries scientists who must develop specific targets for restoration. We were able to use quantitative measurements of shark sizes collected annually and independently of any scientific survey by thousands of recreational fishermen over the last century to document decreases in the size of large sharks from the northern Gulf of Mexico. Based on records from fishing rodeos in three U.S. coastal states, the size (weight or length) of large sharks captured by fishermen decreased by 50–70% during the 20 years after the 1980s. The pattern is largely driven by reductions in the occurrence and sizes of Tiger Sharks Galeocerdo cuvier and Bull Sharks Carcharhinus leucas and to a lesser extent Hammerheads Sphyrna spp. This decrease occurred despite increasing fishing effort and advances in technology, but it is coincident with the capitalization of the U.S. commercial shark long‐line fishery in the GOM.
Received April 10, 2012; accepted March 7, 2013
Killer whale (Orcinus orca) depredation (whales stealing or damaging fish caught on fishing gear) adversely impacts demersal longline fisheries for sablefish (Anoplopoma fimbria), Pacific halibut (Hippoglossus stenolepis) and Greenland turbot (Reinhardtius hippoglossoides) in the Bering Sea, Aleutian Islands and Western Gulf of Alaska. These interactions increase direct costs and opportunity costs associated with catching fish and reduce the profitability of longline fishing in western Alaska. This study synthesizes National Marine Fisheries Service observer data, National Marine Fisheries Service sablefish longline survey and fishermen-collected depredation data to: 1) estimate the frequency of killer whale depredation on longline fisheries in Alaska; 2) estimate depredation-related catch per unit effort reductions; and 3) assess direct costs and opportunity costs incurred by longliners in western Alaska as a result of killer whale interactions. The percentage of commercial fishery sets affected by killer whales was highest in the Bering Sea fisheries for: sablefish (21.4%), Greenland turbot (9.9%), and Pacific halibut (6.9%). Average catch per unit effort reductions on depredated sets ranged from 35.1-69.3% for the observed longline fleet in all three management areas from 1998-2012 (p
Dolphins are often blamed for reducing fisheries catches and may be killed in retaliation. Depredation of fishing gear in coastal Mediterranean waters is normally caused by bottlenose dolphins. Economic impact, however, may be modest even within areas of reportedly acute conflict.
Boat surveys and interviews were conducted to investigate dolphin occurrence and interactions with fisheries within the 167 km ² Porto Cesareo Marine Protected Area (MPA) in southern Italy. Based on 69 interviews with fishermen using bottom‐set trammel and gill nets, there was reportedly a high occurrence of depredation by bottlenose dolphins. Depredation was reported by 92% of the fishermen operating in or near the MPA, and 67% of them claimed an economic cost in excess of €1000 per year, with a mean reported cost of €2561: a higher impact than in other Mediterranean studies.
According to local fishermen, dolphin occurrence and depredation peaked in spring and autumn, coincident with the study's surveys at sea. Dedicated visual surveys totalling 1255 km of effort, however, resulted in no encounters with cetaceans. Information from interviews and boat surveys was therefore contradictory, suggesting that reports of acute depredation do not imply a constant presence of dolphins within the MPA.
While depredation in the MPA might be caused by wide‐ranging dolphins or incursions occurring overnight, damage may well be overestimated or over‐reported. As local fishermen had previously benefited from subsidies, interviews made during this study could be perceived by some as an opportunity to influence future decision‐making regarding monetary compensation for the impact of depredation.
Evidence from interviews also indicated that species and factors other than dolphins were responsible for part of the damage. Copyright © 2011 John Wiley & Sons, Ltd.
Cryptic, not readily detectable, components of fishing mortality are not routinely accounted for in fisheries management because of a lack of adequate data, and for some components, a lack of accurate estimation methods. Cryptic fishing mortalities can cause adverse ecological effects, are a source of wastage, reduce the sustainability of fishery resources and, when unaccounted for, can cause errors in stock assessments and population models. Sources of cryptic fishing mortality are (1) pre-catch losses, where catch dies from the fishing operation but is not brought onboard when the gear is retrieved, (2) ghost-fishing mortality by fishing gear that was abandoned, lost or discarded, (3) post-release mortality of catch that is retrieved and then released alive but later dies as a result of stress and injury sustained from the fishing interaction, (4) collateral mortalities indirectly caused by various ecological effects of fishing and (5) losses due to synergistic effects of multiple interacting sources of stress and injury from fishing operations, or from cumulative stress and injury caused by repeated sub-lethal interactions with fishing operations. To fill a gap in international guidance on best practices, causes and methods for estimating each component of cryptic fishing mortality are described, and considerations for their effective application are identified. Research priorities to fill gaps in understanding the causes and estimating cryptic mortality are highlighted.
Some populations of marine mammals (particularly odontocete cetaceans, and pinnipeds) have responded to the expansion of fisheries by modifying their behaviour to take advantage of the foraging opportunities provided by fishing. This has led to interactions that include forms of “depredation”, referring to the removal of, or damage to, marketable organisms as well as bait from fishing gear. The current scientific and technical usage of depredate or depredation appears inconsistent with some of the meanings found in dictionaries, such as to plunder (typically using force), pillage, ravage, lay waste, despoil, destroy, commit waste, or ransack. We suggest that the use of “depredation” when referring to marine mammal behaviour could strengthen misperception and misunderstanding, hardening notions that they are unfairly taking or destroying what is ours. Though most contemporary researchers do not mean to imply that predators are “stealing our fish”, continued reference to the mammals’ behaviour as depredation may reinforce, at least in some minds, the belief that fish and other marine resources “belong” only to humans. Alternative wording would help to prevent ambiguity in communications, especially outside the scientific community, and preserve recognition of the ecological roles that large marine predators play. ---
AVAILABLE AT: https://doi.org/10.1093/icesjms/fsac173
Human-wildlife conflicts (HWC) are increasingly prominent worldwide, which can complicate conservation efforts for wildlife. Shark depredation, when a shark preys on a fishers' catch, is a growing HWC in global fisheries and is particularly contentious in Queensland, Australia, causing fisher frustrations and monetary losses. However, social research on depredation remains nascent and has yet to incorporate insights emerging from terrestrial HWC research. To address this gap, this study draws on the Levels of Conflict framework to investigate how fishers experience and perceive shark depredation. Through fisher interviews, we explored beyond surface level aspects of depredation into deeper-rooted clashes in values among key stakeholders. At the surface level, fishers expressed varied perceptions about what drives depredation and, contrary to a focus of previous research, did not emphasize economic costs. On a deeper level, we found a clash of perceived stakeholder conservation values, specifically between shark conservation efforts versus maintaining fish stocks and ecosystem balance. This conservation conflict was further complicated by historically driven fisher distrust of management and science. These findings support the need for a pragmatic approach to managing shark depredation in Queensland fisheries that extends beyond immediate costs. Our findings also suggest the need to reexamine the nature of depredation conflicts globally considerate of local fisher values. This may assist in rebuilding fisher trust and enhance collaboration to develop mitigation strategies. More broadly, incorporating human use of marine ecosystems in conservation narratives may be a promising means to address the conservation conflict between fisher values and shark conservation initiatives.
The loss of hooked fish from shark depredation has become an increasing problem in marine recreational fisheries worldwide, particularly among charter and private-boat recreational fishers. There is growing need to understand the prevalence of shark encounters, where depredation occurs and how recreational fishers respond to and mitigate depredation. This study of 1340 charter and private-boat recreational fishers in north-western Australia, included both probability-based (telephone and online) and opt-in (online) survey methods and is the first to document mitigation methods used by recreational fishers. More than half of the respondents (728) who completed the survey indicated that they had attempted to mitigate depredation. In the probability-based survey, the main mitigation methods reported by charter and private-boat fishers were to move spots, use wire trace or stop fishing. Depredation evokes strong opinions from some sections of the fishing population. Although more avid fishers self-selected for the opt-in surveys, the inclusion of information from these respondents, particularly from open-ended questions, provided detailed information on attitudes among fishers where this issue is of concern. This study highlights the wide range of views and concerns regarding depredation, all of which need to be considered when developing policies and guidelines around this issue. As with other contentious issues where changes in fishing behaviour are required, decision-makers will need to devise strategies to inform and educate the fishing public in how to mitigate against depredation.
Interspecific interactions can play an essential role in shaping wildlife populations and communities. To date, assessments of interspecific interactions, and more specifically predator–prey dynamics, in aquatic systems over broad spatial and temporal scales (i.e., hundreds of km and multiple years) are rare due to constraints on our abilities to measure effectively at those scales. We applied new methods to identify space use overlap and potential predation risk to Atlantic tarpon (Megalops atlanticus) and permit (Trachinotus falcatus) from two known predators, great hammerhead (Sphyrna mokarran) and bull (Carcharhinus leucas) sharks over a three year period using acoustic telemetry in the coastal region of the Florida Keys (USA). By examining spatial‐temporal overlap, as well as the timing and order of arrival at specific locations compared to random chance, we show that potential predation risk from great hammerhead and bull sharks to Atlantic tarpon and permit are heterogeneous across the Florida Keys. Additionally, we found that predator encounter rates with these game fishes are elevated at specific locations and times, including a pre‐spawning aggregation site in the case of Atlantic tarpon. Further, using machine learning algorithms, we identify environmental variability in overlap between predators and their potential prey, including location, habitat, time of year, lunar cycle, depth, and water temperature. These predator–prey landscapes provide insights into fundamental ecosystem function and biological conservation, especially in the context of emerging fisheries‐related depredation issues in coastal marine ecosystems.
Shark depredation, the full or partial removal of a hooked fish by a shark before it is landed, is anecdotally increasing in the United States. Perceptions of depredation by anglers and fishing guides may influence their behavior and have cascading effects on sharks and recreational fisheries. However, to date, these perceptions have not been broadly quantified. To better understand how anglers and guides respond to shark depredation in recreational fisheries, we used an online survey open to saltwater anglers in North America, distributed electronically via social media and online platforms. Of the 541 respondents, 77% had experienced depredation in nearshore and pelagic fisheries in the last five years, with depredation more commonly reported in the southeastern United States. Emotional responses to depredation were significantly different between anglers and guides, with the latter feeling more intense negative emotions. Behavioral changes in response to depredation, such as targeting and harvesting sharks, were driven largely by negative emotional responses and perceptions of sharks as threats to target species, while changes to protect target species varied with positive emotional responses and angler demographics. Guides were predominantly concerned about increased mortality to their target species and loss of trophy fish from the population. In fact, 87% of guides experienced depredation when fishing with clients and overwhelmingly reported that depredation has a negative effect on their livelihood. Overall, these results can be used to help inform strategies to reduce depredation while accounting for the values of stakeholder groups, particularly anglers and those advocating for shark conservation.
Ecosystem-based approaches are increasingly used in fisheries management to account for the direct trophic impacts of fish population harvesting. However, fisheries can also indirectly alter ecosystem structure and functioning, for instance via the provision of new feeding opportunities to marine predators. For instance, marine depredation, where predators feed on fishery catches on fishing gear, is a behaviour developed by many marine species globally. This behaviour can modify both the ecological role of predators and fisheries performance. Yet, these ecosystem-wide effects of depredation are rarely considered holistically. In this study, we explored different ways of incorporating depredation into an Ecopath trophic model. We assessed, through a subantarctic case study, how three alternative model structures can account for depredation effects on fishery catches, predator and non-commercial prey populations, as well as target fish stocks. While none adequately addresses all facets of depredation, the alternative models can to some extent capture how depredation can lead to increased fishing pressure on stocks. As structural specificities of Ecopath prevented us from representing other depredation effects such as provisioning effects for predator populations, we conclude this study with a set of guidance to effectively capture the complex effects of depredation in marine ecosystems and fisheries models.
The sustainable mitigation of human–wildlife conflicts has become a major societal and environmental challenge globally. Among these conflicts, large marine predators feeding on fisheries catches, a behaviour termed “depredation,” has emerged concomitantly with the expansion of the world’s fisheries. Depredation poses threats to both the socio‐economic viability of fisheries and species conservation, stressing the need for mitigation. This review synthesizes the extent and socio‐ecological impacts of depredation by sharks and marine mammals across the world, and the various approaches used to minimize it. Depredation was reported in 214 fisheries between 1979 and 2019 (70% post‐2000) and affected fleets from 44 countries, in all sectors (commercial, artisanal and recreational), and in all major fishing techniques (nets, traps and hook‐and‐lines). A total of 68 predator species were involved in depredation (20 odontocetes, 21 pinnipeds and 27 sharks), and most (73%) were subject to either by‐catch and/or retaliatory killing from fishers when interacting with gear. Impacts on fishers were primarily associated with catch losses and gear damage but often lacked assessments. Deterrence was a major mitigation approach but also the least effective. Gear modifications or behavioural adaptation by fishers were more promising. This review highlights the need for improved monitoring, and interdisciplinary and integrated research to quantify the determinants and impacts of depredation in the socio‐ecological dimension. More importantly, as the conflict is likely to escalate, efforts directed towards changing perceptions and integrating knowledge through adaptive co‐management are raised as key directions towards coexistence between fisheries and large marine predators.
Shark encounters while fishing in Western Australian waters have been perceived to be increasing by some fishers in recent years. A lack of quantitative information remains a significant obstacle to determining the nature and magnitude of these encounters. A probability-based survey was implemented to assess the occurrence of and attitudes toward shark encounters by commercial fishers, charter tour operators and private boat-based recreational fishers during 2015/16. Of the 906 fishers interviewed, 52% indicated they had experienced at least one shark encounter while fishing during the previous year. The loss or damage of fish was involved in over half of these encounters while charter fishing and nearly a third while recreational fishing. The level of concern towards shark depredation was highest among charter tour operators statewide and all sectors in the Gascoyne bioregion. Multiple logistic regression analyses indicated fishing method and bioregion were the most important predictors of encounters. Depredation through fish loss below or at the surface was highest for pelagic or demersal line fishing in the North Coast and Gascoyne bioregions. Overwhelmingly, the majority of fishers in all sectors were satisfied with their fishing experience despite the occurrence of shark encounters. Future research on shark depredation would benefit from focusing on fishing methods and bioregions where depredation events were highest, with consideration of associated behavioural and environmental characteristics likely to influence depredation rates. The approach outlined here could easily be applied to other human-wildlife interaction studies where representative views of stakeholders are required for policy development and effective management.
Objective. In the course of daily teaching responsibilities, pharmacy educators collect rich data that can provide valuable insight into student learning. This article describes the qualitative data analysis method of content analysis, which can be useful to pharmacy educators because of its application in the investigation of a wide variety of data sources, including textual, visual, and audio files.
Findings. Both manifest and latent content analysis approaches are described, with several examples used to illustrate the processes. This article also offers insights into the variety of relevant terms and visualizations found in the content analysis literature. Finally, common threats to the reliability and validity of content analysis are discussed, along with suitable strategies to mitigate these risks during analysis.
Summary. This review of content analysis as a qualitative data analysis method will provide clarity and actionable instruction for both novice and experienced pharmacy education researchers.
There is a rapidly growing body of scholarship on climate change adaptation in diverse contexts globally. Despite this, climate adaptation at the community level has not received adequate conceptual attention, and a limited number of analytical frameworks are available for assessing place-specific adaptations, particularly in a fisheries context. We use conceptual material from social-ecological systems (SES) resilience and human development resilience to build an integrated framework for evaluating community adaptations to climate change in a fisheries setting. The framework defines resilience as the combined result of coping, adapting, and transforming recognizing resilience as a system's capacity and as a process. This understanding of resilience integrates with the three development resilience concepts of resistance, rootedness, and resourcefulness to develop 'place-based elements' which refer to collective action, institutions, agency, and indigenous and local knowledge systems. The proposed framework can capture a local setting's place-specific attributes relating to the well-being of individuals , households, and communities, and the through integration of SES and human development con-ceptualizations addresses some of the key critiques of the notion of resilience. We have proposed this framework for application in context-specific environments-including fisheries-as a means of assessing community adaptations.
Human-wildlife conflict has been receiving increased scientific and management attention, predominantly in terrestrial systems, as a side effect of successful predator conservation and recovery. These same conflicts exist in the ocean; however, they are mostly regarded in a region- or taxa-specific context despite evidence that human-wildlife conflict is prevalent across the global oceans and likely to increase as a result of successful conservation measures. Can the lessons learned from conflicts on land promote more sustainable success in the sea? Or, do ocean human-wildlife conflicts create unique challenges that require new solutions? This paper synthesizes evidence from human-wildlife conflicts in the ocean and provides initial suggestions for progressing with effective management in the ocean. Humans have extensive experience managing conflict with terrestrial predators and several of the strategies are transferable to marine predators, but several important differences between systems necessitate a marine-specific focus and evaluation of existing mitigation strategies. Further, in managing marine wildlife conflict, it is crucial to recognize that perceived conflicts can be just as important as actual conflict and that, in many cases, human-human conflict is at the root of human-wildlife conflict. As efforts to recover important predator populations continue, humans are faced with the exciting opportunity and a new necessity to constructively manage these recoveries to continue to meet goals for marine conservation while simultaneously promoting human safety and industry in the seas.
An improved understanding of interaction dynamics between dolphins and trawlers is essential for improving bycatch mitigation strategies. In-situ observations using video at increasing distances from the net opening during 50 commercial fish trawls, recorded 5908 common bottlenose dolphin (Tursiops truncatus (Montagu, 1821)) interactions and provided details on their duration, depredation rates, and behaviours. Dolphin interactions with trawls were very common (98% of day-trawls, 118 ± 16 interactions per trawl), with durations and prey consumption positively correlated with the distances ventured into the net. Acoustic deterrents (pingers) had no effect on interaction numbers or durations. Based on in-situ observations, the factors that contribute toward dolphin bycatch in demersal fish trawls were likely associated with (i) risky dolphin behaviour (i.e., entering net during hauling, residing deep within trawl for extended periods or social aggression) and (or) (ii) instability of fishing gear resulting in entrapment. Given the high level of dolphin attendance during most day-trawls, mitigation strategies that focus on improving and monitoring the stability of trawl gear would be more effective than current acoustic deterrent devices aimed at modifying dolphin behaviour.
Despite the perilous status of many shark populations, rallying support for their conservation has been challenging, due in part to both long held negative perceptions and desire for shark fisheries. Recreational anglers are often advocates of conservation and can act as valuable partners with resource managers in developing fisheries management and conservation strategies. However, understanding their attitudes and perceptions, particularly towards resource status and management, is essential to developing successful management strategies and predicting outcomes. As a case study for assessing the complex challenges of sustainable shark fisheries, Florida recreational anglers were surveyed to understand how attitudes and perceptions influenced their willingness to donate for shark 1) conservation and protection or 2) fisheries sustainability. Overall, recreational angler willingness to donate was 25.5%, but attitudes and perceptions helped explain dramatic divides. For instance, willingness to donate was only 6% among the subset of anglers that perceived a growing large coastal shark population as a threat to recreational fishing opportunities. Highest support for shark conservation was shown by anglers who value seeing sharks in the wild (41.4%), and even more so among individuals who occasionally target sharks while fishing recreationally (65.8%). Pervasive among anglers unwilling to donate was a perception that shark populations were increasing, and thus not in need of further protection. These findings illustrate attitudes and perceptions that challenge shark conservation and fisheries management, as well as the critical importance of engaging anglers when developing strategies that rely on the recreational angling community for support.
For centuries, the primary manner in which humans have interacted with sharks has been fishing. A combination of their slow-growing nature and high use-values have resulted in population declines for many species around the world, and to date the vast majority of fisheries-related work on sharks has focused on the commercial sector. Shark recreational fishing remains an overlooked area of research despite the fact that these practices are popular globally and could present challenges to their populations. Here we provide a topical overview of shark recreational fisheries, highlighting their history and current status. While recreational fishing can provide conservation benefits under certain circumstances, we focus our discourse on the relatively understudied, potentially detrimental impacts these activities may have on shark physiology, behavior, and fitness. We took this angle given the realized but potentially underestimated significance of recreational fishing for shark conservation management plans and stock assessments, in hopes of creating a dialogue around sustainability. We also present a series of broad and focused research questions and underpin areas of future research need to assist with the development of this emergent area of research.
We documented depredation by bottlenose dolphins (Tursiops truncatus) in the Florida king mackerel (Scomberomorus cavalla) troll fishery. Between March and June 2003, we conducted 26 interviews of charter and commercial fishermen in Islamorada, Florida, and 23 along Florida's east coast from Fort Pierce south to Lake Worth Inlet. All fishermen indicated they had observed bottlenose dolphins depreciating bait or catch-king mackerel being the species most often taken by dolphins. During on-board observations of depredation between March and June 2003, we found that dolphins took 6% of king mackerel caught by charter fishermen and 20% of fish caught by commercial fishermen. We concluded that depredation by bottlenose dolphin occurs commonly in this fishery and has the potential to incur a significant economic cost to king mackerel fishermen. To address this concern, we conducted preliminary tests of a gear modification designed to reduce depredation in the king mackerel fishery between December 2003 and January 2004. These tests demonstrated that a modification to the outrigger planer will successfully deter bottlenose dolphins from engaging in depredation, without causing a reduction in catch.
Odontocete bycatch on and depredation from tropical pelagic longlines is globally widespread, having negative impacts on the economic viability of affected fisheries and on the conservation of affected odontocete populations. Reports by fishers that depredating odontocetes avoid gear tangles has underpinned the development of simulated structures to physically deter depredating odontocetes. This study assessed the efficacy of two such devices developed to mitigate odontocete depredation and associated bycatch. Of particular interest was their impact on (i) soak depth and (ii) sink rate using truncated trials, before determining their impact under full operational conditions on rates of (iii) catch of the five most economically important fish, and (iv) odontocete depredation and bycatch, on changes in (v) fish survival and size, and (vi) setting and hauling speed. The results indicated that the inclusion of devices on longlines had negligible impact on soak depth, thus were unlikely to impact on the suite of fish specifically targeted and caught. The sink rate was slowed, perhaps by drag, trapped air, or propeller wash, although the addition of weight might remedy this if the devices were to be used in areas where seabird bycatch could occur. Most importantly, trials conducted in Australian and in Fijian waters indicated that pooled fish catch rates (i.e. albacore, yellowfin, bigeye, mahi mahi, and wahoo) increased in the presence of the devices, possibly because more fish were attracted by them or because more depredators were deterred. Catch rates on control gear next to gear with devices attached were higher than more distant control gear, suggesting the influences of the devices may have extended to adjacent branchlines. The size of caught fish was mostly unaffected, although the survival of yellowfin and bigeye increased significantly in the presence of the devices. Hauling was slowed by the use of the devices and the need for an extra crewmember during setting and hauling, which could be cost prohibitive in some fisheries, especially if economic benefits from their use are not obvious. Despite the small sample size, odontocete bycatch only occurred on unprotected fishing gear and all individuals were released alive, although their fate was uncertain; there was evidence of injuries sustained from the event. The outcomes are positive and should motivate stakeholders to view such devices as a potentially effective tool for mitigating odontocete bycatch and depredation in this and similar longline fisheries. Future efforts should focus on improving operational integration and reducing implementation costs to encourage voluntary uptake and thus avoid non-compliance and the need for costly monitoring. The use of this technology could bring about marked improvements to the conservation situation for affected odontocete populations and to the economic situation for affected longline fisheries. © 2015 International Council for the Exploration of the Sea 2015. All rights reserved. For Permissions, please email: [email protected]
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Harvests from recreational fishing are increasingly as important as commercial harvest to populations of popularly fished marine recreational species. However, it has yet to be determined whether the increasing importance of recreational fishing is a general trend of marine fisheries in the US or whether such a trend is limited to only those species recognized as popular recreational fishes. 71% of marine species in the US have experienced an increase in the proportion of total harvest from the recreational sector during the time harvest data are available for both sectors. Species demonstrating an increase in the proportion of harvests by the recreational sector included those generally regarded as commercial, bait, and bycatch species, as well as those considered recreational species. Marine species categorized as overfished could not be predicted from either fishery characteristics or life history characteristics in a PCA analysis of available data for fished species in the US. Consequently, there appears to be little to predict vulnerability of populations to fishing efforts save that all fished species can be made vulnerable to overexploitation. Well-developed yield-based strategies, designed for commercial fisheries, are not likely to be effective in managing populations as the diverse recreational fishing sector continues to increase in its importance. Thus, new management strategies for US marine fisheries are needed. Some possible alternative strategies are discussed.
Sustainability may be defined as the maintenance of the quality, diversity and availability of fishery resources in sufficient quantities for present and future generations. But how do modern management systems aim to achieve this in the face of natural fluctuations and human-induced pressures? Using four case study fisheries (northern Atlantic cod and North Sea cod [both Gadus morhua], Pacific sablefish Anoplopoma fimbria, and South African West Coast lobster Jasus lalandii), we examine the components and considerations used in the development of management systems. Historically, these considerations have been biology-based, incorporating reference points appropriate for management goals or targets. Following some quite spectacular failures, however, inputs from disciplines such as socio-economics and ecosystem science are increasingly important drivers behind management decisions, but have the potential to increase management complexity greatly. We identify three areas of particular importance. Precautionary, robust and responsive management is needed, with pre-agreed actions to be taken when particular conditions are experienced. Management decisions need to be based upon adequate scientific information, particularly given the increasing variety of drivers for management. Finally, fisheries management needs to be a collaborative process, involving all stakeholders, thereby raising the credibility of management for all participants. Integrating all these aspects within the fisheries management framework is complex, but when combined with the realisation that harvests are likely to be lower than historical levels, there appears to be a greater chance of successful sustainable exploitation.
Most research on catch-and-release (C&R) in recreational fishing has been conducted from a disciplinary angle focusing on the biological sciences and the study of hooking mortality after release. This hampers understanding of the complex and multifaceted nature of C&R. In the present synopsis, we develop an integrative perspective on C&R by drawing on historical, philosophical, socio-psychological, biological, and managerial insights and perspectives. Such a perspective is helpful for a variety of reasons, such as 1) improving the science supporting successful fisheries management and conservation, 2) facilitating dialogue between managers, anglers, and other stakeholders, 3) minimizing conflict potentials, and 4) paving the path toward sustainable recreational fisheries management. The present work highlights the array of cultural, institutional, psychological, and biological factors and dimensions involved in C&R. Progress toward successful treatment of C&R might be enhanced by acknowledging the complexity inherent in C&R recreational fishing.
Abstract Odontocete depredation involves stealing or damaging bait or prey already captured by fishing gear. The increase in depredation is of concern for small stocks of cetaceans because interactions with fishing gear can lead to serious injury or mortality through entanglement or ingestion. Using long-term data sets available for the bottlenose dolphin (Tursiops truncatus) community in Sarasota Bay, Florida, we investigated recreational fishing gear interactions by (1) examining temporal patterns in depredation and associated behaviors from 2000 to 2007; (2) quantifying the behavior of dolphins that depredate or engage in associated behaviors; and (3) identifying factors associated with the rise in depredation locally. The number of incidents of dolphins (primarily adult males) interacting with recreational anglers and boaters increased following 2004. Depredation and associated behaviors increased during red tide lags and tourist seasons during times of prey depletion and heightened angler and boater activity. Dolphins with a history of fishing gear interactions shifted away from natural activity patterns and were more likely to be within 50 m of fishing lines. Recreational fishing gear interactions were attributed to a two percent population decline in Sarasota Bay in 2006 and need to be considered along with other cumulative human impacts in the development of conservation measures for dolphins.
Internet and Mail Surveys: the Tailored Design Method
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Report on the workshop on interactions between cetaceans and longline fisheries held in apia
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Co-producing a shared characterization of depredation in the Gulf of Mexico reef fish fishery: comprehensive report
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reef fish fishery: comprehensive report. New England Aquarium Aquatic Forum
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Why is Florida the 'fishing capital of the World?
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Commercial Fishing Gear Profile: the Bandit Rig. Collier County Sea Grant Extension Blog
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