Enhancing catch-and-release science with biotelemetry

Catch‐and‐release (C&R) angling is widely practised by anglers and is a common fisheries management strategy or is a by‐product of harvest regulations. Accordingly, there is a growing body of research that examines not only the mortality associated with C&R, but also the sublethal physiological and behavioural consequences. Biotelemetry offers a powerful means of remotely monitoring the behaviour, physiology and mortality of fish caught and released in their natural environment, but we contend that its usefulness is still underappreciated by scholars and managers. In this study, we review the applications of biotelemetry in C&R science, identify novel research directions, opportunities and challenges. There are now about 250 C&R studies but only one quarter of these utilize biotelemetry. In fact, almost all of the C&R studies that have used biotelemetry have been conducted within the last decade. We found that the majority of C&R telemetry studies used either radio or acoustic telemetry, while comparatively few studies have used satellite technologies. Most C&R biotelemetry studies have been used to assess mortality rates, behavioural impairments or to evaluate the effects of displacement on fish. A small fraction of studies (<8%) have used physiological sensors despite the fact that these tools are highly applicable to understanding the multiple sublethal consequences of C&R and are useful for providing mechanistic insights into endpoints such as death. We conclude that C&R science has the potential to benefit greatly from biotelemetry technology, particularly with respect to providing more robust short‐term and delayed mortality estimates and adopting a more integrative and comparative approach to understanding the lethal and sublethal impacts of C&R. However, there are still a number of challenges including (i) the need for appropriate controls and methodological approaches, (ii) the need for accounting for tagging and handling stress and mortality, and (iii) the need for certainty in assessing mortality. However, the benefits associated with C&R biotelemetry outweigh its disadvantages and limitations and thereby offer C&R researchers a suite of new tools to enhance fisheries management and conservation.     

A comparative and evolutionary approach to oxidative stress in fish: A review

Oxidative stress results from an imbalance between the production of reactive oxygen species and the antioxidants defences, in favour of the former. In recent years, the association between oxidative processes, environmental change and life histories has received much attention. However, most studies have focused on avian and mammalian taxonomic groups, with less attention given to fish, despite their ecological and socio‐economic relevance. Here we present a review of the extrinsic and intrinsic factors that influence oxidative processes in fish, using a comparative and evolutionary approach. We demonstrate that oxidative stress plays a key role in shaping fish's responses to environmental change as well as life history strategies. We focus on representative examples to compare and contrast how levels of oxidative stress respond to changes in temperature, salinity and oxygen availability. Furthermore, we describe how emerging threats (i.e. pollution) affect oxidative stress parameters in fish. Oxidative stress indicators are increasingly being used as biomarkers to understand the mechanisms of various human‐induced stressors, but also to understand the physiological consequences of how animals are distributed in space and time and influenced by different life stages. Despite the expansion of the field of ecological oxidative stress, we are only beginning to understand the complex ways in which oxidative stress may interact with both extrinsic and intrinsic factors in fish. We conclude with a research agenda for oxidative research on fish and note that there is need for further research particularly in the area of life history strategies and ecological implications of oxidative status, as this type of research has the potential to help us understand patterns and dynamics relevant to fish conservation.     

Integrating physiology and life history to improve fisheries management and conservation

Knowledge of life‐history traits is increasingly recognized as an important criterion for effective management and conservation. Understanding the link between physiology and life history is an important component of this knowledge and in our view is particularly relevant to understanding marine and freshwater fishes. Such linkages (i.e. the life‐history/physiology nexus) have been recently advocated for avian systems and here we explore this concept for fish. This paper highlights the gap in fisheries literature with regard to understanding the relationship between physiology and life history, and proposes ways in which this integration could improve fisheries management and conservation. We use three case studies on different fishes (i.e. the Pacific salmon, the grouper complex and tuna) to explore these issues. The physiological structure and function of fish plays a central role in determining stock response to exploitation and changes in the environment. Physiological measures can provide simple indicators necessary for cost‐effective monitoring in the evaluation of fisheries sustainability. The declining state of world fisheries and the need to develop and implement restoration strategies, such as hatchery production or protected areas, provides strong incentive to better understand the influence of physiology on population and reproductive dynamics and early life history. Physiology influences key population‐level processes, particularly those dealing with reproduction, which must be incorporated into the design and successful implementation of specific and broadscale initiatives (e.g. aquatic protected areas and bycatch reduction). Suggestions are made for how to encourage wider application of the physiology/life‐history link, in fisheries management and conservation, as well as more broadly in education and research.     

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

Discarding non‐target fish from commercial fisheries is controversial and has been a persistent concern for fisheries managers globally. Discard management strategies typically begin by understanding mortality rates among discarded fish, a challenging task given the dynamic, highly context‐specific nature of fisheries. An alternative is to develop our knowledge of how stressors operate by first understanding the causes of mortality that drive this context dependence. Particularly relevant to mitigation efforts is an understanding of how fish respond to the physical factors of fishing, such as the gear itself and methods of fishing and handling the gear. We provide a synthesis of how commercial fishing methods may influence discard mortality and outline means by which capture‐induced stress and injury can be mitigated for common commercial gear types, emphasizing method variants or alternatives during capture, handling, and release that could improve survival. This synthesis identifies exhaustion and injury as the most detrimental and ubiquitous stressors experienced by discarded fish, with few options for mitigating their effects. Trawls and hanging net fisheries are identified as the most harmful gears for by‐catch, characterized by high stress regardless of method variants and limited options for mitigation. Irrespective of gear type and type of stressor, minimizing durations of capture and handling and encouragement of good handling behaviour (e.g., during landing and sorting) will reduce the magnitude of stress and injury in fish, and ultimately increase survival.     

Contrasting recreational and commercial fishing: Searching for common issues to promote unified conservation of fisheries resources and aquatic environments

Commercial fishing has repeatedly been identified as a major causal factor for global declines in fish stocks. Recently, recreational fisheries have also been considered as having the potential to contribute to fisheries declines. Here, we take a global focus, contrasting the characteristics of commercial and recreational fisheries relevant to conservation and sustainability of exploited fishes in both marine and freshwater environments. We provide evidence to support our assertion that the same issues that have led to global fisheries concerns regarding commercial fishing can have equivalent, and in some cases, magnified effects in recreational fisheries. Contrasts revealed that the issues of bycatch and catch-and-release, fisheries-induced selection, trophic changes, habitat degradation, gear technology, fishing effort, and production regimes are remarkably similar among fishery sectors. In recognition of this conclusion, we present a new vision for recreational fishing that positions it on the same scale and urgency as commercial fisheries. Efforts to manage and conserve fisheries must recognise that issues and threats are similar in these fundamentally and philosophically different fisheries, as may be the solutions. Failure to recognise the similarities will further polarise these sectors and retard efforts to conserve aquatic resources. Fishing activity of any kind, whether commercial or recreational, has the potential to affect negatively fish and fisheries, as well as aquatic environments.     

Historical overfishing and the recent collapse of coastal ecosystems

Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degradation of water quality, and anthropogenic climate change. Historical abundances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone.     

Physical activity and behavior of a centrarchid fish, Micropterus salmoides (Lacépède), during spawning

Abstract – The spawning behavior of male and female largemouth bass Micropterus salmoides (Lacépède) was studied in central Illinois during the spring of 1998 to examine patterns of muscular activity associated with different spawning related behaviors and to evaluate whether electromyogram (EMG i ) telemetry could be used to detect spawning activity. Fish were implanted with EMG i transmitters (8 females, 16 males) on April 7, prior to the initiation of spawning, and were released in four 0.10-ha earthen research ponds. Continuous EMG i records, underwater videography and additional visual observations for one pair of EMG i tagged fish were collected throughout the entire spawning event, allowing us to quantify behavioral correlates of physical activity. Male EMG i activity patterns were only correlated with female patterns during courting and periods of male aggression toward the female. Overall, EMG i activity was highest for the female during shuddering (gamete deposition), whereas male EMG i activity was similarly high during periods of nest excavation, shuddering and post-spawn parental care activities. During spawning, female EMG i activity was positively correlated to shuddering. Average daily EMG i activities for females peaked on the day of spawning. As a result of their engagement in parental care activities, male activity continued to rise even after spawning was completed. EMG i telemetry appears to be a useful technique for monitoring the reproductive activity of largemouth bass, especially in areas of high cover or turbid water or during low light conditions. This technology permitted us to quantify and contrast the activity patterns associated with different spawning related activities, information that will be required to construct accurate, gender-specific bioenergetics models for this species.     

Cellular Composition and Viability of Cloned Bovine Embryos Using Exogene-Transfected Somatic Cells

The present study compared the efficiency of transgenic (TG) cloned embryo production by somatic cell nuclear transfer (SCNT) with fetal-derived fibroblast cells (FFCs) which were transfected with pEGFP-N1 to in vitro-fertilized (IVF), parthenogenetic and SCNT counterparts by evaluating the rates of cleavage and blastocyst formation, apoptosis rate at different developmental stages, cell number, ploidy and gene expression in blastocysts. In SCNT and TG embryos, the rates of cleavage and blastocyst formation were significantly lower (p < 0.05) than those of IVF controls, but it did not differ between SCNT and TG embryos. In IVF control, 86.7% embryos displayed diploid chromosomal complements and the rates were significantly (p < 0.05) higher than those of SCNT and TG embryos. Most TG embryos (79%) with FFCs expressed the gene by both PCR and under fluorescence microscopy. The expression of apoptosis by TUNEL was first detected at six to eight cell stages in all embryos of IVF, SCNT and TG groups, but the expression rate at each developmental stages was significantly higher (p < 0.05) in SCNT and TG embryos than in IVF counterparts. The expression rate in inner cell mass (ICM) of TG embryos was significantly higher (p < 0.05) than in SCNT and IVF embryos. These results indicate that the high occurrence of apoptosis observed in SCNT and TG embryos compared with IVF counterparts might influence the developmental competence. Moreover, the SCNT embryos derived using non-transfected donor cells exhibited a lower apoptosis expression in ICM cells than in TG embryos derived using pEGP-N1-transfected donor cells suggesting a possible role of negative gene effect in TG embryos.     

A comparative assessment of potential components of partial disease resistance to <Emphasis Type="Italic">Fusarium</Emphasis> head blight using a detached leaf assay of wheat,barley and oats

The relative resistance of 15 winter barley, three winter wheat and three winter oat cultivars on the UK recommended list 2003 and two spring wheat cultivars on the Irish 2003 recommended list were evaluated using Microdochium nivale in detached leaf assays to further understand components of partial disease resistance (PDR) and Fusarium head blight (FHB) resistance across cereal species. Barley cultivars showed incubation periods comparable to, and latent periods longer than the most FHB resistant Irish and UK wheat cultivars evaluated. In addition, lesions on barley differed from those on wheat as they were not visibly chlorotic when placed over a light box until sporulation occurred, in contrast to wheat cultivars where chlorosis of the infected area occurred when lesions first developed. The pattern of delayed chlorosis of the infected leaf tissue and longer latent periods indicate that resistances are expressed in barley after the incubation period is observed, and that these temporarily arrest the development of mycelium and sporulation. Incubation periods were longer for oats compared to barley or wheat cultivars. However, oat cultivars differed from both wheat and barley in that mycelial growth was observed before obvious tissue damage was detected under macroscopic examination, indicating tolerance of infection rather than inhibition of pathogen development, and morphology of sporodochia differed, appearing less well developed and being much less abundant. Longer latent periods have previously been related to greater FHB resistance in wheat. The present results suggest the longer latent periods of barley and oat cultivars, than wheat, are likely to play a role in overall FHB resistance if under the same genetic control as PDR components expressed in the head. However the limited range of incubation and latent periods observed within barley and oat cultivars evaluated was in contrast with wheat where incubation and latent periods were shorter and more variable among genotypes. The significance of the various combinations of PDR components detected in the detached leaf assay as components of FHB resistance in each crop requires further investigation, particularly with regard to the apparent tolerance of infection in oats and necrosis in barley, after the incubation period is observed, associated with retardation of mycelial growth and sporulation.     

Analysis of head and leaf reaction towards <Emphasis Type="Italic">Microdochium nivale</Emphasis>

This research examined the variation in the response of eight commercial wheat cultivars to Microdochium nivale isolates using both in vivo FHB tests (AUDPC and RHW measurements) and in vitro detached leaf assays (LGR). Irrespective of fungal variety, the two Italian cvs Fortore and Norba exhibited the greatest amount of visual disease symptoms (mean AUDPC=2.2 and 2.3, respectively), being significantly more susceptible than the other six cultivars (AUDPC 1.24) (P < 0.05). Irrespective of fungal variety, the Italian cv. Norba and the Irish cv. Falstaff were more susceptible than the other cultivars (except Fatima 2) in terms of RHW (P < 0.05), while the cvs Fortore, GK Othalom and Consort were more resistant than the other five cultivars (P < 0.05). In the detached leaf assay, the Hungarian cv. GK Othalom and the Italian cv. Norba were more susceptible (mean LGR=0.79 and 0.81 mm day^–1, respectively) to M. nivalethan the other six cultivars (mean LGR=0.51–0.72) (P < 0.05). Analysis of the relationship between head and leaf reaction to M. nivaleinfection revealed no significant correlation.