Search

AbstractAtlantic Sturgeon Acipenser oxyrinchusaggregate in Minas Basin in the inner Bay of Fundy, Nova Scotia, during summer, presumably to feed on abundant intertidal invertebrates. The Atlantic Sturgeon aggregation is composed of multiple stocks from Canada and the USA. Government agencies from both nations have recently recognized Atlantic Sturgeon as threatened or endangered due to overfishing and habitat degradation. Little is known about the fate of Atlantic Sturgeon that are captured as bycatch in fisheries targeting other species, making it difficult to determine the extent to which bycatch is contributing to the Atlantic Sturgeon population's decline. To characterize the effects of otter trawl capture and release on Atlantic Sturgeon, we calculated a minimum survival rate for fish after catch and release by using acoustic telemetry, and we examined physiological indicators of stress. The minimum postrelease survival rate from otter trawl capture events was high (94% survival). Results also demonstrated that the magnitude of blood lactate in trawl-captured fish relative to experimental control fish increased with longer handling times. Trawl capture and handling did not cause significantly elevated levels of blood glucose or cortisol relative to those of controls. Minimization of handling time (i.e., time on deck) should be a priority in trawl fisheries that capture Atlantic Sturgeon as bycatch. Future studies should attempt to quantify the postcapture behavior of these fish to better understand whole-organism condition after fisheries encounters.Received August 30, 2012; accepted May 8, 2013

AbstractWe compared exhaustion-related physiological stress and physical injury as contributors to fish condition, longevity, and egg retention in two Pacific salmon species after their arrival at spawning areas. Adult female Pink Salmon Oncorhynchus gorbuschaand Chum Salmon O. ketawere exposed to six experimental capture treatments that represented different levels of exhaustive exercise, air exposure, and injury. After we evaluated its reflex impairment and obtained a blood sample, each fish was released into its natal spawning channel with an external tag and later retrieved postmortem to evaluate spawning success via examining egg retention. Reflex impairment, plasma lactate, chloride, potassium, and osmolality varied among treatments, with differences generally driven by the length of exposure to capture stress, which included exhaustive exercise and air exposure. However, overall prespawn mortality was negligible (about 5%) and consistent across treatments for both species. We hypothesize that Pink and Chum Salmon are resilient to capture-related exhaustion upon reaching spawning areas because of a combination of low water temperature (about 12°C in this study) and a physiological shift towards increased use of anaerobic pathways during their final weeks of life. The capture and release of fish arriving at the spawning ground does not appear to influence survival, in contradiction to the results of other studies, which focused on earlier components of Pacific salmon spawning migrations. Fisheries adjacent to spawning sites represent the end of the continuum of salmon fisheries that begin with the high seas fishery and extend through the coastal and riverine environments. The mortality rates in this study should be interpreted cautiously by management until research efforts are broadened to provide a better understanding of how postrelease outcomes at different life stages compare in natural systems and under conditions more representative of real fisheries.Received May 20, 2012; accepted October 25, 2012

AbstractJuvenile hatchery-reared Sockeye Salmon Oncorhynchus nerkafrom Cultus Lake, British Columbia, were implanted during their smolt phase with one of three sizes of dummy acoustic tags to assess how tag burden (tag mass: body mass ratios ranging from 1.3% to 13.6% in air) influenced prolonged swimming performance, survival, and postsurgical wound healing in freshwater for up to 16.5 d and following a transition to seawater for 9 d. Tagged fish were compared with surgical shams and control fish (no tag, no surgery). Fish subjected to sham surgery treatments had mean swim times similar to those of control fish; however, tagged fish had a significantly lower probability of swimming the mean time of nontagged control fish. In addition, we found that the effect of tagging on swimming performance was exacerbated by tag burden and that higher tag burdens decreased the swimming performance of tagged individuals. Fish with tag burdens ≥8% had shorter swimming durations than fish with tag burdens <8%. The incisions of fish implanted with smaller tags healed more quickly than those of fish implanted with the largest tag. Overall, survival was high (≥95%) and in freshwater mortalities only occurred in fish that had tag burdens greater than 6%. These findings have important implications for studies using tagging technologies to examine the behavior and survival of migrating salmon smolts.Received October 13, 2011; accepted October 22, 2012

AbstractWe compared detection efficiency for three lengths (12, 23 and 32 mm) of half-duplex (HDX) passive integrated transponder (PIT) tags for both manual tracking and fixed array applications. In a stream we used a wand-type manual tracking antenna and determined that detection efficiency was considerably influenced by tag size (i.e., 20% for 12 mm, 43% for 23 mm, and 81% for 32 mm) and water depth. Vertical and horizontal read range also varied among tag sizes (lower for smaller tags) and orientation (12-mm and 23-mm tags oriented perpendicularly failed to read in the horizontal test). Using a fixed PIT array, we also compared the detection efficiency of the same three sizes of PIT tags in Shorthead Redhorse Moxostoma macrolepidotumreleased into a fishway. Again, detection efficiency increased with tag size: 12 mm = 55.8 ± 9.2% (mean ± SE), 23 mm = 91.0 ± 1.8%, and 32 mm = 97.0 ± 1.5%. When using PIT telemetry on smaller fish species and/or life stages, we suggest that researchers consider the tag size, as the diminished detection efficiency of 12-mm tags could introduce a bias and impede the ability to address some research questions.Received July 11, 2012; accepted September 20, 2012

AbstractCatch and release is a common practice among recreational anglers. In instances when fish are deeply hooked, the proper techniques for promoting survival are poorly understood, although evidence suggests that the fishing line should be cut rather than attempting to remove the hook. Bluegills Lepomis macrochiruswere used as a model to identify the role of hook size (sizes 8 and 12), style (Aberdeen, baitholder, single egg), and the presence of barbs (only for baitholder hooks in size 10) on survival and hook retention for fish deeply hooked and the line cut. Eight hook style and size variants were manually embedded in the dorsal esophagus of fish, monitored over 10 d, and compared with unhooked controls. There was some evidence that Aberdeen style and larger hooks (size 8) incurred greater mortality over the 10-d monitoring period, while barbless hooks did not improve survival. Hook retention was high (>90%) for all deeply hooked fish. “J” style hooks, such as Aberdeen, and larger hooks may not be warranted for bluegills; however, we suggest that anglers use an adaptive approach when they select for a gear type appropriate to their target catch and simply adjust for alternate gear and techniques if deep hooking persists.Received May 25, 2012; accepted June 5, 2012

AbstractA growing body of work is focused on attempting to understand the biological mechanism(s) by which some fish are highly vulnerable to angling while others are not. We used electromyogram telemetry to monitor routine locomotory activity of artificially selected largemouth bass Micropterus salmoidesin experimental ponds to test two potential explanatory hypotheses: (1) that the difference in angling vulnerability between high-vulnerability (HV) bass and low-vulnerability (LV) bass is related to a difference in routine activity level between the two groups, and (2) that the difference in vulnerability between HV and LV bass is related to a difference in the diel activity pattern displayed by each group (e.g., LV fish are more active at night, a time where there is typically little bass fishing effort). Neither hypothesis was supported by our results. Differences in vulnerability to angling in artificially selected lines of largemouth bass were not related to inherent differences in routine locomotory activity in our ponds. Mean daily activity levels were close to 5% of maximum swim speed in both groups, which we estimated to reflect a mean swimming distance of approximately 5,875 m (range = 1,280–9,670 m) per day. There was also no difference in the diel pattern of activity displayed by the two groups. Both HV and LV bass displayed a significant diurnal activity pattern: 16% and 19% higher activity levels during the day than at night, respectively. These results contribute to the ongoing efforts to understand the behavioral basis of vulnerability to angling in largemouth bas and other fish species.Received January 19, 2012; accepted April 18, 2012

ABSTRACTRecreational fishing constitutes the dominant or sole use of many fish stocks, particularly in freshwater ecosystems in Western industrialized countries. However, despite their social and economic importance, recreational fisheries are generally guided by local or regional norms and standards, with few comprehensive policy and development frameworks existing across jurisdictions. We argue that adoption of a recently developed Global Code of Practice (CoP) for Recreational Fisheries can provide benefits for moving recreational fisheries toward sustainability on a global scale. The CoP is a voluntary document, specifically framed toward recreational fisheries practices and issues, thereby complementing and extending the United Nation's Code of Conduct for Responsible Fisheries by the Food and Agricultural Organization. The CoP for Recreational Fisheries describes the minimum standards of environmentally friendly, ethically appropriate, and—depending on local situations—socially acceptable recreational fishing and its management. Although many, if not all, of the provisions presented in the CoP are already addressed through national fisheries legislation and state-based fisheries management regulations in North America, adopting a common framework for best practices in recreational fisheries across multiple jurisdictions would further promote their long-term viability in the face of interjurisdictional angler movements and some expanding threats to the activity related to shifting sociopolitical norms.

AbstractThe Ocean Tracking Network (OTN) Canada is an integrative seven-year research program initiated in 2010 with academic, government, and industry partners. The team makes use of novel biotelemetry (primarily acoustic telemetry curtains), biologging, and oceanographic technologies to better understand changing ocean dynamics and their impact on ocean ecosystems, animal movements, and ecology and the dynamics of marine animal populations, many of which are commercially important. The network is organized around three ocean arenas (i.e., the Atlantic, Arctic, and Pacific) where specific research projects will occur. However, all projects will contribute toward addressing a single unifying nationalscale question—what are the movements of continental shelf marine animals, how do these movements affect species interactions, and what are the consequences of environmental variability/change and human activities on these species’ distributions and abundance? Taxa that will be tracked include diadromous (e.g., salmon, eels, sturgeon) and marine (e.g., sharks, capelin, cod) fishes and a variety of marine mammals (e.g., grey seals, killer whales). Some of the common activities that occur in all arenas include measurements of oceanographic characteristics and variability at various spatial and temporal scales, movements of key species at several trophic levels, and use of key acoustic “bioprobes” (animals that carry tags that record locations visited, ocean conditions, and interactions with other tagged animals) and “roboprobes” (remotely controlled autonomous vehicles such as gliders that measure physical, biological, and chemical conditions) to complement measurements from fixed OTN acoustic telemetry curtains. Ultimately, scientific information generated will inform resource management, help formulate new socioeconomic policies, and provide some impetus to the reformulation of governance practices and legal standards.All authors are part of the Ocean Tracking Network Canada (OTN Canada), Faculty of Science, Dalhousie University in Halifax, Nova Scotia.

AbstractAnesthetics immobilize fish, reducing physical damage and stress during aquaculture practices, stock assessment, and experimental procedures. Currently, only tricaine methanesulfonate (MS-222) is approved for use as an anesthetic for food fish in Canada and the United States; however, MS-222 can only be used with certain fish species, and treated fish must be held for a specified period of time before release into the wild. Two forms of electroanesthesia and carbon dioxide (CO2) were evaluated as anesthetics for adult walleye Sander vitreusto determine their suitability for use before intracoelomic implantation of telemetry transmitters. Walleyes were subjected to one of three treatment groups: constant direct current (CDC), pulsed direct current (PDC), and CO2. Fish subjected to these treatments were monitored for induction (where appropriate) and recovery time and whether these forms of anesthesia were conducive to implanting telemetry transmitters, that is, whether they fit a surgery threshold range of 250–350 s. Additionally, all fish were monitored for posttrial survival, and radiographs were taken to determine whether any vertebral damage was associated with the electroanesthesia treatments. Although all anesthetic treatments successfully immobilized fish for enough time to implant a transmitter, PDC electroanesthesia is recommended because of its immediate induction time, quick recovery, high immediate and short-term survival, and lack of evidence of vertebral abnormalities.Received January 11, 2011; accepted May 24, 2011

AbstractTraditional funding programs for fisheries, aquaculture, and aquatic research provide short-term support for an individual or small research team to test a specific hypothesis, often having only limited spatial applicability. To tackle more complex issues existing at larger spatial scales (national or continental), other approaches are necessary. In Canada, the Natural Sciences and Engineering Research Council has developed the Strategic Network Grants (SNGs) program that enables multi-institutional teams of academics (typically 10 to 20 co-principal investigators) to work with industry and government partners on large-scale, multidisciplinary research projects in targeted research areas. The network model is intended to create unique training opportunities and enable researchers to study problems at spatial and temporal scales that could not be addressed with traditional funding. Currently, six of the 30-plus SNGs in Canada are focused on fisheries, aquaculture, and aquatic sciences issues, namely, impacts of hydropower on fish and fish habitat, capture fisheries, integrated multitrophic aquaculture, healthy oceans, and the spatial ecology of aquatic vertebrates in coastal waters. Here we introduce five case studies that will examine the motivation, scientific research objectives, and operation of networks in detail. In addition, we explore the perceived benefits and challenges with the research network-funding model with specific reference to the advancement of large-scale studies in fisheries, aquaculture, and aquatic sciences.

ABSTRACT:We compared biological and ecological traits between global game fish and non-game fish species using an analysis with randomly chosen fish species from each group and an analysis where species were matched by body length. We used data from the International Game Fish Association (IGFA), FishBase, and the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Game fish species were defined as being present in the IGFA world record list. The random comparison revealed that on average game fish were significantly larger (155.0 ± 121.5 versus 34.1± 59.5 cm), occupied shallower minimum depths (19.4 ± 58.8 versus 130.0± 359.0 m), had a broader latitudinal range (51°.2 ± 29.4° versus 31.1°± 25.9°), and significantly higher trophic levels (4.1 ±0.1 versus 3.4± 0.1 trophic units) than non-game fish species. The length-matched analysis simüarly identified that game fish species occupied higher trophic levels than non-game fish (3.9 ± 0.4 versus 3.6± 0.6 trophic units), but latitudinal range and depth associations did not differ between groups. Both the random and length-matched analyses revealed that game fish were more commonly found in freshwater than non-game fish. Both analyses found that game fish species were more migratory and that both groups differed in their geographical distributions. The random comparison revealed that game fish were significantly more targeted by commercial fisheries, less resilient, and more threatened relative to non-game fish. Caution must be exercised when synthesizing data from broad data sources, yet this study identifies important differences between game fish and non-game fish species, which are relevant to management and conservation initiatives.

AbstractAlthough a great deal of effort has been expended to try to understand the consequences of fishing-induced selection by commercial fisheries, relatively little effort has been put into trying to understand the selective effects of recreational angling. We conducted a long-term selection experiment to assess the heritability of vulnerability to angling in largemouth bass Micropterus salmoides. Three successive generations of artificially selected largemouth bass were produced from a single experimental study population. Within each generation, individual adult largemouth bass were identified as having either high or low vulnerability to angling through a series of controlled catch-and-release angling trials. Individuals of each vulnerability group (high and low) were then selected from that population for breeding to produce the next generation. The response to selection for vulnerability to angling increased with each generation; that is, the magnitude of the difference between the high- and low-vulnerability groups of fish increased with each successive generation. Realized heritability was calculated as 0.146 (r2= 0.995), indicating that the vulnerability of largemouth bass to angling is indeed a heritable trait. Our results indicate that recreational angling has the potential to alter the gene pool of wild fish populations, which may indirectly affect population characteristics such as survival, growth rate, and reproductive output as well as directly affecting angling success rates.

AbstractManagement policies related to catch-and-release (CR) angling of smallmouth bass Micropterus dolomieuvary widely across the geographic distribution of the species. Some jurisdictions, principally in the northern latitudes, prohibit or limit angling efforts that target nesting male smallmouth bass, whereas angling during the nesting period is generally unregulated in southern jurisdictions. Existing studies of individual-level angling impacts on nesting smallmouth bass have primarily been conducted in the north; thus, the extent to which these findings are relevant to other regions is unknown. In the current study, we sought to systematically evaluate the rates of nest abandonment by nesting smallmouth bass subjected to common angling practices (CR treatment: Brief angling and no exposure to air; air exposure [AE] treatment: Exhaustive angling and 3 min of AE) and tournament practices (simulated tournament [ST] treatment: Exhaustive angling, 2 h of live-well retention, and 3 min of AE prior to release) across a latitudinal gradient encompassing virtually the entire south-north range of smallmouth bass (i.e., southern Missouri [MO], southern Ontario [SON], and northern Ontario [NON]) and compared these treatment groups with nonangled controls. We also quantified the extent to which physiological disturbance associated with angling varied across latitudes (peripheral populations [MO and NON] versus the intermediate-latitude population [SON]). Whole-blood lactate and glucose levels were highest in fish subjected to ST conditions, indicating increased stress; this pattern was conserved across all latitudes (although there was some evidence of intraspecific variation in stress response). Additionally, the pattern of brood abandonment was similar among fish at all three latitudes; ST fish exhibited the highest rates of nest abandonment (MO: Control = 9.1%, CR = 0%, AE = 9.1%, ST = 100%; SON: control = 10%, CR = 10%, AE = 10%, ST = 50%; NON: control = 7.7%, CR = 0%, AE = 9.1%, ST = 50%). Interestingly, fish from the most southerly latitude, where regulations are the most liberal, abandoned nests at higher rates than did fish from the other latitudes. Collectively, these data reveal that the reproductive success of individual smallmouth bass can suffer from interaction with anglers, particularly in a tournament context, regardless of the region. Further study is needed to determine the extent to which individual nest success is relevant to recruitment and how this relationship varies across latitudes.

AbstractCatch-and-release practices are common in recreational fisheries, yet little is known about the behavior, physiology, and ultimate fate of released fish. We used a combination of radiotelemetry (external attachment) and nonlethal blood sampling (i.e., the blood concentrations of lactate and glucose and plasma concentrations of aspartate aminotransferase (AST), Na+, K+, and Cl−) to assess the relationship between the prerelease physiological status and postrelease behavior and mortality of largemouth bass Micropterus salmoides. The experiments were conducted at two temperatures: approximately 15°C and 21°C. Immediately after capture by standard angling techniques, largemouth bass were exposed to air for 0 to 15 min to assess the consequences of air exposure at two moderate water temperatures. Fish exposed to air for long periods (approximately 10 min or more) had significantly higher concentrations of blood glucose 30 min after air exposure and took significantly longer to regain equilibrium than fish exposed for shorter periods (approximately 3 min or less). The responses of other physiological indicators were inconsistent. Interestingly, at lower water temperatures, males had greater initial concentrations of glucose and AST than females, revealing the importance of sexual differences in the response to angling stress. The fish exposed to air for longer durations tended to exhibit behavioral impairments and remained close to the release site longer than those exposed for short periods. Despite exposure to air for lengthy periods, no postrelease mortality was observed during the 5-d monitoring period. Although the two water temperatures that we used were moderate for this species, a number of sublethal differences (e.g., physiological disturbances and behavioral impairments) were evident in the longer-air-exposure treatment group, highlighting the need to minimize air exposure during catch-and-release angling to maintain the welfare of angled fish.

AbstractWe examined the relationship between bait and lure size and type and body size, injury, and handling time for northern pike Esox lucius, an important recreational fisheries resource in much of North America and Europe. Bait type and size were significantly related to the size of fish captured and hooking location. Hooking in critical locations (i.e., gills, gullet) was more likely to occur with natural bait, soft plastic shads and jigs, and spoons than with spinners and wobblers (i.e., plugs). Small baits (<75 mm) were more likely to hook the fish in the gills and less likely to hook the fish in the upper jaw than larger baits. It took longer to remove hooks from gills than from other hooking locations. Frequency of bleeding was related to depth of hooking but was unrelated to fish size, bait type, bait size, or fishing method. Initial mortality of northern pike was low (mean ± 95% confidence interval = 2.4 ± 1.5%), and hooking mortality was significantly related to the level of bleeding as a proxy for severity of injury. Results of this study suggest that using large artificial lures and large natural baits can effectively reduce the incidence of hooking small northern pike (i.e., those that are sublegal in some jurisdictions). However, the use of natural bait can also result in a higher incidence of deep hooking, which in turn increases the likelihood of injury and bleeding. This study revealed the complexity associated with using bait and lure restrictions to complement standard harvest regulations in northern pike recreational fisheries.

AbstractMuch research on the fish physiological consequences of tournaments has been conducted to date and has provided anglers and tournament organizers with strategies for reducing stress and mortality. However, one aspect of tournaments that has received little attention is barotrauma. At a fall competitive angling event on Rainy Lake in northwestern Ontario, we evaluated the incidence of barotrauma among tournament-caught smallmouth bass Micropterus dolomieu; we then tagged and released a subset of fish that had severe barotrauma indicators and compared physiology, postrelease behavior, and fate between these fish and those with negligible signs of barotrauma. Overall, 76% of fish had at least one sign of barotrauma (either hemorrhaging or swim bladder distention), but only 32% of fish had two or more indicators and were thus deemed to have severe barotrauma. When telemetered fish were released at a common site, we determined that fish with negligible signs of barotrauma evacuated the release site more rapidly than fish with severe barotrauma did. Some fish with barotrauma floundered at the surface when released, and one of these fish was subsequently hit and killed by a boat. At the end of the monitoring period, 20% of fish with severe barotrauma had died; two additional individuals (20%) that were still at the release site were moribund (failed to respond to diver stimuli). Conversely, we failed to observe any mortality in fish with negligible signs of barotrauma. All tournament fish had elevated levels of blood glucose and lactate. However, stress indices were higher in fish with barotrauma and tended to be highest among fish with barotrauma that died after release. This study revealed that the incidence of barotrauma in tournaments can be high; moreover, outside of a laboratory environment, a significant proportion of fish with severe barotrauma may die after release. Additional research is needed to determine the seasonal variation in incidence and consequences of barotrauma as well as the effectiveness of different depressurization techniques in the field that could be used during fishing tournaments.

AbstractMaturing female anadromous salmonids receiving intraperitoneally implanted telemetry transmitters (tags) may experience difficulty depositing eggs during natural spawning. We allocated maturing adult female steelhead Oncorhynchus mykissto three treatment groups: (1) fish whose tags were surgically implanted in the body cavity (internal), (2) fish whose tags were implanted between the skin and muscle tissue (subdermal), and (3) nontagged fish. The steelhead were then allowed to spawn in an experimental channel. Internally tagged females retained significantly more eggs than did the subdermally tagged and nontagged control groups; subdermally tagged and nontagged control fish did not differ significantly. Females in the internally tagged, subdermally tagged, and nontagged groups retained an average of 49, 11, and 2% of their eggs, respectively. The onset of sexual activity did not differ significantly among treatments. Postspawning mortality was 70% for internally and subdermally tagged females and 0% for nontagged females. Each research or monitoring program should weigh the costs associated with transmitter use (where they are known) against the value of information obtained and should carefully evaluate assumptions about transmitter effects. For these reasons, the use of electromyogram electrodes and other telemetry transmitters for monitoring imperiled fish populations should be employed with caution. We suggest that subdermal implantation techniques be considered in future studies during the reproductive period to reduce egg retention caused by internally implanted transmitters.

AbstractStrict harvest regulations and a strong catch-and-release ethic among recreational anglers of muskellunge Esox masquinongyhave led to interest in developing strategies for reducing injury and mortality of released fish. With many anglers using live baitfish to capture muskellunge, the use of circle hooks may reduce deep hooking and hence mortality. We contrasted the performance of circle hooks and J-style aberdeen hooks when capturing juvenile muskellunge with actively fished live baitfish. The J hooks performed better than circle hooks in terms of capture efficiency. The J hooks were more efficient at hooking muskellunge than were circle hooks, but landing efficiency was similar between the two types. Interestingly, injury was judged to be low regardless of hook type. Neither anatomical hooking location nor hooking depth differed significantly between fish captured on J and circle hooks. No fish were hooked in potentially lethal locations (e.g., gullet or eye) during the use of either hook type. Ease of hook removal did not differ between hook types, and hooks were generally categorized as easy to remove. Bleeding was considered minor and did not differ between hooks. We observed no initial or delayed mortality for fish captured on J or circle hooks. Given that J hooks have a higher muskellunge capture efficiency and that the use of circle hooks did not provide any compelling conservation benefits, anglers will probably continue to use J hooks and avoid circle hooks. Nonetheless, use of circle hooks could be advantageous for other fishing styles (e.g., still fishing, where baitfish are often swallowed), other species, or different sizes of muskellunge.

AbstractThe goal of the current study was to examine the physiological disturbances in walleyes Sander vitreusthat occurred during the different phases of a live-release angling tournament. To achieve this, we took blood and white muscle samples from walleyes during experiments that simulated different aspects of a live-release tournament (angling, live-well confinement, and weigh-in procedure). In accordance with recent findings for largemouth bass Micropterus salmoides, the physiological disturbance experienced by tournament walleyes results mainly from two distinct bouts of anaerobic metabolism occurring during angling and the weigh-in procedure. These periods are characterized by large increases in white muscle and plasma lactate concentrations, reductions in white muscle ATP, phosphocreatine, and glycogen and a significant cardiac disturbance. The physiological effects of angling are already well understood, but the physiological disturbance that occurs during the weigh-in procedure of tournaments has received little attention. In view of the results from our tournament simulations, a final set of experiments was conducted to examine more closely the bout of anaerobic metabolism experienced by walleyes during the tournament weigh-in. The results of these experiments showed that the magnitude of the physiological disturbance in tournament-caught walleyes is directly related to the duration of air exposure occurring during the weigh-in. Based on these findings, we suggest that to reduce the physiological disturbance experienced by tournament-caught walleyes, tournament organizers should strive to minimize air exposure during the weigh-in procedure.

AbstractAir exposure has been hypothesized as one of the primary stressors present during catch-and-release angling. However, there are few studies that systematically vary air exposure duration and evaluate the consequences on individual fish. Here, we evaluated the short-term, sublethal effects of exercise (to simulate angling) and air exposure on the swimming performance of hatchery brook trout Salvelinus fontinalis at 10°C. The duration of the angling event (i.e., chasing the fish by hand) was held constant at 30 s, while air exposure duration was systematically varied between 0, 30, 60, and 120 s. The results showed that air exposures of 60 s or less did not affect swimming performance. However, air exposure of 120 s resulted in a dramatic (∼75%) reduction in swimming performance. In fact, nearly half of the fish held out of the water for 120 s were unwilling or unable to swim at all. No mortality was observed after any of the treatments (fish were monitored for 3 months). This work suggests that fish possess air exposure thresholds that, once exceeded, result in performance impairments. Fish released after extended air exposure may become easy prey for predators or could be displaced downstream by flows in fluvial environments. We conclude that air exposure should be restricted to less than 60 s and ideally should be avoided entirely.

AbstractThe purpose of the present study was to characterize the surgical methods researchers use to implant telemetry transmitters in fish and obtain their opinions on fish surgical techniques. The majority of respondents (74%) use monofilament suture to close transmitter incisions, mirroring recent findings that monofilament can help reduce tissue inflammation and promote wound healing. An equal number also believe that maintaining sterile equipment between surgeries is important to preserve fish health. Despite the difficulty of maintaining sterile surgical equipment and surgery areas in field conditions, this opinion does coincide with those of veterinarians. Opinions about what component of surgery is the most hazardous for fish were mixed: 37% believed it to be the initial incision, closely followed by wound closure (23%), insertion of the transmitter and its components (22%), and anesthesia and the handling of the fish (18%). A large proportion (73%) of researchers practice at least occasionally to maintain or improve their surgical skills. The fact that approximately 18% of fish surgeons do not practice was a surprise. Although responses regarding any observations between surgical experience/volume and outcome (e.g., survival) were disparate, the majority (69%) of respondents identified this as an important research area. Furthermore, the majority of researchers (62%) believed it was important to use the individual surgeon for each fish as a covariate when analyzing the data obtained during a study involving multiple surgeons. Despite the variety of practices and opinions of fish surgeons, the majority of responses conformed with or promoted the use of surgical techniques that would benefit the health and welfare of fish. This information should help fisheries researchers refine their surgical techniques and assist governing agencies in forming important regulations on laboratory and field surgical procedures.

AbstractHook size is an important consideration in the use of circle hooks as a conservation tool for minimizing the injury and mortality of marine fishes, but little is known about the role of hook size in the performance of hooks in recreational freshwater fisheries. In this study, we angled 100 bluegills Lepomis macrochirus on each of five different-sized circle hooks (1/0, 2, 6, 10, and 14). The largest hook size (1/0) had low hooking and capture efficiency but selected larger individuals. The smallest hook size also had low hooking efficiency and resulted in the selection of smaller individuals. Intermediate hook sizes captured fish of intermediate size. Jaw hooking rates generally increased with decreasing hook size, whereas roof hooking rates decreased. Gullet hooking was restricted to the three smallest hook sizes. Relative hooking depth and incidences of bleeding were uniformly low for all hook sizes. Similarly, the fish were generally easy to remove from the hook irrespective of hook size. Our mortality projections revealed no trends associated with hook size, our overall mortality rate being less than 1%. This study suggests that circle hooks function most effectively when the entire hook can fit in the mouth of the fish and when the shank-to-point distance is large enough to permit jaw hooking. Size selectivity for larger individuals can be achieved by using larger hook sizes. However, large circle hooks will also catch smaller fish that will be more likely to be hooked in injurious anatomical locations. Therefore, we recommend the use of intermediate-sized hooks for maximizing hook performance in terms of size selectivity, efficiency, and conservation.

AbstractIn the current study, we simulated different components of a live-release angling tournament (angling, live-well confinement, and weigh-in) to determine the relative physiological significance of these tournament components for largemouth bass Micropterus salmoides. Our results indicated that depletions of white muscle energy stores and accumulations of muscle lactate (i.e., a large metabolic disturbance) are the most important consequences of live-release angling tournaments for largemouth bass. This study also showed that there are two distinct components of a live-release tournament that cause a metabolic disturbance in largemouth bass: angling and the weigh-in. While the physiological consequences of angling are already well understood, this is the first study to show that the weigh-in portion of a live-release tournament also causes a large anaerobic disturbance in largemouth bass. In our simulation, the weigh-in resulted in a 75% decrease in white muscle phosphocreatine, a 46% decrease in ATP, and a 62% decrease in glycogen relative to control largemouth bass. The weigh-in simulation also caused the lactate concentration in white muscle to increase by about sevenfold relative to control fish and resulted in significant changes to cardiac function. Based on these results, subsequent experiments were performed to determine the main factor(s) responsible for the metabolic disturbance that results from the weigh-in. These experiments demonstrated that the period of air exposure during the weigh-in was a major cause of this disturbance. We recommend that tournament organizers minimize the air exposure that largemouth bass receive during the weigh-in to improve the physiological condition of released tournament-caught fish.

AbstractAlthough largemouth bass Micropterus salmoidesare frequently subjected to sublethal stressors (e.g., angling), the associated effects on their reproductive success have not been assessed. We examined the reproduction of largemouth bass that were subjected to the stress of exhaustive exercise, air exposure, culling, live-well conditions, and weigh-in procedures. Age-0 largemouth bass produced from parents subjected to stress were smaller (total length, 31 ± 0.4 mm (mean ± SE)) and weighed less (0.59 ± 0.04 g) than controls that were not stressed (35 ± 0.4 mm; 0.76 ± 0.03 g). Adults that were stressed had offspring with later swim-up dates than did controls. Our results provide evidence that stress before spawning has the potential to negatively affect largemouth bass reproductive success.

AbstractThe advantages and disadvantages of aerial (i.e., through the air–water interface) and underwater tracking of radio-tagged free-swimming fish are compared. A novel device is described that can be used to detect radio signals from depths exceeding the detection range of aerial antennas. This device can be used in small, confined bodies of water to track seasonal movements of fish into deep water, to identify locations of lost or expelled transmitters, to monitor relatively immobile benthic species, and to determine swimming or suspended depth while retaining several other advantages associated with the use of radio (versus ultrasonic) transmitters. The device is inexpensive, simple to construct, and easy to use with any commercially available telemetry receiver.

AbstractLonger angling durations (capture by hook and line) and higher water temperatures are generally thought to be more detrimental to angled fish. Here, this concept was investigated in smallmouth bass Micropterus dolomieuby monitoring cardiac output (CO) and its components, heart rate (HR) and stroke volume (SV), before, during, and after a simulated angling event in a Blazka-type respirometer. Fish (total n= 31) were acclimated to 12, 16, or 20°C and exposed to conditions that elicited repeated burst swimming either briefly (20 s) or to exhaustion (120–180 s). Resting CO and HR increased significantly with increasing temperature (Q10∼ 2), indicating temperature conformity, whereas SV was not affected by temperature. Recovery times (time after angling until cardiac parameters returned to resting levels) ranged from 0 to 85 min (mean ∼ 40 min) for briefly angled fish and from 20 to 210 min (mean ∼ 105 min) for exhaustively angled fish. These recovery times increased significantly with angling duration but were not affected by water temperature. Almost all of the increase in CO during recovery was attributable to increased HR. At 20°C, the increase in HR was sufficient to result in an increase in CO despite a decrease in SV during the initial portion of recovery. During recovery, both CO and HR increased to approximately 1.8 times and as much as 2.65 times the resting values, whereas SV increased to approximately 1.2 times the resting value. At 20°C, SV typically decreased to 0.8 times the resting value for the initial part of recovery. Recovery intensities (maximum increases in cardiac values) were generally not affected by angling duration. Fish acclimated to 16°C generally had larger recovery intensities than fish at 12°C and 20°C, indicating that for smallmouth bass, 16°C may be an optimal temperature relative to the other two temperatures. From a management perspective, the results suggest that (1) angling duration should be minimized, (2) angling at high as well as low temperatures may be detrimental, and (3) even when fish are angled very quickly, they still undergo a period of increased CO that can last as long as 1 h.

AbstractWe studied the effects of catch-and-release angling on rock bass Ambloplites rupestrisa small but common centrarchid species in North America. A field study of hooking injury and mortality was conducted in Lake Erie at a water temperature of 16°C. We captured fish using one of four terminal tackle types: barbless worm, barbed worm, barbless jig, and barbed jig. No mortality was observed in any of the four treatments even after holding fish for 5 d. Fish captured using worms were hooked more deeply than fish caught on jigs. Fish captured on barbless jigs were unhooked most easily and more rapidly than with all other tackle types, resulting in an average of only 20 s of air exposure. Because they were more difficult to remove from the hook, fish captured on other terminal tackle experienced at least twice as much air exposure. To assess sublethal effects, we measured the cardiac responses of rock bass exposed to 30 s of simulated angling followed by 30 or 180 s of air exposure. These air exposure durations were intended to simulate the conditions faced by fish that were either easy or difficult to remove from the hook. Fish experienced arrhythmia during angling, although overall cardiac output increased. Fish experienced severe bradycardia during air exposure, but after being returned to the water, all fish exhibited elevated cardiac output. Fish exposed to 30 s of air exposure required 2 h for full recovery, whereas those exposed to 180 s of air required 4 h. During periods of cardiac disturbance, increases in cardiac output were due to both heightened heart rate and stroke volume. Our results suggest that hooking mortality did not vary with bait or hook type and that physiological disturbance of rock bass was influenced by the duration of air exposure, as influenced by bait and hook choice. We recommend that anglers attempt to minimize handling and air exposure of angled fish and keep pliers or other hook removal devices readily accessible to facilitate rapid release of fish not intended for harvest.

AbstractAlthough regulations prohibiting the use of natural baits are relatively common, new regulations specifically targeting the use of chemical attractants have recently been implemented. While no citeable evidence for these new regulations exists, they may have been promulgated due to a perceived increase in the risk of fish mortality from scented lures compared with unscented lures. The present study investigated the hooking injury and short-term mortality of 238 adult smallmouth bass Micropterus dolomieucaptured on Lake Erie by both experienced (fished > 100 d/year) and novice (fished < 10 d/year) anglers on actively fished jigs similarly threaded with minnows, nonscented plastic grubs, or grubs scented with chemical attractants. The depth of hook ingestion, the anatomical hooking location, the presence of bleeding at the hook wound, and the total amount of time taken to remove the hook were noted on all captured fish. The fish were then transferred to a retention cage, and their survival was monitored for 72 h before release. None of the fish captured suffered any immediate (<1 h) or short-term (<72 h) mortality. The type of bait used to capture the fish had no significant effect on the depth of hook penetration or the anatomical hooking location. More experienced anglers, however, hooked the fish significantly deeper in the mouth than the novice anglers. These results suggest that the use of the chemical attractants tested in the present study do not deleteriously affect the injury rates or survival of captured smallmouth bass. Therefore, regulations prohibiting the use of chemical attractants on actively fished single-hook jigs for smallmouth bass appear unjustified if the intent was to reduce hooking injury and mortality.

AbstractResearchers conducting fish telemetry studies using the intraperitoneal surgical implantation of radio transmitters with whip antennas can configure the antenna to exit the body cavity through a small puncture wound (external) or leave the antenna coiled within the body cavity (internal). We conducted a behavioral field study to examine movement patterns of smallmouth bass Micropterus dolomieucarrying radio tags with internal or external antenna configurations. Fish movements, number of days tracked, and number of detected signals did not differ between internal or external treatment groups. To complement the field study, we conducted a laboratory investigation to examine possible effects that these treatments (antenna type) may have on the swimming performance of smallmouth bass by comparing critical swimming speeds. Swimming performance was not significantly altered by the surgical procedures related to transmitter and antenna placement. Our results also suggest no significant differences in swimming performance or movement rates of fish related to antenna configuration. However, transmitter signals were attenuated with the internal antenna configuration. As such, decisions regarding which antenna configuration to use should be based on fish morphology, study objectives, and site-specific environmental conditions.

AbstractLittle is known about the effects of the different types of fish retention gear commonly used by recreational anglers, such as stringers, fish baskets, and keep nets. The injury and short-term mortality of 313 adult smallmouth bass Micropterus dolomieuwere studied at Lake Erie over a range of water temperatures (10.6–21.8°C). Lure-caught fish were retained by one of the following six gear types or methods for 3–5 h: metal stringer through lip, metal stringer through gill arch, cord through lip, cord through gill arch, wire fish basket, and nylon keep net. Fish were then transferred to a holding pen and their survival estimated relative to control fish over a 48-h period. Control fish exhibited very little mortality (3%) and had negligible physical injury across all sampling periods. Most retained fish (95%) experienced some form of injury or mortality. In general, increased injury and mortality coincided with higher water temperatures, particularly when water temperatures reached 21.8°C. Survival and injury varied among retention gears, but gill damage or fungal lesions associated with abrasion, along with the cumulative stress of angling and retention, appeared to be the precursors to most deaths. These results suggest that even at low water temperatures, significant injury can occur from retention gear; at higher temperatures, this injury seems to manifest itself in death. For this reason, these gears should only be used with fish that are to be harvested, not those that are to be temporarily retained before release.

AbstractCatch-and-release angling of black bass Micropterus spp.during the parental care period may lead to brood predation and premature nest abandonment. Furthermore, physiological disturbance incurred while landing angled males may impair their ability to provide parental care long after release. To assess the extent of this physiological disturbance, we examined the relative energetic expenditures of nesting (N= 4) and nonnesting (N= 2) male largemouth bass Micropterus salmoidesexposed to staged angling events in experimental ponds. Information on fish locomotion, through activity of the axial musculature, was remotely collected using electromyogram transmitters. During angling, nonnesting fish fought with a higher intensity, probably expending significantly more energy than did nesting fish. In addition, although the locomotory activity of nonnesting fish appeared to recover as early as 2 h after angling release, the locomotory activity of nesting fish was still impaired 24 h postangling. Overall mean activity for 24 h postrelease was 98% of basal for nonnesting fish, but only 63% for nesting fish. The reduced energetic capability of a nesting male largemouth bass following angling, together with brood predation incurred as a result of the temporary removal of that fish from the nest during angling, increases the likelihood of that male abandoning his brood prematurely. This study provides further insight into the physiological disturbances and behavioral consequences incurred as a result of catch-and-release angling and highlights the need for addressing population level effects of catch-and-release angling on parental care and reproductive success of black bass.

AbstractThe behavior of smallmouth bass Micropterus dolomieu was studied in the Nanticoke Thermal Generating Station discharge canal on Lake Erie during the winter to examine the effects of thermal tempering pump operation. A series of seven fixed underwater antennas continuously monitored movements of 20 radio-tagged fish from Jan 7 until Mar 15, 1998. Fish were released at the head of the discharge canal, upstream from the eight tempering pumps where they were captured. Most fish spent the entire study within 25 m of the release site. Small-scale movements occurred when fish moved back and forth from the most upstream tempering pump (which was not operational during the study) to an adjacent eddy. Five fish moved greater distances throughout the length of the discharge canal, with most of their time spent in areas that provided velocity refuges and cover (e.g., large rip-rap and oil-boom structures); their movements appeared to be independent of environmental conditions. The benefits of the thermal tempering pumps for smallmouth bass in the discharge canal in winter appear to be minimal because the majority of their time was spent upstream of pump influence. The design and operation of power plant cooling systems should consider the tradeoffs between the actual mitigative effects of tempering pump operation and the increased fish impingement and entrainment associated with such operating conditions.

AbstractSwimming performance was compared among groups of juvenile rainbow trout Oncorhynchus mykiss (5–10 g) with and without intraperitoneally implanted radio transmitters. The generally accepted rule of 2% body weight : transmitter weight was extended to a 6–12% ratio, and swimming performance was not altered by the presence of the transmitter or effects of the operation. Also, no relationship was found between the weight of the fish and its swimming performance among the groups examined. Although we found swimming performance was not affected by implantation of transmitters weighing up to 12% of the body weight, changes in behavior were not evaluated. We suggest further research be done so that the “2% rule” can be replaced by an index with a more scientific basis. Instead of using a scale based on percentage of transmitter to body weight in air, preferred indices could be weight in water, volume of the tag, or both.