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To evaluate the vulnerability of Bull Trout Salvelinus confluentusto potential climate changes across its range in Oregon, we compiled disparate expert knowledge of the distribution of spawning and rearing and combined these probabilistic statements as data along with documented records of breeding and rearing in a joint occupancy model. The joint expert knowledge–occupancy model, which was based on discrete patches of cold water (≤13°C) suitable for spawning and rearing, permitted the association of true occupancy with climate and other explanatory variables while accounting for variation in detection probability. We then applied estimated relationships of patch occupancy with explanatory variables to projected coldwater patch configurations in the years 2040 and 2080. Projections of the kilometers of occupied coldwater patch in future decades suggest precipitous declines if current relationships of occupancy with environmental variables are maintained. Impacts of climate changes in future decades manifest directly through the outright loss of coldwater patches and increases in winter high flows but also indirectly by increased isolation. Combining probabilistic statements of species distributions from knowledgeable experts with sparse occupancy data may be a robust and timely alternative when large numbers of repeated occupancy surveys are infeasible. Impact statementThis study provides a novel approach for developing species distribution models using expert knowledge. This approach may be valuable for applications to species that are difficult to otherwise study or survey. This study provides a novel approach for developing species distribution models using expert knowledge. This approach may be valuable for applications to species that are difficult to otherwise study or survey.

Angling for trophy Largemouth Bass Micropterus salmoidesand Florida Bass M. salmoides floridanussupports popular fisheries, particularly in the southern United States, where conditions are favorable for growing large fish. Traditional standardized sampling gears, such as electrofishing and creel surveys, often prove ineffective at obtaining sample sizes that are adequate for assessing the quality and temporal trends in trophy fisheries. In this study, we assessed the trophy Florida Bass population in the newly impounded Calling Panther Lake (163 ha), Mississippi, by using a nontraditional, specialized angling technique, and we compared the results with data collected by the more traditional techniques of creel surveys and electrofishing. The specialized angling technique utilized a select few highly skilled and devoted anglers that targeted only the largest bass in the population. The specialized angling technique collected nearly 8 and 24 times more trophy Florida Bass (≥3.6 kg or ≥56 cm TL) than creel surveys and electrofishing, respectively. As a result, this was the only method that reliably collected enough trophy‐sized fish to estimate the population size in Calling Panther Lake. Mark–recapture data were used to estimate an abundance of 150 trophy Florida Bass (95% confidence interval [CI] = 118–206) in 2011 (density = 0.92 fish/ha; 95% CI= 0.73–1.26). The use of data collected by specialized anglers provided vital information for the trophy segment of this bass population, which is often difficult for fisheries managers to obtain with traditional techniques.

Angling for adult black bass Micropterusspp. as they defend nests containing eggs or fry (i.e., bed‐fishing) has drawn concerns from fishery managers and anglers due to negative impacts on reproductive success. Research efforts, however, have failed to consider bed‐fishing scenarios other than male‐directed targeting, which may inaccurately reflect angler behaviors. To gain insights into the behaviors, motivations, and attitudes associated with bed‐fishing across a large extent of the global distribution of black bass, we surveyed tournament anglers from the southeastern United States and South Africa (where black bass were introduced in 1928). Responses from 440 black bass tournament anglers indicated that during the reproductive season nearly half of all anglers spent 50% or more of their time bed‐fishing and that larger, female fish were preferential targets. Overall, the responses from U.S. and South African anglers were very similar, but significant attitudinal differences were associated with the perceived impacts of bed‐fishing on adult reproduction and juvenile production. Our results suggest that there are commonalities among the preferences and behavior of anglers from disparate geographic regions, and we highlight the need for future research on the impacts of size‐ and sex‐selective bed‐fishing of basses.

Black bass Micropterusspp. support popular freshwater sport fisheries in North America. Bass anglers commonly adopt catch and release as a conservation practice, and frequently over 75% of angled black bass are released back into the water. If fish survive the angling event, the practice of catch and release as an alternative to harvest reduces direct mortality, but it has the potential to affect the postrelease feeding behavior and survival of the fish. The act of lifting black bass for handling, hook removal, and photograph opportunities may cause stress and injury, and the degree of injury sustained could be influenced by fish size. Holding fish in a tilted grip by the jaw has raised concern among anglers about potential damage to jaw musculature and tendons, as they may not support the fish's body weight out of water, particularly for trophy bass. We conducted an experiment with Florida Largemouth Bass M. salmoides floridanusto evaluate the relative differences in survival, jaw mechanics, and feeding success after the use of three common handling treatments: (1) a vertical hold using a lip-grip device (vertical treatment); (2) a tilted, one-handed grip using only the lower jaw (horizontal treatment); and (3) two-handed support to the lower jaw and body (support treatment). The time taken by fish to regain equilibrium and resume normal swimming behavior after handling differed among the three treatments; the recovery period was shortest for fish in the support treatment (mean ± SD = 7 ± 10 s; vertical treatment: 33 ± 74 s; horizontal treatment: 12 ± 16 s). Minor injuries (e.g., abrasions and sores) and diseases (e.g., tumors and fungus) tended to increase after handling across the entire sample. Results suggested no evidence of handling-specific differences in fish feeding behavior, jaw adjustments, and mortality after release. However, based on our results, we recommend that anglers use two-handed support to handle Florida Largemouth Bass, thus minimizing the mean amount of time for an individual fish to regain equilibrium after an angling event. Received February 22, 2016; accepted October 7, 2016 Published online February 22, 2017

AbstractBlack bass Micropterusspp. support popular freshwater sport fisheries in North America. Bass anglers commonly adopt catch and release as a conservation practice, and frequently over 75% of angled black bass are released back into the water. If fish survive the angling event, the practice of catch and release as an alternative to harvest reduces direct mortality, but it has the potential to affect the postrelease feeding behavior and survival of the fish. The act of lifting black bass for handling, hook removal, and photograph opportunities may cause stress and injury, and the degree of injury sustained could be influenced by fish size. Holding fish in a tilted grip by the jaw has raised concern among anglers about potential damage to jaw musculature and tendons, as they may not support the fish’s body weight out of water, particularly for trophy bass. We conducted an experiment with Florida Largemouth Bass M. salmoides floridanusto evaluate the relative differences in survival, jaw mechanics, and feeding success after the use of three common handling treatments: (1) a vertical hold using a lip-grip device (vertical treatment); (2) a tilted, one-handed grip using only the lower jaw (horizontal treatment); and (3) two-handed support to the lower jaw and body (support treatment). The time taken by fish to regain equilibrium and resume normal swimming behavior after handling differed among the three treatments; the recovery period was shortest for fish in the support treatment (mean ± SD = 7 ± 10 s; vertical treatment: 33 ± 74 s; horizontal treatment: 12 ± 16 s). Minor injuries (e.g., abrasions and sores) and diseases (e.g., tumors and fungus) tended to increase after handling across the entire sample. Results suggested no evidence of handling-specific differences in fish feeding behavior, jaw adjustments, and mortality after release. However, based on our results, we recommend that anglers use two-handed support to handle Florida Largemouth Bass, thus minimizing the mean amount of time for an individual fish to regain equilibrium after an angling event.Received February 22, 2016; accepted October 7, 2016 Published online February 22, 2017

The relative abundance of the largest size-classes of individuals within a fish population has an important influence on recruitment success. Fishing regulations with a basis in size (e.g., minimum-length limits) can directly impact the abundance of these larger individuals and thus potentially influence recruitment. We analyzed whether recruitment of exploited native Brown Trout Salmo truttapopulations was affected via the extraction of large individuals (>220 mm, i.e., minimum-length limit). The study was replicated temporally (2007–2009) and spatially across seven recreational fishing sections (four exploited and three catch-and-release sections) within the River Tormes located in central Spain. Catch-and-release sections were used as reference points to compare with exploited sections. We tested the hypothesis that minimum-length limit regulations would adversely affect fish recruitment through fishing-induced mortality of large individuals. Spawning stock (measured as fish >220 mm) and young-of-the-year abundances were estimated using multiple-pass depletion methods. We modeled the relationship between spawning stock and subsequent recruitment using a nonparametric approach (generalized additive models) to fit the best stock–recruit relationship. Additionally, von Bertalanffy growth and yield-per-recruit models were generated to evaluate the potential for growth and recruitment overfishing. The restrictive length limits used to regulate harvest in the study area limited both recruitment and adult abundance. The present study provides evidence that the use of minimum-length limit regulations in the management of recreational fisheries has the potential to adversely affect the species’ recruitment. Such adverse impacts could be occurring via both recruitment overfishing and growth overfishing, exemplifying that the removal of the larger size-classes of individuals through recreational fishing could have important consequences for recruitment. Management actions should be directed to protect large individuals (e.g., via harvest slots) rather than promote their removal, thereby reducing the chances of overfishing. Received November 25, 2015; accepted April 18, 2016Published online August 24, 2016

AbstractThe relative abundance of the largest size-classes of individuals within a fish population has an important influence on recruitment success. Fishing regulations with a basis in size (e.g., minimum-length limits) can directly impact the abundance of these larger individuals and thus potentially influence recruitment. We analyzed whether recruitment of exploited native Brown Trout Salmo truttapopulations was affected via the extraction of large individuals (>220 mm, i.e., minimum-length limit). The study was replicated temporally (2007–2009) and spatially across seven recreational fishing sections (four exploited and three catch-and-release sections) within the River Tormes located in central Spain. Catch-and-release sections were used as reference points to compare with exploited sections. We tested the hypothesis that minimum-length limit regulations would adversely affect fish recruitment through fishing-induced mortality of large individuals. Spawning stock (measured as fish >220 mm) and young-of-the-year abundances were estimated using multiple-pass depletion methods. We modeled the relationship between spawning stock and subsequent recruitment using a nonparametric approach (generalized additive models) to fit the best stock–recruit relationship. Additionally, von Bertalanffy growth and yield-per-recruit models were generated to evaluate the potential for growth and recruitment overfishing. The restrictive length limits used to regulate harvest in the study area limited both recruitment and adult abundance. The present study provides evidence that the use of minimum-length limit regulations in the management of recreational fisheries has the potential to adversely affect the species’ recruitment. Such adverse impacts could be occurring via both recruitment overfishing and growth overfishing, exemplifying that the removal of the larger size-classes of individuals through recreational fishing could have important consequences for recruitment. Management actions should be directed to protect large individuals (e.g., via harvest slots) rather than promote their removal, thereby reducing the chances of overfishing.Received November 25, 2015; accepted April 18, 2016Published online August 24, 2016

Supplemental stocking of fingerling or advanced fingerling Largemouth Bass Micropterus salmoidesis a common management strategy for augmenting natural production in low-recruitment systems. Few studies, however, have evaluated the impact of stocking adult bass taken from donor lakes. Over a period of 6 years, University of Florida researchers stocked Florida Lakes Griffin and Dora with 24,781 wild Florida Bass M. s. floridanuscollected by electrofishing from other Florida lakes. During stocking years, stocked fish made up to 10% of the population in Lake Griffin and 27% in Lake Dora from electrofishing samples. However, 1 year after all stocked fish had been released, the proportion of stocked bass had declined to less than 5%, and 3 years after it had declined to less than 1%. We did not detect an increase in recruitment (catch of age-1 bass) following stocking, so any benefit from stocking was likely short-lived. We also could not conclude that stocking was responsible for increasing fishing effort because total fishing effort did not increase after stocking. As a result, no additive economic benefits could be attributed to the stocking program. During randomized electrofishing sampling, we collected 51 wild bass that had been released during the stocking program, and genetic analysis determined that two (3.9%) were hybrids and had alleles from nonnative Largemouth Bass. The extrapolation of these results estimated that almost 1,000 hybrids had been introduced into Lakes Griffin and Dora, which were historically identified to contain pure Florida Bass populations. Future wild bass stocking programs should include an appropriate study design for evaluating changes in fish populations, changes in the fishery, and economic consequences of stocking. Furthermore, a risk–benefit assessment should be completed before any stocking program is initiated, including consideration of any potential impacts on biodiversity. Received February 26, 2015; accepted January 6, 2016 Published online May 9, 2016

AbstractSupplemental stocking of fingerling or advanced fingerling Largemouth Bass Micropterus salmoidesis a common management strategy for augmenting natural production in low-recruitment systems. Few studies, however, have evaluated the impact of stocking adult bass taken from donor lakes. Over a period of 6 years, University of Florida researchers stocked Florida Lakes Griffin and Dora with 24,781 wild Florida Bass M. s. floridanuscollected by electrofishing from other Florida lakes. During stocking years, stocked fish made up to 10% of the population in Lake Griffin and 27% in Lake Dora from electrofishing samples. However, 1 year after all stocked fish had been released, the proportion of stocked bass had declined to less than 5%, and 3 years after it had declined to less than 1%. We did not detect an increase in recruitment (catch of age-1 bass) following stocking, so any benefit from stocking was likely short-lived. We also could not conclude that stocking was responsible for increasing fishing effort because total fishing effort did not increase after stocking. As a result, no additive economic benefits could be attributed to the stocking program. During randomized electrofishing sampling, we collected 51 wild bass that had been released during the stocking program, and genetic analysis determined that two (3.9%) were hybrids and had alleles from nonnative Largemouth Bass. The extrapolation of these results estimated that almost 1,000 hybrids had been introduced into Lakes Griffin and Dora, which were historically identified to contain pure Florida Bass populations. Future wild bass stocking programs should include an appropriate study design for evaluating changes in fish populations, changes in the fishery, and economic consequences of stocking. Furthermore, a risk–benefit assessment should be completed before any stocking program is initiated, including consideration of any potential impacts on biodiversity.Received February 26, 2015; accepted January 6, 2016 Published online May 9, 2016

Size-at-age information is critical in estimating growth parameters (e.g., the von Bertalanffy growth function [VBGF]) that are used to assess fish populations. Due to gear selectivity, single sampling methods rarely sample all ages or all sizes equally well. Most growth estimates rely on samples from a single gear or a haphazard combination of gears, potentially leading to biased and imprecise growth parameter estimates. We evaluated the efficacy of combining samples from two gears with different size selectivity to estimate VBGF parameters; we then applied that approach to a case study on the Lochloosa Lake (Florida) population of Black Crappies Pomoxis nigromaculatus. Simulated age- and size-structured populations were randomly sampled with two gears characterized by different size-selectivity curves (one gear was selective for smaller fish; the other was selective for larger fish). Maximum likelihood VBGF estimates obtained for each gear separately were compared with estimates from a combined VBGF fitted to data from both gears. In every simulated scenario, a combined-gear approach reduced bias and increased precision for estimating the VBGF, but the gear-specific proportions that improved VBGF estimates depended on size selectivity. The VBGF estimates for the Black Crappie population showed that the combined-gear method yielded intermediate parameter values relative to single-gear approaches based on (1) trawl sampling (fishery-independent survey) and (2) angler harvest (as determined from carcass collections; fishery-dependent data). Furthermore, the combined-gear approach had greater precision in individual parameter estimates and much less variance than single-gear approaches when estimating the VBGF. Combining data from two gears can increase sample representativeness, leading to improvements in VBGF estimation. Such approaches can reduce uncertainty in VBGF estimation and can provide insight into key demographic processes occurring in fish populations for which ontogeny and gear selectivity lead to imperfect sampling. Received January 22, 2015; accepted July 30, 2015

The Murray Cod Maccullochella peeliiand Golden Perch Macquaria ambiguaare important recreational species in Australia's Murray–Darling Basin (MDB); both species have declined substantially, but recovery is evident in some areas. Minimum length limits (MLLs)—implemented to ensure fish could spawn at least once prior to harvest eligibility—have increased three times in the past decade. We quantified variation in length at 50% maturity (LM50), age at 50% maturity (AM50), and von Bertalanffy growth parameters (k= Brody growth coefficient; L8= asymptotic length; t0= theoretical age at zero length) of these species within two rivers and two reservoirs of the MDB; to investigate whether fish length is a suitable surrogate for AM50 in setting MLLs. Between 2006 and 2013, we collected 1,118 Murray Cod and 1,742 Golden Perch by electrofishing and gillnetting. Values of kand L8were greater for reservoir fish than for riverine fish. For both species, AM50 was generally greater in rivers than in reservoirs; for Murray Cod, LM50 was greater in reservoirs than in rivers. A yield-per-recruit model demonstrated that smaller Murray Cod MLLs would be required for rivers and that an MLL at or below 600 mm (the existing MLL) across all populations could lead to overfishing in some systems. The differences in growth rate and the onset of reproductive maturation between riverine and reservoir populations suggest that system-specific regulations would be more effective at reducing the overfishing risk and meeting fishing quality objectives. Received August 18, 2014; accepted September 10, 2015

AbstractThe Murray Cod Maccullochella peeliiand Golden Perch Macquaria ambiguaare important recreational species in Australia's Murray–Darling Basin (MDB); both species have declined substantially, but recovery is evident in some areas. Minimum length limits (MLLs)—implemented to ensure fish could spawn at least once prior to harvest eligibility—have increased three times in the past decade. We quantified variation in length at 50% maturity (LM50), age at 50% maturity (AM50), and von Bertalanffy growth parameters (k= Brody growth coefficient; L∞= asymptotic length; t0= theoretical age at zero length) of these species within two rivers and two reservoirs of the MDB; to investigate whether fish length is a suitable surrogate for AM50 in setting MLLs. Between 2006 and 2013, we collected 1,118 Murray Cod and 1,742 Golden Perch by electrofishing and gillnetting. Values of kand L∞were greater for reservoir fish than for riverine fish. For both species, AM50 was generally greater in rivers than in reservoirs; for Murray Cod, LM50 was greater in reservoirs than in rivers. A yield-per-recruit model demonstrated that smaller Murray Cod MLLs would be required for rivers and that an MLL at or below 600 mm (the existing MLL) across all populations could lead to overfishing in some systems. The differences in growth rate and the onset of reproductive maturation between riverine and reservoir populations suggest that system-specific regulations would be more effective at reducing the overfishing risk and meeting fishing quality objectives.Received August 18, 2014; accepted September 10, 2015

AbstractSize-at-age information is critical in estimating growth parameters (e.g., the von Bertalanffy growth function [VBGF]) that are used to assess fish populations. Due to gear selectivity, single sampling methods rarely sample all ages or all sizes equally well. Most growth estimates rely on samples from a single gear or a haphazard combination of gears, potentially leading to biased and imprecise growth parameter estimates. We evaluated the efficacy of combining samples from two gears with different size selectivity to estimate VBGF parameters; we then applied that approach to a case study on the Lochloosa Lake (Florida) population of Black Crappies Pomoxis nigromaculatus. Simulated age- and size-structured populations were randomly sampled with two gears characterized by different size-selectivity curves (one gear was selective for smaller fish; the other was selective for larger fish). Maximum likelihood VBGF estimates obtained for each gear separately were compared with estimates from a combined VBGF fitted to data from both gears. In every simulated scenario, a combined-gear approach reduced bias and increased precision for estimating the VBGF, but the gear-specific proportions that improved VBGF estimates depended on size selectivity. The VBGF estimates for the Black Crappie population showed that the combined-gear method yielded intermediate parameter values relative to single-gear approaches based on (1) trawl sampling (fishery-independent survey) and (2) angler harvest (as determined from carcass collections; fishery-dependent data). Furthermore, the combined-gear approach had greater precision in individual parameter estimates and much less variance than single-gear approaches when estimating the VBGF. Combining data from two gears can increase sample representativeness, leading to improvements in VBGF estimation. Such approaches can reduce uncertainty in VBGF estimation and can provide insight into key demographic processes occurring in fish populations for which ontogeny and gear selectivity lead to imperfect sampling.Received January 22, 2015; accepted July 30, 2015

Species-specific harvest regulations in recreational fisheries are commonly applied regionally to protect stocks from overharvest and satisfy a diverse set of anglers. While setting regulations is a complex task and may incorporate the best available social and biological information, fisheries managers commonly obtain directed fishing mortality estimates within a single lake and then assume similar rates among other systems when setting regional harvest regulations. Thus, there is a need to assess regional levels of fishing mortality for informed use of regionally applied regulations. We implemented a practical method for assessing catch and harvest for a recreational fishery across a broad spatial region. We used a passive tag-reward study design and a regional management regulation area for Florida Largemouth Bass Micropterus salmoides floridanusin central Florida as our case study. The estimated fishing mortality rate included both harvest and deaths due to catch and release. We found overall regional fishing mortality for Florida Largemouth Bass in central Florida was relatively low. From the 247 dart tags returned, the mean annual instantaneous total fishing mortality rate was 0.11 (95% credible interval = 0.08–0.15). We also found fishing mortality rates did not vary with lake size or fish total length. Our study design did not provide mortality estimates for any specific lake due to a low number of tagged fish per lake, but the method could be used to elucidate the effectiveness of regulations that are applied at a regional scale. Received November 20, 2014; accepted March 31, 2015

Reduction in transmitter size used in telemetry studies have allowed researchers to tag and track fish that are much smaller than could have been tagged previously. Researchers seek information on juvenile or small fish movement, behavior, and survival to better understand recruitment processes. Juvenile or small-bodied fish that have been tagged have an increased risk of predation, which results in transmitters being consumed. Knowledge about radio transmitter accumulation in a predator's gut and evacuation times are critical for interpreting locations of radio-tagged fish and their predators. Our objective was to determine what factors influenced the evacuation time of transmitters (0.3 g), implanted in juvenile Largemouth Bass Micropterus salmoidesthrough the digestive system of adult Largemouth Bass that had preyed upon those tagged juveniles. All transmitters ingested by the predators were evacuated within 84 h. A Poisson regression model showed that transit time decreased significantly with temperature and increased with prey length and predator length. The results of this study suggest that miniature radio transmitters (e.g., 0.3 g) do not accumulate in the digestive tract of predators and that after consumption, up to 3 d of behavior (i.e., movement and habitat use) by the predator, movements could falsely be attributed to the juvenile fish. Therefore, if a distinction cannot be made between predator and tagged juvenile Largemouth Bass, we recommend not including information from the final 3 d before cessation of movement when analyzing the behavior of tagged fish. Received June 9, 2014; accepted January 28, 2015

AbstractSpecies-specific harvest regulations in recreational fisheries are commonly applied regionally to protect stocks from overharvest and satisfy a diverse set of anglers. While setting regulations is a complex task and may incorporate the best available social and biological information, fisheries managers commonly obtain directed fishing mortality estimates within a single lake and then assume similar rates among other systems when setting regional harvest regulations. Thus, there is a need to assess regional levels of fishing mortality for informed use of regionally applied regulations. We implemented a practical method for assessing catch and harvest for a recreational fishery across a broad spatial region. We used a passive tag-reward study design and a regional management regulation area for Florida Largemouth Bass Micropterus salmoides floridanusin central Florida as our case study. The estimated fishing mortality rate included both harvest and deaths due to catch and release. We found overall regional fishing mortality for Florida Largemouth Bass in central Florida was relatively low. From the 247 dart tags returned, the mean annual instantaneous total fishing mortality rate was 0.11 (95% credible interval = 0.08–0.15). We also found fishing mortality rates did not vary with lake size or fish total length. Our study design did not provide mortality estimates for any specific lake due to a low number of tagged fish per lake, but the method could be used to elucidate the effectiveness of regulations that are applied at a regional scale.Received November 20, 2014; accepted March 31, 2015

AbstractReduction in transmitter size used in telemetry studies have allowed researchers to tag and track fish that are much smaller than could have been tagged previously. Researchers seek information on juvenile or small fish movement, behavior, and survival to better understand recruitment processes. Juvenile or small-bodied fish that have been tagged have an increased risk of predation, which results in transmitters being consumed. Knowledge about radio transmitter accumulation in a predator's gut and evacuation times are critical for interpreting locations of radio-tagged fish and their predators. Our objective was to determine what factors influenced the evacuation time of transmitters (0.3 g), implanted in juvenile Largemouth Bass Micropterus salmoidesthrough the digestive system of adult Largemouth Bass that had preyed upon those tagged juveniles. All transmitters ingested by the predators were evacuated within 84 h. A Poisson regression model showed that transit time decreased significantly with temperature and increased with prey length and predator length. The results of this study suggest that miniature radio transmitters (e.g., 0.3 g) do not accumulate in the digestive tract of predators and that after consumption, up to 3 d of behavior (i.e., movement and habitat use) by the predator, movements could falsely be attributed to the juvenile fish. Therefore, if a distinction cannot be made between predator and tagged juvenile Largemouth Bass, we recommend not including information from the final 3 d before cessation of movement when analyzing the behavior of tagged fish.Received June 9, 2014; accepted January 28, 2015

Trophy-size fish are a critical component of recreational Largemouth Bass Micropterus salmoides floridanusfisheries; therefore, many agencies have prioritized management actions to improve catches of large fish. Length-based harvest regulations are commonly used to increase the abundance of trophy-size fish, but the rarity of large fish in sampling programs makes it difficult to use field data to evaluate the effectiveness of those regulations. We used an age-structured simulation model parameterized for a trophy Largemouth Bass fishery to evaluate the potential for a range of size limits to increase abundance and angler catches of trophy Largemouth Bass (>610 mm TL). We compiled creel information from four Florida lakes with varying harvest regulations that were known to have high-quality trophy fisheries in order to assess the performance of the model. Model results were scaled to represent trips per trophy catch for a range of size limits. The model predicted that the average number of angler trips required to catch a trophy fish were expected to decline from 83 under a 350-mm minimum length limit (e.g., baseline model that represents the standard length limit in the peninsula of Florida) to 47 for a 600-mm minimum length limit if exploitation rates were 0.2. Maximum size limits and protective slot limits also showed potential to substantially improve trophy catches. The model results and creel estimates showed similar trends for the predicted number of angler trips required to catch a trophy fish on lakes managed for trophy Largemouth Bass in Florida. Our model could be combined with fish population data to forecast the effectiveness of regulation changes on trophy fish catches. This could provide insight into trophy fisheries, where field measurements of trophy abundance and angler catches are difficult to obtain with traditional sampling programs. Received August 31, 2012; accepted January 17, 2013

Small impoundments or ponds represent important fisheries resources, both recreationally and economically. These systems are small relative to most large public reservoirs and natural lakes and thus they are more easily manipulated to improve fishing quality. The utility of some pond management techniques in improving fisheries is not well understood. We combined a telephone survey and field sampling to quantify the characteristics and use(s) of private ponds in central Alabama and determine the efficacy of the most often used pond fishery enhancement techniques. The three most common techniques were fertilization (used by 48% of surveyed pond owners), supplemental feeding with pellets (45%), and the stocking of supplemental prey for largemouth bass Micropterus salmoides(12%; the species most often stocked was threadfin shad Dorosoma petenense). We sampled 66 ponds using boat electrofishing to assess largemouth bass and Lepomisspp. population responses to these management techniques. Fish populations varied greatly within management categories. However, ponds with threadfin shad exhibited overall greater largemouth bass length, length frequency indices (PSD and PSD- P, -M), growth, body condition, and density than ponds without threadfin shad. Bluegill Lepomis macrochiruspopulation characteristics were similar among all ponds using fertilizer and threadfin shad. Of these techniques, we found that fertilization improved bluegill populations and that threadfin shad can improve largemouth bass populations without compromising bluegill size structure and abundance. Received January 26, 2012; accepted August 7, 2012

The bull trout Salvelinus confluentusis an apex predator in native fish communities in the western USA and is listed as threatened under the U.S. Endangered Species Act (ESA). Restoration of this species has raised concerns over its potential predatory impacts on native fish fauna. We held a five-person expert panel to help determine potential impacts of reintroducing bull trout into the Clackamas River, northwest Oregon, on the viability of four anadromous salmonid populations that are listed as threatened under the ESA: spring and fall Chinook salmon Oncorhynchus tshawytscha, coho salmon O. kisutch, and winter steelhead O. mykiss. The panel session was rigorously structured and used a modified Delphi process with structured expert elicitation, disclosure, discussion, and brainstorming. Each panelist distributed 100 score points among seven categories of potential bull trout impact (from no impact to very high impact) on extinction probabilities for the anadromous salmonids. Results were provided by individual panelists rather than as a group consensus and were summarized as means and variations in scores to express the panelists’ individual uncertainty, variability among the panelists, and expected differences among the affected salmonids. Score results suggested that panelists viewed the potential impact of bull trout as very low or moderately low for spring Chinook salmon, coho salmon, and winter steelhead and mostly none to very low for fall Chinook salmon. Panelists also provided 19 possible monitoring activities and 21 possible management actions for assessing potential impacts and taking remedial action if bull trout are found to have unacceptable adverse effects. Results of the panel were used by the U.S. Fish and Wildlife Service to help craft and execute a plan to reintroduce bull trout into the Clackamas River system under the ESA. This rigorous expert panel process can be used for a wide range of evaluations in situations where empirical data are sparse or ecological interactions are too complex for explicit analytic solution. Received September 5, 2011; revised December 12, 2011; accepted January 3, 2012

Gizzard shad Dorosoma cepedianumhave been the target of removal efforts in eastern North American lakes due to their omnivorous feeding, which may increase nutrient cycling and contribute to high phytoplankton abundance. We used a simulation model to evaluate the efficacy of a gizzard shad removal program at the Harris Chain of Lakes (HCL), Florida, by testing the effects of the exploitation rate, gill-net mesh size, and harvest interval on the total population biomass and spawning potential ratio (SPR). The analysis accounted for compensatory density dependence of the gizzard shad population and uncertainty in life history parameters. The reductions in gizzard shad biomass and SPR were less than 50% for the two largest mesh sizes (89 and 102 mm) at realistic annual exploitation rates of 0.6–0.8. However, the use of smaller mesh sizes (51 and 64 mm) produced biomass and SPR reductions that exceeded 75% at comparable harvest rates. Current removal efforts at the HCL, which employ a minimum gill-net mesh size of 102 mm, are unlikely to reduce gizzard shad biomass substantially. However, smaller mesh sizes could result in increased bycatch of economically important black crappies Pomoxis nigromaculatus. Our study sheds light on the importance of using simulation models to forecast the effects of removal efforts on target fish species. The results of such models can be used to inform harvest practices to achieve desired outcomes. Received May 12, 2011; accepted September 12, 2011

The golden perch Macquaria ambiguais a recreationally important freshwater sport and food fish species found throughout southeastern Australia. Stocking golden perch in impoundments has been used by fisheries managers to enhance existing wild populations for over 30 years. Despite widespread stocking, the contribution of stocked fish to golden perch populations has not been investigated. We evaluated the stocking contribution by using chemically marked golden perch fingerlings introduced into three lakes in which natural recruitment is low. We surveyed the lakes to determine the contribution of the stocked fish to the lake populations and found an overall contribution of 47 ± 9% (mean ± SE) at Reedy Lake, 55 ± 9% at Kangaroo Lake, and 90 ± 5% at Lake Charm. Our results indicate that, rather than replacing wild fish, stocked fish increased the abundance of adult fish at all three lakes. The contribution of stocked fish to each population declined with increased connectedness to the Loddon River, which served as the probable source for the wild fish population. Stocking programs can substantially augment fish populations when natural recruitment is very low.

Commercial bycatch can potentially induce high fishing mortality and represents serious concerns for the sustainability of some fisheries. We evaluated the potential population-level impacts of commercial gill-net bycatch and recreational fishing mortality on black crappie Pomoxis nigromaculatusin Lake Dora, Florida. We assessed total black crappie bycatch and the mortality rates of black crappie entangled in gill nets, quantified recreational fishing effort and harvest, and estimated exploitation for the recreational and commercial (bycatch) fisheries. We used an equilibrium age-structured population model to assess potential population-level impacts of bycatch and recreational fishing mortality. Onboard observer data of commercial fishers showed that about 17,000 and 30,000 black crappie were captured in gill nets in 2005 and 2006, respectively. Cage experiments revealed that about 30% and 47% of black crappie captured in gill nets experienced mortality after 72 h in 2005 and 2006, respectively. The recreational fishery exploitation rate was estimated to be 42% based on angler tag returns in 2006, and commercial exploitation via bycatch from commercial gill nets was 15%. The population model suggested that the level of recreational fishing mortality observed in 2006 was probably sustainable but that additional commercial or recreational exploitation would create a risk of recruitment overfishing. The greatest risk for recruitment overfishing via bycatch occurs when other sources of exploitation are also high (e.g., via a recreational fishery).

We built a simulation model to assess the performance of catch-curve residuals as an index of year-class strength for a short-lived and a long-lived fish life history type across a range of assumed values for the variation in recruitment (CVR) and fishing mortality (CVF). The magnitude of CVRstrongly influenced the utility of catch-curve residuals in assessing year-class strength. The probability of finding a significant correlation between catch-curve residuals and true recruitment values exceeded 0.9 when CVRwas greater than 0.5 for the long-lived and greater than 1.0 for the short-lived life history types. This suggests that larger recruitment values have a greater probability of being successfully “tracked” through the age structure. Conversely, the magnitude of interannual variation in fishing mortality weakly influenced the performance of catch-curve residuals. The inspection of individual catch-curve residuals relative to the known recruitment values that produced them showed considerable scatter, indicating that the utility of this metric in assessing individual year-class strength is small. Sensitivity analyses showed that the performance of catch-curve residuals improved modestly with equal sampling vulnerability across ages and decreased slightly with increased fishing mortality. Our results suggest that catch-curve residuals can serve as a rudimentary measure of recruitment under ranges of recruitment and mortality variation similar to those frequently observed in field studies.

Standardized protocols for sampling fish in lentic systems were recently established for the Florida Fish and Wildlife Conservation Commission. One of the main concerns of state biologists is that standard sampling methods could reduce the value and comparability of long-standing, fixed-transect historical data sets. Therefore, largemouth bass Micropterus salmoides were sampled by electrofishing in six lakes using both the historical and the new standard methods in spring 2006. Based on a two-way analysis of variance, the mean log-transformed catch per unit effort (CPUE) and proportional size structure of quality-size fish (PSSQ) and preferred-size fish (PSSP) did not differ significantly between the two sampling methods for any lake, when all samples were included. Based on bootstrapping analyses, which controlled for differences in sample sizes between the standard and historical methods, the variation associated with mean CPUE was generally higher for the standard method, whereas the variation associated with mean PSSPwas generally higher for the historical method. Aside from PSSQ, the sample size required to obtain adequate levels of power and detection were met only by the standard method, for which a larger number of samples were collected. Our study suggests that the point estimates (i.e., means) from the historical methods can be used in trend analyses in concert with the new standard methods but that the standard method provides for better comparisons among water bodies.

We reviewed estimates of annual exploitation (u) and total mortality (Z) for populations of largemouth bass Micropterus salmoides and used a simulation model to explore how temporal changes in u have influenced those populations. The review produced 32 estimates of u and 30 of Z spanning 51 years. Fishing mortality was roughly parabolic through time, with a mean of 0.35 for 1976–1989 and a mean of 0.18 for 1990–2003. Thus, average fishing mortality rates have declined by about one-half since about 1990. Total mortality declined with the decline in u, suggesting that changes in u caused lower overall total mortality rates. The evidence further suggests that the decline in u was caused by the voluntary release of fish by anglers rather than by changes in overall fishing effort. The simulation model showed that the decline in exploitation increased adult largemouth bass abundance but reduced the ability of size and bag regulations to improve population metrics owing to low rates of directed harvest. Discard mortality (i.e., the mortality of fish caught and released) would not negate the benefits of lower exploitation unless the mortality of fish caught and released was 0.3 or higher. Changes in angler behavior have substantially reduced fishing mortality for largemouth bass fisheries, which should be considered when developing management plans for this species and others with high rates of voluntary release.