Knowledge of animal spatial ecology is essential for the design and siting of proposed aquatic protected areas (APAs), as well as the assessment and monitoring of existing ones. Acoustic telemetry is one of the primary tools for the assessment of animal movements in aquatic systems through either manual tracking or the establishment of fixed receiving stations. Recent technological developments in code division multiple access (CDMA) acoustic telemetry now enable the simultaneous real-time monitoring of numerous individual fish at fine time scales providing APA researchers with a robust new tool. Fish can be positioned in three-dimensions with sub-meter accuracy in both deep and shallow waters. Here, we describe a whole-lake environmental observatory that includes a 13-hydrophone acoustic telemetry array that has been used to monitor the position of 22 tagged fish at 15 sec intervals. Although we use a freshwater fish and environment as a case study, this telemetry system is equally useful for marine environments including under-ice. We evaluate the applicability of CDMA MAP technology to address pressing questions in applied APA research. The CDMA MAP system provides the flexibility to collect information at multiple spatial-temporal scales, responding to the varied levels of detail and precision required for different applications in APA research. When combined with the suite of other telemetry and monitoring approaches available, CDMA MAP technology will enable researchers to document the spatial ecology essential for improving APA science. Furthermore, because numerous animals from different trophic levels can be tracked in real time, CDMA MAP technology will also aid in our understanding of complex community-level dynamics consistent with the shift towards ecosystem-based APA management.
Species of armoured catfishes differ significantly in their cellular DNA content and chromosome number. Starch gel electrophoresis of isozymes was used to determine whether each of 16 enzyme loci was expressed in a single or duplicate state. The percent of enzyme loci exhibiting duplicate locus expression in Corydoras aeneus, Corydoras julii, Corydoras melanistius, and Corydoras myersi was 37.5 percent, 18.75 percent, 12.5 percent, and 6.25 percent, respectively. The percentage of loci expressed in duplicate is higher in the species with higher haploid DNA contents, which are 4.4 pg, 3.0 pg, and 2.3 pg, respectively. These differences in DNA contents are also associated with differences in chromosome number. These data are consistent with the hypothesis that increases in DNA contents and enzyme loci occur both by tetraploidization and by regional gene duplication and that these increases are then followed by a partial loss of DNA and a reduction in the number of the duplicate isozyme loci expressed. Such analyses provide insight into the mechanisms of genome amplification and reduction as well as insights into the fats of duplicate genes.
Physiologically, oxidative stress is considered a homeostatic imbalance between reactive oxygen species production and absorption. From an ecological perspective, oxidative stress may serve as an important constraint to life history traits such as lifespan, reproduction, and the immune system, and is gaining interest as a potential mechanism underlying life history trade-offs. Of late, there has been much interest in understanding the role of oxidative stress in the ecology of wild animals, particularly during challenging periods such as reproduction. Here, we used a long-term study population of a fish with sole-male parental care, the smallmouth bass, Micropterus dolomieu, to examine the associations among oxidative stress indicators and life history variables in nest-guarding males. In addition, we investigated the potential role of oxidative stress as a physiological mediator of the life history trade-off decision of paternal smallmouth bass to stay with or abandon their brood. We found that oxidative stress was significantly related to the life history of paternal smallmouth bass, such that older, larger fish with greater reproductive experience and larger broods nesting in cooler water temperatures had lower levels of oxidative stress. However, we found no significant correlation between oxidative stress and nesting success, suggesting that oxidative stress may not be involved in the decision of male smallmouth bass to abandon their brood. Wild fish have been relatively understudied in the emerging field of oxidative ecology, and the study presented here makes noteworthy contributions by revealing interesting connections between the life histories of paternal smallmouth bass and their oxidative status.
Abstract We evaluated the reproductive contribution of stocked Largemouth Bass Micropterus salmoides relative to resident populations. The reproductive contribution of stocked fish was determined using the MDH‐B2* allele as a genetic tag for fingerlings stocked into five study lakes. We first determined the relative survival of stocked fish by calculating the proportion of adults (which were clipped at stocking) in the population and compared it with initial survival the first fall after stocking. Stocked fish relative survival to adulthood varied among the five study lakes and was lower than initial survival after stocking. Once these stocked fish were mature, it was possible to assess their reproductive contribution to each population by comparing the prestocking frequencies of the MDH‐B2* allele with poststocking frequencies. Reproductive contribution of stocked fish was high in small lakes but relatively low in larger ones. Neither adult Largemouth Bass density nor prey density affected reproductive contribution of stocked fish. Based on the proportion of stocked adults in the populations, reproductive contribution of stocked fish was similar to that of wild fish. Our results indicate that reproductive contribution of stocked fish will depend on survival of stocked fish to maturity. The influence of stocked fish will likely persist in successive generations, and potential genetic effects on wild populations of Largemouth Bass should be taken into account when making stocking decisions.
Abstract This paper summarises recent peer‐reviewed literature addressing the effects of catch‐and‐release angling on black bass, Micropterus spp., to facilitate management and conservation of these fish. Traditionally, the effects of catch and release have been evaluated by measuring mortality. Many recent studies have measured sublethal effects on physiology and behaviour. There is also greater emphasis on adding more realism to sublethal catch‐and‐release experiments through angler involvement in research activities and by conducting studies in the field rather than in laboratory environments. Owing to these advances, there have been a number of recent findings, which are summarised here, related to air exposure, gear (e.g. circle hooks) and the weigh‐in procedure that are particularly relevant to black bass anglers, tournament organisers and fishery managers. Additional research is particularly needed for: (1) population‐level effects of angling for nesting fish; (2) population‐level effects of tournament‐associated mortality; (3) effectiveness of livewell additives for enhancing survival; (4) consequences of fish displacement in competitive events; (5) effects of weigh‐in procedures and other organisational issues on fish condition and survival; and (6) reducing barotrauma.
Annual recruitment in fish is undoubtedly impacted by a vast number of biotic and abiotic factors. That is especially the case for fish species such as the black bass (species in the genus Micropterus), where there is extended parental care. Although much focus has been given in the past on determining the roles that many of these factors (e.g., temperatures, wind, flow rates, and habitat change) play in determining recruitment among the back basses, little attention has been given to assessing what role reproductive success plays in that determination. To address this question, we conducted a long-term study on two adjacent smallmouth bass (SMB) Micropterus dolomieu Lacepède, 1802 populations in eastern ON to assess the relationship between annual fry cohort size (FCS) (i.e., population-wide reproductive success) and annual recruitment. To measure population-wide annual FCS, we used snorkel surveys to conduct a complete census of nesting SMB males during the spawn from 1990 to 2015. During those surveys, we quantified mating success, determined which nests were successful or not, and calculated the number of independent fry produced each year by summing those numbers across all successful nests. Summer snorkel surveys from 1991 to 2016 assessed annual recruitment through visual counts of age 1+ juveniles. Results demonstrated a highly significant, positive, linear relationship between annual FCS and annual recruitment.
Abstract The status of freshwater fishes continues to decline despite substantial conservation efforts to reverse this trend and recover threatened and endangered aquatic species. Lack of success is partially due to working at smaller spatial scales and focusing on habitats and species that are already degraded. Protecting entire watersheds and aquatic communities, which we term “native fish conservation areas” (NFCAs), would complement existing conservation efforts by protecting intact aquatic communities while allowing compatible uses. Four critical elements need to be met within a NFCA: (1) maintain processes that create habitat complexity, diversity, and connectivity; (2) nurture all of the life history stages of the fishes being protected; (3) include a long‐term enough watershed to provide long‐term persistence of native fish populations; and (4) provide management that is sustainable over time. We describe how a network of protected watersheds could be created that would anchor aquatic conservation needs in river basins across the country.
Abstract Hook 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.
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