Steven J. Cooke

Physiological and Behavioral Consequences of Long‐Term Artificial Selection for Vulnerability to Recreational Angling in a Teleost Fish

Few studies have examined the physiological and behavioral consequences of fisheries‐induced selection. We evaluated how four generations of artificial truncation selection for vulnerability to recreational angling (i.e., stocks selected for high and low vulnerability [HVF and LVF, respectively]) affected cardiovascular physiology and parental care behavior in the teleost fish largemouth bass Micropterus salmoides. Where possible, we compared artificially selected fish to control fish (CF) collected from the wild. Although, compared to control fish, resting cardiac activity was ∼18% lower for LVF and ∼20% higher for HVF, maximal values did not vary among treatments. As a result, the HVF had less cardiac scope than either LVF or CF. Recovery rates after exercise were similar for HVF and CF but slower for LVF. When engaged in parental care activities, nesting male HVF were captured more easily than male LVF. During parental care, HVF also had higher turning rates and pectoral and caudal fin beat rates, increased vigilance against predators, and higher in situ swimming speeds. Energetics simulations indicated that to achieve the same level of growth, the disparity in metabolic rates would require HVF to consume approximately 40% more food than LVF. Selection for angling vulnerability resulted in clear differences in physiological and energetic attributes. Not only is vulnerability to angling a heritable trait, but high vulnerability covaries with factors including higher metabolic rates, reduced metabolic scope, and increased parental care activity. Despite these energetically costly differences, HVF and LVF of the same age were of similar size, suggesting that heightened food consumption in HVF compensated for added costs in experimental ponds. Ultimately, angling vulnerability appears to be a complex interaction of numerous factors leading to selection for very different phenotypes. If HVF are selectively harvested from a population, the remaining fish in that population may be less effective in providing parental care, potentially reducing reproductive output. The strong angling pressure in many freshwater systems, and therefore the potential for this to occur in the wild, necessitate management approaches that recognize the potential evolutionary consequences of angling.

Injury rates, hooking efficiency and mortality potential of largemouth bass (Micropterus salmoides) captured on circle hooks and octopus hooks

Abstract We compared the injury rates, hooking efficiency, and mortality potential of circle hooks and the more conventional octopus hooks for largemouth bass (Micropterus salmoides) captured on minnows in central Illinois. Fish captured on circle hooks (N=125) were hooked less deeply, exhibited less bleeding, and were more easily removed from the hook than were those captured on octopus hooks (N=134). The majority of fish captured using both hook types were hooked in the upper lip. Mortality rates were uniformly low for both hook types (circle, 5.1%; octopus, 6.6%). Fish that were identified as potential mortalities were typically hooked deeply in a vital organ or tissue (i.e., heart, gullet, gill arch), exhibited substantial bleeding, and were difficult to remove from the hook. No size-selective trends were noted among hook types, nor were there any differences in total length among mortalities and survivors. Capture efficiency for circle hooks was half that of octopus hooks. Our results suggest that circle hooks do provide some minimal conservation benefits relative to conventional octopus hooks despite having similar mortality rates.

Life-history traits and energetic status in relation to vulnerability to angling in an experimentally selected teleost fish.

In recreational fisheries, a correlation has been established between fishing‐induced selection pressures and the metabolic traits of individual fish. This study used a population of largemouth bass (Micropterus salmoides) with lines of low vulnerability fish (LVF) and high vulnerability fish (HVF) that were previously established through artificial truncation selection experiments. The main objective was to evaluate if differential vulnerability to angling was correlated with growth, energetics and nutritional condition during the sub‐adult stage. Absolute growth rate was found to be between 9% and 17% higher for LVF compared with HVF over a 6‐month period in three experimental ponds. The gonadosomatic index in females was lower for LVF compared with HVF in one experimental pond. No significant differences in energy stores (measured using body constituent analysis) were observed between LVF and HVF. In addition, both groups were consuming the same prey items as evidenced by stomach content analysis. The inherent reasons behind differential vulnerability to angling are complex, and selection for these opposing phenotypes appears to select for differing growth rates, although the driving factors remain unclear. These traits are important from a life‐history perspective, and alterations to their frequency as a result of fishing‐induced selection could alter fish population structure. These findings further emphasize the need to incorporate evolutionary principles into fisheries management activities.

Individual Reproductive Success of Largemouth Bass and Smallmouth Bass Subjected to Different Components of Competitive Angling Events

Abstract The continued popularity of angling for largemouth bass Micropterus salmoides and smallmouth bass M. dolomieu has led to concerns about the effects it may have on fish populations, including the realized fitness of individuals. Although catch-and-release angling and its effects on nest abandonment have been well documented, very little research has examined the effect that competitive angling practices may have on nest abandonment. We subjected nest-guarding male largemouth bass in one lake and smallmouth bass in four lakes to various competitive angling practices (i.e., livewell retention, release after displacement from the nest, and a combination of these practices) and assessed subsequent nest abandonment. We also examined the importance of nest predation on the nest abandonment decisions of male bass by protecting some of the nests from predation after the angling event. Nest abandonment by largemouth bass was affected by angling treatment, the water depth at the nest site, and brood size bu...

Failure of low-velocity swimming to enhance recovery from exhaustive exercise in largemouth bass (Micropterus salmoides)

This study was intended to discover whether forcing largemouth bass (Micropterus salmoides) to swim at 0.5 body lengths/second following exercise would expedite recovery relative to fish recovered in static water. Exercise resulted in a suite of physiological disturbances for largemouth bass that included a depletion of anaerobic energy stores, an accumulation of lactate, and increased cardiac output. At 1 h following exercise, exhaustively exercised largemouth bass forced to swim exhibited expedited recovery relative to fish in static water, evidenced by lower concentrations of lactate in white muscle, elevated concentrations of phosphocreatine in white muscle, and reduced concentrations of glucose in plasma. By 4 h postexercise, largemouth bass forced to swim during recovery exhibited signs of physiological disturbance that were absent in fish recovered in static water. These signs of disturbance included a loss of osmotically active particles from plasma, elevated lactate in plasma, reductions of phospocreatine in white muscle, and increased cardiac output. These results are discussed in relation to the body of work with salmonid fishes showing physiological benefits to recovering fish in flowing water.

Cardiovascular performance of six species of field-acclimatized centrarchid sunfish during the parental care period

SUMMARY Parental care is an energetically costly period of the life history of many fish species characterized by extended high intensity activity. To date, there have been no studies that have investigated the cardiovascular correlates of extended parental care in fish. Using Doppler flow probes, the cardiovascular performance of six syntopic centrarchid fish species (N=232) that provide sole, male parental care was examined across a range of water temperatures that encompass their reproductive periods (14–26°C). Experiments were restricted to males but included both nesting and non-nesting individuals to evaluate the cardiovascular performance of fish during parental care. Resting values for cardiac output () and heart rate (fH) tended to be higher for nesting fish when adjusted for variation in temperature. Both of these cardiac variables also increased with water temperature. Stroke volume (VS) was similar among nesting and non-nesting fish and was generally thermally insensitive. When exposed to exhaustive exercise, nesting fish took longer to exhaust than non-nesting individuals. The high resting levels found in nesting fish accompanied by only minor increases in maximal values typically resulted in reductions in cardiac scope. Cardiovascular variables recovered more quickly in nesting fish, which could facilitate the high activity and bursting associated with parental care. Interspecifically, several cardiovascular variables were correlated with parental care activity. Parental care investment became more energetically expensive as the degree of cardiac frequency modulation decreased. Additionally, as the duration of parental care increased, so did the time required for fish to become exhausted, although this relationship was probably influenced by the fact that the larger species (e.g. smallmouth bass Micropterus dolomieu; largemouth bass Micropterus salmoides) provided the lengthiest care. Collectively, these data indicate that fish that provide parental care possess adaptations, including sufficient phenotypic plasticity, such that they can enhance their ability to provide high intensity protracted care, and emphasize the nexus between behavior and physiology.

Potential consequences of angling on nest-site fidelity in largemouth bass

Breeding site fidelity has evolved in many vertebrate taxa, suggesting both that site selection has an important influence on fitness potential and that the decision to reuse a nesting site is related to the individual’s prior nesting success at that location. For a species that provides parental care, such as the Largemouth Bass Micropterus salmoides, catch-and-release angling impacts individual nesting success and fitness through physiological disturbance and by removing the nest-guarding male from its brood, thereby allowing temporary access to eggs and hatchlings by brood predators. To assess the impact of catch-and-release angling on nest site fidelity, we compared the consequences of angling on individually marked (i.e., with passive integrated transponders) nest-guarding male Largemouth Bass in Ontario. An extremely high degree of nest site fidelity in year two was observed for males that were angled only once during year one (87% within 10 m of the previous year’s nest), 96.7% of which remained on the nest and completed parental care activities. There was significantly lower fidelity in year two, however, for males that were angled multiple times during year one (27% within 10m of the previous year’s nest), only 5.6% of which remained on the nest and completed parental care activities. This observed difference suggests that angling nesting bass may cause them to avoid previously used nest sites and instead search for alternative sites during future reproductive seasons. This human-induced impact on nest site choice may impact the future reproductive success of those Largemouth Bass.

Using Transdisciplinary Research Solutions to Support Governance in Inland Fisheries

The diverse nature of internal and external threats and fishery attributes in inland fisheries indicates that the development of long-term solutions to governance issues will require interaction among multiple disciplines and actors. Pollution, habitat alteration, invasive species, and hydropower development are widespread problems that are often external to threats imposed by inland fisheries, but greatly impact fishery productivity. Within inland fisheries, challenges of overfishing, equitable access, conflict, and an overall lack of political will to sustain inland fisheries at the regional, national, and international policy levels serve to pressure the sector further. Power dynamics, governance systems, and regulations play a role in determining the perspectives from which solutions to these issues are viewed, and thereby the perspectives from which they are defined as a success. Promoting transdisciplinary research in inland fisheries can support development of successful governance solutions by providing relevant insights to identify and inform these perspectives. Here, we offer examples of redefined governance problems and potential strategies for addressing them using transdisciplinary research approaches. We conclude by offering suggestions for improving transdisciplinary research in inland fisheries.